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Indianapolis Bolt Test


Frank Iannamico
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Well,

 

I finally got out and tested the new-made Indianapolis bolt, the bolt fit and functioned perfectly!

HOWEVER, the redesigned Keystone titanium firing pin broke after 400 rounds, looks like there still is a problem to solve.

 

BTW the firing pin was shortened to an inertia-type as per the instructions on this site.

http://www.machinegunboards.com/forums/index.php?showtopic=8854

 

I'll post some pictures later.

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  • 2 weeks later...

pictures added

 

The "in the white" bolt is a NOS H&R Reising bolt. The darker one is the new Indianapolis Ordnance bolt.

The key to the new bolt is a radius cut where the action bar fits. This is a common area of cracking on original bolts due to the sharp corner. The standard action bar functioned, no alterations needed.

 

Also shown is Keystone's titanium firing pin. This one lasted 410 rounds. IMHO this is still a problem area. Any engineers out there with a solution?

rei2.JPG

rei1.JPG

rei 3.JPG

rei6.JPG

rei50.JPG

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The firing pin could have the same issue as the original bolt, not enough radius in the area where the smaller diameter meets angle of the larger diameter.

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it's not the broken firing pin tip that concerns me, there are many possible answers to that riddle and a stress concentration where it necks down is certainly among them. What puzzles me is the deformity in the firing pin shaft about 1/4 of the way back from the tip and a somewhat smaller one about 3/4 of the way back. Both are clearly shown if you look at the shadow line on the picture of the broken pin. The force, whether axial or transverse, that would be required to cause that is massive, orders of magnitude more than could ever be exerted by the hammer. Whatever caused that is what is causing the pin failures

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it's not the broken firing pin tip that concerns me, there are many possible answers to that riddle and a stress concentration where it necks down is certainly among them. What puzzles me is the deformity in the firing pin shaft about 1/4 of the way back from the tip and a somewhat smaller one about 3/4 of the way back. Both are clearly shown if you look at the shadow line on the picture of the broken pin. The force, whether axial or transverse, that would be required to cause that is massive, orders of magnitude more than could ever be exerted by the hammer. Whatever caused that is what is causing the pin failures

I thought someone would catch that deformity, that is a SNAFU from trying to remove dog hairs from the pin with PhotoShop. The pin is not deformed there. I have a white bulldog that sheds like crazy.

I removed the altered photo and replaced it with the original with the dog hair.

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Frank,

Have you looked into the possibility of modifying a firing pin from some other gun, one that doesn't have a bad rep, into a Reising pin.

Perhaps a BAR pin?? Remington 870 ??

 

Jim C

I am going to try that. That was my previous plan, but a friend/C2 mfg. Made me one that "wouldn't break." Well it did break. A BAR firing pin is candidate as well as a M16 pin.

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I took my broken Keystone titanium firing pin and drilled the end out with a 1/16" drill. I then broke the shank off of the drill and brazed it into the firing pin. I then ground the new tip down to the recommended length by Paul F. I still have feeding problems that I need to work on but the firing pin has lasted a lot longer.

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I took my broken Keystone titanium firing pin and drilled the end out with a 1/16" drill. I then broke the shank off of the drill and brazed it into the firing pin. I then ground the new tip down to the recommended length by Paul F. I still have feeding problems that I need to work on but the firing pin has lasted a lot longer.

Drill rod may be too brittle, if it breaks, try the tip from an M16 or BAR firing pin.

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