Posted: 1/9/2015 3:22:32 PM EDT
Mark has graciously agreed to allow a permanent hand-loading thread dedicated to the pursuit of accuracy using LaRue's weapon systems. 
Be SAFE!!! Feel free to contribute any information you choose; however, with technical data more information is usually better.  Also, it probably goes without saying, but PICs, or it didn't happen. 
Suggested information:
Also, please include the following:
If you choose to include any additional information such as the range, location, distance, weather/atmospherics, case preparation, etc. please feel free. The goal here is to leverage all of our collective experiences to improve our own information sets, and to have fun. |
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Please make this happen. It would also be nice for people to state if their barrel is one of the original LW50 barrels or one of the LaRue MG barrels.
I've got quite a bit of load work up planned for my tOBR, and it would be awesome if there was a central repository for reference loads. -ZA |
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Being new to reloading, I have been meticulous about everything. I have purposely used only one powder for my .308. It was several weeks before I finally loaded my first rounds. I cleaned and prepped a ton of brass. I read through several reloading manuals. I watched videos. And, I read about the horror stories like the one in Mark's link. You would have thought I was handling "nitro glycerin" the first time I measured the powder and finished the first batch. (Still that way) That sounds silly, even after my limited experience. But, I hope that I never become complacent with reloading. It is easy to understand why several people advised me to start with a single stage setup. Probably will stay with that, too. My first attempt at reloading was a great success, by the way. And, I thoroughly enjoy the time reloading. I will eventually be able to step out of my barn/shop/man cave and test a batch of reloads. I look forward to coming here to learn what other LT shooters have success with. |
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Being new to reloading, I have been meticulous about everything. <snip> Quoted:
Being new to reloading, I have been meticulous about everything. <snip> That's a good way to be. It's better to go achingly slow than to lose a couple fingers, or an eye, or worse... |
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I read a similar article where the shooter loaded his 338 LM with H110 instead of H1000. The scope saved his bacon when the action exploded. Separate those powders, don't drink and reload, take your time, start low and work your way up, and double-check your work. |
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This was my first five shots with the following load: 44.5 gr IMR 4064 150 gr Nosler Ballistic Tip Federal Brass Federal 210 primer OAL 2.75 7.62 PredatAR 16" barrel suppressed https://farm9.staticflickr.com/8652/15792945636_64116647e9_z.jpg Zeroed at 200 yards and I was good to go for hunting.  Was this one of LaRue's in house MG barrels or one of the old ones? ZA |
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Rifle: LaRue Tactical OBR 7.62 16"
Scope: Bushnell Elite Tactical 6-24x50 FFP G2DMR Cartridge: Bullet: 155 grain Palma HPBT Sierra Match King Brass: Lapua .308 Primer: CCI #200 Large Rifle Powder: IMR XBR 8208 42.6 grain OAL: 2.775" 3-Round Group Result: .316 MOA 
ETA: I'm off to post in "Outshoot the Shootist"
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Nice shooting Hollywood and Mickey80! Thanks, it gets significantly easier with proper ammo ETA: If I can get in some range time this week, I'm going to go for 1 MOA ALL DAY |
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Here are some of my favorite loads:
Varmint Load: Bullet: Nosler 60gr VMax Brass: WW Powder: 25.8 gr Varget Primer: CCI 400 COAL: 2.260 Velocity: 3,085 out of 18" Barrel ES: ?? This has been a solid load for multiple squirrel guns including my Stealth. Accuracy Loads: Bullet: Berger 77 gr Tactical OTM Brass: WW 1x Powder: 22.5 gr Varget Primer: Rem 7 1/2 COAL: 2.260 ES: ?? Velocity: 2,600 Here is the target shot with my 16" Tobr 
Bullet: Sierra 77 gr MK Brass: WW 1x Powder: 23.7 gr Varget Primer: CCI 400 COAL: 2.260 ES: ?? Velocity: 2,695 This load ran @ .7-.8 in the Tobr I have the new TMK's on order and will add those when I get a chance. Hunting: Bullet: Barnes 70 gr TSX Brass: WW 1x Powder: 24.5 gr Varget Primer: CCI 400 COAL: 2.260 ES: Not great but still came in very accurate. Needs more testing. Velocity: 2,682 This load ran @ .5-.8 in the Tobr. This load is sub MOA out to 300, as far as I have tested it... Kiled 2 deer this season with this load: 
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Alright…these Match barrels are ridicules
Finally received my 16" 7.62 OBR back…now with its Match Grade barrel. The Field Grade barrel was a great shooter, but this match grade is on a different level. I simply can't stop thinking about how amazing they performed today…group after group, these barrels shot lights out! We ran 3 and 5 shot groups with various hand loads, nothing over 1 MOA…NOTHING! Normally i'll have a few screwed up groups that dig into my averages for that day. But today was flawless! Today's average: .492, both 7.62 & 5.56…with a pretty good left to right wind!
