AR-15 bcg question

[dashowdy 141]

I have a LE trade in colt 6721 HBAR made in august of 2004 just before the ban sunset. The good is it has the smaller fcg pins and takedown pins as well as the larger handguard with duel heat shields.

 

The bad is that it has the half moon carrier and unshrouded firing pin, the pin is fine and does not seem to be contacting the retainer, I understand that the M16 group can be swapped as long as it does not have the sear block, which mine does not, so...

 

Can I buy a m16 bcg and just drop it in, the gun is used so I do wonder about headspace and wear and should I get a heavier buffer or will the stocker work, I dont think it is the newer Heavy buffer that colt uses. It is a wierd rifle in that it has some updates like the new ones but some old crap as well.

 

What should I do here guys, leave it or swap it. If so mfg. reccomendations?

[fast2gnt 16]

Any bcg shall work, just depends on your budget.

[SwissyJim 117]

yeah, any BCG should be good. I like to stay with the ones I know... Colt, BCM, so on. Really, as long as they are C158 bolts and properly staked gas keys I'm happy. That said, I have the stuff to stake my own so really it's just the material that concerns me.

 

As far as the buffers, I like to go as heavy as my rifle will run reliably. Slows down the cycling, and reduces any problems... to a point. Too heavy an you induce more problems. I've switched all my AR's over to Vltor A5 systems, they seem to run so much better, smoother, and slightly slower cycling.

 

I do headspace  any rifle that I change barrels or bolts in, just to be safe. I know some guys that haven't and have no problems, but on the other hand I have seen the results of NOT headspacing, and I don't want to be on the receiving end of that fiasco.

 

The only realy way to know if the buffer spring/buffer/BCG combo works is to shoot it. It took a few tries with different buffers to get mine dialed in, but not that I have... it shoots so damn nice it's scary.

but then I takemy S308 out and forget I have an AR...

[storm6490 2,768]

drop in a surplus assembly and go at it. she will still be a 5.56

 

It's nutted M16A2 so you can slop parts around in them. Please clean the shit out of it first. The discrepancies will quickly be removed and you will find it when you detail your rifle again.

 

Don't fuck with the buffer. It's a waste of money and time. It's a colt, leave it alone.

 

If you have an A2 and it works fine, I would leave it alone. Whats so bad about having the carrier that can't possibly run 3 shot bursts?

Edited November 16, 2013 by Stryker0946

[dashowdy 141]

thanks for the replies guys, stryker I would prefer at least a ar 15 semi carrier so the back of the firing pin is shrouded and not reseting the hammer. I guess it could potentially fail if that retaining pin broke or bent on the bolt.

 

I have the money to pick up a bcm, but is it really worth it like stryker said, It is a solid bolt I just hate the unshrouded firing pin on the half moon carrier.

Edited November 16, 2013 by dashowdy

[storm6490 2,768]

Well, do about 20K rounds and inspect the firing pin retaining pin. You will find out it's harder than you in a strip club. The carrier will go before that unobtanium GI pin.

[dashowdy 141]

Haha will do stryker, I will pick up some spare bolt parts just in case.

 

 

I know what you mean, been to the spearmint rhino in vegas, must be a hard ass pin.

[HB of CJ 1,263]

You might also want to change out the hammer, (if necessary) when you go to the M16 type BC.  You MAY have the older SP-1 hammer which MAY not be compatable with SOME M16 FPs.  Not always.  Even Colt had several combinations of stuff; most which worked together, a few that did not.  Enjoy.  HB of CJ (old coot)

 

If you have the older Colt SP-1 FCG and BCG, understand that they may be somewhat $collectable$ in nature and might fetch some $$$ on the net auctions.  FWIW.  Might be enough to pay for cool hi grade current stuff.  If you have the SP-1 stuff, how about swapping out ALL of it except I would consider keeping the original bolt. 

[Sdustin 578]

If you don't want to spend alot just buy a carrier. Use your bolt. Maybe rebuild the extractor.

[EthanM 514]

I'm a big fan of bcm. I just purchased another one of their bolts for a build.

[dashowdy 141]

I appreciate the advice guys, I realize the bolt could be worth it to someone who has a sear blocked colt lower and needs a bcg that would work. I found some spikes m16 bcg for a good price so I may go with that as it is affordable but still well reviewed.

 

I really dont want to screw with the buffer, I think it has a carbine buffer right now, will this be sufficient for the m16 bcg, I am not trying to lessen recoil, I just want it to cycle well even with stuff that may be loaded a little weak.

 

Or would just a straight semi ar 15 carrier be a better choice and just use my original bolt? I know I am a bit of a noob in AR land but I am learning.

[Sdustin 578]

Id get an auto one slightly more weight. And just shoot it with tge buffer you have. If it works good if not then try other buffers.

[Capt Nemo 882]

I've got one of the newer SP1's.  Those unshrouded FP's suck!  Rather have the 16 carrier and unnotched 16 hammer.

 

And HEADSPACE EVERY TIME A BOLT CARRIER GROUP OR BARREL IS CHANGED!!!!!  I've seen one go BOOM!  NOT COOL!!!

[dashowdy 141]

I am going to use the old bolt on a new stag carrier, this is my easiest way out and should eliminate any headspace issues.

[Sdustin 578]

For what its worth a local gunsmith told me ges built thousands from new parts and headspaced all of them and never had one be out.

 

How would you adjust the headspace on an ar?

[dashowdy 141]

Monty I believe it is headspaced when barrel is put in.

[Sdustin 578]

I think the only way to headspace would be to move the barrel extension that's normally always pressed on when the barrel is made.

[dashowdy 141]

I am going to get a carrier for now, I will more than likely get a m16 bcg but the semi is closest in weight to what I have in the half moon design, so better chance it will work without changing buffer. Once i am a bit farther along I may do the switch, but I know the stock bolt will be headspaced properly in a new carrier

[mostholycerebus 415]

What should I do here guys, leave it or swap it. If so mfg. reccomendations?

Are you having malfunctions? Why do you want to swap the BCG on a working gun?

 

Headspace is set when the barrel maker puts the extension on with 150ft-lb of torque. Some AR15 assemblers have put together and sold hundreds of rifles never bothering to check headspace. Though you could always be the new example. How many rounds has this rifle seen that you think the headspace may be off?

 

I build with an adjustable gas block, so I dont have to fiddle with heavy carriers, heavy buffers, heavy springs. I have a Saiga if I want a heavy rifle.

 

If yer gonna replace anyway, at least make it an upgrade, get a NiB BCG.

Edited November 19, 2013 by mostholycerebus

[dashowdy 141]

It is the unshrouded firing pin that is my bugaboo, the retainer get bent and chewed up as a result, the rifle has been shot some but not bad, use to belong to north carolina sbi.

 

or pick up a spikes m16 bcg from aim for 140 shipped?

 

best guess the gun is 10 years old, spent 6 years in service with qualification twice a year, maybe 1.5k to 4k rounds maybe less as the rifling is excellent and the feedramp looks great.

Edited November 19, 2013 by dashowdy