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Posted: 12/17/2009 3:24:30 PM EDT
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Hey guys. Just built an ar-style 308 and am having an issue. I can only get the bolt to lock back if i pull extremely hard on the charging handle. I am thinking i might have the wrong length buffer spring.
Here are the specs: DPMS Lower receiver & LPK, buffer tube, rifle buffer spring, rifle buffer DPMS upper receiver, carrier, charging handle. Krieger 18" SS 1:10 match barrel & bolt Ace skeleton 9.9" stock PRI MSTN QC brake Thanks |
| Actually you have this same post in the troubleshooting forum that I answered there.Check the screw in the end of the buffer tube holding on the stock/rubber pad.If it's too long it will hit the buffer and make it nigh impossible to pull back far enough to hold open. |
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308 springs are heavier than 223 springs but if you can use the bolt catch at all then the spring shouldn't be too long.
If you had too long a spring, it would stop dead short of the bolt catch. Something else might be wrong. Does it require an unusual amount of pull force the whole length of travel or does it only happen after a certain length is traveled? B-Man |
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Thanks for the replies. Tried loosening the screw on the rear of the ace stock....no change. However, I noticed that if I hold the bolt release in and pull the CH back it will lock just fine with no increased effort.
The pull effort gets harder toward the end of the pull. sometimes it will only halfway lock and if I bump the muzzle on the ground the bcg will release. Thanks for the replies. |
Try this experiment:
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Quoted:
Tried the above steps. Same amount of pull with or without spring in. What i dont understand is how i can pull the charging handle back while holding in the bolt release and it works fine........ Does the bolt catch work when an empty mag . is in place. You have not said you have fired this weapon ,have you ? Could be tight bolt catch or weak spring . |
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Yes, I am using a rifle tube.
OK, I seperated the upper and lower, removed the bcg and simulated its movement on top of the lower. I found that with a mag inserted, the bolt is getting hung up on the bolt release. Not sure why and not sure what to do to fix it. New bolt catch........ File a little bit off......????? Thanks again for everyones help. |
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Quoted:
Anyone ever have a problem with an out of spec bolt catch? Yes, I have seen a few TWISTED bolt catches that would not move freely until you took off a bunch of material. You could SEE that it somehow got twisted in the Manufacturing process. Also be on the lookout for pivot/takedown pins that are OVERSIZE at the tips. Thought I had a weird lower since the pivot pin wouldn't go into certain uppers. I found one of those a few weeks ago. Parts came from DPMS or RRA. B-Man |
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Photo's would be helpful ,if possible .Sounds like the catch is sticking ,check for full freedom of movement (you can use another M16/AR15 catch to see if its any better, I use the larger 308 ones though ).
Remove it to see if there are binding marks or burs or machining material in the spring hole . I have a billet lower that had debris in the pivot pin spring hole and had to ream it out by hand with the proper size drill bit to remove the particles in there . |
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Buffer tube and spring are definately correct. Got my 20 rd. P-mags in today and tried those with no change in performance. My digital cam just took a shit so I cant post pics.
The bottom of the bolt is hanging up on the bolt catch. If i hold the bolt catch down while charging the weapon, it functions flawlesly. Some times the little pin that sticks out of the front of the catch will get stuck behind the mag follower. I am going to order a new catch tonight and see what happens. When I take it apart to replace I will inspect for burrs or machining marks like Survivalshop mentioned. Thanks for your help guys. |
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Fulton Armory sells them for $14.95. I bought 2 bolt catches from DPMS which had hideous looking casting shuts. I then bought 2 bolt catches from Fulton. The parts sold by Fulton look better than parts from DPMS. I suspect Fulton screens them. Go to fulton-armory.com Select "308 Titan Pages" from the menu on the right, then select "308 Titan Parts & Etc" |
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Quoted:
Buffer tube and spring are definately correct. Got my 20 rd. P-mags in today and tried those with no change in performance. My digital cam just took a shit so I cant post pics. The bottom of the bolt is hanging up on the bolt catch. If i hold the bolt catch down while charging the weapon, it functions flawlesly. Some times the little pin that sticks out of the front of the catch will get stuck behind the mag follower. I am going to order a new catch tonight and see what happens. When I take it apart to replace I will inspect for burrs or machining marks like Survivalshop mentioned. Thanks for your help guys. Find out what is pushing it up. Once it is down it should stay down. |
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Quoted:
My only issue is getting the bolt to lock back. It's not shoirt stroking or anything like that. Still sounds like a catch problem . Sounds like the mag. follower does not enough pressure on it to push it (bolt catch )up to engage the bolt . Which could mean its( bolt catch ) tolerances are out or its hanging up some where. If you can push it up & it functions correctly , its working. You should be able push it up & it should spring back on its own with out hanging up or being stiff to operate. Get another catch & make sure it has complete freedom of movement . Also You said you did have a 308 full length buffer spring in there ? Have you test fired this weapon ? |
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Yes, It has a 308 Rifle length buffer spring. The problem is def in the catch. It has no problem being pushed up by the follower. What i think is happening is when the bolt is pulled back, and starts to hit the catch, the tension placed on the catch is causing it to bind and not move all the way down to allow the bolt to pass and subsequently lock. I am ordering a new catch and catch bolt from F-A. I removed the catch last night and the bcg now has full range of motion, but obviously wont lock back. Thanks for everyones help. Will report back when the parts arrive.
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Quoted: You might consider getting another bolt catch spring and detent too for a couple more bucks.Yes, It has a 308 Rifle length buffer spring. The problem is def in the catch. It has no problem being pushed up by the follower. What i think is happening is when the bolt is pulled back, and starts to hit the catch, the tension placed on the catch is causing it to bind and not move all the way down to allow the bolt to pass and subsequently lock. I am ordering a new catch and catch bolt from F-A. I removed the catch last night and the bcg now has full range of motion, but obviously wont lock back. Thanks for everyones help. Will report back when the parts arrive. |
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