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Old 09-20-2019, 02:51 AM
bert2368 bert2368 is offline
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Join Date: Jun 2014
Location: Blasted hellish frozen Northern wastelands, AKA Minnesota
Posts: 58
Default Seating depth: How well does it translate across propellants in the same rifle?

While waiting for the "new toy" AR10 in 6.5 Creedmoor to cool between groups, I have been putting some previously made up test loads through other rifles to pass the time.

I dug out a dozen leftover loads for the 6.5x55 Swede CZ 550 with the 120gr. Barnes TTSX. The original loading with H414 was done at Barnes recommended OAL (3.000"). These shot over 3" for 3 a round group at 100 yards... And I set the rest asside, probably 2 years ago.






So I found them in a box yesterday, took the remainder and played with seating them deeper. I seated 3 rounds at each .02" interval SHORTER. And at .06" shorter than the original recommended depth, they suddenly grouped under 1".

It was 75 F. when I made that discovery. I hunt deer somewheres around +20F to -10F, usually... H414 is NOT well known for temperature stability.

I had a jug of H1000 on hand, and anecdotal information that it might work with the cartridge/projectile/environmental conditions I expect to hunt in. So, I set up a ladder test, starting a bit above minimum charge and WELL below Barnes recommended OAL, as this OAL had worked with the H414 loads.

What do you all predict... Is the length I discovered to be reasonably accurate with H414 likely to translate to another propellant?

I'll probably know the results by tomorrow around noon, but am curious what the more experienced people might expect my method to produce. I'm butt ignorant and trying to learn something of the basic principles here-
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