Resizing for Garand surprise!


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jr_roosa
February 19, 2013, 01:21 AM
I discovered something shocking while demonstrating some things to a friend about headspace and gas guns. Apparently what I found is nothing new, but I can't believe that I never saw this anywhere in the years that I have been reloading for my rifle.

I have a series of sized brass that is about 0.001" or 0.002" shorter than the next that I used to measure my chambers to set up my sizing die for my Garands, which conveniently are within about 0.001" of each other...close enough for government work.

Anyway, I size brass to about 0.002" shorter than the longest case that will allow the bolt to close (stripped bolt without ejector). Up until this point all is right with the world.

I show him how fired brass won't fit back in the chamber, how commercial brass will fit without any trouble, how properly sized reloads fit just fine...and then I put in some HXP:

http://farm9.staticflickr.com/8368/8483645505_a3baa6ccec.jpg (http://www.flickr.com/photos/67652701@N03/8483645505/) Untitled (http://www.flickr.com/photos/67652701@N03/8483645505/) by jr_roosa (http://www.flickr.com/people/67652701@N03/), on Flickr

And the bolt barely starts to close!!!

I post this on the CMP Garand forum, and it seems to be old news that HXP runs a little long, but the Garand just smooshes it into the chamber without slamfires, out-of-battery discharges, or any small animals being harmed.

Then, they point to Hatcher's Notebook where it shows that GI .30-06 is supposed to be up to 0.006" LONGER in the shoulder than a Garand chamber, and that some machine guns back in the day had a chamber 0.011" short to MAKE SURE THEY SET THE SHOULDERS BACK ON CHAMBERING to prevent case head separation!

So...this begs the question...what is the optimal amount of resizing? 0.002" short? Same as chamber size? A little long?

Thoughts?

My thought is because I use Winchester primers, that I don't have as much leeway on tolerating out-of-battery slamfires, and I should stick with sizing to about 0.002" short, but I don't think that I'll worry if I get a few in a batch that run long.

-J.

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chris in va
February 19, 2013, 02:36 AM
Wow.

I follow the Lee die instructions, trim to length and done. Probably a thousand through my Garand this way.

Reloadron
February 19, 2013, 06:40 AM
Without looking in depth I found some FN 61, LC 65 Match, and a Commercial FC case. All three were 2.049" within +/- .001". I have no experience with the HXP stuff. Do you happen to know the actual headspace of your specific rifle?

Ron

Jeff H
February 19, 2013, 09:36 AM
I just got done resizing and trimming a few hundred HPX cases and I can tell you two things.
1) yes they run long. I had to trim almost all of them and they were once fired.
2) HPX brass is tough. It takes a good amount more effort to resixe than LC or hornday brass.

I can't help you on the headspace. I just set up the die according to the instructions and then check resized cases to make sure they chamber. I call it good if they chamber.

jr_roosa
February 19, 2013, 10:50 AM
Do you happen to know the actual headspace of your specific rifle?

Not really. I can estimate it using the Hornady gauge but it has a slight radius where it measures and the measurement it reads comes up short. 2.035" is what it reads but that's incorrect. I'm going to my gunsmith today and I will zero my gauge to an actual headspace gauge so I can convert to real numbers.

1) yes they run long. I had to trim almost all of them and they were once fired.

Oh, I was talking about length at the shoulder, not trim length.

That cartridge that wouldn't fit is right out of a clip full where none of the 8 will let the bolt close. HXP80 M2 ball ammo.

J.

jr_roosa
February 19, 2013, 07:06 PM
Do you happen to know the actual headspace of your specific rifle?

It looks like it is right about 2.050" or 2.051" from what I can gather with putting my Hornady gauge on some actual headspace gauges. Right in the middle of the acceptable range. The Go gauge I looked at was 2.0487" and that measured about 0.002" shorter than the longest case that would allow bolt closure.

I could measure the actual headspace with some other gauges my gunsmith has that run in 0.001" intervals, but I'd have to take down the rifle and strip the bolt, and my curiosity wore out before I got that far.

FYI, the Hornady gauge measures about 0.016" short of what it should, probably because the soft aluminum comparator body has a slight radius at the opening where it measures.

-J.

NuJudge
February 19, 2013, 07:54 PM
I had the same experience with HXP brass, and my problem was that the sides of the case near the head were not being sized enough. I bought a Small Base die and the problem went away.

I've been loading .30-'06 brass since 1972, and I've never needed a SB die before.

jr_roosa
February 19, 2013, 08:05 PM
Certainly the case head on HXP is bigger than winchester. It hasn't been so big to need a small base die for my GI spec chambers. I have heard it won't feed in 1903s.

The sized brass gives me no problems.

J.

Reloadron
February 19, 2013, 08:27 PM
More out of curiosity than much else I rummaged through a box of assorted 30-06 ammunition that included several military headstamps. Still no HXP though. I did find an EnBlock loaded with DEN 42 black tipped AP stuff, no clue where that came from.

Anyway, as I did this morning I measured a pile of factory 30 - 06. They all come up about the same, within +/- of 2.0487". The way I am doing this is I have a RCBS Precision Mic set for 30 - 06. I even checked the set using a Clymer 30 - 06 Go Gauge from my set. I likely have everything here except HXP cases. :)

I have a full set of .308 headspace gauges similar to what you mention in .001" increments but only a Go - No Go - Field set in 30-06. One trick I have used is to punch out tiny disk of shim stock in assorted thickness. Then use a drop of oil to stick them to the base of headspace gauges. Works pretty well for getting actual headspace dimensions.

As to this HXP I really don't know what to tell you beyond what others have mentioned regarding the HXP ammunition.

I've been loading .30-'06 brass since 1972, and I've never needed a SB die before.

I hear that! :)

Ron

jr_roosa
February 19, 2013, 09:45 PM
Anyway, as I did this morning I measured a pile of factory 30 - 06. They all come up about the same, within +/- of 2.0487". The way I am doing this is I have a RCBS Precision Mic set for 30 - 06. I even checked the set using a Clymer 30 - 06 Go Gauge from my set. I likely have everything here except HXP cases.

My reloads are at 2.049" or so. HXP goes from 2.047" to 2.054"

J.

Reloadron
February 20, 2013, 05:07 AM
My reloads are at 2.049" or so. HXP goes from 2.047" to 2.054"

J.
No, everything I measured was new factory. When I re-size I re size to about 2.049" as measured in my gauge, cartridge base to shoulder datum point. Any brass when fired will expand then slightly shrink, how much it expands depends on the chamber it is fired in.

My understanding here is the HXP starts out from the factory well exceeding the factory brass I have been measuring.

Ron

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