Problem with chambering new brass

Ammunition, reloading, shooting, etc
Zac952
Posts: 159
Joined: Wed Apr 07, 2021 1:37 am

Re: Problem with chambering new brass

Post by Zac952 »

Thank you BR I will surely try some higher pressure loads, that existing load was out of caution and was the starting load for a 180 grain bullet with IMR 4350, I will also use the fillimant spacer to fireform the brass so it chambers the cartridge on the shoulder more and then neck size, that will at least get me enjoying it in the meantime well I consider a more permanent solution, still waiting on that field gauge but in the meantime I used freezer tape on the back of the case stacked up until the bolt was hard to close and I measured it at about .018, so truly my headspace may be slightly long but with Parashooters trick and then necksizing on some lighter cast loads I think I may have a safe shootable Krag in the meantime. Again this forum has been extremely helpful and I'll keep you guys updated on a range report.

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Parashooter
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Location: Kragmudgeon House, CT

Re: Problem with chambering new brass

Post by Parashooter »

Before trying any improvised remedies, please absorb the article at https://www.milsurps.com/content.php?r= ... for-.303-s . Although written for .303 British, most of the content is applicable to the US Krag. For example -
When you fire a new case for the first time, use an improvised spacer ahead of the rim - anything from a precision metal washer to dental floss can work to hold the the cartridge head firmly against the bolt face and eliminate or reduce stretch even if head clearance is significant. Another way of accomplishing the same end is to use a bullet seated out far enough to jam into the lands, "headspacing" on the bullet instead of the case. Such techniques are useful only if the rifle has excess headspace. With normal headspace, initial stretch isn't enough to worry about.

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After you've fire-formed your new cases they will fill the chamber fully, stopping on the shoulder just like a rimless cartridge. If you neck size, you'll have zero "headspace". If you have to full length size, adjust the die so the cases chamber with just a bit of resistance in the last few degrees of bolt rotation.
For your situation, I'll add: it's essential that loads for fire-forming produce sufficient pressure to expand the case fully. Light loads generating less than about 30,000 psi won't always do the job in a cartridge like the .30/40.

Zac952
Posts: 159
Joined: Wed Apr 07, 2021 1:37 am

Re: Problem with chambering new brass

Post by Zac952 »

Thank you BR again for the link to this article, I will be sure to read this, I was curious on where to find more info on it.
Also got my Forster field gauge today, my krag closes easily on it with no pressure whatsoever, this Forster gauge is much better than the Clymer for checking headspace on a Krag, it measures out at .542 and has a beveled radius on the bottom so it sits perfectly on my bolt. Granted this is a sample of one so use caution, I have tried to get a hold of Clymer multiple times with no answer on the phone or replys to email so as of now I'm going to avoid Clymer gauges and especially ones for the 30-40 Krag. Not trying to be a brand basher here but having there gauges prevent a bolt from closing on the no go and Forster brand closing on Field seems like not only could Clymer gauges give you false reading when chambering a barrel, but they could give you a false reading on your existing barrel and potentially put you in a unsafe situation.
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butlersrangers
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Joined: Wed Oct 07, 2009 11:35 pm
Location: Below the Bridge, Michigan

Re: Problem with chambering new brass

Post by butlersrangers »

I can't take credit, "Parashooter' provided the link to his very good explanation of case expansion and headspace in the .303 British chamber.

I'm curious; how thick is the rim on your 'Field' gauge?

Zac952
Posts: 159
Joined: Wed Apr 07, 2021 1:37 am

Re: Problem with chambering new brass

Post by Zac952 »

It is marked .070 and due to the bevel like the cases it is hard to get an accurate measurement but it seems to be right around .070 between .069 and .071 for sure though, and Thank you Parashooter for the hard work in helping those of us with excessive headspace still be able to enjoy our rifles!

Zac952
Posts: 159
Joined: Wed Apr 07, 2021 1:37 am

Re: Problem with chambering new brass

Post by Zac952 »

Also using freezer tape stacked up on the field gauge it seems like I have about .010 of space pass the field gauge.

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butlersrangers
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Re: Problem with chambering new brass

Post by butlersrangers »

Wow, it looks like you were badly failed by 'Clymer Gauges' in your chamber restoration work.

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butlersrangers
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Re: Problem with chambering new brass

Post by butlersrangers »

bumping old thread

ebruce
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Joined: Mon Aug 16, 2021 2:47 pm
Location: Georgia

Re: Problem with chambering new brass

Post by ebruce »

Thank you for bumping this thread. Have learned much by reading the responses. Sincerely. bruce.

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scottz63
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Re: Problem with chambering new brass

Post by scottz63 »

Just measured all 3 of my Forster gauges. Go, No-Go, and Field. All 3 measured listed rim thickness .064, .067, and .070

Rim diameters measured between .529 and .531

All 3 fit easily down flush on the bolt face of my Krag bolt.
14EH AIT Instructor-PATRIOT Fire Control Enhanced Operator/Maintainer

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