Noticed some unusual wear on AR15 firing pin

[OldTengu]

also could just be from beating against the retaining pin

After taking the bolt carrier down again, this looks like a possible explanation. Wear pattern on firing and retention pin match up. Still not great, but at least I have a possible answer. The firing pin moves freely, and bolt carrier cams as it should, at least manually.

 

[User 1234]

Unless you see signs of cracking I would not worry about it. Check it each time you clean it. Or replace firing pin and firing pin retaining pin with Colt parts and keep these as backups.

 

[Cerberus Group]

From the pic of underside of the bolt carrier, it appears the firing pin is not shrouded...thus the hammer rides against the firing pin during recoil/hammer reset and not the carrier itself, which creates accelerated wear.

 

[Cerberus Group]

The one on the right is unshrouded...yours look like that?

 

[OldTengu]

The one on the right is unshrouded...yours look like that?

View attachment 585136

Yup.

 

[Pandaz3]

I think your stock Ruger BCG will last, and a nice Nitrated BCG will cost a quarter the price of a whole Ruger 556, and you can find many more even higher.
I would buy a new stronger firing pin, if trying to stay cheap. No I would not! I'd buy a high end BCG and FCG too because I have the AR disease.
Oh I don't think it's Ruger's fault, the AR556 is a economy gun.

 

[Cerberus Group]

There's a lot of ARs that are not suited to high round count, but are made for the occasional user...this happens to be one of them.

There are some parts companies that go dumpster diving for other companies rejects, rebrand them as their own and sell them...ugh.

There are also companies that have high quality parts...but their BCGs are lacking in quality for long term use.

There have been many BCG maker names mentioned on here as being good to go, some quite well known...but they are not, they won't hold up to hard long term use.
For the occasional user...the average person who goes out 4-5 times a year, fires 200-400 rounds at a time, then back in the safe it goes...for those...most any BCG will work.

A shopping list for a quality BCG;

Bolt:

Carpenter Steel No. 158
Heat treated per mil-spec,
Shot peened per ASTM B851/SAE AMS2430S,
Individual high pressure/proof (HP)
Individual magnetic particle inspection ASTM E1444/E1444M (MP)


Extractor:

Made from 4340 tool steel alloy per SAE AMS6415T/AMS6484D (vs 4140),
Heat treated
Shot peen per ASTM B851/SAE AMS2430S.


Extractor Retaining Pin:

Precision machined and ground S7 Tool Steel
Heat treated per ASTM A681-08
Shot peened per mil-spec


Extractor Spring:

Sprinco 5 coil, ASTM Grade A401 Chrome Silicon wire stock or
Specialized Armament Warehouse HD Green Spring
Please - Do not use the O-Ring!
Mil-spec black insert/synthetic elastomer extractor buffer (nitrile-butadiene, shore hardness 80+/-5 durometer per MIL-PRF-6855)


Ejector:

S7 Tool Steel
Heat treated per ASTM A681-08
Shot peened per Mil-Spec


Ejector Spring:

Heat treated
Mil Spec


Gas Rings:

Standard stainless steel per Mil-Spec X3


Carrier:

Machined from AISI 8620 aircraft qualty alloy per ASTM A108/A322-13
Full auto profile
Heat treated
Carburized/strain relieved, hard chrome bore
Precision ground gas key interface

Gas Key:

Machined from 4130 chromoly steel alloy per ASTM A108/A322-13
Heat treated, hard chrome internal
Permatex sealed
Grade 8 hex screws torqued and staked all per mil-spec

Cam Pin:

Precision machined 4340 chromoly steel alloy per SAE AMS6415T/AMS6484D
Heat treated/processed per mil-spec

Firing Pin:

Precision machined 8640 steel alloy
Heat treated/processed per mil-spec
Hard chrome plate

Firing Pin Retaining Pin:

Precision machined from 1038 carbon steel
Heat treated/processed per mil-spec

From the specs above...who qualifies?

Colt, BCM, Sionics, Sons Of Liberty Gun Works, Daniel defense. If the company selling their BCG won't give specs, and won't do it when contacted, look elsewhere.

