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Posted: 4/2/2012 10:48:47 AM EDT
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Took my psa 14.5 carbine to the range to sight in the acog. The bolt catch doesn't seem to be working right,the last shot doesn't keep the bcg held back. What would cause this?
Update 1- out here at the range again andstill the same problem. Different ammo,different mags and still. After I empty a mag the bolt catch works if the magazine is in the magwell,but once I drop the mag the bcg comes back forward. |
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Took my psa 14.5 carbine to the range to sight in the acog. The bolt catch doesn't seem to be working right,the last shot doesn't keep the bcg held back. What would cause this? could be weak ammo not cycling the bolt all the way. does your bolt catch work when you manually pull the charging handle all the way to the rear and engage the bolt catch? |
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Took my psa 14.5 carbine to the range to sight in the acog. The bolt catch doesn't seem to be working right,the last shot doesn't keep the bcg held back. What would cause this? could be weak ammo not cycling the bolt all the way. does your bolt catch work when you manually pull the charging handle all the way to the rear and engage the bolt catch? it moves like its supposed to. The upper already had 1000 rounds through it but its a new lower build. I was shooting black box ae223 and fiocchi 55 gr fmj. Brand new pmag |
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1.) 1000 rounds.......Did this weapon ever function normally ? 2.) If yes then, maybe this lower power ammo that you list is causing the weapon to "short stroke" ? Need more info on the weapon and on any ammunition that it has been able to cycle. the upper worked flawlessly on another lower. I've shot everything from wolf,ae223, federal xm 193 etc etc. The lower is a new build,this is the first time shooting if. I have pmc bronze and xm193 that il shoot tomorrow and see if it helps. |
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Be sure you can manually lock it back first.
Then: What type of buffer are you running/ Too heavy of a buffer can cause this. What spring are you running? Make sure you are running a mil-spec Carbine spring, not a rifle length What buffer tube are you running? Some aftermarket buffertubes are not to spec and are shallower than others. |
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1.) 1000 rounds.......Did this weapon ever function normally ? 2.) If yes then, maybe this lower power ammo that you list is causing the weapon to "short stroke" ? Need more info on the weapon and on any ammunition that it has been able to cycle. the upper worked flawlessly on another lower. I've shot everything from wolf,ae223, federal xm 193 etc etc. The lower is a new build,this is the first time shooting if. I have pmc bronze and xm193 that il shoot tomorrow and see if it helps. When troubleshooting, go after the easy stuff first.....always. The first thing I would look at are the buffers. Are they different weights ? Buffer springs ? If you swap them always change one component at a time so you can track progress. |
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Be sure you can manually lock it back first. Then: What type of buffer are you running/ Too heavy of a buffer can cause this. What spring are you running? Make sure you are running a mil-spec Carbine spring, not a rifle length What buffer tube are you running? Some aftermarket buffertubes are not to spec and are shallower than others. It's a brownells tube spring and buffer. the tube is tight on my lmt sopmod stock.real tight. |
il check some more things at the range tomorrow.
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Did you assemble it yourself? If so, you may have mixed up the bolt catch spring and the disconnector spring. If you have the disconnector spring behind the bolt catch, it will cause this. 99% sure this is the problem. I always get the two springs mixed up. |
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Does it lock back when you pull the bolt back manually and engage the catch? Did you try only one magazine? Yes it does lock back when I manually engage the catch.I just tried it. Thus far you describe a classic "short stroke " condition. Have you compared buffers and springs with the fully functional lower ?? |
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Are you are using a 20 round pmag? If so then its your problem. They are notorious for this. Nope.Brand new 30 round fde pmag Use whatever mags were functioning with the other lower. Don't introduce any new variables. Will do. Il try a used mag tomorrow and see if that helps any. |
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Are you are using a 20 round pmag? If so then its your problem. They are notorious for this. Nope.Brand new 30 round fde pmag Use whatever mags were functioning with the other lower. Don't introduce any new variables. Will do. Il try a used mag tomorrow and see if that helps any. Assuming you don't have access to the previous, functioning lower, what weight buffer do you have in this lower ? |
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Are you are using a 20 round pmag? If so then its your problem. They are notorious for this. Nope.Brand new 30 round fde pmag Use whatever mags were functioning with the other lower. Don't introduce any new variables. Will do. Il try a used mag tomorrow and see if that helps any. Assuming you don't have access to the previous, functioning lower, what weight buffer do you have in this lower ? I still have the other lower.Il switch them around and see if anything is different. Its a CAR buffer that I got from a seller on the EE. Im trying to find a spikes st-t2 in stock anywhere. The buffer tube is really tight on the lmt sopmod stock for some reason. |
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I had the same problem with a Spikes lower and Stag parts kit. My bolt catch was dragging in the lower. Functioned nice and smooth with your finger to hold the bolt back but as soon as a mag was inserted it would bind and not catch the bolt. Fix was to remove the bolt catch and remove the rough finsih on the back edges with a stone, I could actually see the spot where it was contacting the lower.
