[M1AallTheWay]

...Put about 100 rounds through it, function was flawless, accuracy is CRAP.

• Band tension is present, I can squeeze with thumb and three fingers and get about 1/16 of movement.
  
• Ferrule has about .050" vertical clearance from the front band.

...

For clarity, does this mean that the front of the stock can be squeezed up to the barrel, but the ferrule isn't actually touching the front band lip even when you don't squeeze?

...The reciever does not "walk" around, it is a snug fit. I do not have access to a USGI trigger group so I may shim this one on the rear tab and two front tabs of the trigger group housing.

If you push the ferrule sideways relative to the barrel while watching the receiver where it rests on the top of the stock, do you see any movement between the two?

While the shims will increase the tightness of the lockup, I don't think they'll do anything to apply, let alone increase tension between the ferrule and the front band lip if the heel of the receiver is already in full contact with the stock.

 

[M1AallTheWay]

For clarity, does this mean that the front of the stock can be squeezed up to the barrel, but the ferrule isn't actually touching the front band lip even when you don't squeeze? YES


While the shims will increase the tightness of the lockup, I don't think they'll do anything to apply, let alone increase tension between the ferrule and the front band lip if the heel of the receiver is already in full contact with the stock.There is about .020" clearance between the stock and the heel of the reciever

The barreled action should be contacting the stock in three areas: the front band lip/ferrule, the receiver heel, and, in-between, the area below the scope mount bolt hole. It sounds as if your Bush rifle is in contact with only the middle one. The center area is sort of a fulcrum. When the trigger group locks up, it's supposed to pull the receiver legs down. Since they're behind the fulcrum area, the heel should be pulled down too and sit snugly on the stock. And when the rear of the barreled action is going down, the front should be going up, see-saw fashion. The front, though, has that front band lip hooked under the stock's ferrule, so once the clearance between the two is taken up, the barrel starts to pull up on the ferrule, bending the stock and creating the necessary tension.

If, when the trigger group locks closed, it's still kind of loose in the receiver, the shims where you're considering them will test to see if pulling the receiver further down into the stock will pull the heel down and the barrel up. If that doesn't happen, then there may be something weird with the geometry of the stock and or action. Putting shims on top of the stock in the fulcrum area will also tighten lockup but in addition will increase the see-saw effect, resulting in more tension at the front band. At the same time, this warning is really something to pay attention to:

... but be careful shimming too much, it can go full auto on you, single or couple rounds only for first few test shots...

 

[M1AallTheWay]

Thanks M1Aalltheway, excellent info there. I am going to try some shims from a soda can . .

Qestion . . when properly shimmed the reciever heel should be tight against the stock?? Right now there is a .020" gap there, that is alot to pull down . . . should I shim the reciever heel area as well . . maybe split the difference?? .010" on the trigger and .010" for the trigger tabs???

BTW I have a new GI (used) walnut stock on the way . .

Well, the goal is to get the heel down so the barrel's front band lip will go up, creating the tension at the ferrule. In addition, with the heel clamped to the stock another friction point further back is created which further stabilizes the action's position in the stock. I think shimming under the heel would tend to defeat that.

What comes to mind is a quick and dirty method to see if getting the heel down will get the barrel up. If you have a furniture clamp, such as http://www.harborfreight.com/24-inch-ratchet-bar-clamp-spreader-46809.html , you can clamp the heel tightly to the stock without damaging either and see if you get tension at the stock ferrule. You can even do this without the trigger group installed. If that works, then the shims between the trigger group and the stock should do the trick. If it doesn't, then shim the fulcrum area under the scope mount and try the clamp trick again. Also note that aluminum soda can material is pretty thin (I think about .005") so it'll take a few layers to pull the action into the stock using the trigger group. You might try bending them accordion style so the layers will stay together.

Down the road, if you find a trigger group/stock combination that gives you a really tight lockup without the help of shims, you can use the furniture clamp instead of the trigger guard to close up the gap and then just close the trigger guard to lock everything in place. That way, you reduce stress and wear on the trigger group but still get a good tight lockup.

 

[M1AallTheWay]

Unless you get tension up front along with good groups and the heel is still not touching the stock, which is what happened to me.

I was figuring that with the .050" gap between the front band lip and the ferrule up front and only a .020" gap at the heel, the heel gap would close up first.

On the other hand, I too have a situation where there's a slight gap at the heel but there's tension up front and the rifle shoot better than it ever has.

 

[M1AallTheWay]

Not trying to cause any friction, just saying what I did with mine and it seems to work. I'm no expert, I'm just an amateur and I just relate what it is I have done. When it comes to troubleshooting rifle problems I wish I knew a lot more than what I do know.

No friction at all because I agree with you since I have the same condition you do on one of my M1A's and got the same benefits.

One of the many advantages of TFL is that with a lot of members, there's a lot of experience to draw on and a lot of contributions to make; the M14 is complicated and the interactions among its parts can be subtle, so the more eyes and ideas on the problem, the better off we all are.

 

[M1AallTheWay]

Just so we are clear . . the .050 clearance is between the Vertical surfaces, i.e.; the front face of the ferrule and the back side of the watchamacallit that has the lip on it. There is tension on the band . . takes three fingers to squeeze the tension out . .

I tried a double thickness of a soda can on the three trigger tabs and it does take the heel of the reciever down to the stock, but the stock is not perfect so the heel rests on only one side. . .

Thanks for the clarification on the .050" gap between the front band and the ferrule.

Someone's going to have to help me out here because I don't remember the details but I believe there was a TFL thread about some SAI receivers which were made in such a way that they didn't sit squarely on a typical stock...

Sounds like you've got good tension between the front band lip and the ferrule.