130.00 - 150.00 for a quality BCG is cheap insurance...its also the heart of the AR platform.

 

[titsonritz]

There's a lot of ARs that are not suited to high round count, but are made for the occasional user...this happens to be one of them.

There are some parts companies that go dumpster diving for other companies rejects, rebrand them as their own and sell them...ugh.

There are also companies that have high quality parts...but their BCGs are lacking in quality for long term use.

There have been many BCG maker names mentioned on here as being good to go, some quite well known...but they are not, they won't hold up to hard long term use.
For the occasional user...the average person who goes out 4-5 times a year, fires 200-400 rounds at a time, then back in the safe it goes...for those...most any BCG will work.

A shopping list for a quality BCG;

Bolt:

Carpenter Steel No. 158
Heat treated per mil-spec,
Shot peened per ASTM B851/SAE AMS2430S,
Individual high pressure/proof (HP)
Individual magnetic particle inspection ASTM E1444/E1444M (MP)


Extractor:

Made from 4340 tool steel alloy per SAE AMS6415T/AMS6484D (vs 4140),
Heat treated
Shot peen per ASTM B851/SAE AMS2430S.


Extractor Retaining Pin:

Precision machined and ground S7 Tool Steel
Heat treated per ASTM A681-08
Shot peened per mil-spec


Extractor Spring:

Sprinco 5 coil, ASTM Grade A401 Chrome Silicon wire stock or
Specialized Armament Warehouse HD Green Spring
Please - Do not use the O-Ring!
Mil-spec black insert/synthetic elastomer extractor buffer (nitrile-butadiene, shore hardness 80+/-5 durometer per MIL-PRF-6855)


Ejector:

S7 Tool Steel
Heat treated per ASTM A681-08
Shot peened per Mil-Spec


Ejector Spring:

Heat treated
Mil Spec


Gas Rings:

Standard stainless steel per Mil-Spec X3


Carrier:

Machined from AISI 8620 aircraft qualty alloy per ASTM A108/A322-13
Full auto profile
Heat treated
Carburized/strain relieved, hard chrome bore
Precision ground gas key interface

Gas Key:

Machined from 4130 chromoly steel alloy per ASTM A108/A322-13
Heat treated, hard chrome internal
Permatex sealed
Grade 8 hex screws torqued and staked all per mil-spec

Cam Pin:

Precision machined 4340 chromoly steel alloy per SAE AMS6415T/AMS6484D
Heat treated/processed per mil-spec

Firing Pin:

Precision machined 8640 steel alloy
Heat treated/processed per mil-spec
Hard chrome plate

Firing Pin Retaining Pin:

Precision machined from 1038 carbon steel
Heat treated/processed per mil-spec

From the specs above...who qualifies?

Colt, BCM, Sionics, Sons Of Liberty Gun Works, Daniel defense. If the company selling their BCG won't give specs, and won't do it when contacted, look elsewhere.

130.00 - 150.00 for a quality BCG is cheap insurance...its also the heart of the AR platform.

Amen, preach it, brother.

 

[titsonritz]

The one on the right is unshrouded...yours look like that?

View attachment 585136

AKA, full auto carrier, semi auto carrier and half moon carrier. Hmmm, I wonder which one I want in my gun...

 

[Pandaz3]

Well all mine are full auto, I try to buy all small parts from Colt as they meet the above specs.

 

[Cerberus Group]

Well all mine are full auto, I try to buy all small parts from Colt as they meet the above specs.

Brownells is an easy place to find Colt parts...am sure there are other outlets.

 

[DizzyJ]

I've got a S&W M&P 15T with about 10,000 rounds through it. Now you've got me curious.....

 

[Cerberus Group]

Not saying that every BCG that doesn't meet the above specs are going to fail...just don't hear of the above spec BCG fail as nearly as much as those that do.

I've got a 2006 Ford Escape Hybrid that has close to 430,000 miles on it, and burns less than a quart of oil in a 10,000 mile oil change interval...doesn't mean I'd trust every Ford Escape to do that.