How much clearance?

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hawk-i

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When free floating a barrel how much clearance is necessary?

5 thou, 10 thou, or more?

Does chambering or barrel contour make a difference in the amount needed?

I bought a (new) Kimber last week (Montana 300wm) it had less than 5 thou clearance on the right side.

I've opened it up to 15 thou clearance evenly to both sides of the barrel (looks much nicer), should I go more?

thx
 
The old standard was to run a dollar bill the length of the barrel. Not sure how thick a dollar bill is, but that was always the test we used.
 
I think it would depend on the flexiblity of the stock. If the forend is thin and flexible, you may need more clearance to avoid contact when pressure is applied to the forend of the rifle.
 
hawk-i said:
When free floating a barrel how much clearance is necessary?

Does chambering or barrel contour make a difference in the amount needed?
Click to expand...

Clearance is clearance, a little or a lot is still clearance.

Some barrels may benefit from a pressure point near the forend tip. Some barrels may need support just forward of the receiver, tho this falls more into the category of bedding rather than free-floating.

Be sure to seal the stock to help prevent moisture problems. Check occasionally to see if there is movement that results in contact.

I too use a dollar bill.
 
The rifle is a Kimber Montana, it comes with a composite stock...not wood or plastic...it also comes with a very thin contour barrel.
 
if it shoots good as is leave it is the advice I follow - my 240 WBY (Vanguard) has a pressure point near the end of the stock - rifle shoots as guranteed by the manufacture - three shots under .99 at 100. A hunting rifle isn't a precision rifle so do not expect all shots touching as the barrel warms up your POI would change. But, remember a hunting rifle is shot a couple times perhaps to get game.
 
IvoB said:
if it shoots good as is leave it is the advice I follow - my 240 WBY (Vanguard) has a pressure point near the end of the stock - rifle shoots as guranteed by the manufacture - three shots under .99 at 100. A hunting rifle isn't a precision rifle so do not expect all shots touching as the barrel warms up your POI would change. But, remember a hunting rifle is shot a couple times perhaps to get game.
Click to expand...

I understand what you are saying, this is a brand new gun which I've only fired about 10 rounds through it to sight in the scope (VX3HD 4.5-14x40ZL2 side focus windplex).

My question isn't a how to get my rifle to shoot question but more of a technical question as to how much is the proper amount of barrel clearance question.

Like when a gunsmith fits a quality composite stock to a hunting rifle what is the barrel clearance he is looking to achieve.

I'm pretty sure 15 thou is plenty but its nice to know what it ideally should be. :)
 
For reliable accuracy in various positions I use a business card to check clearance... make it loose... if the stock is quite flexible, more clearance on the bottom...
 
May not be relevant to a sporter rifle at all - I think a Peter Ladler write up about the No. 4 Lee Enfield said WWII British Army wanted .030" clearance around barrel in forearm channel and under the hand guards (and, of course, "up" pressure near the muzzle). Versus common to use of "dollar bill" - so like .003" or so. Is a bit curious - if you want "free float" to do something - is likely when the bullet is vibrating its way up the barrel, and making that barrel flex - I think - not necessarily what is occurring when you are admiring it in your hands. So I tend to go like some posts above - for "performance", likely want .015" or .020" feeler clearance - for "looks" probably want gap to be even (on each side) and similar gap from receiver end to the forearm tip - maybe is a hidden "up" pressure "button" at front or not - I can not say I have found that to be a sure thing, one way or the other, in hunter weight walnut stocks. By far the most accurate hunting rifle I even built - a Remington 788 in 243 Win - had full continuous accraglas bedding from rear of receiver tang to front of the forearm tip - was no "free float" at all - I might have been very lucky, but have repeated that on several other rifles here.

I suspect is a difference in what application - is no doubt to me has to be different in one rifle for shooting strings at targets versus another rifle for making a single cold barrel shot.
 
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hawk-i said:
The rifle is a Kimber Montana, it comes with a composite stock...not wood or plastic...it also comes with a very thin contour barrel.
Click to expand...

My Kimber Montana "Classic" has a Walnut AA grade stock. "Montana" refers to the action maker.

It also has appx .005 clearance in the barrel channel.

It will put four rounds into sub moa groups before a flyer takes it to moa.

Kimber wood stocks are very stable and IMHO, if there is any issues with barrel/stock clearance, it will be caused by bedding issues at the receiver.

Proper torqueing of the receiver screws is very important.

The bedding in the receiver inlet was very tight, with some bedding behind the recoil lug only. I purchased it third hand and don't know if this is from the factory? There are also stock "pillars" installed to alleviate ''crush'' from over torqueing the screws.

I ended up skim bedding the rear portion of the receiver inlet, to stop all sideways movement during firing.

This gave me an extra shot to POA in the group. If I need a fourth shot, I've likely lost the animal.
 
guntech said:
For reliable accuracy in various positions I use a business card to check clearance... make it loose... if the stock is quite flexible, more clearance on the bottom...
Click to expand...

Thx guntech, I average 17 thou on the business cards I just measured...guess I'll give it a wee bit more :)
 
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