Here are a couple loads that we shot today… 14.5" 5.56 PredatOBR *69 gr - Sierra Match King .223 HPBT *Hornady Brass 8605 - New, but still prepped *23 gr - IMR 4064 *CCI BR4 *COL: 2.235 *2,750 fps Here is one of the better 5-shot groups…YES, 5 shots! 
16" 7.62 OBR (King of the Hill) *168 gr - Sierra Match King .308 HPBT *Federal Brass FC - Once Shot, complete prep *42 gr - Hodgdon Varget *CCI Large 200 *COL: 2.800 Here is a pretty little 3-shot ragged hole…less than 1/4 MOA! 
Such a wonderful day of shooting… 
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So, a few questions that I haven't been able to find answers for through my research. Just finished checking chamber measurements on my tOBR 7.62 to get an idea on the variables and dynamics of bullet seating for this rifle. Before this goes too far, to start with, I will be loading to "standard" magazine length if there is such a thing.
But here is where my curiosity starts wandering. Seating the bullet touching the lands yields an approximate OAL of 2.906. I will not be loading rounds singularly into the chamber by hand, so I understand that is not the route to take, lol. However, I also measured the distance allowed by the LT manufactured magazine which came to 2.869. Now I would guess that loading to that exact length would have the bullet and case rubbing the insides of the magazine, but what about slightly under that. Say more like 2.84" That would almost cut the jump to lands in half, compared to the more conventional magazine length of 2.8", from .1" to .062" When reading that a lot of people seat to something like .002 off the lands in BA rifles, .04 seems like a significant #. I do realize this is an autoloading rifle, and I am aware of possible feeding problems and safety issues which is why I am raising the question. How far do you guys seat for your OBR/tOBR 7.62's? I raise this question as a relative noob to reloading who does not want to hurt myself, or AMERC my rifle into oblivion. I've done a great deal of homework, and I know that the rounds would be g2g once in battery, mostly curious about getting them there. Has anyone else tried to max out the OAL capacity of the LT magazines, and if so what length did you settle on. As stated above, my first work OCW workup will be at the more standard 2.8" mag length, for a baseline if nothing else. |
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So, a few questions that I haven't been able to find answers for through my research. Just finished checking chamber measurements on my tOBR 7.62 to get an idea on the variables and dynamics of bullet seating for this rifle. Before this goes too far, to start with, I will be loading to "standard" magazine length if there is such a thing. But here is where my curiosity starts wandering. Seating the bullet touching the lands yields an approximate OAL of 2.906. I will not be loading rounds singularly into the chamber by hand, so I understand that is not the route to take, lol. However, I also measured the distance allowed by the LT manufactured magazine which came to 2.869. Now I would guess that loading to that exact length would have the bullet and case rubbing the insides of the magazine, but what about slightly under that. Say more like 2.84" That would almost cut the jump to lands in half, compared to the more conventional magazine length of 2.8", from .1" to .062" When reading that a lot of people seat to something like .002 off the lands in BA rifles, .04 seems like a significant #. I do realize this is an autoloading rifle, and I am aware of possible feeding problems and safety issues which is why I am raising the question. How far do you guys seat for your OBR/tOBR 7.62's? I raise this question as a relative noob to reloading who does not want to hurt myself, or AMERC my rifle into oblivion. I've done a great deal of homework, and I know that the rounds would be g2g once in battery, mostly curious about getting them there. Has anyone else tried to max out the OAL capacity of the LT magazines, and if so what length did you settle on. As stated above, my first work OCW workup will be at the more standard 2.8" mag length, for a baseline if nothing else. 2.775" .....but I'm using Pmag GenIII 10-rounders, if that makes a difference ETA: And at that OAL, they just miss touching the inside of the mag |
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Quoted: So, a few questions that I haven't been able to find answers for through my research. Just finished checking chamber measurements on my tOBR 7.62 to get an idea on the variables and dynamics of bullet seating for this rifle. Before this goes too far, to start with, I will be loading to "standard" magazine length if there is such a thing. But here is where my curiosity starts wandering. Seating the bullet touching the lands yields an approximate OAL of 2.906. I will not be loading rounds singularly into the chamber by hand, so I understand that is not the route to take, lol. However, I also measured the distance allowed by the LT manufactured magazine which came to 2.869. Now I would guess that loading to that exact length would have the bullet and case rubbing the insides of the magazine, but what about slightly under that. Say more like 2.84" That would almost cut the jump to lands in half, compared to the more conventional magazine length of 2.8", from .1" to .062" When reading that a lot of people seat to something like .002 off the lands in BA rifles, .04 seems like a significant #. I do realize this is an