June 19, 2013, 05:23 PM | #1 |
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.308 Pressure Questions
Hi all, so far the answers I've gotten to my questions here have been very helpful so I thought I'd try to gain some more knowledge.
I recently put my first rounds through my new rifle, some handloads using Winchester brass, WLR primers, 155gr SMK HPBT, and H 414 powder (starting at 48gr, increasing to 49gr, I didn't have time to shoot any more than that). These loads are all well under the MAX loads listed, and my COAL is 2.800", right where my manuals recommend. My question here is in regards to pressure signs, so I can know all that I need to make sure I'm being safe as I proceed. I have loaded for some time and am familiar with the typical pressure signs (flattened primers, primer pocket expansion, extractor marks, difficult extraction, etc.). The fired brass from my loads had some mild flattening of the primer, though the edges are still round. My main concern is the neck expansion of the brass, when I loaded for my .300 Win Mag, the necks had not expanded much (bullets would still be a snug fit in the neck). With my .308, however, the necks are expanded anywhere between .316-.320 inside diameter. I'm not showing any more pressure signs, and I don't think that I have anything to worry about, but I would love to hear some insight from those with more knowledge to offer. Thanks in advance everyone. |
June 19, 2013, 05:27 PM | #2 |
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That's not a "pressure sign", that is just an indication of a slightly roomy chamber neck or thin brass neck.
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June 19, 2013, 05:31 PM | #3 |
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+1 for Jim's response. Winchester brass is in my opinion soft and thin. You might try using a different brand brass to see if you get the same results but the bottom line is it is not an indication of high pressure.
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June 19, 2013, 05:41 PM | #4 |
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Yep.... no amount of pressure (at least with the gun still in one piece) can expand the brass any larger than the chamber. Whatever size the brass is when it comes out is the size of your chamber. (Technically, it's probably 0.001 or so smaller than the chamber.)
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June 19, 2013, 06:04 PM | #5 |
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That's exactly what I was thinking, just wanted to make sure. Thanks a ton for the quick responses guys.
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June 22, 2013, 06:38 PM | #6 |
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Maybe Dan Newberry will see this and post but with a 155 gr. SMK, you probably can't put enough H414 or W760 in the case to cause an over-pressure problem.
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June 23, 2013, 12:43 PM | #7 |
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Buy a chronograph. A max load of H414 shows a 155 gr bullet @ 2793 fps. When your chronograph gets close that, you are close to the max pressure regardless of the powder charge.
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June 23, 2013, 09:37 PM | #8 | |
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