Spaced out on headspace

Lilswede1 · November 15, 2009, 02:21 PM

Thank you for the help. Problem resolved.

10 Spot Terminator · November 15, 2009, 02:46 PM

If you are looking for benchrest competition performance you might be able to split hairs on the subject of case stretch vs. accuracy but for most of us it is not that critical. Those rounds you fired that mesure .003 to .005 under confuse me a bit as they should be at exact chamber dimensions unless fired with "mouse fart" loads. If you are loading for a bolt rifle seperate your brass by the length at the shoulder for load workup. After they have all been fired in your rifle and go to the press for resizing try to get the set back at close to .002 on the shoulder for good feeding when chambering and minimal case stretch between firings for long case life. If you are shooting an auto loader you may want to be a bit more generous on the setback with maybe .005 or so to prevent jamming .
10 Spot

Creeper · November 15, 2009, 03:26 PM

I agree with 10 Spot in that I'm confused as well. The fireformed cases should have "sprung back" after firing only a minimal amount... under .001", with a resultant near perfect case body and shoulder fit in the chamber.

You might want to look at benchrest grade equipment... small hand presses and bushing type shoulder bump dies like those made by Lynwood Harrell and others.

As a point of reference, with my 6PPC benchrest rifle, I'll typically bump the shoulder back .0005".
With turned necks (in a custom, tight neck chamber), the brass is turned to provide .0008" - .001" clearance between neck and chamber with a loaded cartridge... this provides enough room for the neck to expand, releasing the bullet while at the same time restricting case expansion to an absolute minimum and maintaining near perfect case/chamber concentricity.

This may seem like gross excess to most riflemen, but this and several other "processes" are SOP for benchrest competitors.

I have Lapua .220 Russian brass (the parent case for 6PPC) that after machining and fireforming have seen over 1000 reloadings and still going strong.

Cheers,
C

Lilswede1 · November 15, 2009, 07:43 PM

These cases that are to short are because I resized them too short prior to having the Precision Mic Gage. I also got the Wilson case gage and the short cases are just slightly below the low edge of the gage .001 to .002".
I will reload these cases, fireform them to my gun and reload to spring hunting.
Just wondered if, prior to the rifle range which I cannot get to for awhile, the shorter cases would cause an appreciable difference in accuracy.
Any ideas?

Creeper · November 15, 2009, 07:49 PM

Lots of variables that can affect your accuracy. The short cases maybe a little, maybe a lot... depends on your acceptable level of accuracy.

Use the short cases as foulers and sighters while you "re-fireform' them.

C

wncchester · November 15, 2009, 08:48 PM

"Will the shorter cases affect accuracy to any extent? "

Probably not, not enough to measure anyway. But, now that you can actually measure what you're doing, try to FL size the fired case shoulders back to where they were after firing or .002" more, on average.

You are quickly going to learn that the way you operate the press, how hard you push down and, to some extent, even how long you hold pressure on the case fully up will make a small difference. Ditto the lube and even the amount of lube you use can make 2 thou difference. And individual cases will springback somewhat differently no matter what you do. So, don't go insane trying to make your cases precise duplicates, it won't happen. Nor need it happen, if they chamber well and shoot well with minimal chamber slop you are doing good work!

Lilswede1 · November 15, 2009, 10:04 PM

That's really what I needed to know. Didn't think I had ruined the cases yet but felt like an idiot for not checking with gages before I started resizing. Have about 2M to reload so glad I caught it before going too far.
Yep, have some cheaper bullets and powder to use up and will use it on the shorter rds. Good for plinking and fireforming.
Will load up some of the shorter cases with same loads I will be using in Montana this spring. If no noticeable difference in accuracy at 200 yds. they will work for me.
Been pulling my hair out over variances in shoulder length. Resize a case, measure it using both the Wilson and Precision Mic and get to match a case recently fired from my gun. Then resize 10 more and they vary as much as 006" . Now I remember why.
All those things you mentioned above.
Thanks.

November 15, 2009, 02:21 PM	#1
Lilswede1 Senior Member Join Date: September 8, 2008 Location: NW Wash State Posts: 216	Spaced out on headspace Thank you for the help. Problem resolved. Last edited by Lilswede1; November 16, 2009 at 10:56 AM. Reason: Questions have been answered.

