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[ARCHIVED THREAD] - Loading to 5.56 pressure (Page 1 of 2)
Posted: 11/5/2011 9:19:19 AM EDT
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I'm sure this comes up a lot but I couldn't find anything in the FAQs or search results so here goes:
I want to load 5.56 pressure loads for higher velocity and better terminal effect for my SHTF ammo. The max load listed in manuals is for SAAMI spec so I'm reluctant to go much past it, not knowing what the max load for 5.56 pressure would be. How can I find that information? Any advice on loading for 5.56? The ammunition will ONLY be fired in 5.56 rifles and NOT fired in .223 chambered rifles, ever. |
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Thank you. I should have been more specific. I want to load heavy OTMs for NATO pressure. Using which powder? Ramshot has a section for <62350psi for NATO chambers in their 4.5 load manual. Page 8 here They list data for TAC and X-Terminator for weights from 62 to 90 grains. |
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Thank you. I should have been more specific. I want to load heavy OTMs for NATO pressure. Using which powder? Ramshot has a section for <62350psi for NATO chambers in their 4.5 load manual. Page 8 here They list data for TAC and X-Terminator for weights from 62 to 90 grains. Perfect! Thanks much. I must have had an older .pdf because I don't think that info is on the printout I've been using. I've been working with TAC and Hornady 75 gr BTHP but I didn't see any NATO pressure data on my sheet. This is exactly what I needed. Thanks again. |
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If it helps, when you start approaching 5.56 pressures using approved powders and load data, you will start to get swipes, and possibly primers that are starting to flatten. Do not use standard primers, as they will show signs earlier, but use CCI #41. Light swipes will be normal at anything around 60,000-62,000 psi. Purchase a box of NATO loaded ammo in the weight that you are wanting to load and chronograph it. Use that as your guide, by checking your brass with that from the batch that you bought, and of course chronograph your hand loads.
One thing to remember as well. You may get signs in your handloads before you get the velocity that the factory gets. Get to where you have just a tad more than light swipes, but not extractor marks or gouges, and back off a half grain. That would be about max for your combo,and just below max is usually more accurate. Don't chase that extra 25-50fps if you don't get it safely. You will likely have a less accurate load, and the difference in velocity isn't going to matter to the target. If you need more power than that, try a bullet with different construction, or move up to one of the 6.x calibers. |
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I would like to point out you can get new federal or pmc m193 or m855 for $5.99 per box on the inetz right now. That's cheap and it is made from new components and is exactly what you're trying to copy. It's already ready already. Just buy it.
Reload for 223 to do one of 2 things... make performance ammo (aka varmint/tap/match) or to load reduce power loads to reduce cost and wear on your rifle while training or plinking. Recreating 5.56 mil loads using used components (brass - possibly pulled bullets) with no primer crimp, not only costs about the same as new ammo, it takes a long time and gives you ammo that might be slightly more accurate but is surely more prone to fail from blown primers, case cracks, etc ... exactly what you don't want in SHTF. Also, if it's really just up close personal defense.. it doesnt have to be 5.56 pressure to mess stuff up, any 223 load close will wreck a man in no time. Just something to think about... |
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Also, if it's really just up close personal defense.. it doesnt have to be 5.56 pressure to mess stuff up, any 223 load close will wreck a man in no time. Just something to think about... I was going to make this point, but IIRC Bluefalcon is loading for an SBR, which is the one time (IMO) getting some extra velocity is a decent goal to shoot for. Watch those primers, though. |
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Also, if it's really just up close personal defense.. it doesnt have to be 5.56 pressure to mess stuff up, any 223 load close will wreck a man in no time. Just something to think about... I was going to make this point, but IIRC Bluefalcon is loading for an SBR, which is the one time (IMO) getting some extra velocity is a decent goal to shoot for. Watch those primers, though. Exactly. The higher pressures equal higher velocity, which means increased fragmentation range (even from a 16" bbl). In practice, I'm probably going to end up with a load that's over the max charge for SAAMI .223 but not really pushing 5.56mm that hard. I knew I could exceed SAAMI spec in an AR, I just didn't know by how much. This will help keep me safe. Thanks again, guys. For Cycline: I'm not making M193 or M855 clones. I'm loading 75 gr BTHP over TAC and wanted more velocity for better terminal performance. My plinking and match ammo will still be lower power. |
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Quoted: For Cycline: I'm not making M193 or M855 clones. I'm loading 75 gr BTHP over TAC and wanted more velocity for better terminal performance. My plinking and match ammo will still be lower power. FWIW.... I have gone to 24.0gr and a few tenths beyond without issue. This was in both new LC and 1xfired Winchester brass, with #41's ... It's pretty hard on the brass though. |
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When you start getting swipes that are noticeable but not showing brass flow, just real shiny, you should be around 60K-62Kpsi. That is where NATO is loaded to. Commercial/SAMMI is generally around 50K-55Kpsi.
