Thread: Barrel chop

From 24"to 18" barrel, my 308 165gr dropped about 300ft/s=50ft/s=1". 18inch drop at 300yds from 100ydszero.

Cold bore 2 shot group 300yds,18in drop in nor-west win left to right.No crony,drop is what it is to work out velocity.

Greetings again @yogi,
From my records 44 grains of AR2208 with the 150 grain Hornady in a Winchester case chronographed 2,560 fps in a 20" barrel. This would work out to 2,610 fps with your 45 grain load. Your load is 2 grains under max which is more limited by case capacity than pressure and you may struggle to get the full charge in your case but if you can 47 grains of AR2208 should give you about 2,710 fps or perhaps a little more. It seems that once the pressure drops below a certain point velocity drops at a faster rate. Your loads are only giving around 45,000 CUP or a little more where a full pressure load would develop between 50,000 and 52,000 CUP. Your Sierra Game King projectiles should be a good match for the Nosler BT used in the Hodgdon/ ADI data. I assume that the 159 grain is a typo. If you wanted to go to a different powder I would recommend AR2206H 45 grains of that should give 2,720 fps in your rifle and it will fit in the case better. 45.5 grains is book max. Work up using your chronograph though and expect around 80 fps loss below 24" data as you approach max loads. Or just go hunting with what you have, your choice.
Regards Grandpamac.
PS. My Chronograph is an Oehler 35P with a 4 foot screen spacing and has proved reliable for me.

Originally Posted by andyanimal31

My 308 at 16.5 inches doing 2540 with 168 eldm.
It still flattens deer at 600 so don't over think it.

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Hi,you must reload for that velocity from a 16inch barrel.

@yogi. Ar2206h is a faster burn rate powder than 2208 and so a bit bettet suited to yr shorter bbl than 2208. The mv gain is likely to only about 120fps though. 2206h takes less space than 2208 so at around 45- 45.5 grains there should be no need for compression. Cheers mate.

Originally Posted by Trout

Hi,you must reload for that velocity from a 16inch barrel.

Yep, 2208 in lapua brass.
Can't remember how much but can look it up if ya interested

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The barrel on my 308 is 14.6". After the barrel chop it definitely became fussier with ammo. After trial and error I found that it groups Fiocchi the best for some reason - could be that these are slightly less hot rounds? When I tested it on a chrono it was averaging 2500fps. At 200m I can can shoot about a 3-4" 5 shot group with it off a bipod and bag rest with a 9x scope. With some proper load development, maybe trying a faster burning powder etc, maybe that could be improved. For me it's just a bush gun anyway so being minute of deer at 200m is more than accurate enough.

Thanks alot for the input. Certainly food for thought

A couple of typos on the load.
150gn sierra not 159
46 grains 2208