Newbie Reloading- Headspace sanity check

[Benjamin_Breeg]

So I've essentially spent the last year slowly accumulating my reloading stuff and reading enough to reconfuse myself but between Tre Mon's series of posts and some other info I'm pretty good. So first step was to determine the chamber dimensions for headspace of my two .308s. I took a bunch of fired shells and measured them using calipers and the Sinclair tool. For my 700SPS here's what I got:

1.556" x 2
1.554"
1.557"
1.555" x 5

So should I just use 1.555" and bump it back .003" or use the longest measurement, which I assume could be caused by my lack of experience using calipers and the case could have been skewed a little?

My hunting rifle likewise has measurements ranging from 1.561" to 1.564" with the vast majority being 1.562".

Maybe I'm being too particular? Thanks in advance!

 

[427Cobra]

Re: Newbie Reloading- Headspace sanity check

did you decap the cases first, then measure?

 

[Benjamin_Breeg]

Re: Newbie Reloading- Headspace sanity check

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">did you decap the cases first, then measure? </div></div>

No, they were shot and measured.

 

[427Cobra]

Re: Newbie Reloading- Headspace sanity check

decap first, primers flow and screw up the HS readings I suspect, once all decapped I bet your readings are much more consistent

 

[Benjamin_Breeg]

Re: Newbie Reloading- Headspace sanity check

If I use my sizing die just to decap and don't set it to bump the shoulder, is that ok or will the body sizing affect the case enough to affect my reading? Not sure if that makes sense. In other words, do I need a dedicated decapping die?

 

[bcrich]

Re: Newbie Reloading- Headspace sanity check

Get a decapping die bro they are only like $15 or so (rcbs)

 

[Benjamin_Breeg]

Re: Newbie Reloading- Headspace sanity check

Got it, thanks guys!

 

[427Cobra]

Re: Newbie Reloading- Headspace sanity check

Just extend the decapping assy as far as it will go to pop the primers out of some

 

[prosise]

Re: Newbie Reloading- Headspace sanity check

Here is a little trick I was shown when i first started shooting benchrest. Now this works on Remington actions: Or the like. Get a firing pin removal tool & take your bolt apart, takes like 5 seconds, you dont want the firing pin spring affecting bolt closure. then remove the plunger that kicks the shell out when you open the bolt, ill refer to this later. Now you have a bolt with no parts to push on the sized case. Size the brass and then see if it will chamber without any bolt tension. Slowly adj your sizing die down until you get the brass sized and the bolt will chamber with no force on the bolt handle. The reason for removing the plunger is it protrudes out of the bolt and puts sension on the case when you close the bolt. So when you think you have your sized case ready and your headspace is setup, try a new fired piece and retest. Now here is the kicker, if you think you have oversized the brass you can get a piece of maskint tape and put a layer on the base of the brass, cut around the brass so it doesnt extend out past the edges. this will add about .003" to the OAL. If you cant close the bolt with the tape you are right on the money. If you can close the bolt it is bumped back too far. You can put up to three layers of tape on the back of the brass to troubleshoot oversizing tests. I know this sounds like a bunch of steps but it is really easy. Once you have your sizing die setup lock the set screws down on the ring and your done. If you do any major changes like changing barrel you will have to setup the die again. Oversizing is dangerous as you can pierce primer pockets and get a puff out of the bolt handle. I have seen it. If you have any questions let me know. This was taught to me by Thomas "Speedy" gonzales of SG&Y precision rifles when he lived in Roanoke, tx back in the day. He is in the Benchrest hall of fame, so I know he is qualafied. Good luck & be safe.

Prosise

 

[Benjamin_Breeg]

Re: Newbie Reloading- Headspace sanity check

It's been a while but I don't get to do fun stuff much with my schedule. So I popped the primers, here are the new readings:

1.559 x 3
1.560 x 2
1.561 x 2
1.556 x 2

Should I bump to 1.557"?