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Posted: 6/29/2013 4:07:51 PM EDT
So it seems that this is the hot topic as of late, and I'm not sure I have ever heard a definitive answer as far as which is better.

Given that it is a metal, there has to be a concrete answer.
So, assuming that they were both made by the same mfg, heat treated correctly, etc, which is better for a bolt? I have seen 9310 advertised as being the "same metal used in high performance racing transmissions", but I'm not sure that would mean it is a better AR bolt.

Any opinions?
Link Posted: 6/29/2013 4:33:57 PM EDT
[#1]
Both alloys come from the same place (Carpenter). IIRC Carpenter stated that 9310 is ~%8 stronger. Whether that increase is worth it is up to you. I personally went KAC E3 and never looked back.
Link Posted: 6/29/2013 7:05:36 PM EDT
[#3]
Link Posted: 6/29/2013 7:27:23 PM EDT
[#4]
Everything I've read says 9310 is better but I don't know how true that is.

As far as 9310 being used in transmissions, lots of performance trannys use 9310 shafts
Link Posted: 6/29/2013 8:33:59 PM EDT
[#5]
They are both excellent. 9310 has  a small amount of molybdenum, 158 does not. 158 has a little more chrome than 9310. Otherwise they are almost identical. 9310 is more available. I use S-7 . A little more expensive, but easier to heat treat with little if any distortion. You can get 55 c scale with S-7 air quench. The other two have to be done in a carbon gas atmosphere . S-7 has a higher shock rating, but slightly less in the wear and abrasion than 9310 or 158.
Link Posted: 6/29/2013 8:58:07 PM EDT
[#6]
Quoted:
They are both excellent. 9310 has  a small amount of molybdenum, 158 does not. 158 has a little more chrome than 9310. Otherwise they are almost identical. 9310 is more available. I use S-7 . A little more expensive, but easier to heat treat with little if any distortion. You can get 55 c scale with S-7 air quench. The other two have to be done in a carbon gas atmosphere . S-7 has a higher shock rating, but slightly less in the wear and abrasion than 9310 or 158.


IIRC Ronnie Barrett uses S-7 for the bolts in the Barrett M107 .50
Link Posted: 6/29/2013 9:05:21 PM EDT
[#7]
Here is the conclusion I've came to after doing the research and having a conversation with a metallurgist.

Assuming both are heat treated properly, 9310 will be slightly less brittle. Heat treating is where the problem lies however. 9310 heavily relies on proper heat treating in order to become slightly stronger. The heat treating tolerances for 9310 are extrememly tight.

The best way I can put it is:

9310 heavily relies on heat treating

C-158 doesn't rely as much on proper heat treating.

At the end of the day, it's much easier to screw up the heat treatment process on 9310.

Which ever bolt you choose to get, just make sure you're buying it from a reliable company and your chances of failure should be pretty damn slim.

I have both 9310 bolts and C-158 bolts. I haven't had a failure with either one but I prefer BCM bolts which use C-158. There aren't too many other companies that have the track record BCM has when it comes to bolts.
Link Posted: 6/30/2013 2:28:07 PM EDT
[#8]
Quoted:
Here is the conclusion I've came to after doing the research and having a conversation with a metallurgist.

Assuming both are heat treated properly, 9310 will be slightly less brittle. Heat treating is where the problem lies however. 9310 heavily relies on proper heat treating in order to become slightly stronger. The heat treating tolerances for 9310 are extrememly tight.

The best way I can put it is:

9310 heavily relies on heat treating

C-158 doesn't rely as much on proper heat treating.

At the end of the day, it's much easier to screw up the heat treatment process on 9310.

Which ever bolt you choose to get, just make sure you're buying it from a reliable company and your chances of failure should be pretty damn slim.

I have both 9310 bolts and C-158 bolts. I haven't had a failure with either one but I prefer BCM bolts which use C-158. There aren't too many other companies that have the track record BCM has when it comes to bolts.


Who does BCM get their bolts from?
Link Posted: 6/30/2013 3:25:49 PM EDT
[#9]
Quoted:
Quoted:
Here is the conclusion I've came to after doing the research and having a conversation with a metallurgist.

Assuming both are heat treated properly, 9310 will be slightly less brittle. Heat treating is where the problem lies however. 9310 heavily relies on proper heat treating in order to become slightly stronger. The heat treating tolerances for 9310 are extrememly tight.

The best way I can put it is:

9310 heavily relies on heat treating

C-158 doesn't rely as much on proper heat treating.

At the end of the day, it's much easier to screw up the heat treatment process on 9310.

Which ever bolt you choose to get, just make sure you're buying it from a reliable company and your chances of failure should be pretty damn slim.

I have both 9310 bolts and C-158 bolts. I haven't had a failure with either one but I prefer BCM bolts which use C-158. There aren't too many other companies that have the track record BCM has when it comes to bolts.


Who does BCM get their bolts from?


Lord Sauron

Link Posted: 6/30/2013 3:57:27 PM EDT
[#10]
Quoted:
Quoted:
They are both excellent. 9310 has  a small amount of molybdenum, 158 does not. 158 has a little more chrome than 9310. Otherwise they are almost identical. 9310 is more available. I use S-7 . A little more expensive, but easier to heat treat with little if any distortion. You can get 55 c scale with S-7 air quench. The other two have to be done in a carbon gas atmosphere . S-7 has a higher shock rating, but slightly less in the wear and abrasion than 9310 or 158.


IIRC Ronnie Barrett uses S-7 for the bolts in the Barrett M107 .50


S-7 was my favorite tool steel to work with when I was a moldmaker one career ago.
It would make a very good bolt; can be made reasonably hard (58 Rockwell C scale) and excellent toughness.

As others have said, theoretically 9310 would make a better bolt (with proper heat treatment).
I bought a few BCGs recently with 9310 bolts. Don't have a lot of rounds on them but so far so good.

Regardless, I have a spare bolt on hand, a spare BCG, too. Shit happens.

Joe
Link Posted: 7/28/2013 5:21:12 AM EDT
[#11]
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Quoted:


Lord Sauron

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Quoted:
Quoted:
Quoted:
Here is the conclusion I've came to after doing the research and having a conversation with a metallurgist.

Assuming both are heat treated properly, 9310 will be slightly less brittle. Heat treating is where the problem lies however. 9310 heavily relies on proper heat treating in order to become slightly stronger. The heat treating tolerances for 9310 are extrememly tight.

The best way I can put it is:

9310 heavily relies on heat treating

C-158 doesn't rely as much on proper heat treating.

At the end of the day, it's much easier to screw up the heat treatment process on 9310.

Which ever bolt you choose to get, just make sure you're buying it from a reliable company and your chances of failure should be pretty damn slim.

I have both 9310 bolts and C-158 bolts. I haven't had a failure with either one but I prefer BCM bolts which use C-158. There aren't too many other companies that have the track record BCM has when it comes to bolts.


Who does BCM get their bolts from?


Lord Sauron


lmao
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