Different lots of H4350 / barrel wear

[michael_aos]

I worked up my current 260 Remington load almost exactly a year ago. Was kind of nice to have one load, and one rifle. Done.

I just kept loading and shooting. Eventually switched to a different lot of H4350, but didn't notice any difference at 100yds, and even seemed fine at our local ~425yd matches.

Recently shot it over a chronograph and found I'm down ~60fps. I'm assuming this is mostly due to the powder, but I do have a lot of rounds through this barrel now.

I think I can get that velocity back by adding about 1/2 grain or so.
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[buffybuster]

Re: Different lots of H4350 / barrel wear

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body">I worked up my current 260 Remington load almost exactly a year ago. Was kind of nice to have one load, and one rifle. Done.

I just kept loading and shooting. Eventually switched to a different lot of H4350, but didn't notice any difference at 100yds, and even seemed fine at our local ~425yd matches.

Recently shot it over a chronograph and found I'm down ~60fps. I'm assuming this is mostly due to the powder, but <span style="font-weight: bold">I do have a lot of rounds through this barrel now</span>.

I think I can get that velocity back by adding about 1/2 grain or so.
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How many rounds?

Your throat could be moving forward enough to account for the velocity loss.

 

[michael_aos]

Re: Different lots of H4350 / barrel wear

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: buffybuster</div><div class="ubbcode-body">How many rounds?</div></div>

Honestly I haven't recorded that as I probably should have.

I would guess around 2K, maybe +/- ~500rds.

I think I had it built over the Winter between 2007 & 2008, and started shooting it mid-2008. Maybe 700rds/yr for the last 3yrs. I also used RL17 for about a year, which may have accelerated throat wear.
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[michael_aos]

Re: Different lots of H4350 / barrel wear

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: buffybuster</div><div class="ubbcode-body">How many rounds?</div></div>

~2200-ish