77/44 Bolt face damage

[Otley]

Having shot many light and medium loads through my stainless 77/44, I thought I'd try some full loads to see if I could get good accuracy at 100 yards. I loaded 24 grains of H110 with a 240 grain jacketed bullet and Remington primer. Groups were good, but after thirty shots, there was a covering of unburned powder on the bench. I then tried Winchester primers that were claimed to be suitable for magnum loads to try and eliminate this unburned powder and accuracy did further improve. But - I'd fired thirteen rounds when I noticed that there was a black ring around the primer on my fired cases. The primers didn't look particularly flattened and extraction was normal.

I then checked my bolt face and saw that it was pitted around the primer periphery. Aargh!! My perfect rifle is not perfect anymore! I live in the UK. Does anyone know if I would have any chance of buying from Ruger a new bolt front half? I could do any machining that might be necessary to set the headspace correctly.

 

[Jimbo357mag]

The part (* Breech Block Assembly J20906 77/44 RSP) is a factory fitted part and Ruger won't sell them. Those burns from primer leakage can be caused by the cases having been reloaded too many times. The primer pockets can get loose after a while. I always check for burnt marks around the primers after shooting and recycle those old cases. I don't believe those tiny pits in the breach face have any effect on the gun's performance.

 

[Chief 101]

as was mentioned should be no negative effects from shooting the gun like this but I have tig welded bolts with this condition and machined them back to original...just a thought

 

[22/45 Fan]

From Hogdon's web site reloading data your 240 gr JHPwith 24.0 gr of H110 is right at their max load. If the cases had been fined a number of times, the leakage may be due to loose primer pockets that wouldn't tolerate that pressure level.

 

[RJ556]

Otley, About two years ago, I had the same experience with my 77/44. using Winchester primers. I posted it all here. You can do a search and read what I posted. My cases were once fired, no worn out case problem here. Also, my loads were below maximum. Looking at the spent fired cases under magnification, you could see where the primer actually ruptured in two or three places and the gas escaped to erode the bolt face of my rifle. I wrote Winchester a letter and sent pictures of the cases, explaining everything. They would not pay for the damaged bolt face but sent me an ammunition voucher worth a measly $25 towards the purchase of Winchester ammunition. Since I now live in Romania, I cannot reload, but if I ever did again, I would never use Winchester primers again.

 

[Otley]

Thanks for the replies - I suspected it might be tricky getting and then exporting a replacement bolt half. I know the pits in the bolt face don't affect the gun's functioning or safety, but then a dent in your new car doesn't affect its performance. It's just annoying.

 

[Otley]

Just an update - I searched through my reloading room rubbish bin and found some of the Winchester primers that I'd removed from the fired cases. I looked at the primer through a 40x loup and in each case, there was a small rupture at the edge of the primer:

They definitely shouldn't oughta do that....

 

[Jimbo357mag]

RJ556 I remember that thread in the reloading section. Those primers and Otley's primers are definitely defective. I would not use that lot of primers for anything other than light or moderate loads and if you are lucky they won't leak. Good catch Otley. :shock:

 

[RJ556]

That is a good picture Otley. That is exactly what I had. That pic shows that your loads were not excessive, as the primer cups still have a nice radius on them.

 

[Ol'Freak]

Could be due to excessive headspace.

 

[mike7mm08]

Could be due to excessive headspace.

Headspace is usually not much of an issue with straight wall cartridges. Look how generous heapspace is with a revolver.

Would see primers backing out before ruptures typically. More likely to see that if headspace was too little. Tight chamber hot load pressure needs to go somewhere. Primer pocket is weakest link. But hard bolt lift after firing as well as hard chambering would usually go along with that.

 

[Otley]

I always thought that the sequence of events when a centre-fire gun fires is as follows:
1. Firing pin hits primer and shoves the complete cartridge forwards as far as the headspace will allow.
2. Primer explodes and backs out of the case until it hits the breech face.
3. Powder ignites and, as pressure builds, the case is now pushed back until it hits the breech face and the primer is re-seated. Primer and case now act as a unified pressure containment vessel.

Excessive headspace may mean that the firing pin protrusion is inadequate to fire the primer after the cartridge has been shoved fully forward, or that the primer fires and the case is then inadequately supported by the chamber during the final part of the sequence.

I take it that no one who might work in the Ruger spares department is planning a trip to Europe this summer, possibly with a J20906 somewhere in their luggage?

 

[RJ556]

Otley, I know what you mean about the Ruger parts situation outside of the USA. I live in Romania and own several Ruger rifles. But I am pretty sure Ruger would not mail you a bolt head even in the USA, since it is a fitted ( headspace) part. What galls me is the fact that Winchester Ammunition will not admit they are selling defective components and pay for the damage done to customers rifles. RJ

 

[Ol'Freak]

A fair amount of pressure gets wasted out the cylinder gap of a revolver soon as the projectile exits the case. That pressure isn't exhausted when the same sort of round is fired in a sealed chamber, like that of a bolt gun.

Figger if'n the pressure goes high enough with the primer backed against the bolt face but before the case head does same, it'll leave a length of the primer's side wall equal to the amount of head space, unsupported. Those primers show a shallow pin hit along with the worst of the leak hole blown through the perimeter of a mushroom what appears to be taller than the pin hit is deep, even after the mushroom got flattened as the case head finally did back against the bolt face, reseating the now well mushroomed and torched primer.

Or, maybe that's what all spent primers look like coming out brass that was fired in that rifle? I don't see anything lookin' like that amongst the .44 Mag fired from my Contender.

 

[63November]

Apparently there has been a rash of issues with recent Winchester primers, a quality control issue. John Barsness has noted the problem with a fairly lengthy list of manufacturing code numbers. That type of crack does not appear to look typical to what one can see when the cause is simply excessive pressure.