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[ARCHIVED THREAD] - 6.8mm SPC FAQ & Load Data Part III (Page 8 of 20)
I used the same load in my bolt gun with great accuracy at 100-200 yards. When I visited the 600 yard line these bullets were subsonic and tumbling!!! Now the 115gr. Hornadys were FINE at 600 and were almost as accurate as my best load, 110VMAX. COMING SOON... Watersniper's Suppressed SBR in 6.8SPC! (Thanks to Silentbushmaster) |
KEEP SAYING IT, RANDALL. I'm not going back through all the pages to figure it out... BUT SOMEBODY DROPPED THE DA-DA-DAMN BALL ON THE 6.8 CHROME-LINED SPECS. And I say BEAT THE SHIT out of the horse and kick SAAMI and all involved sign-off engineers in the nuts! Dave S Now, where can I get a "properly" spec'd 18"-20" Chrome-Lined 6.8 barrel? |
I have a Stag 6.8, mfg in April and purchased in July. Mine would not cycle properly (short stroking) with the Hornady 110gr V-Max factory rounds - shot about 100 rounds through it with about 6 cycling correctly. I've got 200 rounds of SSA Xtreme (standard loading) coming to see if the higher pressures make a difference. I'm also going to load my own. Art at SSA seems to recall the Stags have a tight chamber and will not do very well with his combat loadings. I'm going to wait to see if my Stag loosens up a bit and cycles better after a few hundred rounds. It's already been back to Stag once for work (they "polished the feed ramps and replaced the bolt carrier"). If it continues to short stroke, I will most likely ask for a replacement rifle from Stag. |
Hmmm............doesn't sound too encouraging. I'll let you know how it turns out with mine. I've got Rem. SPC's to start with. I have an order for SSA's coming. |
I didn't see any answer to txsouthpaw's question, but I know they are available now. I would like to know how the MRP 6.8 chrome lined barrels are working out. I've been holding out for a while for an upper I really like and this just might be the one. |
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OK guys... Just FYI the SSA Xtreme rounds will NOT feed in a Stag 6.8 carbine because the blunt nosed bullets impact the front wall of the upper receiver before they can get to the feed ramp. I tried loading a single round from a C Products 6.8 mag and the impact of the bullet against the upper set the bullet so far back in the casing that the round is now unusable. I don't know if the Stag 6.8 carbines are supposed to have extended feed ramps, but mine does not. I can feel a sharp shelf on the upper immediately below the ramps on the barrel extension - does this mean the upper should have extended ramps so this shelf does not exist? I do know this shelf scratches the hell out of my Hornady V-Max rounds, which feed correctly otherwise (but to date have not reliably cycled the action). I've had nothing but trouble with my Stag, and yes I've already given the factory a chance to fix it. My understanding is that a well built AR should run from the get-go with no break-in required, so I don't quite know what to think at this point. Just some food for though for all of you thinking about the Stag 6.8... |
For the PRI mags Randall came up with a very minor feed lip tweak that made my 6.8 feed flawlessly. I will enc a pic. The lower mag has had the front part of the feel lips bent upward about .020 or so. Just a little tweak tapering back to the untweaked rear of the mag body. rj |
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The tweak as RJAY suggested is good for all rounds. As his picture shows the cartridge is laying nearly flat in the un-tweaked mag. Yes, poly tipped as well as more pointed bullets will feed better in an un-tweaked mag but you can still damage the tips effecting accuracy. The scratches are not helping your accuracy and velocity either. Art - SSA |
Did you just grab a set of pliers and bend the feed lips upward, or was there a different tool involved? How sensitive is the mag to +/- tolerances on the .020 figure? Anyone know if this same mod works on the C Products 6.8 mags? If this does work, I guess I have a full evening ahead as I try to mod 12 mags... Thanks very much. |
The 6.8 is a great caliber with great preformance. Weapons are nothing more than a mechanical device no matter what caliber. Like all machnical devices whether a car, weapon or machinery they need some attention. Have you ever purchase a new car and had problems with it from the get go. Hell the .223 hass been around for 40 plus years and it still has issue's, hence the 6.8. Art - SSA |
Duly noted....and as I'm already comitted (and highly invested) in the 6.8 arena, I'll try approach it with an open mind and see what happens. |
