BCG Staking

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BCG Staking

Postby Angryben on Sun Sep 02, 2012 9:53 pm

Hello!

I brought my newly assembled AR to the field and I had some issues with 'short stroking'. I'm going through the list of culprits I dug up online and I'm questioning if my BCG is adequately staked. It's a Stag Arms chrome BCG.

Any recommendations on where to get it restaked if you think it needs to be done? Thanks

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Re: BCG Staking

Postby JJ on Sun Sep 02, 2012 10:21 pm

Have the bolts backed out? If not, staking is doing its job just fine.
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Re: BCG Staking

Postby SparkyJeff on Mon Sep 03, 2012 1:06 am

Pics look staked well to me, but it might not have been 'good to go' before staking.
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Re: BCG Staking

Postby Hmac on Mon Sep 03, 2012 6:15 am

The staking looks OK, but is the gas key actually tightened down? Re-staking is no big deal. All you need is a padded vise, a punch, and a hammer. There can be other causes for short stroking, which you probably found in your research.

I'd start by checking the gas tube alignment, the FSB alignment, cleaning the bolt and chamber, checking and lubing (lightly, preferably with a dry lube) the buffer spring, and make sure you have an appropriate buffer (probably either an H or C) and make sure it doesn't bind. Then, I'd clean and blow some air through the gas tube using using an air compressor or some Gun Scrubber with the red tube attached in case there's some manufacturing crud partially blocking the gas port (won't help if it's only partially drilled, or if there's a burr). Then completely disassemble the BCG and soak all of the parts in solvent, scrub 'em up and reassemble. Check the gas rings while you're there, make sure all three are intact. Also check the extractor in case the problem is FTE rather than short-stroking. Look at the extractor spring and insert and O-ring (if it has an O-ring), and at the edge of the extractor to make sure it's intact and not chipped. Then I'd shoot at least a couple of hundred rounds, see if maybe the BCG parts don't just need to wear in a little. If everything else looks OK and the short-stroking persists, you might have a gunsmith check the chamber and make sure it's not oversize or gouged. If you just can't find the problem, Stag has pretty good customer service. They'll fix it for you if none of the above work.
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Re: BCG Staking

Postby Angryben on Mon Sep 03, 2012 10:00 am

Thanks for the feedback. It's frustrating but it's kind of fun getting to know my rifle better

I don't have a torque wrench to confirm they are at the appropriate torque setting, looks like 40-55 inch/lbs recommended online. Is a firm torque by hand sufficient for these screws?

Thanks!
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Re: BCG Staking

Postby Countryfried Frank on Mon Sep 03, 2012 10:25 am

Angryben wrote:I don't have a torque wrench to confirm they are at the appropriate torque setting, looks like 40-55 inch/lbs recommended online. Is a firm torque by hand sufficient for these screws?

Thanks!

Where are you located? I'd be willing to bet that there are a few of us willing to loan one out. Add in a cold beverage and you might even get some good conversation and/or advice from someone who has been there and done that.
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Re: BCG Staking

Postby yuppiejr on Mon Sep 03, 2012 11:44 am

How did you arrive at the gas key as the culprit? I'm sure a few of us would be glad to help you troubleshoot but if you could provide some specifics about your rifle and what you've done to test so far it would help a lot.

What ammo are you using? Is this a rifle style buffer/tube or carbine, have you installed an aftermarket buffer or spring? Gas system length? Does your rifle have a standard FSB or a low profile model that uses set screws?
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Re: BCG Staking

Postby Angryben on Mon Sep 03, 2012 1:56 pm

Specs:
Upper - Link to specs: http://palmettostatearmory.com/index.ph ... andle.html
PSA Charging Handle
Stag Arms Chrome BCG
Lower - SAA Lower with generic stock - Can't remember the name. Purchased from a board member
Buffer - Weighed the buffer and it's a standard carbine
Buffer Spring - Assuming it's a standard strength/length.

The only modifications I made are a new trigger guard and grip.

I took it out the other weekend and had issues right off the bat. I could fire the first round in the mag, sometimes two but then it would jam. It would eject the spent casing but not fully grab the next round, catching it right in the middle of the round (should have taken a pic). I had lubed the gun per online instructionals with EWL prior to shooting. I put in a few single rounds and confirmed that it was not locking back after shooting the last round in the mag. I was shooting Federal .223 from the 100 round packs they sell at Fleet Farm.

This may be ill-advised but I shortened the buffer spring from 11.5" to about 10.5" with a bolt cutter and took it back out. I shot thirty rounds and it locked back when the mag was empty. There were no issues on the next 50 rounds but then it started having the exact same failure and wouldn't lock back on the last round.

I don't have any reason to believe that it's gas key. I'm just thinking that I must be losing some gas if I'm using a carbine buffer and a shorter spring and I'm still having the issue.

Would that ammo be considered 'underpowered'? By the end of the day, it had about 100 rounds through it. That shouldn't be enough to get it so dirty it start 'short stroking' again, should it?

Thanks for any help.....sorry for the novel :)

I'm located in Blaine
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Re: BCG Staking

Postby Hmac on Mon Sep 03, 2012 2:39 pm

Any normal AR15 with a carbine gas system should be able to shoot that ammo all day long without a firearm-induced failure, especially with a shorter buffer spring (I think that was OK as an experiment, but you'll need to get a new carbine-length spring for when you get the problem fixed).
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Re: BCG Staking

Postby Drizzle on Mon Sep 03, 2012 4:26 pm

Since no one has mentioned mags, I will. You said it would eject fine, but not pick up the new round? Sounds like the extractor is working fine, but maybe the mag springs aren't getting the round up enough for the new round to be chambered properly. Buy a couple of new mags (PMAGS for choice), number your new and old mags and see which of them are in use when the issue occurs.

Also, as someone mentioned, check to make sure your gas rings are staggered. That could maybe cause more gas to get by the BCG than it's designed to and cause the bolt to not run enough. I'd recommend getting a new standard buffer spring as well.

My MP 15 needed some break in when I bought it. This may as well.
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Re: BCG Staking

Postby Hmac on Mon Sep 03, 2012 4:50 pm

Drizzle wrote:Also, as someone mentioned, check to make sure your gas rings are staggered. That could maybe cause more gas to get by the BCG than it's designed to and cause the bolt to not run enough. I'd recommend getting a new standard buffer spring as well.


In the Staggered Gas Rings: Fact or Myth category, lot's of argument. I have been taught by more than one AR15 armorer that it's a myth, including one who demonstrated that his rifle ran fine with only one gas ring in the bolt. I have no direct experience other than that, but I've never paid any attention to my gas rings.
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Re: BCG Staking

Postby rugersol on Mon Sep 03, 2012 6:42 pm

I'd swap the upper/lower with a well-running rifle ... see which way the problem goes! ;)
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Re: BCG Staking

Postby ScatterGun4015 on Mon Sep 03, 2012 6:44 pm

Like drizzle said id be looking at mags or mag release. I was having short stroke issues where the bolt would not lock back when the mag was empty. I tightened the mag release button down one more turn and have not had any issues since.....that was 1000 ago. Take a look at the button. The threads should be even with the outside edge of the button
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Re: BCG Staking

Postby bri on Wed Sep 05, 2012 3:11 pm

Before you make any further mods, make sure you try some different ammo and magazines.
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Re: BCG Staking

Postby bulletproof on Wed Sep 05, 2012 3:18 pm

You need to get that sucker welded on.
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