Gunsmithing Barrel Free Float and Forearm Flex

[Ballistic Artist]

Hey all,
I got a Rem 700 custom in 300 Win Mag with a 26" Bartlein #9 heavy varmint countour barrel sitting in a Mcmillan A5 stock. A 17lb tank. I have a .125" free float. I have noticed that when the rifle is sitting on a bipod, the forestock is flexing enough to get too close to the barrel in my opinion. The last time I had the action out of the stock, I noticed a small patch of bluing missing from the bottom of the barrel about 1.5" behind the tip of the forend. NOT GOOD!

This explains my flyers i think. Or Im flinching...

When I bedded the action, I "fully" free floated the barrel. I mean i did not bed the first 1.5" of barrel in front of the recoil lug as Ive seen alot of guys do. Is this a bad thing? Could this be part of the forend flex problem? The barrel is a tank and the A5's forend is not the tallest one. I know I need to increase the free float but how much do I increase it? Also, should I try to stiffen up the forend somehow? If so, what would be the best way to do this? Onr other thing. I tighten my pillar svrews to 36 inch pounds. Is this too much? To little? Someone told me to go 60 inch lbs. Seems too much to me. There aint alot of threads in that front screw hole on a 700 reciever. Im afraid of pulling the threads out of the reciever. I know I have too many questions.

Thanks very much for the input.

 

[E. Bryant]

Re: Barrel Free Float and Forearm Flex

0.125" should be enough clearance. Are you sure that this clearance is maintained along the entire barrel channel? The missing bluing is interesting, but not conclusive. I'd recommend putting a touch of Prussian blue marking grease (non-drying marking compound) on this spot, shooting the rifle, and then seeing if any of it transfers to the stock.

For action screw torque, let's just say that opinions vary. AI recommends 55 lb-ft for screw torque on the AICS, and that should also suffice for any properly-bedded stock. 60-65 lb-ft is fine for the screws themselves, but as you point out, it may be too much for the action threads. That being said, I still use 65 lb-ft as my default value.

 

[alibi]

Re: Barrel Free Float and Forearm Flex

Set rifle on butt, hold rifle vertical by barrel, smack forearm from underside with free hand. If you can hear, or feel, the forearm hit the barrel you'll need more clearance. Mine is floated around 1/4" of clearance the full length of the barrel. My BC stock may not be nearly as stiff as a McMillan.

 

[Ballistic Artist]

Re: Barrel Free Float and Forearm Flex

So dont try to stiffen the forend? And pressure bedding the first 1.5" of bbl. wont help? I know alot of rifle manufactures do this. One of em is G A Precision. I didnt because I always thought the bbl should be FULLY free floated. But at school, they did the first 1.5" of bbl. And the rifle I built there shoots good.
Thanks for the input.