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I used a 6" adjustable wrench tightened up to grip the feed lip and gently work the feed lips . Tweak the front slightly , move back a little and tweak, etc . You are just barely changing the angle. Do one and try it before messing with all your mags. I went from having probably 25% FTF to zero ftf. rj |
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As far as reliability issues I've none with mine. I built it up from different manufacturers using a barrel built by Randall (AR15barrels.com). I've only ran a couple of mags using the new C-Products mag but all have been flawless. Sorry to hear about the trouble some of you are having. The feed lip fix is interesting, should help some of you. |
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I just purchased a gently used CMMG barrel from one of the members here. So far it's a shooter! I ran a quick 20 rounds down the pipe yesterday. 14.5" CMMG Chrome Lined 1-10" twist, midlength gas system, 1/2-28 threaded muzzle. Accuracy looks real promising! I used 20 rounds of my 110gr. VMAX load I made for my bolt gun. I re-seated them just deep enough to fit in the PRI magazine. BTW I had ZERO feeding issues with my setup. I looked at the rounds after being chambered, there was no scratching or dented polymer tips. Feeding was so far, flawless. I ran 4 shots slow fire to test function and be sure there was no key holing. I then attached my suppressor and ran the remaining 16 rounds rapid fire. No issues what-so-ever. HERE'S THE INTERESTING PART- I gauged the chamber and found the same chamber length as my Remington bolt gun. The max OAL for several bullets was about .005" shorter than the bolt gun. Max. chamber length was 1.715". I plan to cut the barrel down to about 12.5" and thread it for the 5/8-24 thread to fit my suppressor. I used a thread adapter today. This is obviously an SBR setup for short to medium range  ETA: My barrel has M4 ramps but the receiver DOES NOT. Is this an issue? I could always take out the DREMEL! 
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I picked mine up today. I'm new to rifles. What does an "extended Feed " look like. Just cycling a round thru mine (Rem 6.8SPC) it chambered and ejected several times, without problems. Are you having problems, just getting a round to feed? |
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I have had my 20" 6.8 for two years. I reload all my ammo for it and have been using 110 gr. Hornady HP and V-max and Sierra 110 gr. SP bullets loaded out to 2.3" without problems. Having followed this thread since the beginning of Part I the biggest problem has been with blunt pointed bullets. M4 feedramps seem to alleviate this problem. nugun55 the ewasiest way to determine if you have M4 ramps is to look at your receiver. Inside where the barrel extension and receiver mate together at the top of the magwell will be 2 small radius cuts in the receiver itself. When looking at it be sure not to mistake the end of the extension with the receiver. If the receiver itself is completely round then you do not have the M4 cuts in your receiver. The cuts in the receiver are extensions of the ramps cut into the barrel extension. Go to AR discussions and I am sure you will find pics somewhere there. |
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Quoted: I just purchased a gently used CMMG barrel from one of the members here. So far it's a shooter! I ran a quick 20 rounds down the pipe yesterday. 14.5" CMMG Chrome Lined 1-10" twist, midlength gas system, 1/2-28 threaded muzzle. Accuracy looks real promising! I used 20 rounds of my 110gr. VMAX load I made for my bolt gun. I re-seated them just deep enough to fit in the PRI magazine. BTW I had ZERO feeding issues with my setup. I looked at the rounds after being chambered, there was no scratching or dented polymer tips. Feeding was so far, flawless. I ran 4 shots slow fire to test function and be sure there was no key holing. I then attached my suppressor and ran the remaining 16 rounds rapid fire. No issues what-so-ever. Glad the barrel is working out for you. I am going to be working on some sub sonic load data for the 6.8 SPC and a spring combo to cycle a AR rifle. I have to work on some load data for the 221/300 with a 170 grain FP first.  |
| Have any of you had the oppurtunity to try the SSA Barnes TSX load? I've got some on the way from Midway, the problem is that my Noveske barrel is still probably 6 weeks out. I'm hoping to have the rifle together for deer season. I'll post results on deer, hogs, and coyotes is a few months. |
I was hoping to today, but I ended up having to finish up some work, then paint a couple of rooms so no range time  . I'm hoping to try them next week now.