autoloading rifle, and I am aware of possible feeding problems and safety issues which is why I am raising the question. How far do you guys seat for your OBR/tOBR 7.62's? I raise this question as a relative noob to reloading who does not want to hurt myself, or AMERC my rifle into oblivion. I've done a great deal of homework, and I know that the rounds would be g2g once in battery, mostly curious about getting them there. Has anyone else tried to max out the OAL capacity of the LT magazines, and if so what length did you settle on. As stated above, my first work OCW workup will be at the more standard 2.8" mag length, for a baseline if nothing else. It is always fun and interesting to experiment with load variations and the effects on accuracy. You won't get into trouble seating bullets to the Larue mag max OAL. The best learning tool is to load some ammunition to this length and compare it side by side with identical loaded ammunition seated to 2.800 and go from there. It is likely you will not find a difference in accuracy, at least that has been my experience in my Larue 762s. Hopefully this helps answer your question, it's late and I feel like my post is not as clear as I would like but .....its ....late  |
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Personally I load the ammunition in all of my Larue 762s to 2.805. 2.805 allows P mags to be used if needed. I also use Larue magazines that allow the longer OAL. I have not found this roughly .040 difference in OAL to affect accuracy noticeably. In autoloaders a person can cause problems for themselves with a short jump. It is true that .040 can make a huge difference in accuracy in some rifles (technically it is longer jump than your measurements show from Ogive to lands) but I have not found this in my Larues. This can be attributed to many variables from a forgiving throat design..IE leade angle, on top of the 762 being a forgiving cartridge to begin with. As you have found in your research what is safe and SOP in bolt guns sometimes does not apply to autoloaders. Try to use bullets with a forgiving Tangent or Hybrid ogive, like Sierra MK or Berger Hybrids. These shapes are forgiving and far less sensitive to seating depth. Secant ogive or VLD style bullets will give you fits save those for your bolt guns. It is always fun and interesting to experiment with load variations and the effects on accuracy. You won't get into trouble seating bullets to the Larue mag max OAL. The best learning tool is to load some ammunition to this length and compare it side by side with identical loaded ammunition seated to 2.800 and go from there. It is likely you will not find a difference in accuracy, at least that has been my experience in my Larue 762s. Hopefully this helps answer your question, it's late and I feel like my post is not as clear as I would like but .....its ....late
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So, a few questions that I haven't been able to find answers for through my research. Just finished checking chamber measurements on my tOBR 7.62 to get an idea on the variables and dynamics of bullet seating for this rifle. Before this goes too far, to start with, I will be loading to "standard" magazine length if there is such a thing. But here is where my curiosity starts wandering. Seating the bullet touching the lands yields an approximate OAL of 2.906. I will not be loading rounds singularly into the chamber by hand, so I understand that is not the route to take, lol. However, I also measured the distance allowed by the LT manufactured magazine which came to 2.869. Now I would guess that loading to that exact length would have the bullet and case rubbing the insides of the magazine, but what about slightly under that. Say more like 2.84" That would almost cut the jump to lands in half, compared to the more conventional magazine length of 2.8", from .1" to .062" When reading that a lot of people seat to something like .002 off the lands in BA rifles, .04 seems like a significant #. I do realize this is an autoloading rifle, and I am aware of possible feeding problems and safety issues which is why I am raising the question. How far do you guys seat for your OBR/tOBR 7.62's? I raise this question as a relative noob to reloading who does not want to hurt myself, or AMERC my rifle into oblivion. I've done a great deal of homework, and I know that the rounds would be g2g once in battery, mostly curious about getting them there. Has anyone else tried to max out the OAL capacity of the LT magazines, and if so what length did you settle on. As stated above, my first work OCW workup will be at the more standard 2.8" mag length, for a baseline if nothing else. It is always fun and interesting to experiment with load variations and the effects on accuracy. You won't get into trouble seating bullets to the Larue mag max OAL. The best learning tool is to load some ammunition to this length and compare it side by side with identical loaded ammunition seated to 2.800 and go from there. It is likely you will not find a difference in accuracy, at least that has been my experience in my Larue 762s. Hopefully this helps answer your question, it's late and I feel like my post is not as clear as I would like but .....its ....late
Thanks guys. I am in fact working with Berger Hybrids . Looks like what you guys have experienced lines up with what i was expecting. I should have all of my OCW test rounds loaded up tonight and hopefully life will let me get out to the range next week.