Contrary to what one of the posters mentioned above about not wanting hand loaded ammo for defense due to possible problems, don't worry about it. The reason I load my own for these situations is because I have control over the quality of the ammo. I have never had any of my own ammo give problems, after the load has been worked up, dies set up correctly etc., out of at least 70,000 rounds over the last 10 years. I have had any number of problems with factory ammo. Once, sending an entire half case back of one lot number, and this was premium ammo from a premium ammo company. It was $20+ a box. It was replaced by them with other ammo and worked out great, but what if that had been in a defensive situation when it failed me. I have had surplus not ignite, due to the ammo, not the gun, and of course the cheap stuff sometimes as well. Any ammo I load for SHTF I seal. Primer and neck. Just work up your load. I'm getting ready to start working up some 77gr stuff for my son's rifle soon. It would be a good idea to have some of the sealed spam can stuff as a backup too though. |
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For Cycline: I'm not making M193 or M855 clones. I'm loading 75 gr BTHP over TAC and wanted more velocity for better terminal performance. My plinking and match ammo will still be lower power. FWIW.... I have gone to 24.0gr and a few tenths beyond without issue. This was in both new LC and 1xfired Winchester brass, with #41's ... It's pretty hard on the brass though. According the the Ramshot data sheet posted above 24.1 is the max load for SAAMI. 5.56 starting load is 23.2 and goes up to 25.8 for 75 gr over TAC. That means 24 gr ought to actually be pretty tame with that combo. I'm guessing I'll probably end up in that neighborhood because, as another poster mentioned, max loads usually don't get very favorable results. Anybody know what the fragmentation threshold is for Hornady 75 gr BTHP? |
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Keep us posted on how this turns out for you. I'm currently exploring down the same road (75gr BTHP/TAC + SBR), as I feel that many probably also are, and I'm always interested in what other people achieve and their experiences.  I will. Another member here has a chrono he ma let me use for more precise figures. Once I find a load that my SPRish rifle shoots accurately, I'll post groups and hopefully velocity numbers from 20", 16", 14.5", and 11.5". We'll see if I can make it happen. |
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I see where primers have been mentioned a few times. Primers in Nato\Mil cartridges are crimped for a reason. From what most folks have said it has nothing to do with excessive pressure, but tradition and paranoia over primers backing out under recoil. This makes sense as crimped primers pop out as easily as any other primer in the press and I can't imagine how chamber pressure could push a primer out THROUGH the bolt face. Still, I wonder: is there an affordable and reasonably convenient way to crimp primers at home? |
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When you start getting swipes that are noticeable but not showing brass flow, just real shiny, you should be around 60K-62Kpsi. That is where NATO is loaded to. Commercial/SAMMI is generally around 50K-55Kpsi. Contrary to what one of the posters mentioned above about not wanting hand loaded ammo for defense due to possible problems, don't worry about it. The reason I load my own for these situations is because I have control over the quality of the ammo. I have never had any of my own ammo give problems, after the load has been worked up, dies set up correctly etc., out of at least 70,000 rounds over the last 10 years. I have had any number of problems with factory ammo. Once, sending an entire half case back of one lot number, and this was premium ammo from a premium ammo company. It was $20+ a box. It was replaced by them with other ammo and worked out great, but what if that had been in a defensive situation when it failed me. I have had surplus not ignite, due to the ammo, not the gun, and of course the cheap stuff sometimes as well. Any ammo I load for SHTF I seal. Primer and neck. Just work up your load. I'm getting ready to start working up some 77gr stuff for my son's rifle soon. It would be a good idea to have some of the sealed spam can stuff as a backup too though. I presume you use clear nail polish or something similar. Anyone know where I can get a hold of the tar like substance that Lake City uses to seal M855 and M193? I clean finished ammo in a vibratory case cleaner for a few minutes to remove case lube. If I was going to apply nail polish, it would probably be best to do after final cleaning, right? |
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I see where primers have been mentioned a few times. Primers in Nato\Mil cartridges are crimped for a reason. From what most folks have said it has nothing to do with excessive pressure, but tradition and paranoia over primers backing out under recoil. This makes sense as crimped primers pop out as easily as any other primer in the press and I can't imagine how chamber pressure could push a primer out THROUGH the bolt face. Still, I wonder: is there an affordable and reasonably convenient way to crimp primers at home? No. There's a market opportunity for someone to sell a ring stakeing tool. Or you can punch stake the primers! |