I do not have extended feed ramps. Two (our of 4) of my PRI 15rnd magazines had trouble feeding from one site. These were the older ones with metal followers. I tweaked the lip per Randall's suggestion and they feed fine now. I think there is a discussion of this in the 6.8 FAQ #2 (link can be found in the first post of this thread). |
I tried some of the early ones and got 2680fps avg from an 18" WOA barrel (tight chamber) with no pressure signs and about 1.5 MOA @ 100yds. I'm not sure if Art has spec'd/made the changes yet though. It should be an excellent round for deer'ish stuff out to 200-250 yards. My handloads are 0.5-0.9 MOA with the TSX at the speeds I've gotten so far - with a 1:11 twist too! |
To generally answer your question, if it will work in a .277 bore (i.e. 270 Winchester bore accessories) it will work with the 6.8. There's a bunch of valuable info here Zak Smith's data if you haven't seen it yet. It's a good intro to the caliber, though it hasn't been updated in a while (more 6.8 stuff out there now than when Zak last updated). |
You won't have any problems feeding OTM or V-Max rounds - they have a very sharp nose and will slide right up a rifle feed ramp (not extended) with little problem. My Stag does scratch up my V-Max rounds, however. You will have problems trying to feed the Silver State Armory Xtreme rounds, which have a very blunt tip. There is a magazine modification that works for some, but I've done the mod and still can't get the Xtreme rounds to feed reliably. YMMV, of course. I hope you have better luck with your Stag than I had with mine. What is the manufacture date on the tag that came with your rifle? Just curious... |
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I have a 16" Recon from Denny (GTS) & I'm having serious feeding issues as well. It has the M4 ramps but every time I try to chamber a round, it jams up in the ramps. It happens w/ factory Remington 115g. MC, handloaded 115g.Hornady BTHP, 115g. SMK, 115g rem. FMJ... everything but the V-Max's. It does however scratch the V-Max bullets when chambering. I'm hoping it's a mag issue & Larry at CProducts is going to check out my mags. Also, where can I buy 110g. Hornady OTM bullets? Midway has 115g. HP but not the 110g. BTHP like in their match ammo. Where oh where can they be? |
+1 Just buy cleaning supplies designed for the .270 Winchester and they will work fine. I've used an M4 and a M240 chamber brush and both seem to work fine although the M240 brush is very tight. Stephen |
watson. I have just started loading for 6.8. What load data are you using for the Barnes TSX bullet? I started out with 28 gr of H322 and worked up to 29 gr. The 28.5 and higher loads require quite a bit of powder compression to seat the long solid copper bullet. Have you had any problems with this bullet? |
Short version reply (this is my starting load data only, with my specific equipment/components): 18” WOA barrel w/ “tight” SAAMI chamber 27.5 – 28.5 Hodgdon H322 110gr Barnes TSX SSA large primer brass WLR primers 1.678” trim length Very slight roll crimp (FYI, I’m making a “factory crimp” die this week) 2.290” COAL 1.795” to the ogive (Stoney Point Comparator) No pressure signs/case head expansion 2470fps (27.5gr) – 2550fps (28.5gr) @ 10’ 85deg F, 82% RH, 500’ altitude Long version reply (there will be more to come, soon): No problems yet, including feeding (yes, I have polished M4 ramps). You’re right in the ballpark with what I used for charge weights, but we seem to be different on COL and that may be important in terms of the pressures you’re getting compared to mine, especially if you have a tight chamber/throat. I've got several loads and data I'm working on and will share later, but I started with Hodgdon's data Hodgdon load data link. My initial trials were specifically for large primer (that’s important), SSA cases only with WLR primers. Although Hodgdon doesn’t list the 110gr TSX, there are some reasonable extrapolations I made from the bullets they do list. Besides the 110gr data they have, I took into consideration an important factor: the COL they give is somewhat shortchanging the load potential (they give 2.260" for all their loads except the 90gr Speer). If you load to their COL, you can be way short of what you can actually load for max chamber/mag length and get for a powder charge. As you mentioned, the TSX is a long 110grains and I adjusted the 110gr Vmax data slightly for my seating depth. I would adjust another grain lower (26.5gr for H322) for starting if one feels the need to load the TSX at their 2.260” COL data and they have a “tight” SAAMI chamber. My initial charges between 