Krag bolt interchangeability

U.S. Military Krags
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Parashooter
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Re: Krag bolt interchangeability

Post by Parashooter »

FredC wrote: Tue Jul 13, 2021 2:19 pm Parashooter,
Are you saying that if these were just forced closed with the bolt the process of rearranging the shoulder will make subsequent chambering easy? Trying to envision what would happen while fire forming the shoulder is tough for me. I see 3 possibilities. I could get better, worse or stay the same. Without experimenting I have no idea which out come is more probable. . .
In my experience, when an over-long-shoulder cartridge is "forced closed" and fired with a moderate load (typical Krag pressures) the case expands to fill the chamber during peak pressure and then, thanks to the elasticity engineered into cartridge brass, springs back enough to permit easy extraction. If the case is then reloaded without altering body and shoulder dimensions (neck-sized), it will chamber easily - and continue to do so as long as moderate (or lighter) loads are used.

Why not give it a try and let us know if you get the same result? I've seen speculation that the additional closing force would be hard on the rifle's locking surfaces but this seems unlikely given the relative strengths of the robust steel action and thin brass cartridge. Good lubrication on the bolt is always helpful, of course.

FredC
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Re: Krag bolt interchangeability

Post by FredC »

Parashooter,
Good to know. Right now the only thing I have been shooting is the Remington brass in 35/40. So this Graf brass was just sitting here. They ought to fix it just because it should be right straight out of the bag. If the day comes when I need to shoot this brass I think I would set the shoulder back with the 35/40 die then expand the neck out to 35 in the normal 2 step process (.338 then .358).


Same goes for the die. A full length die should set the shoulder back if you need it. With .022" too deep it is only a neck sizer. Neck sizers have their place but it is stamped full length.

Maybe I have spent too many years making stuff to the drawing and I think every thing ought to be like that.

Zac952
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Re: Krag bolt interchangeability

Post by Zac952 »

Fred thanks again for all the help, maybe this die escaped RCBS QC inspection or some other way was mis spec'd, I agree on the Graf brass being long could potentially cause other mishaps and I wonder if there is more or less case capacity when the shoulder is set back proper, It may not even be enough for concern. But it may affect accuracy if using mixed cases, which I try not to do with rifles at least.
All in all at least all your guys verifying has at least proven that I'm not completely incompetent, I was starting to think I had better lay off that lead pot! Jokes aside I appreciate all the help on this forum, and don't tell the wife but there is a gun show this weekend that I may or may not be attending.

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Parashooter
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Re: Krag bolt interchangeability

Post by Parashooter »

Zac952 wrote: Tue Jul 13, 2021 10:47 pm. . . I wonder if there is more or less case capacity when the shoulder is set back proper, It may not even be enough for concern. . .
It's useful to understand that case capacity properly reflects the internal volume of the case after initial firing pressure has formed it to the chamber (somewhere below ~25,000 CUP for medium military cartridges like .30-40). Since this normally occurs before peak pressure, minor variations in capacity before firing have little influence on performance. Relevant differences of internal case volume are best measured by weight, a quality that disregards external shape pre- or post-firing. After both have been formed to the same chamber, heavy cases necessarily have less internal volume than light ones . Handloaders seeking consistent volume often sort cases by weight and select the most uniform for accuracy loads.

Zac952
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Re: Krag bolt interchangeability

Post by Zac952 »

I was thinking since these Graf cases are longer to the shoulder then theoretically they would have more material, I have observed this when converting 308 to 300 savage it was necessary to neck turn brass to not be oversized after seating a 308 bullet, I never tested these as the Remington 722 extractor didn't like the 308 extractor groove, with the Graf cases this is not as drastic but could be something to consider, I have not compared the weight of Graf to my Remington brass yet, but maybe I'm grasping at straws here as benchrest accuracy loading would sort this out regardless

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Parashooter
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Re: Krag bolt interchangeability

Post by Parashooter »

OMG, if you have .300 Savage dies all you need do is run your Graf cases into one just far enough to push the shoulders back for easy chambering! Think of all the words, pixels, postage, grinding, and agony that could have been avoided. :o :shock: :roll:

Zac952
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Re: Krag bolt interchangeability

Post by Zac952 »

Parashooter, with that logic if you have 300 savage dies you can just forget about having 308, 30-06, 30-40, dies as you don't need em. Although yes that likely would have gotten me by, when firing brass multiple times and in separate rifles it is not only the shoulder dimension that needs to be resized but also the case body, now myself I am not one for hammering the bolt down to force chamber a round. I guess maybe that makes me too picky? But something was wrong and needed addressed, and I for one enjoy the conversation and problem solving of the members on this forum and I think it helps other shooters over the long run.

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Parashooter
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Re: Krag bolt interchangeability

Post by Parashooter »

Zac952 wrote: Wed Jul 14, 2021 1:39 pmParashooter, with that logic if you have 300 savage dies you can just forget about having 308, 30-06, 30-40, dies as you don't need em. . .
There are a couple of flaws in extrapolating that the technique useful for .30-40 would apply equally to .308 Win. or .30-06.
1. .30-40 operates at a working pressure of 40,000 CUP, much less than that of the other two (50K+). One result is that neck-sized .30-40 cases can be reloaded nearly indefinitely without expanding enough to resist chambering (in the same rifle) - while the others may require occasional FL sizing if used with full-pressure loads.
2. Body diameter of .308 and .30/06 is similar to .300 Savage, consequently fired cases may contact interior of FL sizer at body, displacing shoulder forward during neck-sizing attempt. Smaller diameter of .30-40 body precludes this.

FWIW, those emojis in my previous post (" :o :shock: :roll: ") indicate humorous intent.

Zac952
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Re: Krag bolt interchangeability

Post by Zac952 »

Ok Parashooter, I may have misunderstood that so sorry for that, yeah I agree it would have got me shooting, but it wouldn't have let me sleep at night until I found out the problem, I too thank you for the help and insight. For some reason I just can't leave well enough alone!

FredC
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Re: Krag bolt interchangeability

Post by FredC »

Zac,
I still have my dad's old 310 tool for 30-06. Neck sizing die can adjusted quite short and worked just fine for 30/40. Would probably work for most any 30 caliber that the hook would fit and the body would fit through the 06 hole in the tongs. Pretty easy to build a 30 caliber neck sizer. Almost think it is possible that you got a mislabeled neck sizer die instead of the FL die.
Parashooter, Zac's die had a small pressure relief hole drilled cross wise through the die adjacent to the shoulder body intersection. Is that common? I do not think any of my Redding dies have it.
Zac, when you get your die back the hole will be under the adjuster ring. I saw it with a bore scope.

And we would have saved a lot of grief if we had tried to chamber a Graf cartridge instead of assuming Zac's barrel had been Bubbafied.

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