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Discussion Starter #1
It all started a couple weeks ago. I went out to my first Hi power shoot, and promptly got my clock cleaned! I'm pretty sure 95% of the problem was the nut behind the buttplate, but I decided to make sure the other 5% was solid.
I was shooting pulled 147's over 41.8gr IMR4895 in LC '05 cases lit off by a WLR primer. All shot out of a SAI standard, no modifications.
So I got 'hold of some 168 A-Max's and some W748. With the 748, (cases and primers same as above) Primers started to flatten at around 42 gr. Decent results, I think I'll work around this load for more tests. Then I loaded some test rounds with IMR4895. I've seen it several times here and elswhere, 41.5 gr 4895 topped with a 168. I started to flatten and crater at 40.7gr IMR4895. Decent results with the work up here too, I'll certainly find a good load somewhere beneath that. Just curious about the " standard match load" referenced above.
Are you serious match shooters really pushing your components to their limit, or your equipment for that matter, or am I just being a little pansy about the whole thing?

Look forward to your replies and insight.
Andy
 

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I was shooting pulled 147's over 41.8gr IMR4895 in LC '05 cases lit off by a WLR primer.
So I got 'hold of some 168 A-Max's and some W748. With the 748, (cases and primers same as above) Primers started to flatten at around 42 gr. Decent results, I think I'll work around this load for more tests.
Then I loaded some test rounds with IMR4895. I've seen it several times here and elswhere, 41.5 gr 4895 topped with a 168. I started to flatten and crater at 40.7gr IMR4895.
Have you checked the velocities for these loads? I ask because I started to tell you how I didn't see any problems with the powder charge weights and then I realized that you are using LC brass. I normally use Lapua or WCC brass and the powder charges you talk about work well, in fact I use slightly more powder in my loads. I use the QuickLOAD ballistics software to help develop loads and it is accurate enough that I trust it to keep me from blowing up my weapons. At any rate, I ran your loads using the volume for my brass and they were all within safe limits, in fact if anything, they were a little on the light side. Then I used the volume for LC brass...BINGO...pressures jumped up by about 5,000psi.

Let me give you an example of the differences in pressures according to the software (I used the volume for a LC 86 case since that is the only data I know for sure but most LC brass is pretty close to the same and all have less volume than commercial brass).

Case TTL 2.005"
COAL 2.80"
168gr Amax, 40.7gr IMR 4895
Lapua brass 43,600 psi
LC 86 brass 48,000 psi

168gr Amax, 42.0gr Win748
Lapua brass 47,700 psi
LC 86 brass 52,800 psi

Case TTL 2.005"
COAL 2.75"
147gr Win FMJ, 41.8gr IMR 4895
Lapua brass 40,000 psi
LC 86 brass 44,000 psi​

The 147gr load is actually a little light for my taste even with the LC case but the others are getting to the top end of where I like my loads especially the Win748 load. The general rule is to drop a full grain or so on your powder charge weights if you use a load developed in commercial cases with LC cases. If you were to do that then I would bet you will see things change for the better. For example, that Win748 load in the LC brass would drop down to about 49,000 psi if you dropped down to 41.0gr.
 

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I like 40.0 IMR 4895 with 168SMK with LC brass I do 41.0 with commercial brass. Oddly enough the same charges work with the 175SMK in my rifle. I just switched to H4895 and 40.0 in commercial brass with pulled 175SMK was stout but no pressure signs and accuracy was great. I switched to H4895 because it is less temp sensitive,supposedly anyways.
 

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I've been using 41.0 grains of IMR-4895 with the 168 grain SMK and military cases since 1984. It doesn't show pressure signs in my rifle but it seems plenty stout enough that I don't want to load it any hotter. I've found that 50 fps doesn't make any difference, even out to 600 yards. The NRA max load is listed as 40.5 grains in a military case.

Hodgdon's old claim to fame was their powders used to be slightly cheaper. Some of their ball powders were bulk versions of Winchester powders. Now Hodgdon owns IMR and distributes Winchester powders. I think Hodgdon used to allow more lot to lot variation in burning rate to keep prices down. I have read some people complain about the new Hodgdon distributed W748 varying more from bottle to bottle than it used to. My last bottle of IMR-4895 seemed a bit slower / milder than usual. I wonder if Hodgdon is applying their wider lot variations to the other powders they handle now.

I have found H4895 to be a bit faster than IMR-4895 but it doesn't produce as much gas.
 

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Discussion Starter #5
QuickLOAD

Thanks for the thoughts, and for the data RAMMAC. I'll be looking into that program.

So much to learn! I'm fascinated by the differences in individual rifles, John Coleman can run 41 gr while I'm flattening primers at .3 gr less. Is it headspace, brass prep? I'm amazed at how small differences net such big changes!

Thanks again for your replies...Now the next topic, Neck tension!

Andy
 
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