First loads done, crimp and OAL change ?'s

[Kiss of Death]

Thanks everyone for all the great input. I went ahead and ordered some 275 XPB’s - Seated the bullets so I could crimp into that 3rd driving band (closest to point). Here is the result : my COL is 2.189 and the neck after the taper crimp is .475 . I’m feeling much better about how that taper “felt” as I applied it. Maybe it’s all in my mind but it seemed better as I did it.

One last question, with the shorter COL, should I assume slightly higher pressures and therefore my maximum load (37.5 with H110) would be somewhat less?

[Hoot]

You nailed that groove perfectly IMHO. You could have gone down to .474 if you wanted. If you have an inertial bullet puller, chuck one of them in it and give it a single whack approximating that the cartridge sees when chambering. You shouldn't see much pull. The pressure will be slightly higher but not of any consequence, assuming you're not pushing them to the edge of safe already. They're just as lethal at 2200 as 2250 at the range you spoke of. I too hunt northern woods, just further west than you.

Hoot

[Kiss of Death]

Had a chance to get out and shoot these loads, looking for one my rifle likes. Here are the best groups, which came from the moderate loads. The hotter loads spread out laterally.
Bear Creek upper - 16" barrel
Barnes XPB 275 ~ Hornady once fired brass ~ CCI 41 ~ H110 powder
COL 2.189
Taper crimp .475
100 yds ~ 5 mph wind
5 shots each

On the last one (36.5), I either shanked one completely or put 2 through the same hole. All the shots felt good, I fired 5 at each target. The cardboard extended down 8” below the target shown.

[Al in Mi]

Nothing wrong there guy.

I have a hard time concentrating after the 3rd shot especially when I see holes close, then it's a sure bet I'll mess up the next couple shots!!

[Kiss of Death]

So I got to thinking about these as I was getting ready to pack my stuff up for hunting. I never really did check them for length change after dropping the bolt with them when chambering in my AR. Just did and was disappointed to see it did change. Started at 2.189 in the mag, drop the bolt, remove cartridge and length is now ****EDIT *** 2.206

Should I be ok to lower the bolt slowly to hunt with? I have a taper crimp on these of .475 currently. When I get to the press I can try getting them down to .474/.473 and see if that solves the issue.

[Hoot]

So I got to thinking about these as I was getting ready to pack my stuff up for hunting. I never really did check them for length change after dropping the bolt with them when chambering in my AR. Just did and was disappointed to see it did change. Started at 2.189 in the mag, drop the bolt, remove cartridge and length is now 2.010!

Should I be ok to lower the bolt slowly to hunt with? I have a taper crimp on these of .475 currently. When I get to the press I can try getting them down to .474/.473 and see if that solves the issue.

That's the first time i recall reading that a cartridge's OAL got shorter after "slam chambering" in an AR platform. Usually, they get longer from pulling (as in inertial puller). The only time I ever experienced shortening was with 300gr Hornady XTP Mags and that was because they were running into the rifling and getting pushed back a little. Not nearly as much are you are experiencing though. Since you didn't say otherwise, I assume that if you ease the bolt into locked, they don't get shorter?

Good Luck hunting!

Hoot

[s4s4u]

So I got to thinking about these as I was getting ready to pack my stuff up for hunting. I never really did check them for length change after dropping the bolt with them when chambering in my AR. Just did and was disappointed to see it did change. Started at 2.189 in the mag, drop the bolt, remove cartridge and length is now 2.010!

No feed ramp? I am surprised a pointy bullet with a taper crimp would set back in an AR

[Kiss of Death]

sorry guys it's been a heck of a night- I was posting while at the vet with a dog emergency. My bad, it was a typo, they got longer - 2.189 to 2.206
I double checked the crimp and it’s actually .474/.473 and I am still getting that creep forward from the bolt inertia.