27.5 and 28.5gr seem to have worked good for me when I load to max mag length. My mag length allows a lot more room for powder and drops pressure from their load data COL at any charge weight given, and gives the bullet less distance to the lands. Basically, at 28.5gr and at mag length (just under actually) I’m not compressing the charge at all – actually have good room left. I’ve got more than 28.5gr of H322 into some new cases (without compressing the charge) but they are not done being tested yet so I won’t comment on them yet. For that matter, I recommend not loading to what I have without working up powder charges from the bottom. I would opine that 26.5gr should be a safe starting point for H322 and the 110gr TSX with one of the tighter SAAMI chambers (mine is tight) and at the 2.260” COL used by Hodgdon. Further, I recommend anyone to take measurements of their chamber limits first (I use a Stoney Point Bullet Comparator) and mag second (I have CProducts at about 2.304” max length) if/when you increase the recommended length/powder and measure case head expansion/look for pressure signs etc. You know… the standard disclaimer of caution, especially since there are several 6.8 SPC chambers out there. There are 2 basic things to look at for load length: the limits of your chamber for a particular bullet and the limits of your mag. The TSX is a VERY generous bullet on COL length due to it’s ogive (also making it forgiving for pressure). I can seat a 110gr TSX out to a 2.395” COL (that’s not a typo) and just touch the lands and my CProducts mags allow about 2.305" COL. So in this case, the limiting factor is my mag length, by far. I’ve been loading the TSX to 2.290” COL (to allow for “field grit” clearance in the mag) or 1.795” via the Stoney Point Comparator (much better way of determining a consistent load length). The TSX likes/needs a jump to the lands anyway and my load length seems it’s not too much for my chamber - all loads have been sub MOA so far (and that’s been with an EOTech, no less). I trim to 1.678” and the first annular groove of the bullet is completely out of the case at my seat depth. I’m crimping on the first “gas check” or annular ring. It looks a little odd I confess, but I guess none of this is about winning a beauty pageant.  Again, this is my data only for my equipment/components, YMMV, and I encourage caution and due process. Hope this answers your question. BTW, what are you shooting for a barrel, what components are you using, what speed are you getting, and are you seeing any pressure signs (i.e. case head expansion, primer condition, etc.)? |
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Thanks for all the load info. I have a Model 1 20" barrel and I'm using new remington brass with CCI LR mil spec primers. I didn't set up the crony for this first run. This was my first try at working up loads the AR and I wanted to see if the gun would run with these bullets. I seated the bullet all the way to the crimp grove (top groove) and did a slight roll crimp. The only pressure signs I got were slightly flattened primers but I get the same results with factory remington FMJ loads. There is no primer dimpling from the firing pin and no excessive case head expansion. I'll try adjusting the COL to eliminate the powder compression problem. I want to work up a good deer load with the TSX bullet so I would like as much bullet velocity/energy as possible from the round while reataining close to MOA accuracy. EDIT I tried seating to the 2nd groove but the COL is too long for the mag. The magic spot is between the first 2 grooves. I loaded a few test loads with the bullet seated as far out as possible and still get a crimp in the top groove (2.247). As soon as it cools to below 95 this PM, I'll check them for accuracy and MV. |
I don't have much time, but wanted to quickly express some thoughts... You're using milspec primers (a.k.a "magnum") and Hodgdon's data and Zak Smith's data were all with standard, large rifle primers. I'd be real sure to check for pressure signs as your charges may be a bit heavy for those primers with that powder - I'd be leary of that combo personally. EDIT: Not to say it won't safely work, it's just into the gray area for me and I'd be careful in that zone. I also used SSA brass and I am leary of Remington brass. My pre-fire/post-fire measurements show that SSA brass seems to be pretty hard stuff and seems less prone to stertch than Hornady brass. I haven't shot any Remington brass, but I haven't liked what I've seen in other calibers in my personal experience and others here have noted a lot of stretch in the Rem 6.8 brass they used.
