Actually, I find that the StoneyPoint Headspace gauge allows me to take measurements of things that I was previously guessing at.
I have several sets of Redding Comp Bushing Neck Dies. The body dies were adjusted according to the directions provided by Redding. Now that I have had an opportunity to actually measure once fired cases and cases that have been run through the body die I have noticed that some body dies were not touching the shoulder at all while others may have been moving them back more than necessary.
One at a time, I have been adjusting my body dies to move the shoulders back .002-.003". Previously I was only assuming what the body dies were doing and I assumed wrong.
I do not ALWAYS run my cases through the body dies but it is nice to know what you are achieving when you do.
Still learning after all these years. [img]/ubbthreads/images/graemlins/grin.gif[/img]
I'm in the process of ordering a Stoney Point headspace guage. I posed some questions about belted mags some months back as I recall. I'll see if I can find it and post a link; some of the comments may be of interest.
Varmint Hunter, do you adjust for shoulder setback with the gauge after the first firing of new brass (i.e. make the adjustment on once fired), or after a couple of firings?
I recall either Redding or Sinclair providing a description of the "size by feel of bolt close" method (with firing pin removed etc.) suggesting using cases fired several times.
[ QUOTE ]
Bart -- I think you forgot a zero...
5-10 thou shoulder bump [img]/ubbthreads/images/graemlins/shocked.gif[/img]
more like 1-2 thou
i had Lapua 308 cases separate at the web on the 7th firing and i was moving the shoulder 5thou each sizing.
[/ QUOTE ]I was almost right. Thanks for bringing this to my attention.
I've found that belted fired case shoulders need to be set back 5/1000ths to 7/1000ths (not 10/1000ths) of an inch or to about where new cases are relative to chamber headspace. This ensures belted cases headspace and stop moving forward from firing pin contact at the belt, not the bottleneck shoulder. Every time I've tested H&H belted cases for accuracy with the shoulder making contact before the belt does, accuracy ain't so good. New cases shoot more accurate than fired cases full-length then double sized setting their shoulder back only "1-2 thou" in my magnums as you suggested.
Rimless bottleneck cases are different. They gotta headspace on the shoulder. Their shoulders should be set back 2/1000ths to 3/1000ths (.002 to .003) of an inch from their fired position. Doing this with a .308 Win. case made by Winchester and with a full-length sizing die reducing body diameters about .003-inch has got me at least 60 loads per case cause that's the most I ever reloaded one. Others doing this get 80 to 100 reloads per case. (Anybody ever get that many reloads on any other make case?)
Setting fired rimless bottleneck case shoulders back more than about .003-inch will indeed shorten case life. I'm convinced this is why so many folks like to neck-only size or partial-neck size their rimless cases. They set the shoulder back way too far and don't have/use a case headspace gage to measure exactly what they're doing. They over do it full-length sizing and start neck-only sizing and claim better accuracy by doing so. They're right. But if they just got a case headspace gage (RCBS Precision Mic, Stoney Point, there's some that's been available someplace since the 1960's) and used it properly to set up their full-length sizing die, wonderous things would happen.
Bart, I've seen you post this stuff on the belted cases before. It is normal accepted practice and my personal experience that fire formed brass consistently presents the bullets centered in the bore and the case head in close proximity to the bolt face for consistent primer ignition. In bench rest they even cut chambers and necks undersized to tighten the fits up even more. This theory applies to all bottleneck cases. Now I have to ask, why is a belted case is not going to benefit from the same time proven methods?
Please also explain how you get any case life at all if you keep pushing your belted cases back so far that they have to head space on the belt alone.
In your last post you referenced people going to neck sizing and claiming improvements in accuracy. I fall in that group. I don’t even own a full length die for my 257Wby. With fired Lee Collet neck sized brass it shoots in the .2s”. With new brass it shoots ¾ to 1” with the exact same load. What do you think you could gain on this one with your method?
__________________ Some kids want to be a fireman or a doctor to help people. I wanted to be a gunsmith.
Ok, so my previous post that I referred to was on a different forum, Oops!
Yes, I was also under the impression that several times fired was preferred for micing, but I wasn't sure. Thanks.
I've comes across a few interesting discussions and there seem to be a bunch of different opinions on how much to resize. Reference is made to the guys at Sierra and all sorts of long range and bench rest records and practices over time.
I don't have the personal experience to comment, but the general responses seem to focus around full length sizing being best (although there seems to be some use of "full length" to include even bumping the shoulder just a couple of thou as opposed to neck only). Part of the argument against neck sizing is based on precise orientation when chambering a neck sized only cartridge (i.e. you can never index it identically to the previous firing).
From what I can gather things have gone (and still do?) in circles in the neck size, full length size, shoulder bump "is best" argument and it makes me wonder whether there's a definitive answer.
Bench rest accepted sizing practice has also moved about quite a bit from what I can establish and the records seem pretty awesome throughout this.
So I'm looking forward to the responses from those way more experinced and informed than I am, but I'm not expecting to see a clear winner here.