flowrie wrote: ↑Wed Jun 03, 2020 9:20 pm
One other item. Before reloading say 20 rounds, I measure each bullet. Using the longest bullet I seat and then measure the base to ogive then seat all the other bullets at this setting. Trying to achieve a consistent jump to the lands. Seems to help some based on today’s range results.
Pics are with a red dot sight at 50 yds, 68gr Hornandy HPBT match ( 3 distinct holes) and the other is 62gr Sierra SBT ( 3 bullets but looks like two holes).
You mentioned using a mic. If it's accurate to 4 decimal places, check the dia. of the Hornady and the Sierra bullets. Sounds like the Sierra's are slightly smaller in dia. Some of your problems seemed tied to the small base sizing die, so whoever recommended you get one, be sure and thank them for the problems you've had. If you've fired factory ammo in your rifle, and had no problems the small base sizing die was a bit of over-kill.
Check with one of your shooting buddies who handloads .223/5.56mm and uses a standard F/L sizing die and borrow it. See if things don't go much easier.
There are some basic rules for handloading auto-rifle cartridges. Cases must be F/L resized, your bullets need a cannelure, and you need to crimp the case-mouth into the cannelure.
With the increased resistance you're getting in seating bullets due to the cases being resized in a small base sizer, you might think that the increased case-neck tension is enough. It will not, however, prevent set-back as effectively as crimping into the cannelure. And there is still some room for adjusting OACL.
Maybe you're more interested in punching paper than using your AR 15 for tactical purposes. It's your rifle and it's up to you how it's used. Lots of talk about bullets tumbling out to 300 yards and a 77 gr. Sierra MatchKing w/cannelure will do that if it leaves the muzzle at 2700 FPS. It is just as important to know how your bullet performs at much shorter ranges like the 50 yards you fired your targets at. It's very easy to test by lining up 5 or 6 - 1 gallon water filled jugs at 50 yards. If the bullet comes apart, then obviously you want one that doesn't, if there is a tactical purpose for using a particular bullet.
Anything that can be corrupted by man; will be corrupted.
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