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Thanks guys. I am in fact working with Berger Hybrids . Looks like what you guys have experienced lines up with what i was expecting. I should have all of my OCW test rounds loaded up tonight and hopefully life will let me get out to the range next week.Quoted:
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<SNIP> Thanks guys. I am in fact working with Berger Hybrids . Looks like what you guys have experienced lines up with what i was expecting. I should have all of my OCW test rounds loaded up tonight and hopefully life will let me get out to the range next week.Which weight are you using? I've tried for over a month to find Match Hybrids in the 168 or 175 grains range, but I haven't been able to. As a matter of fact, I don't even see anything like that on the Berger web site. Are you going lighter or even heavier? Full disclosure, I'm just now starting to reload  , so I really have no idea what's out there. I have read SO's previous posts though (lots of great info in those), so that's what I based my original search on.
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Which weight are you using? I've tried for over a month to find Match Hybrids in the 168 or 175 grains range, but I haven't been able to. As a matter of fact, I don't even see anything like that on the Berger web site. Are you going lighter or even heavier? Full disclosure, I'm just now starting to reload , so I really have no idea what's out there. I have read SO's previous posts though (lots of great info in those), so that's what I based my original search on.Quoted:
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<SNIP> Thanks guys. I am in fact working with Berger Hybrids . Looks like what you guys have experienced lines up with what i was expecting. I should have all of my OCW test rounds loaded up tonight and hopefully life will let me get out to the range next week.Which weight are you using? I've tried for over a month to find Match Hybrids in the 168 or 175 grains range, but I haven't been able to. As a matter of fact, I don't even see anything like that on the Berger web site. Are you going lighter or even heavier? Full disclosure, I'm just now starting to reload , so I really have no idea what's out there. I have read SO's previous posts though (lots of great info in those), so that's what I based my original search on.168 gr Classic Hunter Hybrid for now. Most of what I plan on for my rifle is hunting within 600 yards, with the occasional elk hunt out west. This round, once I get it worked up should suit my immediate needs just fine. Have you tried Gunstop.com? They usually have a good selection of just about anything you are looking for so long as it isn't powder or primers. In store pick up only on those items. Decent prices and good people to work with also. ETA: they currently have 175gr OTM's in stock |
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Which weight are you using? I've tried for over a month to find Match Hybrids in the 168 or 175 grains range, but I haven't been able to. As a matter of fact, I don't even see anything like that on the Berger web site. Are you going lighter or even heavier? Full disclosure, I'm just now starting to reload , so I really have no idea what's out there. I have read SO's previous posts though (lots of great info in those), so that's what I based my original search on.Quoted:
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<SNIP> Thanks guys. I am in fact working with Berger Hybrids . Looks like what you guys have experienced lines up with what i was expecting. I should have all of my OCW test rounds loaded up tonight and hopefully life will let me get out to the range next week.Which weight are you using? I've tried for over a month to find Match Hybrids in the 168 or 175 grains range, but I haven't been able to. As a matter of fact, I don't even see anything like that on the Berger web site. Are you going lighter or even heavier? Full disclosure, I'm just now starting to reload , so I really have no idea what's out there. I have read SO's previous posts though (lots of great info in those), so that's what I based my original search on.You would be very surprised with the accuracy you get just by replicating your favorite, off the shelf round. Just be consistent & precise with your brass prepping and powder loading, and your groups will shrivel right up with these LaRue rifles...
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4 shot group I made yesterday. Still working on different loads but this looks promising. I only fired the 4 rounds because the wind was a bitch. Scope is a NF 3x15 with the velocity reticule and SF Socom can. http://i57.tinypic.com/vwx53m.jpg 
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Hey guys...
