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Bolt cracked at locking block pivot.


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The area of the bolt where that crack becomes evident is more or less non structural and is most likely related to the metallurgy and heat treat process the part undergoes. We have seen this crack in

I here someone is gonna be makeing a replacement bolt soon!!!

Just post em when ya got em-Im in.

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I HAVE TWO MKA1919. ONE XN THE OTHER NON XN. BOTH HAVE CRACKED BOLTS. THE AREA THERE IS TOO THIN NOT TO CRACK UNDER STRESS.FOR ME IT NOT A PROBLEM. TOO MUCH DRAMA!!

Isaid the same too thin-I was more worried about the barrel.But im looking for the bolt to crack again.
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In very few cases that crack can propagate downwards from the bottom of the hole rather than the top. That is an issue that requires replacing the bolt. Before I replaced my bolt in my personal gun it had roughly 11,000 rounds through it. I had a cracked bolt just like yours from day one, and it never caused an issue. But we've redesigned the bolt and machined it from tool steel, at the moment though it is unfortunately not available for purchase.

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In very few cases that crack can propagate downwards from the bottom of the hole rather than the top. That is an issue that requires replacing the bolt. Before I replaced my bolt in my personal gun it had roughly 11,000 rounds through it. I had a cracked bolt just like yours from day one, and it never caused an issue. But we've redesigned the bolt and machined it from tool steel, at the moment though it is unfortunately not available for purchase.

 

I'm in line for one.

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In very few cases that crack can propagate downwards from the bottom of the hole rather than the top. That is an issue that requires replacing the bolt. Before I replaced my bolt in my personal gun it had roughly 11,000 rounds through it. I had a cracked bolt just like yours from day one, and it never caused an issue. But we've redesigned the bolt and machined it from tool steel, at the moment though it is unfortunately not available for purchase.

Just post em when ya got em-Im in.
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  • 3 weeks later...

Posting again after 160 rounds. The bolt now looks like this. I'm now going to do what I had considered doing when there was just a crack. I'm going to smooth and round out the corners and edges. Originally I was going to remove some of the material where the crack was in the above photo. Obviously I don't need to that now - just smooth it out.

 

CrackinBoldafter2ndSession1_zpsfa53d7a4.

 

Showing a different angle so you can see the gap with the white background . . .

 

CrackinBoldafter2ndSession2_zps1b23a07e.

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  • 1 month later...
  • 11 months later...

3" shells or hot 2 3/4" will break bolts period.

 

light recoil springs can cause the same thing

Many bolts have the crack at the top of the pivot hole, some new ones have it

It does coincide with a sharp corner (stress Riser) and can propagate.

 The wall thickness in the XN bolt is thinner in this area and more prone to break than the pre XN

 

we can make bolts but small numbers make them too expensive at this time 

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we can make bolts but small numbers make them too expensive at this time 

 Would just be easier cheaper to buy another XN just for parts only?

 

no but our billet machined bolt would be $200.00 in small run numbers

it needs to be half that with a little profit for my work to be a viable product

 

 

Its has to use our lock as well, and also uses our extractor (part of why so spendy)

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we can make bolts but small numbers make them too expensive at this time 

 Would just be easier cheaper to buy another XN just for parts only?

 

no but our billet machined bolt would be $200.00 in small run numbers

it needs to be half that with a little profit for my work to be a viable product

 

 

Its has to use our lock as well, and also uses our extractor (part of why so spendy)

 

 

If the billet machined bolt would solve the problem once and for all, then it would be a big seller.  So in time, do you think you will offer these?

 

From what I've read so far it seems like the bolt and drive block are the weak links.  Or is there other parts I need to be concerned about?

 

Thanks.

 

Bill

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I have a few pre XN bolts and carriers

That is good news.

 

I mentioned on another thread that my only concern for the MKA 1919 is parts availability.  As a competitive shooter, my shotgun will see more rounds through it in a month than most sporting shotguns see in a lifetime.  Everyone that I've loaned my gun to has liked it.  The base price to get started is not bad.  Its not a complicated gun to work on and with the current batch of accessories available, it has all the potential needed to be the best competition shotgun out there.

 

A lot of competition shooters do not hesitate to plunk down thousands of dollars for a new gun.  But no reasonable person will spend even half that for a gun that once broken will stay broken. On the USPSA side of things, I'm sure there are handguns out there that would be great for the sport but availability of replacement parts has doomed them to be the occassional oddity at the range.

 

I've been lucky.  My MKA 1919 runs flawlessly and I've had no major broken parts.  But I'm no fool (though some will argue that point) and I know that in time my gun will break.  For insurance, I have a spare stock gun in the safe to be used solely for parts.  Not all are willing to part with that amount of money on the fear that they will not be able to repair a match gun without it.

 

I have four friends that will be joining me at a local 3 gun match in a few weeks.  For three of them, all long time USPSA shooters, it will be their first 3 gun match. All will be using my shotgun.

 

If they love the sport and decide to go all out with new gear, can I recommend the MKA 1919?  And if I do, must I use the caveat that its great now but you may have trouble findiing parts in the future?

 

The success of the MKA 1919 and its variants will not be in the hands of the competitors.  We have tried it and we like it.  It will be on the hands of folks like Jim and Matt and anyone else that is willing to step into the marketplace with the parts to improve these guns and help keep them running.

 

So to Firebird Precision and Tooth and Nail, thank you.

 

Bill

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we can make bolts but small numbers make them too expensive at this time 

 Would just be easier cheaper to buy another XN just for parts only?

 

no but our billet machined bolt would be $200.00 in small run numbers

it needs to be half that with a little profit for my work to be a viable product

 

 

Its has to use our lock as well, and also uses our extractor (part of why so spendy)

 

$200 dollars sounds ok for me? BUT I also need the Locking Block. I have already spent hundreds on top of original price. I would hate to piss that away and have a dead gun. Ive contacted an old supplier, Centerfire, Bill is working hard for me and Im willing to Buy 3 Bolts or Locking Blocks (what ever he can get), New or used at any cost just so this gun doesn't end up never fired again. I love this gun. When I take my son in laws out they always reach for this gun first, then the 44's.

Edited by ekamper
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That $200 price tag sounds high for just a replacement bolt, BUT, if it is an improved version that solves the problem once an for all it will be worth it.  

 

Bill

bolt, bolt lock , firing pin retaining pin, extractor, extractor spring, extractor detent pin

 

Six parts

 

 

For pre-XN guns, do you keep most of these parts in stock?  Are they NOS or are they better than stock parts manufactured by you or someone else?

 

Time to compile a shopping list.

 

Thanks.

 

Bill

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