Reising Broken Bolts

[Frank I.]

Since buying my Reising in 1990, I have broken 2 bolts. I sent one to Indianapolis Ordnance as a model for manufacturing repro-bolts suggesting that they radius the area where the action bar fits to prevent breakage in the area, which has sharp corners on the factory bolts. Their bolts have this radius...

My question is has anyone broken a reproduction Indianapolis Ordnance bolt? 

 

 

[Ryo]

You need to convert your firing pin to a inertia firing pin. Issue is metal fatigue from hammer and bullet primer causing the firing pin to flex. 

 

https://www.machinegunboards.com/forums/index.php?/topic/8854-paulfs-pictorial-guide-to-how-i-made-my-reising-run-great/

[GUNGUY45]

Ryo,  I believe Frank is talking about the type of failure as shown in the following photos;

 

 

[Frank I.]

Both of mine sheared completely off like this one.

All the springs in my M50 are Wolff, which seem to increase the cyclic rate of fire.

The Wolff action bar spring is longer and has a fair amount more tension than an original MAYBE that is a contributing factor?  

NOTE: Both were original H&R factory Reising bolts, including the one pictured below 

 

[StrangeRanger]

The Wolff action bar spring isn't the best part of their kit. I ended up taking mine out.  If you think about how the action bar works, it never loads that area of the bolt.  That lug is pushed from the front only when you manually charge the gun, hardly enough to do any damage. However it is impacted from the rear every time the hammer strikes the back of the bolt.  Because the rear of the bolt is tilted up when it's in battery the impact is borne almost completely by the area that fails.  This is basically a fatigue failure that occurs after tens or more likely hundreds of thousands of impacts and the sharp corner has set up a stress concentration.  The small radius we added (I was also involved with Jason on the project) reduces that stress concentration.  Instead of 80 years, the new bolts should last a couple of centuries.  Everything breaks eventually

The hammer spring massively increased reliability in my gun; I was getting too many light strikes with the H&R spring. I was reluctant to install the Wolff after I realized what was causing the failures but I really had little choice

Edited March 28 by StrangeRanger
grammar

[Frank I.]

Thanks for your input...

Off topic but,

Since you know the guys at Indy Ordnance you should suggest to them to make repro Bolts for the S&W 76 / MK760 subguns.

I will buy the first one!

As I'm sure you are aware, parts are virtually nonexistent for those guns. A few surface on GB occasionally, I saw one that sold for nearly 1k!

 

[GUNGUY45]

Frank,

 

Did you have the firing pins modified to inertia type in the gun when the bolts broke?

I was just wondering if that increases the stress on the bolt.

It would seem that an unmodified firing pin would take most of the stress from the hammer.

I know that the pins are prone to breaking in stock form, but it's cheaper to replace a firing pin, than a bolt.

 

Just wondering.

 

Pete

[Frank I.]

I don't think the firing pin would be a contributing factor.

The first bolt broke with an OEM pin, the second one with a modified-inertia titanium pin.