Caribou Gear Tarp

Kimber 280AI Montana

Muleyfanatic

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Jul 19, 2011
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649
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PA
I finally got to play around with 280ai this weekend. I free floated the barrel, lightened trigger to 2.5 lbs, and set stock stock screws to 50 in lbs tightening the back screw first.
I loaded up 140 accubonds to sammi specs since that is what fits in magazine box without any room to spare this puts the bullet about .300" off the rifling (not misstyped it has that much free bore). I used H4831sc and federal 210 primers. 60 grains grouped good, 60.5 grouped the best, 61 started to open and got worse as I worked up to 62 grains. The group at 60.5 was .380" so I decided to stick with it. On Sunday I went back to the range and chronographed the load since the barrel was now broke in. The load ended up giving me 2882 fps measured with a oehler an es of 22 fps. I am a little disappointed with the velocity but the accuracy is unbelievable staying under .400" consistantly. I guess I got a slow barrel or something because I see a lot of people posting about 3200 fps out of the 24" barrels. I know I get to 3100fps but accuracy suffers to much for me. I topped the rifle with a Boone and Crockett 4.5-14 that I got off predator optics. This bullet weight and velocity matches with in an inch out to 500 yards so figure it will be good medicine on deer, black bear, and back up elk rifle. Will still carry the custom rifle most of the time but am very impressed by the kimber Montana's accuracy for a light weight factory rifle.
 
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TimeOnTarget

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Feb 13, 2015
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Nice set up! I think most people stating 3200fps out of a 280ai are only getting those velocities on the Internet. Always gotta out do the other guy on the net ya know:D

I get 3050 out of a 26" tube with a 150 grain slug. It will hold under .5 Moa to 600yds

I love the 280ai and it's about the only rifle I pick up anymore for everything from coyotes to elk.
 

jryoung

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Jan 16, 2012
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Unable to determine due to velocity
I'd keep tinkering, you know it can shoot, you just need to find the formula that puts the velocity with accuracy. I'd experiment with seating deeper first then try mixing up the powders.
 

1_pointer

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Gotta like that accuracy! I vote with the keep tinkering. You'll find accuracy at a good speed. FWIW, on another board a guy has stated that he gets his best results with Kimbers if he floats them all the way back to the receiver/recoil lug.
 

.280 Remington

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Aug 21, 2012
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Try some different powders if you're after more velocity. No experience with the AI, but I've loaded for 3 different "regular" .280's. I'd probably try 7828 next if I were you. Maybe RL22 after that. 4831 is usually a great powder in a .280, but not always.
 

Ben Lamb

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Aug 6, 2010
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Cedar, MI
try some H4350 or RL17. With that light of a pill, you might do well with a powder that's just a touch faster?
 

tarheel

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Jul 7, 2010
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Piedmont region of North Carolina
try some H4350 or RL17. With that light of a pill, you might do well with a powder that's just a touch faster?

I'll second Ben's recommendation on the RL 17. Since it's burn curve is more linear it minimizes the pressure peaks associated with other powders and you should be able to bump the FPS up about 200 without any pressure problems.
 

BRI

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Sep 30, 2005
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Anduhconduh, Montana
I had a 280ai built last year with a 24" Pacnor barrel and I've found it shoots most loads pretty good. I went with a 160 grain accubond at 57.5 grains of H4831sc and oal of 3.320. It chronographed at 2815 fps. Imr4831 could get over 2900 and I'm going to tinker with that a bit more.
 

TimeOnTarget

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Feb 13, 2015
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Try Imr 7828ssc. You'll pick up some fps in the 280ai using the slower powder In my experience.
 

Muleyfanatic

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Jul 19, 2011
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Thanks for the feedback guys. I will probably try some other powders later but am sticking with this one for now. I'll shoot a deer or two with this year and see how it performs on them. The load is extremely accurate and matches the Boone and Crockett reticle. I figure it is on par with 7mm-08 and everyone seems satisfied with the performance they're getting on game with them.
 

belly-deep

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Oct 31, 2009
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Thanks for the feedback guys. I will probably try some other powders later but am sticking with this one for now. I'll shoot a deer or two with this year and see how it performs on them. The load is extremely accurate and matches the Boone and Crockett reticle. I figure it is on par with 7mm-08 and everyone seems satisfied with the performance they're getting on game with them.


Sadly (or maybe happily), most of us could use a 7-08 and not notice a difference...
 
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