Need an opinion from the guys that reload for 7.62 Larue rifles. I just got a new 16" tOBR and want to make up a few loads to mimic 175 FGMM or some other accurate 175 grn factory load for my first time at the range with this rifle. I have 168 grn FGMM and some 149 grn M80 that I'm going to use for break in, scope zero and initial "getting comfortable with it" shooting. I need to shoot about 20 or so initial reloads using my match prepped LCLR brass I have so I can set my dies to bump the shoulder back .004" back on this brass out of my tOBR's chamber. Right now, I've resized about 50 of the LCLR and prepped it, chambered it, measured it, but I want to use fire formed brass for my final setup on my Redding dies. Based on how they chamber and looking at my case gauge, I'd say I'm currently over doing it on the resizing. Anyway.... I have the following supplies... give me some suggestions on 175/178 grain accuracy loads to check out for this trial using the LCLR brass. Bullets: 175 SMK 178 Hornady HPBT 175 AMAX Primers: CCI BR4 Fed 201M Powders: IMR-4166 IMR-4064 Varget XBR TAC Once I shoot some of these reloads, the 168 FGMM, and the M80, I'll have a pretty good baseline of once fired brass out of this rifle to take exact headspace measurements, set my resizing die and start some OCW workups. Thanks. -ZA |
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After measuring my once fired cases I found that by only resizing and bumping the shoulder back .004 that that was not enough. Most cases will continue to stretch while extracting from the chamber during firing. I used the Hornaday headspace gauge to confirm this. After I set them back the .004 I rechambered them and found that they actually were set back farther due to the bolt slamming the brass into the chamber. I didn't want the bolt to resize my brass so I continued to resize to a point that when I chambered a dummy round there was no difference in headspace.
See my post above for my load and measurements |
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After measuring my once fired cases I found that by only resizing and bumping the shoulder back .004 that that was not enough. Most cases will continue to stretch while extracting from the chamber during firing. I used the Hornaday headspace gauge to confirm this. After I set them back the .004 I rechambered them and found that they actually were set back farther due to the bolt slamming the brass into the chamber. I didn't want the bolt to resize my brass so I continued to resize to a point that when I chambered a dummy round there was no difference in headspace. See my post above for my load and measurements Have you shot that load in LC or LCLR brass? -ZA |
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Rifle: 16" PredatAR 7.62 w/ SureFire Pro Comp MB
Scope: Vortex 2.5-10x42 w/ LaRue mount Ammo: FGMM 175, 2.226" Base-to-Ogive (average) mv: 2414 avg sd: 41 es: 150... ugh! 2310 to 2460, see explanation below. Take out the high and the low, and it becomes 45. **The Chronograph used was a Shooting Chrony F1. It has since been proven to have inaccurate results** (I'll update the velocity info when I get home tonight, I have it written down there.) Interesting thing to note is that the ES was specifically caused by cases that were specifically at the trim-to length of 2.005". The rest of the cases were at 2.012"-2.015". All cases were measure after firing and depriming. If I take the high and low velocities out the SD shrinks to 17, with an ES of 45. The shorter cases showed a slight ejector swipe, but no other overpressure signs. The accuracy was not noted as much, as I was getting a baseline of MV so I can duplicate the load. I now use Nosler Custom Comp 175s as they are dirt cheap for me (18 cents per), and they seem to be shooting accurate enough (see my last post for the picture). The ogive is set a little farther back, so a similar OAL causes a base-to-ogive of 2.222". Loading them out to the same base-to-ogive as the FGMM will still fit in a PMAG, but the resulting extra space in the case can cause a little bit different pressure, so I'll play with that a bit to see if there's a good and happy medium between the base-to-ogive, OAL, and casecapacity fluctuations. Also noted is that the FGMM brass is VERY hard. I would recommend annealing FGMM once-fired before trying to reuse it. This also means that the neck tension will be different than the factory FGMM. I'll measure some factory loaded and some once-fired to see how big of a difference there is between the two. Apparently, loading for extreme accuracy is a bit more involved than jsut cramming a case into a loader, then stuffing teh components in there. Not that my LaRue knows the difference..... it all shoots the same. updated with MV info. |
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OK, so here's what a 175 FGMM looks like:
