|March 22, 2009, 09:17 AM||#1|
Join Date: March 5, 2009
Location: Murray, UT
Bedding Contact on Barrel (aka Free Floating)
I have a Mod 70 chambered in 243 with an Adams and Bennett barrel mounted in a Bell & Carlson Medalist stock. The gunsmith "floated" the barrel when he mounted the barrel. I was getting terrible accuracy and tore the gun down to check all components for tightness. The action screws were very loose, except the middle screw. So I thought the action was being torqued and causing the problem. When I tighten the action screws (front and rear to 65 in-lb, center is very light), the chamber area of the barrel became very tight into the stock. The gun is still not accurate and I'm wondering if this may be the problem.
What is the proper floating zone? Should it free float all the way to the recoil lug? Should the chamber area be supported as it is? Should there be some fore end pressure on the barrel?
Any advice would be appreciated.
Sneak close, shoot small, hit hard!
|March 22, 2009, 04:12 PM||#2|
Join Date: November 13, 2006
Both ways can work,and folks will argue about it.I have found,for me,fully floating the bbl,bedding only the reciever,works best.
And,if one does not work,it is easy to try the other,
The bbl shank area won't need much clearnce ,any is enough.As an experiment,you could use a thin shim even paper,or .oo3 or .005 brass,at the reciever areas at the front and rear guard screws,just to lift it all up a few thousandsths.This should represent something like the idea of pillar bedding,only bearing at the surfaces the receiver design intends as critical.
If you do decide to relieve the bearing on the bbl shank,a piece of .020 to .035 feeler guage can make a great scraper.Just grind the end to an arc,a bit like you were shaping a fingernail on the grinder.The grinding wheel will leave a slight burr on the underside of the feeler guage.That is your cutting edge.
You just drag it on bedding,wood,or whatever you are shaping,and it will scrape nicely.The spring in the feeler gage gives u uniform cutting pressue.
Scrapers such as this can be easily ground to any shape required,and I have used them to break corners doing lathework,or chamfer/deburr edges of plastic and non-ferrous metals.
Using prussian blue or shoe polish on the bbl will transfer the hi spots and show you where to scrape.
Here is another bit of info that may apply.As a moldmaker,I had the benefit of a lot of training on the nature of plastics.Pretty much,all plastics will creep under a sustained load.
So,it is possible ,without the right non plastic re-enforcement,a stock could relax under guard screw tension.It may be that is why your guards screws appeared loose.Many wood stocks have a steel sleeve in the guard screw holes to limit stock compression.
I have no experience with B+C stocks,but it may be such a sleeve is necessary.Also,if resin invaded the guard screw holes,if there is not clearance around the guard screws when they are in place,they can be an accuracy problem.The guard screws must only contact receiver steel.
Last edited by HiBC; March 22, 2009 at 05:55 PM.