Home Forums Hunting & Shooting Hunting Rifles Montana tinkering....

I get several PM's asking questions about what I do to improve accuracy with Kimber Montana's. I've decided to start a thread detailing the steps I take and the things I look for shortly after buying one.

First and foremost, I'm not a gunsmith. These "improvements" weren't mine by design. I asked several questions to several guys on here that assisted me in the process. I'd love for those guys to chime in and add value to the thread too. Everybody has their own methods.

This isn't intended to be a Kimber bashing platform. I'm a huge fan of the rifle. To be perfectly honest, I had some troubled rifles in the beginning of my journey and swore them off a few times. I kept going back because NOTHING feels as good in my hands as the 84M Montana. I learned a few tricks and the rifles soon started to perform up to my expectations. I've owned a few -- my 20th is in route.

This isn't a thread of arrogance. Several guys on here have more rifle knowledge and experience than I possess. I just want to explain in detail what I learned through others and tinkering. I'd rather do this here than go through the process many times via PM.

More to follow...

The first potential accuracy robbing issue hides inside the stock. The last several Montana's I've owned have an issue with the mag box. The mag box has been longer than necessary and this creates undo stress and torque on the action.

The Kimber mag box has three protrusions (223 has three plus the spacer). The protrusions bottom out and won't allow the magazine to "float". The picks below are from a Mountain Ascent. Same insides, just painted a different color.

Note the black spots in the bottom of the stock. This is where the protrusions bottom out and remove the paint/dig into the stock.



The pics below are of the bottom of the mag box. Notice the paint residue on the protrusions.

Tag

The binding mag box creates several issues. Besides the oblivious, I think it creates a bigger issue with Kimber rifles.

The action is small and doesn't have much beef in the metal underneath. I believe the action flexes under recoil and a binding mag box amplifies the problem.

More pics from the Ascent below, but the white paint really shows rubbing well. With the mag box bound, the barrel shank wasn't fully seated against the slave bedding -- which is another problem, but we'll get to that in a bit.

Note the rubbed spots in the shank area of the stock, barrel and tang.







This action was moving upon recoil. You'll never achieve any level of acceptable accuracy with the action moving around in the stock.

The fix for the mag box is simple. Ten minutes with a Dremel and the protrusions are ground down a little. I measure the mag box before I start grinding with a caliper. I try to take off about .050".

I don't want to remove too much, just enough. I reassemble the rifle -- minus the follower and spring -- and torque accordingly. Open the bolt, stick a couple fingers in the action and make sure it has a little wiggle room. If the box is still binding, it won't budge. It should move a little side to side at this point.

If all is good, I polish the metal a little where I've been grinding and hit it with a blue pen.

Tag

As I stated before, I believe the action flexes upon recoil. Kimber's slave bedding aides that issue. The recoil lug is small and the lug inlet in the stock is spacious.

In my opinion, the lug needs to be bedded tight to eliminate this issue. Some guys bed the entire action, some drop a dab in the lug recess and some guys give everything a nice skim bedding.

I usually bed the action forward of the mag well, the lug and a portion of the shank. I also left the shank area free of bedding and allowed the barrel to float all the way to the lug. This has worked well too.

I prep the stock with a Dremel and alcohol, then tape it off.

The pics below show the method I use when I float the barrel all the way back to the lug. Doing this, I only apply bedding to the sides and back of the lug recess. You'll still get some ooze on the front of the lug



After bedding compound is in the stock...



I don't tape the bottom or front of the lug. I know some do, but I want it tight on a Kimber. After the bedding cures, I usually Dremel out the bedding in the bottom of the lug well so it doesn't bottom out.

Awesome buddy!! The same can be said for other makes like the model 70's. This thread should be a sticky...Brad will probably chime in on a few things he has found on the Kimbers as well.

Great idea, SAS, thanks for taking the time to post up your remedies.

I use a bedding stud from Brownells (same as 700) to make sure I have things centered nicely in the front pillar. I tape the stud to allow for minimal clearance and then start spraying. I use Hornady One Shot as my release agent and I've never had a problem. I spray everything (with the stud in), let it dry, then spray again.







Once the action is in the stock, I insert the action screw in the tang. I tighten the screw two-finger tight. I do nothing to the front stud. My goal is totally stress free bedding.

Forgot to mention -- I put a couple of wraps of tape on the barrel near the end of the forearm. I do this to keep the barrel centered in the channel. You can also adjust the spacing of the barrel in the channel when inserting the tang screw. I do both to make sure things are straight..

I use AcraGlas Gel. Other bedding compounds work too, it's just what I started with. My comfort level is there with the product

I let the bedding cure a minimum of 10 hours. I've tried popping it out earlier, but the results were poor for me.

After 5-6 hours, I take a toothpick and clean the bedding ooze from the sides of the action. I wait until it's firm enough to make a nice clean break from the bedding in the stock. The compound will still be a little tacky at this point, but most of the elasticity will be gone. I keep the unused bedding compound to use as a hardening gauge.

I pop the action out of the stock and inspect.



These pics are from a Montana that I bedded under the shank.





I then take an a Exacto knife and trim things up. I remove any excess, trim around the pillar hole and get everything out of the mag well. I don't have a pic in photobucket after I trimmed....but take out everything that doesn't need to be there.

Back to the mag box....

For those of you with a 223 or 204, the pic below show the rear of the mag box with the spacer protrusion.



The spacer always digs into the stock because of the elevated edges in the mag well.



Rather than completely shorten the spacer protrusion, I just shorten it a bit with a Dremel and then do some stock inletting. I basically remove enough of the hump in the bottom of the mag well to allow the magazine to float. It takes a few seconds with a Dremel.

Another accuracy robbing issue I often encounter is the length of the front base screw. I only use Talley LW low's on a Montana. The front most screw is longer than needed. The bottom of the screw bottoms out on the barrel threads. This prohibits the base from being fully seated and allows the front of the base to move. Not to mention the fact that you could be messing with barrel harmonics...

The picture below shows shiny spots on the threads. They don't look like this from the factory. The shiny, flattened spots are a direct result of the screw making contact. I don't have a "before" picture in Photobucket, you'll have to trust me on this...



The pic below shows all four base screws AFTER the front screw has been shortened. All four screws are the same length when shipped from Talley. I shortened the screw on the far left with a Dremel. I'm posting this pic as a reference as to how much I take off the screw.

Hitting the nail on the head with everything so far. I see things that would simplify your approach and get the same results. But looking very good so far. Like I said before, a lot of these same things can be done to the model 70 to insure your going to come out on top in the accuracy dept. Good thread, carry on...

Which gave better results, bedding the lug and shank or just the lug?

The front action screw is also an enemy. It's too long as well and bottoms out in several Montana's I've owned as of late.

The pics below aren't great and it's hard to see what I'm referencing. In person, the results are glaring. The screw makes contact and polishes things up a bit. As usual, if your front action screw isn't fully seated groups will open up considerably.

Some guys use lipstick or a magic marker to check this. I've done so in the past. The action below was as new, then after about 20 shots. Things are polishing up and showing me the screw needs some attention.

As new...



After...

Hard to compare, but the most accurate Kimber I've ever owned had only the lug bedded. It was floated all the way back...

Thx. I have a 270 wsm that is showing great potential....I think one of these easy fixes might just make it perfect.

Look at the mag box first. I think that's the modification that makes the biggest impact. Bedding is good too, but nothing will work if the mag box is too long.

Thanks for the advice