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I see where primers have been mentioned a few times. Primers in Nato\Mil cartridges are crimped for a reason. From what most folks have said it has nothing to do with excessive pressure, but tradition and paranoia over primers backing out under recoil. This makes sense as crimped primers pop out as easily as any other primer in the press and I can't imagine how chamber pressure could push a primer out THROUGH the bolt face. Still, I wonder: is there an affordable and reasonably convenient way to crimp primers at home? No. There's a market opportunity for someone to sell a ring stakeing tool. Or you can punch stake the primers! For some reason an image came unbidden to my mind. Something like this: 
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I use markron, which is similar to nail polish, but is sort of thicker. It isn't perfect. I would like to find the military sealant as well. Primers flattening in the case of CCI #41 with the hard/thick cup is generally from pressure pushing the primer out against the bolt face like you mentioned. The pressure builds up, the case swells and can't extract yet since it hasn't begun to return to a small enough diameter, but since the primer has less resistance, it backs out into the bolt face a tiny amount. After the case returns to a small enough size to move in the chamber, it backs up into the bolt face reseating the the now flattened primer. The combination of cratering around the firing pin indentation and a flattened primer is what I would be concerned with.
The thing to look out for is swipes that show brass flow, ( raised material or material removed ), or damage from the ejector. Anything with that needs to be backed off .5gr. A better way is to measure the diameter of the case near where the reinforced portion meets the thinner case wall, where you see a shiny ring when you fire or size a round. Measure them before you fire them, and afterwards. I don't know the particular number in the case of the 5.56, since I haven't loaded any that hot in that caliber, ( I do with my 6.8 ), but too much growth in that area is a good sign you need to back off, and it will show up before many of the other signs mention. Anything that shows too much growth will shorten case life at the very least, leading to incipient case head separation. |
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Fun fact to remember.
If you load to the edge (5.56 NATO pressure) and rapid fire a 30 round mag (or two or three) your chamber temperature will be really hot. When you load the next mag and chamber a round and let it sit in there for a few seconds your gun powder will be really hot. You will be over pressure very quickly with 200 deg gun powder. just a thought. |
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I figured I'd add to the thread some here...
Here's the results of my experimentation with 75gr BTHP / TAC: 16" CMMG Midlength ~60F 2600ft Miserable, raining sideways, cold day –– the ONLY day like that this year in Tucson, the only day I could take leave...figures... COAL: 2.255 Hornady 75gr BTHP 24.0gr TAC LC once fired trimmed to ~1.755 w/ reamed pockets Wolf SRM primers Avg Vel: 2598 ES: 58 SD: 16.7 I'm not sure that I'd put too much faith into these results. The velocities seem reasonable, and my 22lr control rounds gave me expected results, however, with the overcast sky and the rain, I'm not willing to call these results good. As the sensors began filling up with water, the results became extremely erratic. I put a lot of care into consistency while loading up these test rounds, and I would have expected the SD and ES to be quite a bit lower (unless I suck a lot more than I know). I wasn't able to test for groups (the weather was beyond ridiculous, so I was happy to just get the velocities), but the brass showed no signs of flowing and no ejector marks. The primers were slightly flattened but had no cratering –– I'm curious what they'd look like in a swedged primer pocket as opposed to a reamed pocket. I got those ten rounds over the chrono before it started registering shots on its own, so I gave up and quit. Based on an average of what other rounds do out of my 16" vs. my 11.5", I would theoretically expect them to be running about 2360 (I lose an average of 9% of the velocity). As an aside, the chrono itself, a CED M2, actually exceeded my expectations for the environmental conditions that I was using it in. The water didn't stop it, and once dried out, it went back to functioning normally. If you're looking for a chrono, I can't recommend it enough. Anyway, I'll let you guys know what happens the next time I get out to the range (which might be a little while...terrorists aren't going to fight themselves  ).
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Did you have any shiny spots at all? I would expect very slight swipes at that point, but nothing to worry about. How flat were the primers? Alright bub, you're not allowed to log off until you look at my pics. I was digging spent primers out of the trash for you. 