Product number: GM308M2 Lot: U37M273 These are the average over 40 rounds of the same lot. base-to-ogive: 2.226" neck diameter (factory loaded: 0.339" Neck thickness (once fired): 0.015" OAL: 2.801" With the standard of 59*F and 29.92 inHg, this load gives a 1.82 in teh Miller Stability formula. Normal folks say that anything over 1.0 is good. Realists know that at LEAST 1.5 is the way of the future. With those same environmentals, my Ballistics AE machine says that the load will stay supersonic until 880 yards. For all you hunters, using a 7" vital zone radius (normal deer heart + lungs, right?) the Max Point Blank is out at 234 yards. Using the same program, that hits at 2030 fps with 1598 lb.ft of energy. Yeah, it'll put a hurting on a critter. NECK TENSION!!!!! If I want to figure out the perfect neck tension, here's how I do it: [(width of neck wall x 2) + diameter of bullet] - 0.002" = 'proper' neck tension Here's what the loaded FGMM shows us: [0.339 - 0.308 - (2 x 0.015)] = 0.001" left of neck tension. That means that if we want to duplicate that neck tension we need to get ourselves a bushing/bump die and get ourselves the right die to put THAT neck tension on there. Normal folks don't really care about this, but I'm not afraid of going semi-full retard about the loading. And Mark told me that this wasn't a bench gun..... well, that's not going to stop me from trying!! |
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OK, so here's what a 175 FGMM looks like: Product number: GM308M2 Lot: U37M273 These are the average over 40 rounds of the same lot. base-to-ogive: 2.226" neck diameter (factory loaded: 0.339" Neck thickness (once fired): 0.015" OAL: 2.801" With the standard of 59*F and 29.92 inHg, this load gives a 1.82 in teh Miller Stability formula. Normal folks say that anything over 1.0 is good. Realists know that at LEAST 1.5 is the way of the future. With those same environmentals, my Ballistics AE machine says that the load will stay supersonic until 880 yards. For all you hunters, using a 7" vital zone radius (normal deer heart + lungs, right?) the Max Point Blank is out at 234 yards. Using the same program, that hits at 2030 fps with 1598 lb.ft of energy. Yeah, it'll put a hurting on a critter. NECK TENSION!!!!! If I want to figure out the perfect neck tension, here's how I do it: [(width of neck wall x 2) + diameter of bullet] - 0.002" = 'proper' neck tension Here's what the loaded FGMM shows us: [0.339 - 0.308 - (2 x 0.015)] = 0.001" left of neck tension. That means that if we want to duplicate that neck tension we need to get ourselves a bushing/bump die and get ourselves the right die to put THAT neck tension on there. Normal folks don't really care about this, but I'm not afraid of going semi-full retard about the loading. And Mark told me that this wasn't a bench gun..... well, that's not going to stop me from trying!! Say what now? Are you going to make me google that? |
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Say what now? Are you going to make me google that? Quoted:
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OK, so here's what a 175 FGMM looks like: Product number: GM308M2 Lot: U37M273 These are the average over 40 rounds of the same lot. base-to-ogive: 2.226" neck diameter (factory loaded: 0.339" Neck thickness (once fired): 0.015" OAL: 2.801" With the standard of 59*F and 29.92 inHg, this load gives a 1.82 in teh Miller Stability formula. Normal folks say that anything over 1.0 is good. Realists know that at LEAST 1.5 is the way of the future. With those same environmentals, my Ballistics AE machine says that the load will stay supersonic until 880 yards. For all you hunters, using a 7" vital zone radius (normal deer heart + lungs, right?) the Max Point Blank is out at 234 yards. Using the same program, that hits at 2030 fps with 1598 lb.ft of energy. Yeah, it'll put a hurting on a critter. NECK TENSION!!!!! If I want to figure out the perfect neck tension, here's how I do it: [(width of neck wall x 2) + diameter of bullet] - 0.002" = 'proper' neck tension Here's what the loaded FGMM shows us: [0.339 - 0.308 - (2 x 0.015)] = 0.001" left of neck tension. That means that if we want to duplicate that neck tension we need to get ourselves a bushing/bump die and get ourselves the right die to put THAT neck tension on there. Normal folks don't really care about this, but I'm not afraid of going semi-full retard about the loading. And Mark told me that this wasn't a bench gun..... well, that's not going to stop me from trying!! Say what now? Are you going to make me google that? It's a formula that uses the length of the actual bullet, the weight of the bullet, the twist of the barrel, and the MV and it spits out a number that can (relatively accurately) determine whether you've got enough twist in the barrel. We all hear that to shoot a 77 gr .223 bullet, you need a 1/7 twist.... Well, you can use the miller stability formula and determine that if you push the right bullet fast enough, then you can use a 1/8 twist. Again, anything over 1.0 is 'technically' stable, but in practice y'all better keep it above 1.5..... Here's a link to an online calculator: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi |
