arjunky Posted July 9, 2012 Report Share Posted July 9, 2012 I just had a criterion barrel put on my LR 308,head space was good,and barrel fit nicely. But when my gun smith tried to charge it with with a couple of rounds in the magazine the locking lugs caught the shoulder of the case. The only way to charge it was tolock the bolt back then put the magazine in and drop the bolt. I called DPMS to see if they used a modified bolt carrier or magazine for their 6.5 version. They told me that both were the same 308 components that I had in my gun and no feeding or charging problems. Does anyone have any suggestions to what might be happening with my gun? I was told by one fellow on another forum it may be as simple as radiusing the two bottom locking lugs on the bolt so it won't dig into the case. If anyone has an idea of how to fix this I would appreciate it. Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 9, 2012 Report Share Posted July 9, 2012 I've never done a 6.5 conversion, but for my possible future plans this interests me. I'm not sure I understand you completely. Are you saying that when you slowly allow the bolt to go forward, the bolts llocking lugs are damaging the rim of the case when it strips it from the magazine, or are you saying that the bottom of the barrel extension is catching the shoulder of the case (where it necks down) when the rd comes forward and contacts them. If the latter, I would think that either your mag is low, rd is not aligned with the bore properly, (maybe mag feed lips?) or as you say, if everything is aligned as it should be, then perhaps the fix (as you say) would be to do some work on the lower locking lugs of the barrel extension. If your using the same mags as the .308, can you take a dummy .308 rd, load a mag part way, slowly bring the bolt forward, and watch carfully as the rd is brought forward. I understand that you can't chamber a .308 rd in this barrel, but can't you see if the shoulder of the .308 is aligned so that the shoulder will not hit the barrels locking lugs? If on the other hand, the 6.5 is angled downward, and it's shoulder is hitting the barrels locking lugs, I would think you need to either do something to the mag to get the bullet better aligned with the bore, or do the work on the barrel extension that your suggesting. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted July 9, 2012 Report Share Posted July 9, 2012 I understood the OP different than Jgun. To me it sound like the bullets chamber fine. It's the backwards motion of the BCG that is hanging up on the magazine/bullets. The first thing I'd do is try different magazines. It's a lot cheaper and less perminant. Something in the back of my head is reminding about using Ar10 bolt catches instead of LR308. I need a better rundown of all the parts you are using. Barrel, barrel extension, upper receiver, lower receiver, lower parts kit, charging handle, bolt, bolt carrier and trigger/hammer kit. All those parts require a level of harmony to work well together. If one part is out of whack it causes issues. Like Jgun said, you should try working the bolt over a .308 to see if anything happens. Don't let the BCG slam closed, but see if it's interfering at all. My money says this is a mag issue. Maybe the follower is pushing at an angle, maybe the lips at the top are off a bit. I think the problem is the front of the bullet is too high. Still, I've never heard of a bolt catching like that. Usually the mag spring gives way, allowing the bullets to move out of the path of the bolt. Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 9, 2012 Report Share Posted July 9, 2012 I'm still waiting for clarification from the OP. I read that he says, only way to chamber it is to lock bolt back and hit the bolt release, that sounds like he's saying it needs a running start to get the bullet to make the "jump" into the chamber. Don't the 6.5's have a steeper angle at the shoulder than .308? If he's talking about the shoulder hitting the lugs during chambering, it would sound like an alignment issue. Certainly playing with the mags would be a safer option than permanently altering the barrel. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted July 9, 2012 Report Share Posted July 9, 2012 Welcome from Indiana brother arjunky,lots of sharp guys here that are glad to help. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 10, 2012 Report Share Posted July 10, 2012 I just had a criterion barrel put on my LR 308,head space was good,and barrel fit nicely. But when my gun smith tried to charge it with with a couple of rounds in the magazine the locking lugs caught the shoulder of the case. The only way to charge it was tolock the bolt back then put the magazine in and drop the bolt. I called DPMS to see if they used a modified bolt carrier or magazine for their 6.5 version. They told me that both were the same 308 components that I had in my gun and no feeding or charging problems. Does anyone have any suggestions to what might be happening with my gun? I was told by one fellow on another forum it may be as simple as radiusing the two bottom locking lugs on the bolt so it won't dig into the case. If anyone has an idea of how to fix this I would appreciate it. So , you are saying that the round fed from a locked back bolt ? If that worked , whats wrong ? Was the Smith short stroking the action trying to watch it feed or is the BCG not coming back far enough to grab the cartridge with the charging handle pulled all the way back ? If thats the case , may be some thing in the charging handle or its configuration or some thing not letting it go all the way back far enough. :wwop: Quote Link to comment Share on other sites More sharing options...
