Author Topic: Thought on Lockup and Accuracy (Read 562 times)

mattparliament · « **on:** February 28, 2006, 04:33:13 AM »

Hello all

Here's a thought. Lately I've fitted a barrel or two using the FAQ instructions and they worked really well. Before adding the shim to the lug the lockup had a little side to side wobble though very minimal. When I put on my choate varmint forend lockup was very tight measured with a feeler guage. Do you guys think the shimming could have been avoided with a minimal recoil gun like the 17 remington or 22 hornet and salvage accuracy? Any thoughts? I realize that this isn't the optimum setup but just a thought....

myarmor · « **Reply #1 on:** March 01, 2006, 06:30:23 AM »

I recently traded off a barrel that was a hair loose on lockup on one of my frames. I was wondering the same thing. So I shimed one of my forearms and tightend up considerably. Tight enough that I would have to manuely break open the barrel to pop the shell out. It worked for a few shots, but then it went back to scattering bullets everywhere. Needless to say I didn't shoot it off that frame any more, but made for a good experiment.
-Aaron

quickdtoo · « **Reply #2 on:** March 01, 2006, 06:37:48 AM »

My thinking is that if head space is tight, it's plenty safe to shoot, but accuracy may not be as good as you like. But those that I've checked that were loose, had way too much head space, and puttiing a tighter forend on it isn't going to fix poor head space, it will increase head space if you think about what the tight forend does in relation to the standing breech, it's going to pull the barrel forward...... If I understand what you've said, Matt. :wink:

Tim

mattparliament · « **Reply #3 on:** March 03, 2006, 04:12:49 AM »

You understand completely, that was my thought also. With a forend tightened in that manner it would "spread" the action open as far as possible while closed.... Thanks guys

Mac11700 · « **Reply #4 on:** March 03, 2006, 05:30:36 AM »

Turn the frame up side and look at how the lug fits on the receiver pin...Tight on front of the barrel stud hole in the forearm..it pushes the barrel away from the barrel lug pin...tight on the back of the barrel stud hole..pulls the barrel into the lug pin...Now..if the barrel lug has play in it..and say you have .003" gap between the barrel and receiver....pulling the barrel away from the reciever will increase this gap..which isn't a good thing..which is why you want to shim the barrel lug on it to have a good tight lock up un it to begin with..then you can shim the spacer on the forearm to adjust it some and make it better depending on how good a fit you have on the barrel to begin with..Having a slight gap like on mine of .0015"..I can make the gap even smaller by shimming the forend..and having a tighter lock up...provided the chamber is cut properly to begin with........

Mac