COL For 30-06 in '17 Enfield

[velocette]

I've been having great enjoyment working with my sporterized '17 Enfield. It has a GI barrel that was on the rifle when I got it. With ammo made for my Garand it shoots into about 1 1/2" pretty consistenly, with the first two or 2 into less than 1".
I've decided to try to develop some loads just for the rifle.
So you know what I'm starting with:
Winchester brass, fired from the Enfield, neck sized only.
Sierra 168 gr HPBT Matchking bullets, Fed match primers,
RE-15 powder.
I tried to find how far out I could seat the bullets before engaging the rifling.
This gave me a COL of 3.466" with only a very little of the bullets full diameter entering the case mouth, perhaps 0.06" (remember this is a boat tail bullet)
My question is I realize that best accuracy is gotten with the bullet perhaps 10 ~ 15 thousandths from the rifling. This would place the bullet pretty far out of the case neck with little support.
How much of the bullets shank needs to be within the neck of the case to be both safe and secure?
Any ideas? Suggestions?

TIA
Roger

 

[rcmodel]

The old rule of thumb is "one caliber deep", not counting a boat-tail.

That will give sufficient case neck tension the bullet won't fall out.

Also enough case neck tension to get a consistent powder burn necessary for best accuracy.

IMO: That is more way important then trying to reach the lands.

rc