[kev]

158 Carpenter steel VS 9310 steel Bolt Carrier Group, which one is better and why?

Wilson combat has a 9310 steel Bolt Carrier Group on sale for $98.57, which is something like $70 off regular price.

The three main BCGs I am looking at right now:

PSA premium 158 Carpenter - was on sale for $109 when I put my order in
Rainier Arms 158 Carpenter - on sale for $119
Wilson combat 9310 steel - on sale for $98.57.

BCGs are coming down in price and I want to buy a couple of good quality ones while prices are good. I have a Palmetto State Armory premium 158 Carpenter steel bolt carrier group on the way, I ordered it last week for $109.

The other BCG I was looking at was the Rainier Arms for $119 and a lifetime warranty. But then I saw this BCG Wilson Combat has on sale.

I am probably still going to buy the Rainier Arms BCG in a couple of weeks.

http://shopwilsoncombat.com/Bolt-Carrier-Assembly-556-NATO/productinfo/TR-BCA/

The bolt assembly is machined from Carpenter No. 9310 steel, shot peened for increased strength and a includes tool steel machined extractor and ejector, appropriate extractor spring, and is HPT (High Pressure Tested) and MPI (Magnetic Particle Inspected).

I did a couple of google searches on 9310 vs 158, and from what I found there seems to be mixed opinions, both but types of steel are good?

A couple of forum threads I found out there says 158 has to be bought in bulk? While 9310 can be bought in smaller quantities, but is more expensive?

My main question is, at a sale price of $98.57 is that BCG GTG?

During the last week of November I ordered a Palmetto State Armory rifle kit that includes a basic M16 BCG which is supposed to be made from 158 Carpenter steel.

The PSA upper is going to replace a rather old bushmaster 1:9 twist upper, and the lower parts kit is going to be used to build a new lower. Then next month I want to order a new upper to complete a new rifle.

Would this Wilson Combat BCG be good for a new build?

 

[jknova]

I think 158 Carpenter is usually treated such that it is harder on the surface, softer inside, which should resist scratches while also resisting shearing because there's flex inside. I think 9310 is harder overall. I am not a metallurgist. The workmanship and treatment process probably matters more than the material.

 

[drt4life]

I would not over think it.....or over research it.....millions of opinions either way....If Wilson Combat uses them and sales them that should tell you what you need to know....I have never seen or had a BCG failure in 30+ years of shooting M16/AR15's....

 

[9mmParabellum]

psa also has a nickel baron bcg for 169.makes them much easier to clean.

 

[Unobtanium]

I would get the C158 BCG. I don't think the new "Wondercoatings" are worth all that much in practice. A good lube like FIREClean is likely to show more benefit than any coating. Even Mike Pannone isn't much impressed with the coatings out there, for BCG use, and he used Next Gen rifles and liked them. Robert Silvers (Project lead for 300BLK) could not articulate to me why his NiB carrier was better than a mil-spec phosphate carrier, finally settling on "Well, we spec each and every part, so we know it's quality". He also won't run a coated bolt because of hydrogen embrittlement risks. Their no-expense-spared BCG has a regular bolt. Same for JP with their QPQ carriers, although they are using LW (formerly) designed bolts made out of 9310 and calling them superior to 8620. Note that they compare them to 8620 and NOT C158...

Of the three you listed, I would buy the Rainier Arms BCG. That company is squared away, if a touch pricy on some items.

 

[f402mech]

I researched this topic heavily over the past few months and here is what I came up with; take it with a grain of salt. Carpenter-158 is mil-spec. 9310 "can" be better than C-158 but it all depends on who does the heat treatment and how good it is. It is this variable that keeps me away from them in general, although I do own one 9310 bolt w/ 8620 carrier as a back-up.

I would go with Rainier Arms for their customer service and warranty.

edit: Just looked at the Wilson BCG. It does not specifically say that the BOLT itself is 9310, although I would assume it is. It says that the carrier is 9310, which is the first time I've seen that. Normally it's just the bolt itself that is C158 or 9310, and the carrier is almost always made from 8620 on others that I've seen.

 

[Unobtanium]

I researched this topic heavily over the past few months and here is what I came up with; take it with a grain of salt. Carpenter-158 is mil-spec. 9310 "can" be better than C-158 but it all depends on who does the heat treatment and how good it is. It is this variable that keeps me away from them in general, although I do own one 9310 bolt w/ 8620 carrier as a back-up.

I would go with Rainier Arms for their customer service and warranty.

edit: Just looked at the Wilson BCG. It does not specifically say that the BOLT itself is 9310, although I would assume it is. It says that the carrier is 9310, which is the first time I've seen that. Normally it's just the bolt itself that is C158 or 9310, and the carrier is almost always made from 8620 on others that I've seen.

I agree. 9310 can be about as good as C158 (flip a coin, basically), but the heat-treat is FAR MORE CRITICAL than with C158. So...a bargain basement 9310 part...maybe not so good. C158 has a wider tolerance for the heat-treat.