ETA: Okay, here's the pics. So...not as "nothing at all" as I remembered. I looked at them when I got home for a few seconds, didn't see anything scary, and tossed them in a bin. Upon re-inspection, well, I'll just show you the pics. Click on them for super-hi-res. The primers –– some flattening, but not actually flat. 
And the primers from the top –– no trace of cratering or smeared primer strikes. 
And now the brass. Aligned as best I could from the markings –– appears that the ejector is on the right, extractor on the left (or you could say that the brass is upside down). 
So, a little bit o' shiny on the brass, nothing to really be concerned about (right? ), a little bit of flat on the primers, nothing too bad. I can see that I'm getting there, but I'm not quite there yet. I'm looking to get something in between TAP FPD and 5.56 TAP. According to Hornady's website, in a 16" barrel, TAP FPD runs at 2609 and 5.56 TAP runs 2660.
Anyway, I hope you guys find this useful. Again, I'll let you know what my future experiments yield. |
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Hard to tell much from the primers once they're out of the cases, but yeah, I'd say you have some light swiping going on. Yeah, I wasn't expecting to take pics and post them on arfcom when I popped them out. They're certainly not the anvil flat primers I've seen on some (other peoples') loads.
Anyway, I'm already at the bottom of the velocity range that I'm looking for. I may go up from here, but not by much. We'll see what happens. |
| Those actually look really good. Next time you shoot military surplus 5.56 take a look and compare. They'll be pretty much the same. I looked for some pics of some of my hot 6.8 loads, but can't find them. I have still have about 25 90 TNTs that run 2980fps. They are bad hot, basically max. They have pretty good swipes and the primers are bad flat. My load is actually 2925fps now, just look about like what you have there, but no flattened primers unless everything is really bad hot outside and the gun is heated up bad. |
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Quoted: Quoted: Quoted: For Cycline: I'm not making M193 or M855 clones. I'm loading 75 gr BTHP over TAC and wanted more velocity for better terminal performance. My plinking and match ammo will still be lower power. FWIW.... I have gone to 24.0gr and a few tenths beyond without issue. This was in both new LC and 1xfired Winchester brass, with #41's ... It's pretty hard on the brass though. According the the Ramshot data sheet posted above 24.1 is the max load for SAAMI. 5.56 starting load is 23.2 and goes up to 25.8 for 75 gr over TAC. That means 24 gr ought to actually be pretty tame with that combo. I'm guessing I'll probably end up in that neighborhood because, as another poster mentioned, max loads usually don't get very favorable results. Anybody know what the fragmentation threshold is for Hornady 75 gr BTHP? My loads were in the 24.5 range when I saw pressure signs like flat primers and ejector swipes (those shiny spots on the case head in the pics above). I can't recall for sure, but I think I was getting an average velocity of about 2800 FPS from my 20" barreled varmint gun, which has a wylde chamber. My accuracy suffered when I pushed it higher. I was also getting the same pressure signs from two 5.56mm chambered guns (16 middy, and another 20"). I have pushed TAC up to 26.0gr + under a 55gr bullet, and started seeing pressure signs there too... which is also under their max 5.56mm load for a 55gr bullet by their data. I would say I'm cautious, having pierced primers in hot load with 77gr Noslers, and ruined a firing pin in the process...  The other thing I consider is that I like to run all this ammo on a Dillon 550... so its nice to have a small cushion, in case my measure throws a heavy charge (which I have never seen with TAC), or I otherwise screw up. IMHO a load around the 24.0gr range is a good place to be for accuracy and pressure. I'm not 100% sure but I think the 75gr BTHP frags down to about 1800-2000fps... |
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If you're gonna push them weigh every load. I switched over to an RCBS ChargeMaster a couple of years ago, and it has been a huge time saver for me. I have always weighed every load with my rifle ammo, even when throwing light charges and just using a 5-0-5 scale, and trickling it up from there. The only thing I don't measure every charge with is handgun ammo that isn't near max, and I get good results just loading on a cheap Lee turret press.
