28 Nosler barrel 'sped up'

bodywerks

Gunny Sergeant
Belligerents
Jan 19, 2010
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Tucson,Arizona
#1
This cartridge has been interesting to me. It's the first time I read discussions of barrels speeding up after 'x' amount of rounds.
When I first got the rifle I found an accuracy node pretty quickly of 79.5gr retumbo under 195 bergers on an 'almost' saami spec chamber. Was getting 3050 and driving tacks out to 1k. Fast forward to my hunt, and about 100 rounds in. Went to verify dope, and glad I did, kinda. Found that I was about 7" high at 700 yards. Didn't have my chrono with me at the time, but math calculates it to be about 3125 - 75fps speed up. Of course, with that speed up, my accuracy went down. Went from 4"groups at 1k to 7"groups at 700. No time to work up another load, I just dealt with it. Still got the job done at 575 yards, but now I feel like I need to completely rework my load, on a barrel that already has 1/4 of it's life burned through it. Is this the norm for fast magnum chamberings? If so this might be my last. In the meantime, should I just try to find a load that gets me back to that magical 3050fps, or should I do a complete re-work up?
 

stello1001

Professional newbie
Belligerents
Feb 20, 2017
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Corpus Christi TX
#2
If it were me, I'd try to down your charge a bit and look for your initial speed of 3050. See how that works and groups for you. If not too well, you might have to start load development again from scratch! But more than likely, it will be good once you get back again to 3050!
 
Likes: bodywerks

Jimgal62

Sergeant
Online Training Access
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Jul 10, 2014
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Humble, TX
#3
If it were me, I'd try to down your charge a bit and look for your initial speed of 3050. See how that works and groups for you. If not too well, you might have to start load development again from scratch! But more than likely, it will be good once you get back again to 3050!
I would run five rounds at 3050 FPS with the same jump and expect similar results as before.

Assumes you know how many grains to drop from previous load development and insignificant throat erosion.

You can verify throat erosion prior to the test using Hornady gauge tool.
 

CanSniper

Sergeant
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Jul 25, 2011
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Colorado, Pawnee Grass Land
#4
Yep, just played the same game with a 300wm. Back down your charge to run the same velocity as before. I bet you will be back in your sweet spot. Make sure your increase in pressure is not due to a carbon ring build up.