Wilson should stick with 1911's, IMO. Their stuff just looks froofroo to me, and the use of a 9310 "carrier " isn't inspiring. It's like when LesBaer tried to argue that they put castle nuts on backwards on purpose because "they could snag on something" used normally.

This said, I just (literally just) un-boxed two PSA premium BCG's. I am very impressed. The staking looks effective, if not as over-done as my Daniel Defense, and the bolts are both laser marked MPI/HPT. The only complaint is that one came with a dull and corroded firing-pin. The rest of it looked fine, though. I just replaced the FP. Also, I replaced extractor springs each with the Colt Gold spring, so make that $115/ea). Bought them for some friends to replace the Rubber City Armory BCG's I bought for them last year, that I am highly unimpressed with, in use.

 

[kev]

edit: Just looked at the Wilson BCG. It does not specifically say that the BOLT itself is 9310, although I would assume it is.

I used the contact form on the wilson page and asked what kind of material the bolt itself is made out of.

I'll post the reply when I get it.

 

[cz7]

hands down 9310 ! its better with nickel baron less lub used ...easier to clean .....C158 with m4 gas system the bolts have broken due the speed of unlocking .....

 

[Unobtanium]

AerMet 100 is the only steel better than C158 for the task at hand.

 

[Regular Guy]

Just to chime in and to ask a question from an experienced postition.

Why do you need a nickle boron carrier? I lube with lithium grease and breakfree. I have no issues cleaning the bolt/carrier. Just wipe and relube. AR-15s don't need maticulous cleaning, they need lube. I don't see the need for NB at all.

I see this NB coating business just like the gas pistons systems, just something extra to seperate you from your money without really adding anything. I clip out a few thousand rds a year and attend at least one class a year. I have yet to have any issues with any of my ARs and especially nothing with the bolts.

Just lube your AR and save your money for ammo.

 

[AquaHull]

I just picked the melonited one up for $119 shipped

http://www.hstactical.com

I bought the sales pitch at Michigan Gun Owners by Blackwater NA

I'll see how it goes.

 

[kev]

Why do you need a nickle boron carrier?

Just to clear things up, I do not need, desire or want a nickle-boron carrier.

What I want and need is a good quality bolt carrier group at a good price for my next build.

Rainier Arms and Palmetto State Armory recently put their BCGs on sale. I have a PSA premium BCG on the way. But I need another good quality BCG for next months build.

I ordered a PSA M4 rifle kit a couple of weeks ago on black Friday. The PSA upper is going to replace a rather old bushmaster upper that was built during the assault rifle ban.

The lower parts from the PSA rifle kit are going to a new build I am working on. Hopefully I can get the BCG ordered towards the end of December and the upper ordered in Janaury.

Its not that I want a Nickle-Boron BCG, I just want a good quality BCG at a reasonable price.

 

[AquaHull]

Primary Arms just sent out a holiday email with Spikes Tactical M16 BCG with Carp 158 bolt for $109.99

 

[kev]

Primary Arms just sent out a holiday email with Spikes Tactical M16 BCG with Carp 158 bolt for $109.99

I got the same email.

For the price, that Spikes BCG it is going to be difficult to beat.

 

[luke_a]

9310 is used by the manufacturers who can't afford to purchase the large lots of C158, or just want to save money. 9310 bolts do not last as long as C158 bolts, due to less fatigue resistance. It's been hashed out by industry pro's and manufacturers years ago. If 9310 was better everybody would be using it, because it's also a hell of a lot cheaper and easier to procure. In the end you must make the choice is a broken bolt worth saving $60? I'm not saying it is or isn't, that's your choice to make.

LMT uses AerMet 100 for their enhanced bolts. I know that's not on your short list, but i felt it was pertinent to the discussion.

 

[Skyjump136]

9310 is used by the manufacturers who can't afford to purchase the large lots of C158, or just want to save money. 9310 bolts do not last as long as C158 bolts, due to less fatigue resistance.

That's just wrong.

Both are excellent metals and well suited to use as bolts. 9310 is actually stronger (around 8%) and less brittle than c158. 9310 uses molybdenum and c158 has more chrome content. The only time you would see a 9310 bolt fail before a c158 is in the case of improper heat treating.

However, major manufacturers do their heat treatments properly so you can rest assured that, in general, a name brand 9310 bolt will be stronger and longer lasting than c158. c158 is the "mil-spec" and like all things mil-spec there is heavy demand for it regardless of whether better, cheaper options exist...we also see this with barrel treatments, gas systems, etc.

I own bolts made of each material. My c158 bolts currently reside in the closet, but I haven't had failures from either kind and am perfectly comfortable using either.

 

[Unobtanium]

That's just wrong.