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It's a formula that uses the length of the actual bullet, the weight of the bullet, the twist of the barrel, and the MV and it spits out a number that can (relatively accurately) determine whether you've got enough twist in the barrel. We all hear that to shoot a 77 gr .223 bullet, you need a 1/7 twist.... Well, you can use the miller stability formula and determine that if you push the right bullet fast enough, then you can use a 1/8 twist. Again, anything over 1.0 is 'technically' stable, but in practice y'all better keep it above 1.5..... Here's a link to an online calculator: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi Quoted:
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OK, so here's what a 175 FGMM looks like: Product number: GM308M2 Lot: U37M273 These are the average over 40 rounds of the same lot. base-to-ogive: 2.226" neck diameter (factory loaded: 0.339" Neck thickness (once fired): 0.015" OAL: 2.801" With the standard of 59*F and 29.92 inHg, this load gives a 1.82 in teh Miller Stability formula. Normal folks say that anything over 1.0 is good. Realists know that at LEAST 1.5 is the way of the future. With those same environmentals, my Ballistics AE machine says that the load will stay supersonic until 880 yards. For all you hunters, using a 7" vital zone radius (normal deer heart + lungs, right?) the Max Point Blank is out at 234 yards. Using the same program, that hits at 2030 fps with 1598 lb.ft of energy. Yeah, it'll put a hurting on a critter. NECK TENSION!!!!! If I want to figure out the perfect neck tension, here's how I do it: [(width of neck wall x 2) + diameter of bullet] - 0.002" = 'proper' neck tension Here's what the loaded FGMM shows us: [0.339 - 0.308 - (2 x 0.015)] = 0.001" left of neck tension. That means that if we want to duplicate that neck tension we need to get ourselves a bushing/bump die and get ourselves the right die to put THAT neck tension on there. Normal folks don't really care about this, but I'm not afraid of going semi-full retard about the loading. And Mark told me that this wasn't a bench gun..... well, that's not going to stop me from trying!! Say what now? Are you going to make me google that? It's a formula that uses the length of the actual bullet, the weight of the bullet, the twist of the barrel, and the MV and it spits out a number that can (relatively accurately) determine whether you've got enough twist in the barrel. We all hear that to shoot a 77 gr .223 bullet, you need a 1/7 twist.... Well, you can use the miller stability formula and determine that if you push the right bullet fast enough, then you can use a 1/8 twist. Again, anything over 1.0 is 'technically' stable, but in practice y'all better keep it above 1.5..... Here's a link to an online calculator: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi Thanks, I'll explore that.... |
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OK, so I'm not the most smartest guy on the planet. That is, I'm not about to try reinventing the wheel.
The internet searching yields that the FGMM load 'should' be 41.745 gr of IMR4064 pushing a 175 SMK, housed in Fed Brass, that is ignited by a Fed 210M Primer. Just to be a jerk, I loaded up 50 of those, with two exceptions: I used brass that had been fired once through my LaRue and I used 175 Nosler Custom Comp bc I have an abundant supply of them. Now, on to the nerdy stuff.... I didn't FL size the brass. I didn't even size it back to the factory specs. I bumped the shoulder back 0.003". I only neck sized the brass back so that there's 0.002" of neck tension. This is more than what the FGMM has (based on my measurements), but it's not excessive I don't think. I'm purposely not giving a measurement here bc the shoulder-bump length will be different for each gun. The neck tension will be different for each piece of brass, unless you take the time to neck turn both inside and out. If not, the neck bushing in the die won't size them down correctly, and it'll put different tension on each piece of brass. The Nosler CCs are longer and have an ogive that's set back a little bit farther than the SMKs. The weird part about this is that to load the Nosler out to where the base-to-ogive length is where you get an optimal jump into the lands. This is different for each gun, so you'll need to figure out what jump YOUR gun likes. Range report will follow in a couple days about this load. I doubt that 0.1gr increase from the last load will give the increased velocity, but if the numbers check out and I can still get it out there to 800 or so, then that'll be OK. |
Here's a group I shot with my OBR Lite a couple years ago. Sadly, reloading in general has taken a back seat to other hobbies...