Several hundered rounds later, I have not had a repeat malfunction. |
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Are you are using a 20 round pmag? If so then its your problem. They are notorious for this. Nope.Brand new 30 round fde pmag Use whatever mags were functioning with the other lower. Don't introduce any new variables. Will do. Il try a used mag tomorrow and see if that helps any. Assuming you don't have access to the previous, functioning lower, what weight buffer do you have in this lower ? I still have the other lower.Il switch them around and see if anything is different. Its a CAR buffer that I got from a seller on the EE. Im trying to find a spikes st-t2 in stock anywhere. The buffer tube is really tight on the lmt sopmod stock for some reason. Hard to say what you have for tubes without a caliper. As you may know, a commercial tube will have a larger O.D. The I.D.s will be the same so it won't affect function. The CAR buffer is the lightest....The ST-2, I believe is between H and H2 in weight....it won't help this situation. |
| I see this every once in a while in my gun too. Bolt locks back but when i drop the mag it releases the bolt catch. I think the spring might just be a little stiff and i have too much lube in the gun so there is not enough friction to keep the catch from dropping back down. |
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You still haven't checked the springs as I suggested in the first post of this thread, have you? He didn't check my buffer question on the first request.... When troubleshooting, the n00bs get hit with so many suggestions, you have to ask two or three times to get them to check something. Information overload. Standard procedure. |
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if the disco and bolt catch springs were swapped around would he be having issues with the disco as well? I'm not sure. I never had any issues with mine while they were swapped, but the bolt catch just outright refused to hold the BCG to the rear after the last round. |
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if the disco and bolt catch springs were swapped around would he be having issues with the disco as well? I'm not sure. I never had any issues with mine while they were swapped, but the bolt catch just outright refused to hold the BCG to the rear after the last round. That much extra tension on the disconnector would barely be noticeable, if at all, especially considering the short distance it travels. 86HMMWV, I like your theory, and you may have just taught me a good troubleshooting trick. OP just doesn't want to pull his hammer pin, trigger pin, and bolt-catch roll pin, if he doesn't have to. Can't say I blame him for that, but if nothing else is working... |
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if the disco and bolt catch springs were swapped around would he be having issues with the disco as well? I'm not sure. I never had any issues with mine while they were swapped, but the bolt catch just outright refused to hold the BCG to the rear after the last round. That much extra tension on the disconnector would barely be noticeable, if at all, especially considering the short distance it travels. 86HMMWV, I like your theory, and you may have just taught me a good troubleshooting trick. OP just doesn't want to pull his hammer pin, trigger pin, and bolt-catch roll pin, if he doesn't have to. Can't say I blame him for that, but if nothing else is working... Which is the disconnector spring? Il tear the lower apart tonight and see if I can fix it. |
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Which is the disconnector spring? Il tear the lower apart tonight and see if I can fix it. The disconnector spring and the bolt catch spring are nearly identical, but the disconnector spring is flared on one end. This is a disconnector spring. Notice that it's larger on one end: 
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if the disco and bolt catch springs were swapped around would he be having issues with the disco as well? I'm not sure. I never had any issues with mine while they were swapped, but the bolt catch just outright refused to hold the BCG to the rear after the last round. That much extra tension on the disconnector would barely be noticeable, if at all, especially considering the short distance it travels. 86HMMWV, I like your theory, and you may have just taught me a good troubleshooting trick. OP just doesn't want to pull his hammer pin, trigger pin, and bolt-catch roll pin, if he doesn't have to. Can't say I blame him for that, but if nothing else is working... Which is the disconnector spring? Il tear the lower apart tonight and see if I can fix it. That's the spring that goes in the top rear of the trigger. The two parts that pivot on your trigger pin are the trigger, and the disonnector. You'll have to remove your grip, safety, hammer pin, and trigger pin. Of course, to swap out the bolt-hold spring, you'll just have to remove the roll pin it pivots on. Sounds like you might benefit from having the build your own lower instructional thread handy while you tear your lower apart. You also might want to read through all the steps of building a lower, a few times, before you pick up tools. |
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