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I've broken in my Howa 1500 .308 HB 26" with about 500rds. of 147gr. and 180gr. practice ammo. I've only been shooting at 100yds. for about 2 months and now I'm shooting into one big hole by the time I get 20rds. down range, with a couple of flares. I will be moving on to the 200yd. range soon and I think I need to start thinking about correct bullet weight for my rifling. My Howa is a 1 in 10 and I understand that around 180gr. is where I need to be for the best match for my rifling. This is what I think I've read so far, but I'm still learning long range shooting. After 200yds. the science gets more exact the further out you shoot. But now I'm thinking about buying 500rds. of Federal premium match 175gr. Sierra Matchking HPBT. I don't want to buy a bulk amount of ammo and regret it. So, any thoughts?
 

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I’m not a .308 shooter but it seems to me that these would be a bit heavy. The 30-06 match bullet is 168gr hollowpoints. 30-06 generally shoots a bit heavier bullet than the .308 but again I’m no expert.
 

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Because you aren't hunting and don't have to worry about penetration or expansion, look for stability that produces uniformity. That means uniform pressures, as in repeatability. Look at the narratives in reloading manuals and in on-line articles for the results that have already been discovered and documented for you.

Winchester invented the .308 and introduced it around 1952. They felt 1-in-10" rifling was too fast for 150 grain bullets, so they installed barrels on their .308's with 1-in-12" rifling. When the U.S. Government adopted the cartridge for the M-14, they decided on a rifling between the civilian sector standard and Winchester's choice by stipulating 1-in-11" twist barrels. Barrels of .30 caliber have proven in over 120 years of service, in hunting and war, that the industry accepted standard 1-in-10" rifling twist is best to handle the widest possible range of bullet weights and shapes.

Consistent pressures should be your goal, for reloading and accuracy.
 

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Your 10 twist will stabilize everything up to a 215gr hybrid.

175grSMK's shoot very well in most factory rifles.

Most long range 308 shooters in Fclass use Berger 200gr 20x bullets or Berger 200grHybrids.

If you decide to reload the Berger 185gr Juggernaut is about as big as you can run in most factory offerings due to free bore limitations.

I wouldn't over look the 155gr offering either. https://www.bulletcentral.com/product/berger-ammunition-308-winchester-155-5gr-fullbore-target-60030-qty-20/

Here is a stability calculator you can input different variables and see what does and doesn't work.

https://bergerbullets.com/ballistics-calculator/
 

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If I shoot a 110gr FMJ in my 1 in 10 barrel, at 3200fps, it spins so fast, it comes apart in mid air. If I shoot a 220gr RN in the same rifle, at 2350fps, the bullets will keyhole slightly at the target.
That is all the difference you will find at 200 yards, with a 308.

If I shoot the kind of large 265gr FN, at about 1600fps, in my 44 magnum's 1 in 38 twist; it does well at up to 200 yards, but precision falls apart at over 200, due to transonic flight.


Look at the Rex recommended video on overstabilization.
Twist Rate Stability Calculator
 

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Discussion Starter #7
Thanks for the info on the .308 bullet weights vs. twist. I'm buying my factory ammo at Target Sports online and with the prime prices I'll pay around 1.00 per rd. for Federal Berger buttets in both 185gr. and 175gr. in their match grade ammo. So, thanks again
 

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FWIW, the British IBS 1000 yard group record was set by a gentleman in 2018 shooting Sierra 155 grs SMK in a factory Savage Model 12 FT-R .308 Win.
 

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I'd try boxes of 20, till I was sure I found a bullet the rifle likes, then go for the volume purchase. It's cheaper in the long run.
 

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This is a lesson found by most experimentation older rifles and modern makes, handle bullet weights and powder charges so differently a good load for a Winchester 2001 30-06 may be junk in a Springfield 1903 and vice versa. Lot of reload data it is just crunching what works for you I can tell you it is a lot of work well rewarded.
 
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