Problem rifle

[Kurt]

Chris.

The chamber is on the large end with the case mouth but I don't see this as a problem I have several other make of rifles with a chamber large enough to wrap two layers of my PP paper on the sized case and it would still chamber and the rifle is a good shooter.
The first barrel on that came on this rifle was a blunderbuss. The muzzle end was larger then the breach end by quite a bit and that barrel was changed very fast. The second barrel pulled a lot of lead. That barrel was changed at my expense even though it didn't shoot to bad but after 10-15 rounds I mined lead, so I had it changed. That barrel was split with a band saw to check the bore. The bore looked good.
The barrel is not a problem. I cut a brass gauge slug that just fit the bore and I pushed it through and I did not feel the resistance change in it's entire length.
The next step was the forearm. Thinking it might be causing a problem so I took it off and shot it with out wood. No change with ladder loads PP or GG. I took a forearm off one of the other rifles and used it but only one screw would line up but it was solid. Again no change. There is something going on I just cant put my fingers on. Barrel harmonics??? the way I hold it??? how I rest it???? I checked everything even leaning on a post for a steady off hand shot. Laid the rifle on a sand bad under the lever so nothing is in contact with the barrel. This gave me a 2-3/4" group @200 yards. After marking the target shot again and it turned out a 5" group again. 5" is the average best with this rifle.
The only thing I can think might be giving me fits is, this rifle was build with a single trigger #2 Silhouette and I had a double set milled in. A fine job and I don't see this being a factor.
My next step will be glass bedding all the wood. I free floated the forearm as much as I can putting O rings at the screws to hold the wood away from the barrel and no change.
The next step is extending the chamber to a .45-2.6 maybe it will change the barrel harmonics.

IRR.

I have a friend that has a 73 Springfield floor lamp