AR Sponsor
Posted: 5/11/2014 9:33:15 AM EDT
|
OK this is for you AR10-type guru's.
I have an ALL FACOTRY unmolested DPMS LR-65 that shoots great group wise. HOWEVER... is simply short strokes to the point where it will eject and feed MOST of the time, but NEVER locks back on the last round. I'm a reloader and have reloaded for over 25 years... the ammo I've tried has been from mild to HOT where pressure signs are present and the rifle acts the same. I've oiled the BCG like DPMS said and at first it was a SINGLE SHOT rifle but things got better by the 100 round mark... to where it is now... no longer a single shot BUT still I get a SS jam once ever 10 or so rounds with it NEVER locking back when empty. Because of the care and craftsmanship of the ammo, along with various bullet weights and charge weights, I'm quite SURE it is not an ammo issue. DPMS won't help because of this... not slamming them, their rules. I've removed the gas block, perfect alignment and no signs of leakage there or the BCG... all those things look GTG... In short, I think the barrel gas port is JUST EVER SO SLIGHTLY undersized. QUESTION- I noticed the factory BUFFER is long and was wondering if I could TRY to switch it out with a CARBINE BUFFER in hopes of reducing some of the spring compression/force... any potential problem trying that? I also thought about cutting 2 coils at a time to attempt to reduce the spring resistance... bad idea? Open to suggestions as I don't have the ability to mess with the barrel gas port. |
|
UPDATE- well I said screw it and put a standard AR15 carbine buffer in the rifle and it now eats what I feed it. For the first time ever the BCG locks back. BCG and buffer appear to be cycling slightly farther back allowing for the mag follower to push the bolt catch up locking the BCG back.
Tried two different loads that would not do this previously... so obviously the shorter/lighter buffer is lessening the resistance enough for everything to work properly. Anyone in the know see any potential issues? Looks like issue is resolved but tomorrow I'll have more time to make sure. |
|
Quoted:
Your carrier key is probably running into your receiver now. LR-308 rifle buffers and AR-15 rifle buffers are different. LR-308 buffers are slightly shorter. I think I'd reccomend getting a JP captured spring. Thanks for the input... I ran both buffers today and both worked 100%... perhaps messing with the gas block did the trick. Round after round, even with ammo proven to SS before, the bolt locked back as it should have been doing all along. As of now, I'm back to the factory buffer and all looks well. Fired another great group, this time .650" which is damn great for a factory gas gun. The rifle does not like the 120 A-Max it went about 1.5" or so. Still not bad at all. |
|
QUESTION- I noticed the factory BUFFER is long and was wondering if I could TRY to switch it out with a CARBINE BUFFER in hopes of reducing some of the spring compression/force... any potential problem trying that? It isn't a potential problem, it's a guaranteed problem to use a carbine buffer in a rifle extension without a spacer. Here's why: This system is designed to bottom out the bumper pad in the rear of the extension. If your recoil spring coils impact each other, spring life will deteriorate rapidly, and malfs will begin to occur. Additionally, as mentioned above, you're looking at impacting the rear of the carrier key into the extension tube or lower receiver, causing damage. Sounds like you figured it out by just reassembling the gas system. Another issue is carrier key clipping the gas tube. When I assemble an upper, one of the most important areas I look at is trouble-shooting the carrier key to gas tube interface. If there is binding, problems will arise, and they usually end up in a short-stroke malf. You also see this with gas tube flanges that are worn from a binding arrangement between the key and tube. Carrier keys are supposed to be chrome lined inside, so they will often win against the gas tube. |
|
Quoted:
It isn't a potential problem, it's a guaranteed problem to use a carbine buffer in a rifle extension without a spacer. Here's why: This system is designed to bottom out the bumper pad in the rear of the extension. If your recoil spring coils impact each other, spring life will deteriorate rapidly, and malfs will begin to occur. Additionally, as mentioned above, you're looking at impacting the rear of the carrier key into the extension tube or lower receiver, causing damage. Sounds like you figured it out by just reassembling the gas system. Another issue is carrier key clipping the gas tube. When I assemble an upper, one of the most important areas I look at is trouble-shooting the carrier key to gas tube interface. If there is binding, problems will arise, and they usually end up in a short-stroke malf. You also see this with gas tube flanges that are worn from a binding arrangement between the key and tube. Carrier keys are supposed to be chrome lined inside, so they will often win against the gas tube. Quoted:
QUESTION- I noticed the factory BUFFER is long and was wondering if I could TRY to switch it out with a CARBINE BUFFER in hopes of reducing some of the spring compression/force... any potential problem trying that? It isn't a potential problem, it's a guaranteed problem to use a carbine buffer in a rifle extension without a spacer. Here's why: This system is designed to bottom out the bumper pad in the rear of the extension. If your recoil spring coils impact each other, spring life will deteriorate rapidly, and malfs will begin to occur. Additionally, as mentioned above, you're looking at impacting the rear of the carrier key into the extension tube or lower receiver, causing damage. Sounds like you figured it out by just reassembling the gas system. Another issue is carrier key clipping the gas tube. When I assemble an upper, one of the most important areas I look at is trouble-shooting the carrier key to gas tube interface. If there is binding, problems will arise, and they usually end up in a short-stroke malf. You also see this with gas tube flanges that are worn from a binding arrangement between the key and tube. Carrier keys are supposed to be chrome lined inside, so they will often win against the gas tube. Thanks again for the information. |
AR Sponsor