OAL length and accuacy limitations


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BluegrassDan
August 21, 2011, 06:12 PM
My .308 Win Kimber 84m magazine will only take cartridges with OAL of around 2.825. The chamber length however, with the same bullet, would put the OAL length to around 2.95. I'm quite a bit short of the lands if I want to use my magazine, which I do.

The best 5-shot groups I can achieve are around 1.0"-1.2". I've tried IMR 3031, Win 748, and IMR 4320 using 150 grain NBT and 165 grain Sierra Game Kings.

I'm beginning to think that this gun is incapable of better accuracy with the long jump to the lands. Any thoughts or solutions?

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918v
August 21, 2011, 06:31 PM
You should test the rifle with a known standard, like FCGM 168 or 175gr ammo or Black Hills 175. Then compare your handloads. Don't assime your Kimber is a half-MOA rifle.

T Bran
August 21, 2011, 06:47 PM
Load some up incramentally working towards the lands and single feed them. If your accuracy doesnt improve then the point will be mute however if it does and you are hunting do what I do I have 2 different loads one for the chamber and one for the mag. Since my first shot counts the most I really dont mind if my follow ups have a little bit more spread as long as its not drastic. If you are punching paper I apologise for being a bit long winded and hope you get a better answer as I have similar problems.

T

gamestalker
August 21, 2011, 11:13 PM
I guess I've been fortunate in that I've never run into a rifle that limits my seating options. I think I would probably try T bran's idea, making the first round the good one, since it is the money shot, so to speak.

USSR
August 22, 2011, 07:59 AM
Two things I would suggest you try. First, take 918v's suggest and try a known quantity commercial match ammo such as Federal Gold Medal Match. And second, try loading a few rounds with the bullet seated out so it will be closer to the lands and single load them. In both cases, this will give you a better idea as to whether it's the rifle or the load.

Don

steve4102
August 22, 2011, 06:06 PM
Up close to the lands is not always the most accurate. In fact most rifles have more than one OAL sweet spot, one up close and one way far away. Here is a good read from the guys at Barnes. Scroll down to "From the Lab".
http://www.barnesbullets.com/resources/newsletters/september-2007-barnes-bullet-n/

redbullitt
August 23, 2011, 02:04 PM
For me it depends on the bullet design a lot. Some of the best groups I have shot were with 175smks at standard length.

VLD designs have been another story until I get the length figured out.

For all practical purposes and applications Id not sweat it. BUT it is always fun to tinker.

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