204 AR Posted July 10, 2012 Report Share Posted July 10, 2012 The way I understand it is that it chambers fine, but the rearward motion of the bcg is arrested by the bolt lugs hitting the shoulder of the round in the mag. That's why the bcg has to be locked back before you put a loaded mag in. Is that what you mean? Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted July 10, 2012 Report Share Posted July 10, 2012 I think we've been had again... This guy isn't reading the responses and he's not replying. The OP forgot he asked or doesn't care. Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted July 10, 2012 Report Share Posted July 10, 2012 Look at the two rounds the long neck does not feed the same as a 308.. Either the magazine ears need to be adjusted or the bottom center lug in the barrel extension needs to be ground down a little ,or both. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 12, 2012 Report Share Posted July 12, 2012 The shape is not extreme & shouldn't matter. There's more to this than we are hearing . Quote Link to comment Share on other sites More sharing options...
arjunky Posted July 18, 2012 Author Report Share Posted July 18, 2012 Sorry guys been working. I do appreciate all of your comments. The gunsmith radiused the lugs,and it chambers fine. I just wasn't happy with the dropping the bolt method on the magine,and yeah it fired but it still dented the next case as it cycled. Once the lugs were radiused it jumps the cases without any dents and works fine. The fatter case,and steep shoulder angle just didn't leave enough room for the bolt lugs to clear. The gun started life as a stock LR 308 it has since been rebarreled, jard adj single stage trigger,jp vtac 15.5 in hand guard,magpul prs stock. Has anyone had any luck with the criterion barrels? I haven't shot this gun but twice. I was too pissed off that it didn't charge with the bolt correctly,but I'm anxious to see what it will do with a 140gr amax and H4350. I'm gonna load it to hornady's specs. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 19, 2012 Report Share Posted July 19, 2012 Sorry guys been working. I do appreciate all of your comments. The gunsmith radiused the lugs,and it chambers fine. I just wasn't happy with the dropping the bolt method on the magine,and yeah it fired but it still dented the next case as it cycled. Once the lugs were radiused it jumps the cases without any dents and works fine. The fatter case,and steep shoulder angle just didn't leave enough room for the bolt lugs to clear. The gun started life as a stock LR 308 it has since been rebarreled, jard adj single stage trigger,jp vtac 15.5 in hand guard,magpul prs stock. Has anyone had any luck with the criterion barrels? I haven't shot this gun but twice. I was too pissed off that it didn't charge with the bolt correctly,but I'm anxious to see what it will do with a 140gr amax and H4350. I'm gonna load it to hornady's specs.I have two 308's with them & the 20 " is a tac driver , the 16" only sports MBUS & shoots just fine with iron sights.( well plastic of some sort)So the cartridge is feeding ,but the bolt is denting the next cartridge as it passing over it ? Quote Link to comment Share on other sites More sharing options...
arjunky Posted July 19, 2012 Author Report Share Posted July 19, 2012 Since the bolt lugs have been radiused it feeds perfect,and doesn't dent the other cases at all. Quote Link to comment Share on other sites More sharing options...
dh Posted July 24, 2012 Report Share Posted July 24, 2012 I just received the same barrel as you from FA. Iordered it and and a 12" FF tube dpms heavywall upper and chrome carrier and bolt. Fulton checked headspace before they shipped it all. I did get a chance to task with a smith there about what they do to make the feedind/chambering smoother to help save brass from chewed up shoulders. they told me they do some polishing/grinding on the center bottom lug and take the edges down(radius them). I talked to gunsmith friend that builds ar-15 &ar10. He suggested grinding down the leading edge of the center lug and the ridge that runs up it to the tip of the lug, but not to change the height of the lug in the barrel extension. this was easily accomplished with a dremel and a small stone. I broke the edges with a real fine sanding drum, nothing crazy, just taking the edge off. it feeds great and the sharper shoulders of the cm round is not chewed up at all, much less then the original cmmg does to 308 brass. I was really beginning to think the ar10 was just too hard to shoot. I shoot br and have no problem holding aggs in the hi-middle.1s. I just could not get that cmmg sass to shoot no matter what load I tried. I was at the verge of selling it and probably would have but none of the area shops were interested in a heavy barreled ar10. I have a geissele match trigger set up at 1.75lbs 1st stage, 14 oz 2nd stage, it was in there when it was a 308 and is still in there now. The good news is the cmmg barrel was crap, 1.5 moa was best it could do with a random shot thrown out here or there that could not be blamed on enviro or shooter. I feel vindicated in my skill as a shooter as the initial load development resulted in 3 out of 5 different loads going under .5" at 100 from prone bipod/rear bag. my barrel really liked 123 amax, 44.0 and 44.5 gr h4350 and bullets set to mag length resulted in a .378" and .421" 5 shot group. 140 bthp hornady match and 42.4 gr h4350 shot a .471" 5 shot. This was during initial break-in. after 25 rds cleaning at 5 rds, shoot 10 and clean, shoot 10 and clean. Barrel cleans up real good with little to no trace of copper, I use kg1 for carbon and boretech eliminator for copper. Numbers over the chronograph were lower then my two 26" bolt guns, but that was expected. the 123 amax/44.0 was 2877 with sd of 7.84. 123amax/44.5 was 2907 with sd of 14.23. I built a savage 10 tact with a shilen select match 26" 6.5cm barrel and happened to have it on hand when I was at the range that day, thought I would try it's load in the gasgun. That load is 42.4/140amax at 2.210from the ogive which is mag length in the magpul lr-20 mags. This grouped awesome, i did shank the last shot, but the first 4 rds cut a .274" oblong in the paper. Quote Link to comment Share on other sites More sharing options...
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