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Assume you meant Labor Day even though I wouldn't mind resetting the summer !
Just on their sight this morning getting their grease. Good product. Buy with confidence. Associated with Geissele.
I checked out the site and bought 3 gas blocks.
They have there blems at 50% off also.
I am a ALG fan, BUT:
They are advertising that BCG as mil-spec, I believe C-158 is spec for the bolt, not 9130.
Have one of the bolts (phosphate) on order to try out.
dramabeats
09-03-17, 00:13
9310 is getting more common. Doesn't surprise me one bit
I checked out the site and bought 3 gas blocks.
They have there blems at 50% off also.
I am a ALG fan, BUT:
They are advertising that BCG as mil-spec, I believe C-158 is spec for the bolt, not 9130.
Could they be talking about the carrier re: the 9310?
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9310 is getting more common. Doesn't surprise me one bit
Had a long chat with Bill Alexander at the NRA convention on this topic.
Without rehashing the alloy debates, neither 9310 or C158 are the current sweet spot for AR bolts.
As a cartridge designer, ammo mfg, Etc they look at it from a performance perspective which balances service life with manufacturability.
Ex: C158 was the right pick 40 years ago relative to steels at the time. Still a good steel. But is difficult to heat treat consistently in small parts. So enter testing, proof rounds, Etc. Good material, but requires extremely good process control and you will still see lower production yields which have to be caught and pulled. And some you can't catch, so you still see failures, but it's above the expected service life. Statistically, it's acceptable, thus the tdp usage.
9310, easier to get in bolt mfg quantities, better yields on heat treating, and done right can be as strong as or stronger than c158.
Also, "manufacturability" is not cost to mfg, it's yield and testability. C158 can make strong bolts, but has known heat treat issues that have to be caught/tested for. And will never be 100% caught. Likewise, the testing to screen the heat treat actually reduces the service life of the bolt. A less finicky steel can produce better bolts out the door and long term testing just due to lower failure rates.
So both 9310 and c158 are still not optimal. Both are tradeoffs, there are better steels now that some are using. Names you would know in addition to Alexander Arms. Most already mentioned in this thread.
When you approach it from the perspective of making the best bolt free of cost/tdp constraints you have more options.
One last thing... The volume of fire testing that AA does is truly staggering. Much of it in full auto in the smaller cartridges (Grendel, blackout, Etc). We were chatting about the amount of fire testing done for Grendel steel case alone. I guessed a number and he laughed and threw out the number they budgeted for and executed for the 338 Lapua development alone. Which as a semi-auto, precision offering was much lower (by 10-20x) than the carbine cartridges tested in full auto and for new ammo development.
I mention that to reenforce the point that Bill lives in a world beyond theoretical. They routinely exceed service life of bolts. And have a strong vested interest in using the best steel for the application.
Bolts (and associated rifle/ammo) have to perform after mil specified cold soaks. Hot soaks. Sustained fire. Intermittent fire (heat cycling). Very few have the in house capacity to do that level of development testing. Probably under 5 in the US.
So for me it's back to trusted names... (LMT, KAC, DD, Etc) We want checkoff items (c158, hpt, mpi, Etc). But that's no guarantee, just the minimum.
I'll still use toolcraft carriers, but less confident now about their bolts. To be clear, they are just one of many who don't divulge their mfg. Some of which are still quality bolts.
Back into the party: When I mentioned that ALG listed the BCG as mil-spec and it actually wasn't using C158, I was merely pointing it out so that a mil-spec or die guy wouldn't get surprised.
ALG EMR's are the only rails I use cureently, they fit my needs in an elegant (to me) cost effective way. Likewise I only use Geissele gas blocks I buy through ALG. Good stuff. I trust the company, did not mean to intimate otherwise.
To me, Pinzgauer's informative post points out the importance of not rigidly adhering to the mil-spec mantra if the manufacturer is trusted and has data to back up their material choice.
From what I've read 9130 is more finicky to heat treat correctly than C158. Again from reading, the process is not impossible, it just requires more care. So the entity doing the heat treating needs to be competently reliable. This points out again that you need to trust the manufacturer you are buying the part from - they choose the source.
9310 tool steel is a published industry standard, made all over the world, including China.
Currently China is the world's largest steel manufacturer: In 2011 China was the largest producer of steel in the world producing 45% of the world's steel.......6 of 10 of largest steel producers in the world are in China
I don't think there is probably a lot of trust among us for the average Chinese made product, including steel.
On the other hand C158 is a proprietary alloy of Carpenter Technology. It is produced, by them, in the United States. So with a C158 bolt you can be more assured that the raw material is kosher.
Based on all of this, it is easier for me to adhere to the mil-spec C158 for BCG's in the price ranges I work within.
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