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Free-float clearance on a Kimber Montana

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11 February 2009, 22:50
Kenati
Free-float clearance on a Kimber Montana
Hey fellas-

I pulled the stock on my Kimber Montana today for a thorough cleaning after a sandy adventure and noticed that I had a spot on the stock rubbing at the 6 to 8 o'clock position towards the muzzle end of the barrel channel. This area was roughly the same spot where I originally had a high spot before refinishing, so I'm sure it's just leftover from not sanding the channel enough the first time around. The clearance was probably minimal and the paint filled in the gap after I refinished the stock.

I decided to sand it down again since it would "theoretically" apply an uneven force to the barrel. And since I occasionally shoot off a bipod, I thought that might make it even worse.

Anyway, when I finished up, I was able to slide a worn $1 bill down the barrel pretty easily. A stack of 2 bills showed a little more friction, and 3 well worn bills were the most I could get down the barrel channel.

(A dollar bill is suppose to be .0043" thick.)

Do you think this is enough clearance, or should I go more?

Thanks!

The rig in question:



The original high spot before stock painting with Brownell's Alumahyde coyote brown epoxy paint:


11 February 2009, 23:05
Westpac
Grab the rifle with your right hand and with the palm of your left hand give the forearm a smack, right at the tip. If you hear, or, feel any contact with the barrel, then give it more room.

Remember, the barrel is going to expand and move as it heats up. You need to take that into account when figuring in the overall gap.


_______________________________________________________________________________
This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life.
11 February 2009, 23:12
Kenati
quote:
Originally posted by Westpac:
Grab the rifle with your right hand and with the palm of your left hand give the forearm a smack, right at the tip. If you hear, or, feel any contact with the barrel, then give it more room.


If that's the litmus test, then it failed miserably! haha

Guess it's back to sanding...
12 February 2009, 00:35
Westpac
Well, it is. The last thing you want with a free floated barrel is to have the barrel and stock making contact during the shot. It needs to float just enough to prevent the two from ever coming into contact. It take very little contact to throw a shot. The "bump" check works as good as any.


_______________________________________________________________________________
This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life.
12 February 2009, 02:15
Kenati
Ok. All done. I used a fat highlighter marker wrapped in coarse emory cloth to give a nice uniform clearance down to the barrel shank. It looks to be about a little less than a 1/16 of an inch. I can slide five (5) one dollar bills down without any trouble, but most imporantly, it passed the bump test with flying colors. I have to hit on the very tip of the forend pretty hard to have it make contact with the barrel.

I'm satisfied.

Thanks for the advice.
14 February 2009, 07:36
kcstott
I have to agree with Westpac. Even though this doesn't show barrel vibration it's still just about the best way to check barrel to stock clearance.
Any disruption of the barrels natural vibration pattern is going to throw the shot. How much and how much you will allow is the question. But the contact point can never be uniform and there for the shot to shot consistency can never be uniform.


www.KLStottlemyer.com

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