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View Full Version : Good starting point for H4895 155gr Palma 308?


blockfort
01-29-2013, 8:01 AM
I was shooting Varget but couldn't get any more, so I bought a jug of H4895. I'm shooting SMK 155gr Palma in my Savage 10 XP 20"

Hodgdon gives a range of 43-46gr. I'll be doing a testing session, but would prefer to no have to load everything from 42.5 up to max. Does anyone have any recommendations for a starting point? I was going to load with a 0.020 jump. Any recommendations on that either?

Bill Steele
01-29-2013, 8:14 AM
Are you using small primer Palma cases?

blockfort
01-29-2013, 8:34 AM
No, LRP Lapua cases trimmed to about 2.000

blockfort
01-29-2013, 8:37 AM
If I can't find any info, I'll just load from half a gran below min to half a grain above max in 0.5 steps. Four rounds of each. All at 0.020 jump, since that's what my seating die is set to, though I never did a proper seating length test.

23's Dad
01-30-2013, 8:25 AM
I'm just passing on a little wisdom I learned from Steve Blair this past weekend.

I had some vertical stringing with my loads, and he told me to find my load first, then work on the seating depth.

I too have some load development work ahead of me, so I can't offer any further advice.

phish
01-30-2013, 8:31 AM
Try seating them a bit further back, 0.03". I get best precision with this jump.

I've not used H4895 for Palma/FTR loads, but it should be easier to reach the speed you'll need for the 155s because of its faster burn rate.

blockfort
01-30-2013, 8:49 AM
Try seating them a bit further back, 0.03". I get best precision with this jump.

I've not used H4895 for Palma/FTR loads, but it should be easier to reach the speed you'll need for the 155s because of its faster burn rate.

Will it be particularly good for me because the barrel is only 20" instead of a 30" palma barrel?

crowbar
02-01-2013, 1:59 PM
My Palma rifle used to love the old Sierra 155's and 44.7 grains of H4895. I used Winchester cases and WLR primers. Velocity wise, IIRC, it was right up there with my Varget load of 47.0 grains, same bullet and case, sparked by 210M's.
My preference for load testing when changing powder lots is to use the published starting load and increase by 0.5 grain increments until I am within a grain and a half of published maximum, then go up 0.2 grains until max. is reached. I flattened a few, but never blanked a primer using that method.
In a .308 with 155's, I would approach anything north of 44.5 grs. of H4895 with caution, especially in a Lapua case. You may want to establish just where your rifling lands are too. The Sierra bullets do like the jump.

Just my $0.07 worth.

phish
02-01-2013, 6:53 PM
Will it be particularly good for me because the barrel is only 20" instead of a 30" palma barrel?

It should since H4895 will reach peak pressure faster. I've read articles where it's easier to get H4895 pushing the 155s to ~3000 fps.

blockfort
02-02-2013, 8:30 AM
I did a big test day. From 42.5-46.5! No overpressure signs, but the ladder test gave me a good range from 43-44.5, and bullet seating tests showed 44.5 at 0.010 jump to be the best so far. I need another finer increment test, though.

phish
02-02-2013, 9:54 AM
DoE

blockfort
02-02-2013, 1:52 PM
What does that mean?

ar15barrels
02-02-2013, 5:17 PM
Department of Energy.

phish
02-02-2013, 6:20 PM
Design of Experiments in this context

got JMP?

blockfort
02-02-2013, 6:47 PM
I searched for that and it looks like statistics software. Is that what you're referring to? I am using excel to good effect.

phish
02-02-2013, 7:35 PM
JMP lets you use Taguchi matrices for doe variables. I used it several lifetimes ago, pretty powerful program.

I once did a 20 shot experiment and saw a sinusoidsal trend for bullet speed after plotting it out. Interesting result.