Krag bolt interchangeability

U.S. Military Krags
Zac952
Posts: 159
Joined: Wed Apr 07, 2021 1:37 am

Re: Krag bolt interchangeability

Post by Zac952 »

Just an update, I received my Remington brass today and new unsized out of the bag 10 cases all chambered without resistance in both my 30 inch barreled reciever with my NOS bolt, and my short rifle with my unblued bolt. So I will be replacing my blued bolt with it as it has much tighter headspace and doesn't have play within the reciever as my blued bolt does.
I will keep my blued bolt as a spare as it will not close on a field gauge but likely is close on a no go, if it comes down to another rifle in need of a bolt I may use the blued bolt and use Parashooters trick to custom fit some cases for it!
But all in all the answer was both the Graf brass being slightly long to the shoulder and my RCBS sizing die not quite setting the shoulder back enough.
I sent my sizing die and shell holder to Fred for some thinning of the shell holder so I'll be able to still make use of this Graf brass, and properly resize a case to fit in both my Krag chambers!

FredC
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Location: Dewees Texas

Re: Krag bolt interchangeability

Post by FredC »

I should have Zacs shell holder and die tomorrow. Looking back over the posts I looked to see if Butlersrangers resized any of the Grafs cases in his dies. if so I did not see it.
Skinning .005" of the shell holder will be an easy 5 minute operation. Press and dies are at a back room behind the garage at the house, so i will run over there with the barreled action to see if .005 does the trick before shipping it back. I have plenty of Grafs cases to play with.

Zac952
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Joined: Wed Apr 07, 2021 1:37 am

Re: Krag bolt interchangeability

Post by Zac952 »

Fred, BR did resize one Graf cases in an older set of RCBS dies and then said it chambered fine, his post is on page 4 about halfway down. That sounds like a good plan, I appreciate it.

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butlersrangers
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Re: Krag bolt interchangeability

Post by butlersrangers »

I chambered two of Zac's Graf cases in five different Krags. I started with the rifles that had the most generous 'head-space' and worked my way to the Krags with tighter 'head-space'.
(BTW - None of these Krag bolts would close on a .073" Field Gauge).

In all five Krags, when the Graf cartridge-cases were chambered, there was obvious increased effort in closing the bolt. The two cartridge-cases had rub marks on the base and shoulder area.
One of the cases was full-length resized in an old and well used R.C.B.S. .30-40 F.L. Re-sizing Die.
After F.L. Re-sizing, the Graf cartridge-case chambered quite normally in all of the Krags.

I conclude:
This Graf brass is a bit 'long' or has a slightly different shoulder-angle than my Remington and Winchester brass.
Zac likely has nice 'tight' head-space on his first Krag bolt & action combination, which gave difficulty with 'chambering'.
Zac likely has 'loose' tolerances with his .30-40 Die & shell-holder combination. (Soon to be corrected).

The Graf .30-40 brass is quite nice and could be a real boon for a Krag with generous head-space or in a situation where a tight shoulder fit is desired.

It is likely most .30-40 Dies would F.L. size the Graf brass to fit all chambers.
Occasionally, 'manufacturing tolerances' will all align and work the other way!

(attached photo comparing W-W & Graf cartridge cases - red arrow is Graf case, yellow rectangle highlights apparent differences in shoulder area).
Attachments
comparing cases - red arrow Graf.jpg
comparing cases - red arrow Graf.jpg (73.52 KiB) Viewed 1326 times
Last edited by butlersrangers on Mon Jul 12, 2021 5:07 pm, edited 1 time in total.

FredC
Posts: 1991
Joined: Fri May 31, 2013 4:38 pm
Location: Dewees Texas

Re: Krag bolt interchangeability

Post by FredC »

Zac,
You kind of remind me of me. When I used to work at Phoenix Automatic Machine, they would bring me a bucket of parts and I would pick one up and set up on it. Can not tell you how many times i picked up a bad one that caused grief. Sort of understand it now the guys on the screw machines would set aside their set up parts and throw them in on top of the bucket because they were almost good.

Anyway I have ground off .013 off the top of this shell holder and it still is not enough. Checked against my number 7 RCBS shell holder and it was exactly the same before I started grinding on it. I think I will grind .003 more off and it should size your Grafs brass enough to close with no resistance. right now at .013 there is just the slightest resistance. With a fully assembled bolt you probably would not even notice it.

Discrepant part in this case is the resizing die, you buy another shell holder and it will give you exactly the same problem. Got half a mind to put the die in the lathe and face .015 off it and polish another radius at entrance.

Parashooter, would you do this or say Zac should send it back to RCBS?

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Parashooter
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Re: Krag bolt interchangeability

Post by Parashooter »

Parashooter wrote: Thu Jul 01, 2021 5:20 pm For a handloader, the simplest solution to this kind of minor shoulder interference is just to use a bit more muscle to close the bolt when chambering the "tight" cartridge. On firing, the case will acquire the dimensions of the chamber (AKA "fire-form") and, thanks to the natural elasticity of good cartridge brass, is likely to chamber readily if neck-sized and loaded again.

Should this be ineffective, I would take some height off a cheap shell-holder rather than alter a sizing die. Easy enough with nothing more than some 180-grit wet-or-dry paper and a flat surface.
That's what I'd do. :roll:
In effect, I'd use the rifle's chamber as a sizing die and its bolt as the press. This ain't hard; I've done something similar when trying to illustrate how it's possible to chamber .303 British cartridges in a Krag (NOT to fire them but to show doubters it would be an easy mistake).
303inKrag.JPG
303inKrag.JPG (97.33 KiB) Viewed 1316 times

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butlersrangers
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Re: Krag bolt interchangeability

Post by butlersrangers »

'Parashooter', you are a master of good graphics!

FredC
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Location: Dewees Texas

Re: Krag bolt interchangeability

Post by FredC »

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.
Zac decided to sent the die back as it was recently purchased. I had to grind .022 off the die holder to get to the point where the bolt would close with an occasional shell loose but most still tight the last few degrees of bolt rotation. Clearly the shoulder was too deep in the die. I will give Zac a couple of the cases to show RCBS the problem.

FredC
Posts: 1991
Joined: Fri May 31, 2013 4:38 pm
Location: Dewees Texas

Re: Krag bolt interchangeability

Post by FredC »

Just sent this message to Graf. I have been adding an "s" to their name all along. Just plain Graf. I will let you know what they say or maybe they will reply here.

I purchased some 30/40 brass from you all several years ago and never used it. Someone on the KCA forum reported difficulties with the same product and I check mine and see the same problem. Turns out my new old stock and the OP's newly purchased 30/40 brass have the same issue, too long a distance to the shoulder.
The problem is discussed here:
http://www.kragcollectorsassociation.co ... f=9&t=5938
I am fine and can modify this brass if I ever need it but you all have a problem that needs to be addressed.
Best regards,
Fred C

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butlersrangers
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Re: Krag bolt interchangeability

Post by butlersrangers »

I wonder if the "GRAF" marked .30-40 brass is actually made by Captech?

Graf and Sons sells both their 'house brand' and Captech marked cases for the same price.

Graf and Sons made .30-40 brass available when new Winchester and Remington cartridge cases were not available.

The Graf brass appears quite nice. It just appears to require a bit of sizing, before the first loading, with a F.L. Sizing Die that will 'correct' the shoulder.

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