Headspace help for 308Win

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valmet762

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I re-sized a bunch of brass today... I did about 50 in the same re-sizing die without making any adjustments..

when I put them in my headspace gauge, 5 of them were out of spec..

they stuck out 47 thousands of an inch from the top of the gauge..

all the others were 10 thou, which is the actual length of my chamber..

I ran the long ones thru again with the same result.. any ideas why they wont size to the same headspace even though the die setup hasn't changed?

see pics below.. the first pic shows a .047" (out of spec) and the second pic shows a .010" which is within the specs of the gauge.

the cases were all trimmed to 2.005"

DSC04332.jpg



DSC04336.jpg
 
Please make your pictures smaller.
Cartridges don't have headspace. Headspace is a rifle tolerance. That is a case guage, not a headspace guage. In any case, if the case fits in the chamber of your rifle, it's fine.
 
sorry for the big pics.. i'm new at pic posting...

What i did was:

I took a fire formed case.. I set up my re-sizing die using the "smoked case" method..

I'm assuming this gives me the exact dimension of my chamber from the base of the cartridge to the shoulder..

This is what i measured with my calipers and the cartridge gauge to be .010" (i also had Hungry measure one of my cases at his clinic and he told me I had a "10 thou chamber")

I figure for maximum accuracy and consistency, I should make all my cases "10 thou"..

does this make sense, or am I "out to lunch"?

for the record, the cases all chamber in my rifle properly.


what I dont understand is why some of those cases didn't size to the same measurement using the same setup..
 
No problem. if it chambers, it will come out the same size as all the otehr fired brass.

Redding or RCBS (forget which) sells differnt height shell holders so you can size your brass differnt lengths. i usually use the +4 thou one for my rifles.
 
I am guessing that your rifle is an M14-type? Make sure that your "+10"-sized brass chambers freely (put a sized empty case in, and slowly close the bolt over it. It's OK to feel resistance as the extractor rides over the rim, but there shouldn't be any camming resistance from the brass being slightly over-long in the chamber. With a manually-operated bolt action you can get away with a small amount of an interference fit, but you're really asking for reliability trouble with a semi auto).

Do your "+47"-sized cases also chamber in your rifle? If so, then what you are seeing is some sort of measurement artifact. Perhaps a burr on the rim is preventing the case from fully seating in the gage? The case's _shoulder_ should be contacting the inside of the gage; from the picture of the gauge, it looks like its diameter at the case-head end is such that a small burr there might hold the case back. Note that in a rifle, the backmost 1/8" of the case does not enter the chamber, so a small burr or nick there will not interfere with the rifle's functioning.
 
valmet762 ......

I designed this new Digital Headspace Gauge to help shooters set their resizing die height more accurately. It compares your handloads to one of your fireformed cases. After zeroing the gauge on one of your fireformed cases, you just measure one of your handloads. The gauge then displays the clearance (at the shoulder) that YOUR handloads will have in YOUR particular chamber. This shows where to set your die height, and gets the headspace perfect.

COAD-06SM.jpg

Our patented Digital Headspace Gauge is very simple to operate. There's no need to worry about finding the exact datum point on the shoulder, because the shoulder angle in your chamber is identical to your fireformed case, and it's measured at the exact same width. This tool has some other interesting features. You can read all about it on our website.

- Innovative
 
i'm shooting these in a Norc M305.. I full length re-size all my cases.

the case is definetly being measured off the shoulder.. i put the case in the gauge backwards to make sure that the bottom of the case wasn't binding.. there's no burrs that i can see or feel on any of the cases.

both chambered in my rifle without any problems. i loaded a bunch of the .010 mil cases and they shot a 1 inch group at 100 yds.. i also loaded a few that were .006 mil with same results.. maybe i'll try a couple of the .047 just to see..

I've been loading for about 5 years for this rifle and i've never had any problems of any type... i'm sure that i've loaded cases all over the .006 to .047 range, i just didn't know it.. i just started measuring the cases recently after i bought the gauge..

that digital headspace gauge looks pretty neat, but i think the way I'm measuring it in my gauge is basically the same thing.. the only difference is i cant get a fire formed case into my gauge..

I'll keep playing with it.
 
valmet 762, that sure is odd. Putting the case in upside down does seem to rule out the casehead hanging up on the gage's mouth. And yet both the "+010" and "+047" cases *do* fit in another similar "gage", i.e. the chamber of your rifle....!

I notice that your case gauge is sitting on your table surface. Any possibility that the "+047" cases are overly long, and their case _mouths_ are sitting on the table surface? If you hold the gauge in your hands, will the case go all the way in (and .037" of case mouth stick out the other side)?

Any chance there's a ding or a bulge in the case that your sizing die hasn't fully removed? (sounds like a long shot, to be honest)

Do your "+010" cases slide in easily and stop with a solid "clunk" as they hit the gage's shoulder? Do the "+047" cases also do this, or do they slowly fetch up and bind as they go in?
 
Putting the case upside down in your gauge won't show you anything, because your case is tapered. Your gauge is designed to show case "lengths" within an acceptable range - that's all. It's made wider than your chamber, so that you'll be able to see length measurements only. However, if your cases are so wide that they don't fit inside, they're way too wide. You won't be able to actually "see" anything without measuring your case width.

- Innovative
 
rnbra-shooter said:
valmet 762, that sure is odd. Putting the case in upside down does seem to rule out the casehead hanging up on the gage's mouth. And yet both the "+010" and "+047" cases *do* fit in another similar "gage", i.e. the chamber of your rifle....!

I notice that your case gauge is sitting on your table surface. Any possibility that the "+047" cases are overly long, and their case _mouths_ are sitting on the table surface? If you hold the gauge in your hands, will the case go all the way in (and .037" of case mouth stick out the other side)?

Any chance there's a ding or a bulge in the case that your sizing die hasn't fully removed? (sounds like a long shot, to be honest)

Do your "+010" cases slide in easily and stop with a solid "clunk" as they hit the gage's shoulder? Do the "+047" cases also do this, or do they slowly fetch up and bind as they go in?
Click to expand...


the cases are trimmed to 2.005" and all go in nicely without binding... I'm sure they're resting on the shoulder, in the gauge..

not all these cases were fired out of my m-305.. I'm going to resize some of the longer ones tonight and let you know what happens.
 
valmet762 .......

It sure would be nice to know what your handloads measure (at the shoulder) compared to one of your fireformed cases. It appears that your FL die may not be set low enough. However, if you do have a case width problem, and you blindly push the shoulder back farther . . . . the problem will become worse. That's one very good reason to actually "measure" your handloads.

- Innovative
 
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