A Tale of Two Crush Washers, or Two Crush Washers One Barrel, and other AR oddities

[cmshoot]

Crap BCG‘s have been the bane of my existence for several months now. Spend a few extra bucks and get a truly milspec BCG.

Microbest (also labeled as SOLGW, BCM, DD, and more)

AO Precision

Sionics (FCD)

Stay away from nitride and NiB.

Look for manganese phosphate, hard chrome, or NP3. The last two won’t make the gun run any better than the first one, but they are arguably easier to clean.

Manganese phosphate versions are available for around $160. I’ve seen Microbest BCG’s on sale fairly recently for as little as $100.

There are 8 stages in the cycle of operations for the AR. The BCG is the only part that is involved in all 8 stages.

Can’t count how many AR’s I’ve “fixed” by replacing their crap BCG with a milspec version.

 

[User170512]

Crap BCG‘s have been the bane of my existence for several months now. Spend a few extra bucks and get a truly milspec BCG.

Microbest (also labeled as SOLGW, BCM, DD, and more)

AO Precision

Sionics (FCD)

Stay away from nitride and NiB.

Look for manganese phosphate, hard chrome, or NP3. The last two won’t make the gun run any better than the first one, but they are arguably easier to clean.

Manganese phosphate versions are available for around $160. I’ve seen Microbest BCG’s on sale fairly recently for as little as $100.

There are 8 stages in the cycle of operations for the AR. The BCG is the only part that is involved in all 8 stages.

Can’t count how many AR’s I’ve “fixed” by replacing their crap BCG with a milspec version.

This seemed like a good read on the topic.

The M4 cycle of function.

Im hopeful that members will find this helpful when troubleshooting their ARs. For the most part this comes straight from DOA FM 3-22.9 Rifle Marksmanship M16A1, M16A2/3, M16A4, and M4 Carbine. I have also included the relevant sections from TM 9-1005-319-23&P on troubleshooting each cycle...

www.m4carbine.net

 

[Braxton1]

I was at a "We build AR's" shop in North Carolina this weekend. I actually got to watch the "gunsmith" installing a pencil barrel into an Upper Receiver. It didn't slip in. By the time I left, it had devolved to the point of "Use that big rubber mallet over there".... He put the muzzle on the table and was beating the heck out of the rear of the Upper to force it on. The customer was standing right there watching all of this.

I would hope that somebody would check for burrs or other defects before resorting to such brutish force... :-) His last words to the customer before the whacking began was "I don't know WHAT'S going on here! I've never seen this before".

This was one of those shops where everyone behind the counter (including the two 450 pounders) was an "Operator".

 

[rOmiLaYu]

This was one of those shops where everyone behind the counter (including the two 450 pounders) was an "Operator".

 

[Control for Smilers]

I was at a "We build AR's" shop in North Carolina this weekend. I actually got to watch the "gunsmith" installing a pencil barrel into an Upper Receiver. It didn't slip in. By the time I left, it had devolved to the point of "Use that big rubber mallet over there".... He put the muzzle on the table and was beating the heck out of the rear of the Upper to force it on. The customer was standing right there watching all of this.

I would hope that somebody would check for burrs or other defects before resorting to such brutish force... :-) His last words to the customer before the whacking began was "I don't know WHAT'S going on here! I've never seen this before".

This was one of those shops where everyone behind the counter (including the two 450 pounders) was an "Operator".

jesus...just use a heat gun like a normal human, lol.

 

[C Drill97]

jesus...just use a heat gun like a normal human, lol.

Can’t be tight if it’s liquid

 

[BigMike]

I was at a "We build AR's" shop in North Carolina this weekend. I actually got to watch the "gunsmith" installing a pencil barrel into an Upper Receiver. It didn't slip in. By the time I left, it had devolved to the point of "Use that big rubber mallet over there".... He put the muzzle on the table and was beating the heck out of the rear of the Upper to force it on. The customer was standing right there watching all of this.

I would hope that somebody would check for burrs or other defects before resorting to such brutish force... :-) His last words to the customer before the whacking began was "I don't know WHAT'S going on here! I've never seen this before".

This was one of those shops where everyone behind the counter (including the two 450 pounders) was an "Operator".

Everyone's a gunsmith until it's time to be a gunsmith.

 

[Jambo]

Can’t be tight if it’s liquid

I mean, sure, that's a last resort, but didn't this guy have an angle grinder? What kind of professional gun smith doesn't have an angle grinder? Or at least a carbide burr for the upper?

Man, I would have gone somewhere else.

 

[cmshoot]

I’ve had to heat a receiver AND seat the barrel with a plastic-coated dead blow hammer before.

You can’t heat the receiver past 225 degrees before you run the risk of damaging it, so you can only get it so hot.

You can run into issues where the barrel is designed to be thermal-fitted, AND it’s a bit on the large side of tolerances, AND the receiver is a bit on the small side of tolerances. In that case, you have the choice of forcing the barrel home, or swapping receivers/barrels until you get a “looser” fit.

I had to seat the barrel in that manner on my primary AR. Been running that gun for 2 years now with now issues. She’s accurate and reliable.

 

[BigMike]

I’ve had to heat a receiver AND seat the barrel with a plastic-coated dead blow hammer before.

You can’t heat the receiver past 225 degrees before you run the risk of damaging it, so you can only get it so hot.

You can run into issues where the barrel is designed to be thermal-fitted, AND it’s a bit on the large side of tolerances, AND the receiver is a bit on the small side of tolerances. In that case, you have the choice of forcing the barrel home, or swapping receivers/barrels until you get a “looser” fit.

I witnessed this! Tighter than little E on a banjo.