24 in. Ratcheting Bar Clamp/Spreader

Name: 24 in. Ratcheting Bar Clamp/Spreader
Price: 6.49 USD

M1AallTheWay · May 3, 2010

Locutus_of_Borg said:
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 · Jun 17, 2010

drx said:
Yes, that’s correct, the gap is between the lip of the front band that hooks under the ferrule and the ferrule itself. So it sounds to me that the goal isn't just getting the proper tension between the two, but also pulling the barrel unit away from the stock for clearance, so building up the ferrule or tab so they make contact isn't reaally addressing this.

I think I will try shimming at the fulcrum and see if that helps. Can I do something more permanent if the shims work, like using bedding material instead of shims? Not a full bedding job, but just to raise the fulcrum?

Since I've never bedded a rifle myself, I can't speak to how resilient bedding material is to considerable compression but I'd worry about it being crushed since the contact point is pretty small. If you're using metal shims (I just cut a narrow strip of aluminum from a big sheet .020" thick that I keep around for more extensive shims), just attach them with a little piece of double sided tape. Once it's locked up, they won't be going anywhere. Note that with the shims, lockup can get pretty difficult, so some grease on the trigger guard where it grabs the receiver legs during lockup helps, as does http://www.harborfreight.com/24-inch-ratchet-bar-clamp-spreader-46809.html.

Once you get the tension, so that the curve of the ferrule wants to sit in the curve of the front band lip, you're most likely going to find that squeezing the stock at the ferrule up towards the barrel will cause the side of the of the ferrule to rub against the side of the gas cylinder. Ideally, the only contact in that area should be at the front band lip/ferrule, and one step in match conditioning is to route out that whole area so that there's clearance between the inside of the stock and gas cylinder. But I'd suggest just getting the tension and seeing how she shoots before doing anything drastic.

M1AallTheWay · Jul 9, 2010

drx said:
It takes maybe 4-5 clicks of windage to get zeroed... But it looks like the whole barrel action is over to one side at the ferrule, not just the gas cylinder...
Is this pretty common? I'm assuming bedding it would fix this?

drx said:
...I tried another rifle in the same stock and it was perfectly centered. I then tried the bad rifle in the good rifle's stock and it's pressed over to the side in that one too...

Your swapping test suggests the problem is with the rifle, not the stock. Since the goal is to get the orientation of the receiver and the portion of the stock it's sitting in such that the barrel (and GC) ends up centered at the ferrule end, bedding would take that misalignment into account because, as Dave P says, the routing of the stock in the bedding process gives the receiver some room to move in the stock.

But you might try something simpler first. The horizontal orientation of the receiver in the stock is determined primarily by how the receiver legs engage the cutouts they go into in the stock. If the receiver is positioned parallel to the stock by the legs but the barrel is the least bit crooked to the receiver, you'll get the misalignment you're experiencing. The picture looking up at the GC suggests that if the left receiver leg (looking down and from behind) were pushed a little forward in the stock relative to the right leg, the barreled action would be rotated more towards the center of the ferrule (which is what bedding would be doing). If you added a shim behind that leg, you'd be pushing the leg forward, and the whole action to the right.

How to do it? First, have an aluminum can of beer (soda will work too, but beer is better). With the action out of the stock, you can see where the receiver legs fit down into the stock. Looking forward, you can see a similar cutout where the action also fits inside the stock. Together, it looks like an "L" with a fat foot on its side. If you cut a section of the can to match that shape, you've got a shim for one side of the stock. If you make the "foot" extra fat, you can bend it so that it fits behind the receiver leg as well as beside it, pushing it forward just a bit. Making the "foot" even fatter allows you to double the bend over on itself to push the leg forward even more. Doing this is obviously going to make the fit of the receiver in the stock tighter than it already is, so you may need some help getting the trigger group to lock up. I use something like this http://www.harborfreight.com/24-inch-ratchet-bar-clamp-spreader-46809.html to get the heel down onto the stock before I close the trigger guard.

Of course, another solution is to raise the issue with LRB and see what they say.

24 in. Ratcheting Bar Clamp/Spreader

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