Most loads for every rifle I've loaded for have been the most accurate somewhere within .7gr less than where I get swipes that I can feel, and most have been within .5-.3gr of that. The lowest I recorded was 1gr shy of swipes with a .308 168gr load, and the highest was .3gr shy in a couple of 6.8 loads. The only thing in .223/5.56 I load for is .5gr low of showing swipes with the Hornady 55gr HPBT. |
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I'm not 100% sure but I think the 75gr BTHP frags down to about 1800-2000fps... According to Molon and other sources in his TAP thread, it's at ~2250. Obviously I haven't tested this myself, but he seems to be pretty knowledgeable regarding ammo of pretty much every type, so that's the number I roll with. |
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Take a look at Accurate's Loading Data. Separate Listing about Nato/Mil Pressure Loads.
http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf But for SHTF i think It doesn't matter whether you shoot a few fps more or less. In SHTF only the first rule of gunfight is important. Have a Gun 
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Take a look at Accurate's Loading Data. Separate Listing about Nato/Mil Pressure Loads. http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf But for SHTF i think It doesn't matter whether you shoot a few fps more or less. In SHTF only the first rule of gunfight is important. Have a Gun ONLY the first rule? So a bolt action .22lr rifle would be just as effective as an AR-15 or AK? Sure, having the gun is the most important rule but I want to have lots and lots of opportunities to shoot a motherfucker in the face. I also want each bullet I fire to have the best chance of putting him in the dirt. The first concern is addressed with a modern fighting rifle such as an AR. The second concern is addressed by optimizing a load that provides me the best balance of cost, accuracy, and terminal effect for my needs. I've got a couple thousand M855 sealed in cans and a modest stash of 75 gr Prvi but I want to turn my brass into a couple thousand of the best (most accurate and most terminally effective) ammo that I can afford. Trackin'? |
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Take a look at Accurate's Loading Data. Separate Listing about Nato/Mil Pressure Loads. http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf But for SHTF i think It doesn't matter whether you shoot a few fps more or less. In SHTF only the first rule of gunfight is important. Have a Gun ONLY the first rule? So a bolt action .22lr rifle would be just as effective as an AR-15 or AK? Sure, having the gun is the most important rule but I want to have lots and lots of opportunities to shoot a motherfucker in the face. I also want each bullet I fire to have the best chance of putting him in the dirt. The first concern is addressed with a modern fighting rifle such as an AR. The second concern is addressed by optimizing a load that provides me the best balance of cost, accuracy, and terminal effect for my needs. I've got a couple thousand M855 sealed in cans and a modest stash of 75 gr Prvi but I want to turn my brass into a couple thousand of the best (most accurate and most terminally effective) ammo that I can afford. Trackin'? That jiives. I think he was referring more to the thing where people push it too far chasing after that last 25fps. Sure, it extends your SBR's effective range to 85yds instead of 70yds (notional numbers), but realistically, the engagements we might encounter aren't likely to range that far anyway, and if you're having to engage out past 85 or 100 yards, well, you probably ought to swap that gun out for something a little more appropriate. If you're loading unsafe ammo, you're turning your biggest fighting asset into potential liability. At least, that's how I read it. Anyway, don't wanna get this thread too derailed.
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Roger that.
My goal is to have the fastest (read most effective) 75 gr load that I can while maintaining a high degree of accuracy for my precision rifle and without compromising safety. This will, of course, extend the "effective" range of my SBR but, as you said, it's not the ideal tool for longer range engagements and the probability is that I won't have to use a rifle at all, let alone at 100m. As you mention, it's important to maintain perspective. In the extremely unlikely even that I am forced to engage a target at 200m with my SBR, it's not like the rounds are just going to bounce off them, either. I think I'm going to be able to shoot a few loads tomorrow, if everything works out. I won't be able to chrono but I should be able to see which are going to be most accurate and maybe I can post velocity numbers some other day. |
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i would say, don't overload in search of the last possible fps and risk a kaboom. THEN the shit hits you on hardest way
but i understand you, i would exactly do the same way if possible. the problem is, in europe the first rule is more important than the rest, because our leftwing pussy politicans will ban on guns whatever they can. so its better to have a .22 in hand than dream of a assaultgun. yo americans live in paradise what's about gun laws and with your 2nd amendment no one can disarm lawful citizens. here in switzerland gunlaws are ok at the moment. but the lefties work on bans. self defence is an absolute no go here. at home it is still possible, because normal no gun people don't know that is legal to hold a loaded gun in the house. but legal carry for normal people is not possible since 1999 gun law. Every single time when some one murdered with a firearm, the media and the lefties will disarm the militia and ban private guns. so keep your rights and fight for it, the USA are the last paradise for free man! |
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What would really suck in the event that you needed to use your rifle for social purposes is to pop a primer from a nice hot 5.56 load and have it wedge up between the bolt carrier and the upper receiver, or down under the disconnector or something. Is this common? How exactly does it happen? How can I avoid it? |
