AR Sponsor
Posted: 3/6/2016 6:54:29 PM EDT
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I know they were have MAJOR issues awhile back.
Anyone running one with a high round count? |
| Pursuit. Their bolts are made out of S-7 tool steel. S-7 has the potential to make a strong bolt. Impact rating is off the chart. The problem with it is it has a high carbon content so when it is heat treated, it hardens thru the core. 9310 and 158 do not have enough carbon content to harden by traditional heat treat method. They have to be case hardened in a carbon gas atmosphere. Their core remains softer and helps with shock resistance. The heat treat and tempering process for S-7 is super critical, and if not done precisely, you end up with a brittle part. If done properly, you can not beat it. 9310 and 158 is far more forgiving in the heat treat process. I have used S-7 many times in various applications. I have about 50-50 success. I think that in high production runs, the potential for a higher percentage of failure rate is there. JMO Craig |
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Quoted:
Pursuit. Their bolts are made out of S-7 tool steel. S-7 has the potential to make a strong bolt. Impact rating is off the chart. The problem with it is it has a high carbon content so when it is heat treated, it hardens thru the core. 9310 and 158 do not have enough carbon content to harden by traditional heat treat method. They have to be case hardened in a carbon gas atmosphere. Their core remains softer and helps with shock resistance. The heat treat and tempering process for S-7 is super critical, and if not done precisely, you end up with a brittle part. If done properly, you can not beat it. 9310 and 158 is far more forgiving in the heat treat process. I have used S-7 many times in various applications. I have about 50-50 success. I think that in high production runs, the potential for a higher percentage of failure rate is there. JMO Craig I don't like those odds at all. Seems like a pretty big risk for a company...in terms of both customer satisfaction and lost revenue |
| I am not an expert on heat treating,but a friend of mine is. I have a fairly high tech computer controlled oven and have been doing heat treating for over 15 years. 4130-4140-4340-17-4 stainless and 17-7 stainless I have had zero issues. S-7 kicks my ass. I think I am as careful in the process as can be. Some times it works out fine, others not so good. I have a fixture I use to press pistons off of rods. There are plates that are only .090 thick that you are putting 5000-6000 pounds of pressure against. I break them a lot. They are expensive to buy. I tried making some out of S-7. Some held up well. Others failed the first time. Even in the same batch. I use 17-7 now and they kick ass. Tougher to machine. I wish someone would make a bolt out of it. Craig |
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As soon as I SAW the reliabolt, I was kind of shocked. If you look at it, you can see their "improvement" was to bevel the leading (front) edge of the lugs (supposedly to make room for debris and assist in closing into battery in a chamber full of crud). One problem with this "improvement".... the leading (front) edge of the lugs are what contact the chamber face (which is also under extreme forward pressure during unlocking under gas pressure). So now you have about HALF of the "normal" (designed) surface area for contact. I could totally see this leading to beating the crap out of the chambers beveled edges (as the outermost "squared" edges are no longer there to support the force/pressure).