That's the same place mine are at. It may not have been clear the way I stated it. My case ends about 2/3's the way up the first "ring" (as opposed to "groove). Obviously you can't crimp into a groove there and that's why I use a very slight roll crimp (about 1/8 turn down of the die from touching the case mouth). Any more than that and you start to collapse the case. My neck tension is sufficient to run them without crimping, but I like the extra assurance the bullet won't set back and crimping hasn't affected accuracy in my 5.56 loads. I'm fabricating a factory crimp die from Lee components tomorrow, so the location of the bullet ring/groove won't bee an issue soon.As in my load data post, what I've said reflects my experience and some educated guesses on my part. It's possible a ballistician, powder chemist or more advanced reloader could chime in here and say I'm all wet. Please be careful and work methodically and thoughtfully. I've already seen load data posted here that leaves me a little uncomfortable to think someone might just load it up and shoot it based on the incomplete details. Small and subtle changes can have a BIG impact in controlled explosions ("burning" actually. but you get the point... )
I think Art from SSA will have a good TSX load and I just may end up buying his for hunting myself. I fired some early ones already and got a velocity I'm happy with. He will do/did a little tweaking so maybe he'll chime in here and let us know which edition the rounds already being sold at Midway are. Let us know how your shoot turns out. |
I am not sure where you get "aka magnum" from. Mil-spec primers as far as I know and have ever heard are just a harder primer cup. Perhaps I missed something. I switched over to the large rifle CCI #34 Arsenal primers earlier this year and noticed no difference at all in pressure or velocity using same charges, bullets and seating depths as with Rem 9 1/2's. Of course you should always be wary of any changes made to existing load data and be sure it is acceptable before continuing. |
I just bought 1200 rounds of Xtreme. Why are they so blunt to begin with? Is it just to fit the OAL with more powder or something? Sean |
Apparently it seems a number of people don’t realize it, but they are magnum primers with harder cups. This is from CCI’s own website in their FAQ section under the “Education” tab: LINK “Q: What are CCI No. 34 and NO. 41 primers? A: They are special rifle primers made to military sensitivity specs. They are one method to reduce the occurrence of slam-fires in gas-operated, military semi-auto rifles. See the Speer Reloading Manual for more details. No. 34 and No. 41 primers are MAGNUM primers.” The caps on magnum is theirs, not mine. I guess it would have to make sense though as the military uses ball powders. Also from the same section of their FAQ: “Q: What's the difference between a "standard" primer and a "magnum" primer? A: A magnum primer provides a longer flame duration, a higher flame temperature, or both. In some primers (the CCI small pistol primers, for example) the magnum primer may have a thicker cup to better handle higher pressures. Use magnum primers only where recommended in published load data. Substituting a magnum primer for a standard one without a charge adjustment will nearly always increase pressures. We use Magnum primers in data development with many ball propellants, and with very large-capacity cases. They are also a plus when you are shooting in temperatures below 20 degrees F.” I recently spoke with “someone who should know” about magnum primers in 5.56 loads. He’s the reloading “expert” at a local gun store and “competes” in DCM shoots. He was unaware as well and was boggled when I suggested that the problems he was having using WW748 in his 5.56 loads was because he was using standard primers. I just want to encourage folks to be careful because I think many people will be trying to get more out of their 6.8 than may be safe. If it works safely, then great. But I encourage people to do their own homework and work cautiously. |
Danged if he isn't right. You learn something new every day. I went to the CCI site and found the statement. I've been using CCI mil spec primers for reloading for my SKS, AKs, 5.56 ARs and Garand for a while. As for the 6.8 loads, I'm still not getting bad pressure signs, just slightly flattened primers just like I get with factory ammo. Well, I just might try some of the SSA TSX loads. If the accuracy is there that could be my deer load for this year. |
The X-Treme was designed by Tom Brezinski and Jim House to meet Military terminal preformance and also comply with Hague requirements. The blunt tip aids in the fragmentation of the projectile therefore it is a good less expensive hunting round as well as a good plinking bullet. Accuracy is also good, you should see 1 to 1.25 groups at 100 yards. Art - SSA |
Yes we are loading the Barnes triple shock and our test we ran today show the following results. Thru a Barret 16 inch barrel we have an average velocity with our Combat loads of 2,771 FPS. The projectiles were seated .050 of the lands and the accuracy had a max spread of .467 at 100 yards. Pressures were 51,900 PSI and there were no signs of high pressure on the case or primer. We have tested out to 2,820 FPS with a little shine at the ejector, primer slightly flatten and no other indications. Commercial loads are at 2,715 and it ran like a sewing machine. We had to change our crimp on the projectile to the mid portion of the neck as well at the case mouth because of the small bearing face area of the projectile with the neck. We learned that the normal case mouth crimp was not doing the job and the projectile would loosen up during a lot of handling or during shipment (twist). Watson had to make a very firm crimp on the TSX for the same reason and he seated it much higher to grip the bottom of the bullet. This works fine in his weapon - mag combination and he is getting very good results, but it may not be the same for everyone. We are seating our's at 2.230 a good .060 under Watson's but we have to worry about all weapons systems that are out there. We may be able to seat it higher and we will test that idea in a Model 1 in the next few days and post the results. All the above test were done with our new small rifle primer cases. In a side by side test against small primer verse's large primer we seen about a 15 FPS drop in velocity with the small rifle primer. Art - SSA |
[ARCHIVED THREAD] - 6.8mm SPC FAQ & Load Data Part III (Page 8 of 20)
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