Best bullet weight for 280 Ackley improved with 22 inch barrel

[Warrenoliver]

I hit a good node just under signs of pressure from 63.8-64.1 gr. I hit pressure at 64.5 gr. I have a match chamber, so the throat is long. My COAL is 3.474". ES with new brass was 12 with 3268 fps average. ES with 1x fired brass is 4 with 3264 fps average. Fed 215 M primer.

3268 is really moving. Is 64 grains a compressed load?

 

[Warrenoliver]

I spoke with Berger a few weeks ago about load data for the 168 gr Classic. COAL 3.330"
RL23. START: 54.5 gr 2601 fps
MAX: 60.5 gr. 2864 fps
RL26. Start 56.5 gr. 2640 fps
Max. 63.0 gr. 2951 fps
N560. Start. 56.0 gr. 2631 fps
Max. 62.1 gr. 2929 fps.

Thanks for the Berger recommendations for loads.

 

[dougduey]

3268 is really moving. Is 64 grains a compressed load?

No, it's not compressed but close. Since I have such a long COAL, I don't have a compressed load.
And, you're welcome for the Berger data....glad to pass it on.

 

[CTK]

Not familiar with Talley. Yes as a general rule all copper bullets have had issues with pressure. Barnes is the granddaddy of mono's. Their original bullet was a smooth baring surface. They shot great in some rifles and some rifles would build too high of pressure and others would have accuracy trouble. The age old question is how big in dia to make a copper bullet so that it will seal the bore but not make too much pressure. There is tolerance in bore/groove dia making some tighter or looser than spec. They made a change to the bullets by putting in grooves to eliminate some of the baring surface and relieve the pressure issues. Copper is harder than lead so it can't obturate to conform to the bore size like lead will. Lead will squeeze down in tight rifles and plump up in loose bores from the pressure of the charge behind it. So in loose bores the typical copper bullets will have trouble with accuracy as it rattles down the bore and over pressure in tight bores, and shoot great in the rest. Drive band bullets handle this better than grooved bullets but still have the issue. We solved this by making our drive bands on a radius so that the outside dia of the drive bands are very finite in actual material contact in the grooves. This allows us to cut our bullets larger in dia than caliber without creating extra pressure in tight bores yet still seal up on the loose bores. Hammer Bullets will show less pressure than conventional lead core bullets of the same weight and quite a bit less than most copper bullets.

Had a brain fart while typing this. Had just been looking at scope rings. Meant Barnes not Talley.

 

[CTK]

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The 175 elites have less baring surface the similar 160-168 gr bullets thus can achieve some better velocities. I have seen this in other caliber elites too. Probably a long barrel too.

I agree with this as it relates to Berger bullets other than the Classic Hunters. Assumed it had to do with less bearing surface. I was able to get 2900+ with RL26 and the 168 hvld. I could not get near that with the Classic Hunter.

 

[CTK]

Bob,

Thanks for the great info. This should really help me with working up a load. I have recently switched to the federal magnum primers so that info is especially helpful.

Warren

I have never tried magnum primers In the 280ai. I just bought some 215m's this weekend to try with my new rifle. Glad to hear they are working for you.

 

[Bob Wright]

I hit a good node just under signs of pressure from 63.8-64.1 gr. I hit pressure at 64.5 gr. I have a match chamber, so the throat is long. My COAL is 3.474". ES with new brass was 12 with 3268 fps average. ES with 1x fired brass is 4 with 3264 fps average. Fed 215 M primer.

I think my finicky load is partly due to a standard Sammi chamber depth. I need it throated for other bullets so might as well get it in the schedule. Both 145 class monos are seated deep and eating up a lot of volume. Will run it by the smith.

 

[dougduey]

I think my finicky load is partly due to a standard Sammi chamber depth. I need it throated for other bullets so might as well get it in the schedule. Both 145 class monos are seated deep and eating up a lot of volume. Will run it by the smith.

Sounds like a good idea. That's why you did the AI over the 280.......extra case capacity. If you're not getting that improvement, you need to.

 

[Bob Wright]

Sounds like a good idea. That's why you did the AI over the 280.......extra case capacity. If you're not getting that improvement, you need to.
[/QUOT
Saw your COAL, just checked it against mine. .140" less in mine..
Boat tail junction is .140 below the neck shoulder junction. Maybe why I'm seeing pressure earlier than others and have a narrow powder tolerance for accuracy. It goes from .25" groups to 1.0" groups in .2 grains either slower or faster. Not good enough. It was the same with Barnes 145LRX.

 

[dougduey]

Sounds very plausible