November 15, 2009, 03:26 PM	#3
Creeper Senior Member Join Date: September 9, 2008 Location: Woooooshington Posts: 1,797	I agree with 10 Spot in that I'm confused as well. The fireformed cases should have "sprung back" after firing only a minimal amount... under .001", with a resultant near perfect case body and shoulder fit in the chamber. You might want to look at benchrest grade equipment... small hand presses and bushing type shoulder bump dies like those made by Lynwood Harrell and others. As a point of reference, with my 6PPC benchrest rifle, I'll typically bump the shoulder back .0005". With turned necks (in a custom, tight neck chamber), the brass is turned to provide .0008" - .001" clearance between neck and chamber with a loaded cartridge... this provides enough room for the neck to expand, releasing the bullet while at the same time restricting case expansion to an absolute minimum and maintaining near perfect case/chamber concentricity. This may seem like gross excess to most riflemen, but this and several other "processes" are SOP for benchrest competitors. I have Lapua .220 Russian brass (the parent case for 6PPC) that after machining and fireforming have seen over 1000 reloadings and still going strong. Cheers, C __________________ Shoulder Drive Nicholson Club

November 15, 2009, 07:43 PM	#4
Lilswede1 Senior Member Join Date: September 8, 2008 Location: NW Wash State Posts: 216	ADDED INFO These cases that are to short are because I resized them too short prior to having the Precision Mic Gage. I also got the Wilson case gage and the short cases are just slightly below the low edge of the gage .001 to .002". I will reload these cases, fireform them to my gun and reload to spring hunting. Just wondered if, prior to the rifle range which I cannot get to for awhile, the shorter cases would cause an appreciable difference in accuracy. Any ideas?

November 15, 2009, 07:49 PM	#5
Creeper Senior Member Join Date: September 9, 2008 Location: Woooooshington Posts: 1,797	Lots of variables that can affect your accuracy. The short cases maybe a little, maybe a lot... depends on your acceptable level of accuracy. Use the short cases as foulers and sighters while you "re-fireform' them. C __________________ Shoulder Drive Nicholson Club

November 15, 2009, 10:04 PM	#7
Lilswede1 Senior Member Join Date: September 8, 2008 Location: NW Wash State Posts: 216	Thanks to winchester and all That's really what I needed to know. Didn't think I had ruined the cases yet but felt like an idiot for not checking with gages before I started resizing. Have about 2M to reload so glad I caught it before going too far. Yep, have some cheaper bullets and powder to use up and will use it on the shorter rds. Good for plinking and fireforming. Will load up some of the shorter cases with same loads I will be using in Montana this spring. If no noticeable difference in accuracy at 200 yds. they will work for me. Been pulling my hair out over variances in shoulder length. Resize a case, measure it using both the Wilson and Precision Mic and get to match a case recently fired from my gun. Then resize 10 more and they vary as much as 006" . Now I remember why. All those things you mentioned above. Thanks.

November 15, 2009, 02:46 PM	#2
10 Spot Terminator Senior Member Join Date: January 3, 2008 Location: Central Oregon Posts: 348	If you are looking for benchrest competition performance you might be able to split hairs on the subject of case stretch vs. accuracy but for most of us it is not that critical. Those rounds you fired that mesure .003 to .005 under confuse me a bit as they should be at exact chamber dimensions unless fired with "mouse fart" loads. If you are loading for a bolt rifle seperate your brass by the length at the shoulder for load workup. After they have all been fired in your rifle and go to the press for resizing try to get the set back at close to .002 on the shoulder for good feeding when chambering and minimal case stretch between firings for long case life. If you are shooting an auto loader you may want to be a bit more generous on the setback with maybe .005 or so to prevent jamming . 10 Spot

November 15, 2009, 08:48 PM	#6
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"Will the shorter cases affect accuracy to any extent? " Probably not, not enough to measure anyway. But, now that you can actually measure what you're doing, try to FL size the fired case shoulders back to where they were after firing or .002" more, on average. You are quickly going to learn that the way you operate the press, how hard you push down and, to some extent, even how long you hold pressure on the case fully up will make a small difference. Ditto the lube and even the amount of lube you use can make 2 thou difference. And individual cases will springback somewhat differently no matter what you do. So, don't go insane trying to make your cases precise duplicates, it won't happen. Nor need it happen, if they chamber well and shoot well with minimal chamber slop you are doing good work!