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i would say, don't overload in search of the last possible fps and risk a kaboom. THEN the shit hits you on hardest way
but i understand you, i would exactly do the same way if possible. the problem is, in europe the first rule is more important than the rest, because our leftwing pussy politicans will ban on guns whatever they can. so its better to have a .22 in hand than dream of a assaultgun. yo americans live in paradise what's about gun laws and with your 2nd amendment no one can disarm lawful citizens. here in switzerland gunlaws are ok at the moment. but the lefties work on bans. self defence is an absolute no go here. at home it is still possible, because normal no gun people don't know that is legal to hold a loaded gun in the house. but legal carry for normal people is not possible since 1999 gun law. Every single time when some one murdered with a firearm, the media and the lefties will disarm the militia and ban private guns. so keep your rights and fight for it, the USA are the last paradise for free man! I feel for you guys, I really do. America was blessed with a happy combination of geographical location, asshole colonists, and Britain's entanglement in other affairs. We got our panties in a wad, started shooting people in the face over it and to this day we threaten to shoot people over really minor stuff. Europeans have been far too civil to each other for far too long.You need more asshole. A more fundamental problem is the way we see freedom. At our core, most Americans see freedom as freedom from interference; personal liberty. Europeans see freedom as freedom from worry or freedom from want. They replaced their kings with totalitarian "democracies" and demanded that their government still control every aspect of their lives and provide for them. We rid ourselves of the crown and sought a way to avoid government wherever possible. Until your European brethren embrace the concept of personal liberty and accountability, you will continue to traipse down this path to slavery. Don't worry, though. We're headed there too, you just have about a two hundred year head start. |
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you hit it exactly in the center, bluefalcon. one of the biggest problems of (west)european is, we ar all lethargical, spoiled and the biggest grudgers on planet. not all, thats clear, just as not all americans are freedom-loving self dependent people. the government managet it, mostly with the ok of the citizens, to make a wide number of people dependent of them. the result ist, more and more lame dreamers lean back and live of cost of the working people. and then they dictated in democratical way what we have to pay......people forget about, that this live is not the normal way. every one had to work for his own live. one day, it will come tho a big bang in europe. and all the people that learned for generations to live at rules from others, that the government managed their live, that they not must thinking, will not survive that time very long.
but the people who know that this is not normal, that prepare for what ever can happen is not the badest idea (including gun and ammo, illegal if necessary) are growing up...... well, enough to whine, i have to do some reloads for saturday
keep your freedom guys, dont walk in the trap of government managed live! |
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What would really suck in the event that you needed to use your rifle for social purposes is to pop a primer from a nice hot 5.56 load and have it wedge up between the bolt carrier and the upper receiver, or down under the disconnector or something. Is this common? How exactly does it happen? How can I avoid it? I don't know how common it is, both times it's happened to me have been with factory ammo. But yeah, there are a couple really lousy places for primers to end up; when I got one wedged between the BC and the upper, that thing was locked up tight and it took a big-ass screwdriver and a reckless disregard for my rifle's finish to get it out. |
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What causes the primer to actually leave the case? As I understand it the pressure loosens up the primer pocket, and as the case is leaving contact with the bolt face it simply falls out. Without a doubt the higher pressure you load to the more loose primer pockets become an issue. |
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Thank you.
Had an opportunity to test some loads yesterday. I tested three 75 gr BTHP loads and as an after thought tested one each of 68 gr BTHP and 65 gr Game King. I also fired ten round groups of M855 and 75 gr Prvi Partisan for fun. For the record, I think I can get more out of this rifle with a new crown. Barrel is 20", 1:8". Distance was 100m. Wind was very light and variable. The smallest group I got was with 24.0 gr TAC under the 65 gr SGK, 2.255" COAL. It measures right about 2.25" for the ten round group below. I really wanted the 75 gr loads to work well but all three were substantially larger and I see no reason to pursue it any further. I will experiment with a few other charges with the 65 gr SGK to see if I can tighten that group at all. I'll still use Prvi 75 gr for my HD SBR but it looks like my SHTF stash is going to be 65 gr SGKs. The good news is that, although the BC is different, I ought to end up with something similar enough in weight and MV to M855 for the BDC in my ACOG to be really close. Thanks for all the help, guys. I'll try to get some chrono numbers if I can get out there with my other buddy. |
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Looking at the pictures of the primers and the cases, to me it looks like you are removing a little to much brass when you are reaming... do you know anyone with a swager? Had one and broke it. Maybe I should get another one or send mine back to RCBS. |
[ARCHIVED THREAD] - Loading to 5.56 pressure (Page 1 of 2)
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