Both are excellent metals and well suited to use as bolts. 9310 is actually stronger (around 8%) and less brittle than c158. 9310 uses molybdenum and c158 has more chrome content. The only time you would see a 9310 bolt fail before a c158 is in the case of improper heat treating.

However, major manufacturers do their heat treatments properly so you can rest assured that name brand 9310 bolts will be stronger and longer lasting than c158. c158 is the "mil-spec" and like all things mil-spec there is heavy demand for it regardless of whether better options exist.

I own bolts made of each material. My c158 bolts currently reside in the closet, but I haven't had failures from either kind and am perfectly comfortable using either.

The bcg PiP wrapped up early. The C158 milspec phosphate bcg proved more durable and reliable than offerings from lmt, LWRC, and others, including competing materials and designs, coatings, etc. It was so open and shut that the PiP was concluded months ahead of schedule.

 

[Skyjump136]

The bcg PiP wrapped up early. The C158 milspec phosphate bcg proved more durable and reliable than offerings from lmt, LWRC, and others, including competing materials and designs, coatings, etc. It was so open and shut that the PiP was concluded months ahead of schedule.

I know they tested a new CARRIER (currently made of 8620, not 9310 or c158). I'm not aware of any recent tests to the bolt itself...but I'd love to see them if you can link to them.

Right now JP is the most respected, high-end bolt on the market. You'd pay more for the bolt itself than Kev is planning to spend on an entire BCG. It is made with 9310 and here's their rationale:

http://www.jprifles.com/1.4.7_bc.php

JP EnhancedBolt™

9310 Bolt assembly with standard extractor. Available for .223 and .308 (DPMS LR-308 application).

To satisfy customer requests, we now offer the new JP EnhancedBolt™ with great life expectancy while utilizing a standard configuration extractor.

The truth is, the standard Mil-spec C-158 (Carpenter 158) bolt has a number of factors limiting its performance, not the least of which is that the life expectancy of such bolts is only about 6,000 rounds. In fact, standard bolts will start to show stress cracks on the locking lugs adjacent to the extractor cut after only 3,000 rounds. Cracking at the cam pin hole and weak extractor spring tension only add to the problems of the Mil-spec bolt.

Typical bolt failure mode next to extractor cut.

The material used in these standard bolts is also not the best choice by today's standards, but if you remember the old story that explains why “Mil-spec never dies,” that applies here as well; they make them this way because they’ve always made them this way.

The latest edition JP EnhancedBolt™ is made from SAE 9310 high-grade steel. This material makes for an extremely hard surface with a tough, ductile core resistant to structural failure and a life expectancy far exceeding Mil-spec C-158 bolts. SAE 9310 is the same type of steel used in the transmission gears of Formula One racecars, and the high-load application of a bolt assembly is ideal for this state-of-the-art material; the results of actual full-auto endurance torture tests prove it.

The design of the JP EnhancedBolt™ addresses many other fine points, the most important of which is the utilization of a standard configuration extractor. Most users want the ability to replace extractors and other parts with commonly available Mil-spec parts instead of being dependent on proprietary parts that can be difficult to acquire. Therefore, this new bolt will accept standard extractors, pins and springs.

The JP EnhancedBolt™ will now be standard equipment on all JP .223 and .308 rifles and uppers, and we highly recommend it as a complement to your JP High Performance Bolt Carriers or any rifle system. The .223 version of the bolt is compatible with any AR-15 platform using a Mil-spec bolt carrier and subcomponents. The .308 version is compatible with the JP LRP-07 and the DPMS LR-308 platforms (or clones thereof) only and cannot be used to replace bolts in the Armalite AR-10 platform (or clones thereof).

 

[luke_a]

That's just wrong.

Both are excellent metals and well suited to use as bolts. 9310 is actually stronger (around 8%) and less brittle than c158. 9310 uses molybdenum and c158 has more chrome content. The only time you would see a 9310 bolt fail before a c158 is in the case of improper heat treating.

However, major manufacturers do their heat treatments properly so you can rest assured that, in general, a name brand 9310 bolt will be stronger and longer lasting than c158. c158 is the "mil-spec" and like all things mil-spec there is heavy demand for it regardless of whether better, cheaper options exist...we also see this with barrel treatments, gas systems, etc.

I own bolts made of each material. My c158 bolts currently reside in the closet, but I haven't had failures from either kind and am perfectly comfortable using either.

"Stronger" how? Tensile strength? Yes. Wear? Yes Fatigue resistance? No. 9310 is harder, exhibits less wear, but fatigues faster than C158. It has alloying components that promote stress fractures under repeated heating and cooling cycles. It's not a poor choice for a bolt, but there are better options such as C158 and A-100.

It has nothing to do with demand for "mil-spec" components, Noveske, LMT, PSA, Daniel Defense, Rainier Arms all sell components that do not meet mil-spec yet they are in high demand because they are quality parts.

Did you know that Carpenter makes all three materials mentioned in this thread? Guess which one they recommend for AR15/M16/M4 bolts? It's not 9310.