Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Hunting > Long Range Hunting & Shooting

Long Range Hunting & Shooting Nightforce Optics


Reply

Kimber 8400 Select Grade 338 Accuracy Fix

 
LinkBack Thread Tools Display Modes
  #1  
Old 03-02-2012, 05:20 AM
ERH ERH is offline
Junior Member
 
Join Date: Jun 2011
Location: New Hampshire
Posts: 7
Kimber 8400 Select Grade 338 Accuracy Fix

I own a Kimber 8400 Select Grade in .338 Win Mag in French Walnut. It shoots Nosler 180 grain AccuBonds at 1 MOA but when I shoot 200, 225 and 250 my spread increases to 2.5 inches at 100 yards. At 1 inch my long range is limited to say 600 yard 6 inch kill zones. Kimber says the 8400 is best shot in the 200 grain and 210 grain heads and suggests Barnes Triple X which I have not shot. I shoot Nosler's in most all of my rifles because they use gilding metal and not soft copper.
I hate cleaning copper out of Rifle bores so I stick with gilding copper. A break in of the rifle was performed with regular barrel cleaning but I never followed a shoot 5 and clean process as some suggest for 50 rounds. I don't know many folks that do that and hey perhaps they should.
Today it is known by serious shooters and rifle gunsmiths that thinner sporter barrels that are free floated are more prone to resonance, torquing and the like. Free floating is best on a heavier barrel, again experts say. I am not an expert, let me say that. I do experiment however after significant study and am good with tools and the like.
I have placed a Limbsaver sporter barrel deresonator (donut) on the 8400 and it shoots the 180 grain Noslers at sub MOA at almost 3/4 inch groups. But as you well know it is an eye sore on such a fine rifle. The ultimate fix many experts suggest is to use upward stock pressure, say 8 to 10 pounds on the front tip of the stock. I found an article by Glass Bedding a Sporter Rifle that instructs on Glass Bedding and making a separate 2.5 inch contact surface at the tip. He uses Devcon 10110 Putty to form the contact surface and utilizes Kiwi natural shoe polish as a mold release agent for the barrel and surrounding wood surfaces as it is cheap and does the release trick nicely. I called Larry recently and he suggested using business cards at the front tip until there was enough pressure to tighten groups. At that point you can use the putty forward of the business cards. Alternatively his article suggests just adding a 8 to 10 lb weight to the sling swivel while the barrel holds the weight of the rifle during the curing process.
I have ordered the putty and kiwi shoe polish from Amazon.com and it seems that Amazon knows that trick as they suggest the Kiwi shoe polish to add to the Devcon sale. I bought in at $58 dollars delivered and am waiting for the package of putty and polish to arrive. Larry's experience with this process of forward pressure on sporter barrels has taken a so so shooter rifle and now consistently shoots 1/2 inch to 3/4 inch groups and it looks just like the factory made it that way. This process and knowledge is not new, it has been around for many many years, just seek and ye shall find. Craig Boddington wrote about adding business card shims in his book. Make it accurate.
I have not gone to the range with the business cards yet but will add threads as I go through the process. Note: Kimber gave me a torque value of 60 inch-pounds for the Allen head lug screws for my model but a Kimber tech offered that since it is aluminum pillar bedded, the screw will bottom out on the pillar and does not necessarily require torque just a tight Allen wrench will do. I have two torque wrenches. I use a Wheeler fat wrench that goes to 60 inch pounds (you can buy it from many hunting suppliers, a great tool as I torque my scope screws to a value as well). Inspection of the Kimber bedding I found to look very solid and very professional. The tolerances for inserting the barrel onto the stock are very tight. Talk again soon...
Reply With Quote
  #2  
Old 03-03-2012, 07:51 AM
ERH ERH is offline
Junior Member
 
Join Date: Jun 2011
Location: New Hampshire
Posts: 7
Re: Kimber 8400 Select Grade 338 Accuracy Fix

Ok I went to the 100 yard bench rest range yesterday with 200 g e-Tips and Ballistic tips from Nosler and started testing the business card theory by adding them to the stock for-end. Since it was already a free floating barrel one business card just filled the gap so i shot with 2 business cards side ways to no effect to reduce the vertical stringing. I added a third business card but because I was alone, I struggled to get the card in with the other two and managed to get part of it in there. Bullets were raised on the target about 6 inches by adding the third card. Shots began to tighten vertically but interestingly they began to spread horizontally a bit. As I said earlier by putting the deresonator on the rifle alone I could achieve 1 1/16 groups at 100 yards with the 200g ammo so the business card trick should get me some reduction without the deresonator.
Analysis:
Since I can shoot 180 grain AccuBonds at MOA with nothing on the rifle and no business cards stuck in it; I will now go back to the range with three business cards and the 180g ammo and see if it improved groups at that level. Waiting to get more heads to load. In the mean time I will scrub the barrel and affix the three business cards properly. May take a week to see the next thread...will try different powders and charge weights too. It is important to note not to mix testing of say powder and movement of b cards at same time because you will not know which change was better or worse. Also I need to move cards backwards toward the barrel incrementally up to 4 inches to see what changes work.

Last edited by ERH; 03-03-2012 at 08:21 AM. Reason: add info about not doing two tests at same time
Reply With Quote
  #3  
Old 03-19-2012, 07:31 AM
ERH ERH is offline
Junior Member
 
Join Date: Jun 2011
Location: New Hampshire
Posts: 7
Re: Kimber 8400 Select Grade 338 Accuracy Fix

Ok I moved the business cards but no luck on 180 grain accuracy improvement better than MOA, in fact it deteriorated. I know this pressure method will work but am not finding the right spot or inadequate pressure. With the deresonator from Limbsaver and a floating barrel I can get groups to 13/16 inch. So that is the simplest correction without sending to a gunsmith who specializes in accurizing at substantial cost.
Done and done. The deresonator wins on this rifle when I want to hunt beyond 600 yards in a bean field or across a canyon. At MOA I am in good stead with the 180 grains that fly at 3200 fps for all North American and most African Game out to nearly 700 yards or out to 200 yards with 250 grain heads for Brown bear.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Kimber 8400 Select Grade 338 Accuracy Fix
Thread Thread Starter Forum Replies Last Post
New member.. Kimber 8400 300WSM accuracy?? gt1900 The Basics, Starting Out 24 03-01-2012 09:33 PM
Any experience with a FN A3G or Kimber 8400 AT? kifeter Rifles, Bullets, Barrels and Ballistics 5 02-14-2012 08:32 PM
Kimber 8400 vinjesvingen Rifles, Bullets, Barrels and Ballistics 5 11-22-2011 11:33 PM
Kimber 8400 in WSM dimecovers3 Rifles, Bullets, Barrels and Ballistics 11 02-12-2005 06:45 AM
Kimber 8400 in WSM dimecovers3 Equipment Discussions 0 01-25-2005 10:07 PM

Current Poll
Do you archery hunt for elk?
YES - 34.48%
120 Votes
NO - 48.28%
168 Votes
Not yet, but I plan to. - 17.24%
60 Votes
Total Votes: 348
You may not vote on this poll.

All times are GMT -5. The time now is 03:47 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC