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Author Topic: Forearm fit and accuracy  (Read 495 times)

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Offline Ol BW

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Forearm fit and accuracy
« on: January 30, 2013, 08:40:57 AM »
I got a new (to me) barrel in and was doing some swapping and found I had one forearm that fit really tight.  Another forearm I have is so loose, when you break open the action the barrel is free to wobble back and forth. When I investigated the reason why it was so tight was because the distance from the barrel lug to the receiver was shorter with this barrel in place.  I started thinking how this might affect accuracy.  I have read in the FAQ's and different accuracy threads about "free-floating" the forearm with an o-ring and forearm screw tension and such but this is not upward pressure but outward pressure.
 
Has anybody done any testing or had any experience with accuracy differences between tight and loose forearms? Seems like this may be another accuracy variable that I have not seen addressed here.  (Maybe it has and I have missed it?  Where's Quick?)
 
I know that I have read about this making the action tighter especially on a new gun that is stiff to open.  Usually it is a complaint which is remedied by sanding the wood on back of the forearm, re-installing and testing until the action opens smoothly. 
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Offline quickdtoo

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Re: Forearm fit and accuracy
« Reply #1 on: January 30, 2013, 11:13:18 AM »
See forend fit in the FAQs, I prefer not sanding the forend, but the spacer itself, it's much easier to keep it square and costs a lot less to replace if needed.  ;)

Tim
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Offline Ol BW

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Re: Forearm fit and accuracy
« Reply #2 on: January 30, 2013, 03:30:22 PM »
I understand that I can adjust the forearm to fit, I just wondered if anyone here has noticed better accuracy with a tight fitting forearm as apposed to a loose fitting forearm?  I realize once the action is locked up (assuming the barrel is fit properly) that the barrel should not move, but how is the harmonics of the barrel affected with outward tension between the frame and the forearm stud?  If tightening or looseing the forearm screw affects accuracy, and forearm pushing up against the barrel affects accuracy, this should affect accuracy too I would think?   :-\
 
I just don't want to spend alot of time trying to test this out if someone here has already studied it. . .
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Offline PineyCreek22

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Re: Forearm fit and accuracy
« Reply #3 on: January 30, 2013, 03:45:58 PM »
IIRC there is a post by Tim in FAQ outlining a nylon spring loaded pressure device.   This device exerts pressure from the forarm against the rounded front  of the receiver.  I incorporated a version of this in my "monoblock carbine" and will post pictures Thursday or Friday.  I will probably be able to do a range test this weekend.  Regards PC
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Offline Ol BW

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Re: Forearm fit and accuracy
« Reply #4 on: January 30, 2013, 04:10:16 PM »
Alright PC! 8)   I can't wait to see it.  I figured someone else had done some tinkering with it here.
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