Problem with chambering new brass

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

Re: Problem with chambering new brass

Post by FredC »

In the past we have addresses too large a headspace on Krags with lots of miles on them and there are some tricks to fireform the cases then barely bump the shoulders back when reloading. When done correctly the effective headspace is controlled by the shoulder. I will look for some links. Parashooter has posted photos of this corrected measure several times.

http://www.kragcollectorsassociation.co ... 001#p24001

In this thread there was a several calls for sanity checks. On your fixing the head space you made it tight on a go gauge (.064) and if Graf's cases are really .050 then that is .015 space. If you take SAAMI's -.010 on the case and add the .007 on the chamber you could have a maximum with all in spec with .017 clearance and maybe .019 using a .073 field gauge. For just a couple of uses of the brass you would probably have no issues at all. I would think that you would get thinning just forward of the rim with continued reloading with full length resizing and lots of firings later you might run into separations.

The brass should probably be sent back for replacement if it is out of tolerance, but just measuring the edge of the rim may not really tell you what you have.
Last edited by FredC on Mon Apr 26, 2021 3:25 pm, edited 1 time in total.

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

Re: Problem with chambering new brass

Post by Zac952 »

Well I may have figured out my problem, I reamed out the chamber and checked it very frequently with a go guage, I stopped reaming when it would close tightly on a go guage. It would not close on a no go guage. These are Clymer guages which have a good reputation but they are out of spec.
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Notice the measurement of diameter at .550, 5 thousandths larger than saami specifications.
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What this did was the guage sat proud in my bolt giving me a false reading as I was reaming the chamber
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Notice above the bolt not closing on the Clymer no go guage

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

Re: Problem with chambering new brass

Post by Zac952 »

Screenshot_20210426-085953_Gallery.jpg
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Notice above the bolt closing on the Clymer go gauge

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

Re: Problem with chambering new brass

Post by FredC »

Rim diameter of the chamber is .555 plus or minus .012. Not even sure what a gauge is supposed to measure. The thickness you should check on the gauge should be .064. In the shop we do not trust digital or dial calipers for close measurements. If you checked the rim thickness with that set of calipers I would only consider it a rough measurement.

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

Re: Problem with chambering new brass

Post by Zac952 »

This was a check of rim diameter, according to the specs I have it calls for .545 rim diameter. These Clymer guages are at .550 rim diameter, so they won't sit flush in the bolt head. Notice how they are both crooked in the bolt head

My measurement of the case rim thickness may be wrong, I was scouring to try to figure out why my rifle would check out with guages but seem to have excessive headspace, and after deciding that something still seemed odd I looked more into I and the guages are 5 thousandths larger in rim diameter than saami specs for a 30-40 rim diameter, so they wouldn't sit flush in the bolt head.

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

Re: Problem with chambering new brass

Post by FredC »

I assume you have cleaned out the recess in the bolt? The several bolts i have examined all had flat bottoms initially in the cartridge head recess, on worn bolts the head of the end of the cartridge eventually wears them more in the center of the recess. Seems like to me the gauge should have a large bevel on the end to measure true head space on a worn bolt. As funny as the gauge sits in your bolt I would think you have a ding or crud that was not cleaned out, the unworn portion of the recess should still be flat. Would clean it again and recheck before sending the gauge back.

One question, the rim diameter on the reamer is larger than the OD of the rim (that .550) on the gauge, right?

One further point is the recess in the bolt is less then the rim thickness of most cases and definitely any gauge. The gauge should sit proud of the end of the bolt. I just measured the depth of a NOS bolt and the recess is .055 deep. That is .009 less than the go gauge.

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

Re: Problem with chambering new brass

Post by Zac952 »

Yes the bolt was cleaned with solvent and a brass brush, no crud or anything on the bolt head, the guage has no bevel but has a square end on the bottom, the case has little room to move around on the bolt head but still sits flat regardless of movement, so it seems to have no bevel on the face of the bolt from wear, I can feel the guage not sitting flat regardless of movement, I can take some more pictures tonight after work. Also the guage doesn't just angle that way, it will angle whatever way you have the bolt tipped, so its not sitting on a ding or crud, it is just to big to sit in the recess.

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

Re: Problem with chambering new brass

Post by FredC »

Not having anything in my hands makes this a challenge. Maybe the firing pin hole is dimpled out?

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

Re: Problem with chambering new brass

Post by Zac952 »

No I don't believe it is the guage doesn't pivot from the center it just seems to stop on the ring around the bolt head, around where it is recessed, maybe I have too tight of bolt head recess, I know it measured less than the guage but I will measure it later.

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

Re: Problem with chambering new brass

Post by FredC »

Just tried to mike 2 bolts with an ID mike. The recess appears to be tapered with the root diameter of .550. I will turn a bar end tomorrow to .550 and see how it fits in the bolts on hand. If it is .550 with a small radius on the corner we may have found a problem.

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