Neck Tension Conundrum

[RTK]

That little red man has caused me fits over the last 30 plus years of reloading
Forgot to mention the caliber, it's a 300wm. I usually try to head space off of the shoulder instead of the rim so I tend to let them run a little long in that regard, don't know if it helps or not just one more thing I try for better performance. This is the second barrel the gun has worn.
Wish I could shot it as well as my 22-250AI

 

[Bart B]

Most belted cases like the .300 Win Mag shoot most accurate when they headspace on their shoulder. That better aligns the case neck and bullet with the bore.

However, folks handloading new belted cases seating bullets to set back a few thousandths by crunching into the lands when chambered have got sub 5/8 MOA accuracy at long range with new cases. This is what the military teams did with the .30-.338 back in the '60's when normal full length sizing of fired cases didn't do so well. Even when setting the shoulder back a couple thousandths. So they just used new cases tossing them to civilians when the match was over.

One other thing about belted cases. The ridge that builds up right in front of the belt has to be sized down else it'll interfere with repeatable case positioning at its back end. Full length sizing dies do not size the case all the way to the belt; they stop 1/32 to 1/16 inch short. A collet die's needed such as the one sold at Innovative Technologies - Reloading Equipment. Before that colled die was offered, folks cut the shoulder off a belted case full length sizing die as well as the bottom just above the belt clearance. Squared both ends then slightly radiused the bottom part. Set that die in the press such that the case stopped just as the belt touched that die. Best accuracy with reloaded belted cases ever; other than new cases.

 

[RTK]

I have one of the innovative tech dies, expensive they are, unfortunately I have never found the need for it before. The primer pockets usually become loose before they need re-sizing that low.

 

[Bart B]

I have one of the innovative tech dies, expensive they are, unfortunately I have never found the need for it before. The primer pockets usually become loose before they need re-sizing that low.

That ridge shows up with the first firing of a new case with normal peak pressures. It starts interferring with case position in the chamber then.

If you don't get at least 15 loads per belted case and still have tight primer pockets, your peak pressures are probably too high and above SAAMI's safe limits.

Regarding that collet die, if your ammo can consistantly shoot under 1/3 MOA at 200 yards,1/2 MOA at 600 yards or 3/4 MOA at 1000 yards with your reloaded belted cases it a top quality match grade barrel, then I agree; you don't need that collet die.

 

[RTK]

I wish I could shoot those MOA's at those yards that you posted, unfortunately myself the wind and many other factors always seem to get in the way

My fired cartridges always fall to the belt using the other side measuring hole of the die, this is after many loadings so my pressures must not be hurting anything. Haven't used it to date except for checking them every now and again.

After I send my scope in for a tracking problem maybe I can obtain that 3/4 MOA at 1000, but I really doubt it...