Good Backup BCG

peeplwtchr · May 29, 2020

Hi All-

So I am far enough along in building out my guns with the essential accessories to start thinking about backup parts. I have the DD V7, and S&W M&P AR15s, and am looking for a hopefully inexpensive, yet reliable backup BCG that is well known to be "Upper agnostic". This BCG may never be used. I want to be able to use it in either gun if necessary. Any suggestions, and why?

Chuck R. · May 29, 2020

I've had great success with both of these, and they're very reasonable:

PSA nitrided:

https://palmettostatearmory.com/psa-5-56-nitride-mpi-full-auto-bolt-carrier-group-516446953.html

They'll often list them on sale for their daily deals.

One of my favorites is one of the Toolcraft nitrided, you can also find them on sale pretty reasonably:

https://www.armorally.com/shop/toolcraft_5-56_nato_black_nitride_bolt_carrier_group/

I check headspace to make sure, only takes a couple minutes with the right tools, but a lot of guys don't bother.

taliv · May 29, 2020

it's your $ so do what you want, but the carrier is almost never a failure part. i can't think of ever seeing one fail when the gas key was properly attached.

buying a spare bolt is definitely a good idea. i am a fan of BCM's bolt repair kits. they'll handle the wear parts (extractor, springs, gas rings). and in the off chance you crack a bolt lug or at the cam pin hole, you'll have a spare bolt. i'd also keep a spare firing pin (the tips can get damaged from pierced primers) and the small parts like the pin that goes in the side to hold the firing pin in. if you're shooting a lot, that makes sense because you'llwear all those out.
the one advantage of the entire spare BCG is you don't have to take it apart. just pull the old one out and slide the new one in.

there are some old threads on all the wear parts on ARs. I used to keep a tackle box in my truck full of parts and tools.

peeplwtchr · May 29, 2020

Chuck R. said:
I've had great success with both of these, and they're very reasonable:

PSA nitrided:

https://palmettostatearmory.com/psa-5-56-nitride-mpi-full-auto-bolt-carrier-group-516446953.html

They'll often list them on sale for their daily deals.

One of my favorites is one of the Toolcraft nitrided, you can also find them on sale pretty reasonably:

https://www.armorally.com/shop/toolcraft_5-56_nato_black_nitride_bolt_carrier_group/

I check headspace to make sure, only takes a couple minutes with the right tools, but a lot of guys don't bother.

Check headspace?

Varminterror · May 30, 2020

I’m with @taliv - the entire carrier won’t be the problem, just the bolt or firing pin. I’ve seen pictures of broken cam pins, but never broken one myself. Have damaged FP’s and broken lugs.

Is this going to be a “low cost spare part to get me back in action until I get a proper replacement,” or a “proper replacement waiting for its turn”? I usually have a spare BCG just because they haven’t grown into complete uppers or rifles yet, but I’d just get a spare high performance bolt, maybe splurge on a JP enhanced bolt, and be happy.

My personal “spare” BCG’s have often been toolcraft, Bushmaster, or Rock River. But like I said, they usually get replaced as they grow receivers and barrels like mold...

Shawn Dodson · May 30, 2020

Either an SOLGW or BCM BCG. Both are made by Microbest, which is one of the top MilSpec producers of quality BCGs.

peeplwtchr · May 30, 2020

taliv said:
it's your $ so do what you want, but the carrier is almost never a failure part. i can't think of ever seeing one fail when the gas key was properly attached.

buying a spare bolt is definitely a good idea. i am a fan of BCM's bolt repair kits. they'll handle the wear parts (extractor, springs, gas rings). and in the off chance you crack a bolt lug or at the cam pin hole, you'll have a spare bolt. i'd also keep a spare firing pin (the tips can get damaged from pierced primers) and the small parts like the pin that goes in the side to hold the firing pin in. if you're shooting a lot, that makes sense because you'llwear all those out.
the one advantage of the entire spare BCG is you don't have to take it apart. just pull the old one out and slide the new one in.

there are some old threads on all the wear parts on ARs. I used to keep a tackle box in my truck full of parts and tools.

This is true, my scope is probaly wrong, a

Varminterror said:
I’m with @taliv - the entire carrier won’t be the problem, just the bolt or firing pin. I’ve seen pictures of broken cam pins, but never broken one myself. Have damaged FP’s and broken lugs.

Is this going to be a “low cost spare part to get me back in action until I get a proper replacement,” or a “proper replacement waiting for its turn”? I usually have a spare BCG just because they haven’t grown into complete uppers or rifles yet, but I’d just get a spare high performance bolt, maybe splurge on a JP enhanced bolt, and be happy.

My personal “spare” BCG’s have often been toolcraft, Bushmaster, or Rock River. But like I said, they usually get replaced as they grow receivers and barrels like mold...

It'll be this: "“low cost spare part to get me back in action until I get a proper replacement,”. I want the easiest route to back in action, but want it to work.

TBL65 · May 30, 2020

For an inexpensive option BCG I would look into Toolcraft or maybe even a PSA premium.

For a premium back up BCG id look at BCM or SOLGW.

Ks5shooter · May 30, 2020

Toolcraft here as well. Be patient and keep an eye out for the sales.

Chuck R. · May 30, 2020

peeplwtchr said:
Check headspace?

https://www.ammoland.com/2018/01/headspace-check-ar15-rifle/#axzz6Nvzc84Pd

It's a peace of mind thing, probably about 99.98% of AR15 bolts and barrel extensions are good to go. I've built multiple AR15s, early on I bought a set of headspace gauges and a bolt disassembly tool (not needed but makes things easier). The whole kit is about $80. Since then I've had 1 bolt that wasn't in spec and closed on a Colt field gauge. The same bolt failed headspace check in multiple carbines.

Cool part was I could speak to the manufacturer explaining to him exactly what was happening and got a replacement.

Another method some guys use is to just shoot it and measure their brass. I'd just rather buy the stuff to do it right and actually the easy way. It's also easier to check before the barrel's installed. That way IF there's a barrel extension issue I haven't installed it yet.

Good Backup BCG

peeplwtchr

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