I no longer own this OBR, because I want a new house and PredTOBR more.
77gr SMK 20.0grs H4895 2.260"COAL Federal small rifle primer New Winchester brass Load found right on the Hodgdon website. |
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Finally got out to the range to run my first set of test loads, from my first time reloading. I am happy to announce that I still have fingers and face attached!
Anyway, Open to opinions on OCW interpretation. I have a good idea where I'm going, but would like feedback.  
168gr Berger Varget powder, charge wt listed w correlating group Fed 210M primers Fed once fired brass |
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Quoted: Finally got out to the range to run my first set of test loads, from my first time reloading. I am happy to announce that I still have fingers and face attached! Anyway, Open to opinions on OCW interpretation. I have a good idea where I'm going, but would like feedback. http://i1030.photobucket.com/albums/y365/Roentgun/IMG_0637_zpsmljlnod7.jpg http://i1030.photobucket.com/albums/y365/Roentgun/IMG_0638_zpskftrnryq.jpg 168gr Berger Varget powder, charge wt listed w correlating group Fed 210M primers Fed once fired brass |
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OK, here goes (again, Mark once told me that these aren't benchrest guns. I took that as a challenge, so now I'm going to get pretty nerdy about it.):
my 41.7 grain batch that had the ogive matching the FGMM had an averag MV of 2369fps, with an SD of 12 and an ES of 30. That's over a group of 20 rounds that were full length sized to the same measurements as the FGMM. The 10 shot group was about 1.1". That's not too bad, but I think there's room to improve. Here's what was rolling around the ole brain housing group today. I sized the brass too much be FL sizing it. I took Federal brass that was once-fired from my LaRue. Then I bumped the shoulder back 0.002". Then I bushing sized the necks (still at 0.015" thick) to 0.002" of tension. Then I loaded each round to 2.353" OBTO. The OAL is too long to fit in a magazine, so I'll have to single feed these with a dummy round behind it. This ensures that there's no last round jump that a lot of folks think semi-sutos have. Why to that length? 1. My barrel has a max OBTO (Overall Base To Ogive) of 2.359". I've tested it with multiple tools and multiple methods. All readings point to that as the longest the bullet should be, when the ogive comes in to play. In my bolt guns, I always START the loading at either 0.006" or 0.015" of jump. If it's a barrel burner round (.260 Remington or .243 Win, for example), I'll find a bullet that's ok with both jumps and then load it long so that as the throat erods, I don't have to continually load the longer and longer; they'll already be OK with that amount of jump. 2. When you load the bullet longer than SAAMI spec, you increase the volume of the combustion chamber. This allows for the possibility of increasing MV without causing a spike in the pressures. YMMV on this last point, so pay attention to what you're doing and the pressure signs that YOUR gun is showing you. So, with the same charge as last time, and a larger combustion chamber, I should see a decrease in pressure as well as a decrease in MV. 3. Because Mark said these weren't benchrest guns, and I took that as a challenge. My next test is to use an optic that has more than 10x on the top end. |
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Rather than talk another diatribe about what works for me and what doesn't, here's the short and skinny about what I learned:
Resizing brass to fit your chamber is a good idea. By working the brass as little as possible, you prevent case hardening. Loading the bullets farther out isn't really that big of a deal. I found no performance gain in it.. that is, my 10-shot groups weren't noticeably smaller than when I loaded them to 2.806" OAL. I tried a different powder in a bunch of different kinds of brass. I shot 5-shot averages for each of these types of brass. Here's the key to the notes: brass, MV avg, pressure signs, POI shift from my FGMM zero SSA,, 2526, none, .5 low, .1l left RP, 2523, slight ejector swipe, .1 low, .2 left Fed M1A, 2552, none, .5 low, .1 left Win, 2507, none, .3 low, .2 left LC Nato, 2589, none, .5 low, .4 left Lapua, 2518, none, .5 low, .1 left ADI, 2543, small ejector swipe, .5 low, .4 left HOrnady, 2540, none, .6 low, .2 left Now that I know that various types of brass do well with that load, I'll now risk it with some of my FGMM prepared brass. Since, I plan on using this load (whatever it finally gets developed into) for a couple competitions, I'll probably tweak this a little bit. Here's what I learned: 1. It's fun to shoot guns. 2. It's fun to figure this stuff out. **The Chronograph used was a Shooting Chrony F1. It has since been proven to have inaccurate results** |