This bolt looks like it was designed by someone who does not understand how the AR system works. HELL no, for me. |
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Quoted:
As soon as I SAW the reliabolt, I was kind of shocked. If you look at it, you can see their "improvement" was to bevel the leading (front) edge of the lugs (supposedly to make room for debris and assist in closing into battery in a chamber full of crud). One problem with this "improvement".... the leading (front) edge of the lugs are what contact the chamber face (which is also under extreme forward pressure during unlocking under gas pressure). So now you have about HALF of the "normal" (designed) surface area for contact. I could totally see this leading to beating the crap out of the chambers beveled edges (as the outermost "squared" edges are no longer there to support the force/pressure). This bolt looks like it was designed by someone who does not understand how the AR system works. HELL no, for me. It's the rear of the bolt lugs that are forced against the barrel extension lugs during firing |
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Quoted:
I am not an expert on heat treating,but a friend of mine is. I have a fairly high tech computer controlled oven and have been doing heat treating for over 15 years. 4130-4140-4340-17-4 stainless and 17-7 stainless I have had zero issues. S-7 kicks my ass. I think I am as careful in the process as can be. Some times it works out fine, others not so good. I have a fixture I use to press pistons off of rods. There are plates that are only .090 thick that you are putting 5000-6000 pounds of pressure against. I break them a lot. They are expensive to buy. I tried making some out of S-7. Some held up well. Others failed the first time. Even in the same batch. I use 17-7 now and they kick ass. Tougher to machine. I wish someone would make a bolt out of it. Craig Semi-topic, I noticed several knife makers stopped using S7 a few years ago. I wonder if that is why. |
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Quoted:
I am not an expert on heat treating,but a friend of mine is. I have a fairly high tech computer controlled oven and have been doing heat treating for over 15 years. 4130-4140-4340-17-4 stainless and 17-7 stainless I have had zero issues. S-7 kicks my ass. I think I am as careful in the process as can be. Some times it works out fine, others not so good. I have a fixture I use to press pistons off of rods. There are plates that are only .090 thick that you are putting 5000-6000 pounds of pressure against. I break them a lot. They are expensive to buy. I tried making some out of S-7. Some held up well. Others failed the first time. Even in the same batch. I use 17-7 now and they kick ass. Tougher to machine. I wish someone would make a bolt out of it. Craig That's a good question why bolts or barrels aren't made of 17-7 because before heat treat their Vickers is likeparts. I'm assuming there may be issues under heat + friction + impact which is why it isn't used on barrels, carriers, bolts, or other parts? Corrososion resistance is bar none. |
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Quoted:
It's the rear of the bolt lugs that are forced against the barrel extension lugs during firing Quoted:
Quoted:
As soon as I SAW the reliabolt, I was kind of shocked. If you look at it, you can see their "improvement" was to bevel the leading (front) edge of the lugs (supposedly to make room for debris and assist in closing into battery in a chamber full of crud). One problem with this "improvement".... the leading (front) edge of the lugs are what contact the chamber face (which is also under extreme forward pressure during unlocking under gas pressure). So now you have about HALF of the "normal" (designed) surface area for contact. I could totally see this leading to beating the crap out of the chambers beveled edges (as the outermost "squared" edges are no longer there to support the force/pressure). This bolt looks like it was designed by someone who does not understand how the AR system works. HELL no, for me. It's the rear of the bolt lugs that are forced against the barrel extension lugs during firing Initially yes. Not once there is gas pressure separating the bolt/carrier (which is also when the wear occurs). |
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Quoted: Pursuit. Their bolts are made out of S-7 tool steel. S-7 has the potential to make a strong bolt. Impact rating is off the chart. The problem with it is it has a high carbon content so when it is heat treated, it hardens thru the core. 9310 and 158 do not have enough carbon content to harden by traditional heat treat method. They have to be case hardened in a carbon gas atmosphere. Their core remains softer and helps with shock resistance. The heat treat and tempering process for S-7 is super critical, and if not done precisely, you end up with a brittle part. If done properly, you can not beat it. 9310 and 158 is far more forgiving in the heat treat process. I have used S-7 many times in various applications. I have about 50-50 success. I think that in high production runs, the potential for a higher percentage of failure rate is there. JMO Craig Good info. |
| 17-4 or 17-7 makes one hell of a barrel. Noveski tried it. The scrap rate is too high. Rifle drilling it is a bitch. It kills tooling. If the drill looses it's edge at 15 1/2 inches into the hole and skates the drill for just a second, the material work hardens instantly and you are done. I read some where that his scrap rate was over 50 percent. He figured they he would have to get $700-$800 a barrel to make it worth while. The really good thing is that the barrel bore gets harder the more you shoot it. The bore starts out at C scale 34-38 when it is machined. It work hardens eventually to 40-42. In comparison, 4140 -4150 barrels are in the 28-32 range. What is really nice about 17-4 and 17-7 is that you can finish machine to exact dimension and then heat treat it with zero distortion.(maybe .0001-.0002 at most) It heat treats as low as 900 degrees and air quenches. 17-4 will go c scale 45-47. 17-7 will go 50-52. I use it in the hot side of all my piston rifles. Tough to beat. Craig |
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