Bolt Action Loading: Is Purpose Of Min Shoulder Bump Accuracy and/or Brass Life?

[Offfhand]

That's news to me.

I don't know, nor ever heard of, any specific dimension a fired case needs to be resized to in order the process be called "full length sizing." As long as the case dimensions from pressure ring forward are reduced any amount, it's full length sized.

Bart, apparently you need to get out more.

 

[Bart B.]

Definitions change.

 

[RugerBassMan]

Let me say that I am not a bench rest shooter - any thing less than .5 at 100 makes me happy. Accuracy like that under field shooting conditions will allow hits on small targets up to 600 yards or so, small being a prairie dog or similar sized rodents that are now my sole hunting pursuits.

Today at the range I fired my 6.5-06, hardly a bench rest cartridge. The rifle was a Ruger MKII, hardly a bench rest rifle. The barrel was a McGowen #4 contour 24 inch 1-8 twist. The folks at McGowen squared off the receiver ring and lapped (probably common valve grinding compound) the bolt lugs in - this is not considered to be a "blue print", the bolt face among other things was untouched. I performed a trigger job after the re-barrel. Lots of epoxy was used to bed the receiver and barrel shank.

My ammo was common Winchester brand .30-06 once fired (real cheap). Upon necking the brass down to 6.5 from .30 the bolt would not easily close. I screwed down the 6/5-06 F/L size die more until I was able to very easily close the bolt - a noticeable resistance upon contacting the shell holder. Then my next step was to chuck up the brass in my DeWalt cordless and using an outside neck turner reduce the neck diameter to .288 - this allows 6.5 bullets to be easily inserted into fired 6.5-06 brass in that particular chamber. It shot real good using 140 grain Barnes Match Burners (good deal) and Ram Shot Magnum & CCI 250 primers - this made me happy. Looking at the rounds before firing there was a noticeable ring just in front of the shoulder and this is where the rounds were head-spaced. The shoulders of the brass might have even not touched the inside of the chamber. Slight resistance occurred upon closing the bolt having lapped lugs that fit precisely against the inside of my investment cast receiver upon the resized brass having a slight bump at the junction of neck and shoulder..

That rifle also shoots real good using H1000 (CCI 200's) but H1000 does not flow through my powder measure as good as the R-S Magnum.

The photo above showed a 3 shot group at 200 using H1000 - RS Magnum also works good.

The common ordinary 6.5-06 RCBS F/L die reduced the dimensions of the reformed .30-06 brass enough so I could easily close the MKII's bolt (I put a light coat of wheel bearing grease on the locking lug surfaces). I guess the brass was F/L sized, if I only sized the neck it would be "neck sized" and I don't do that..