Let me start by disclosing - I'm new to the forum and my gunsmithing experience is limited. That said, and despite the many caveats I've read, I've decided to take a sporterized Long Branch No. 4 Mk1* I picked up and create a repro "(T)" sniper. I've thoroughly read the excellent posts by Peter Laidlericon. I purchased a set of pads, screws, and mount from Acuumount, and a No. 32 MKII repro scope from Numrich. Per Peter's instructions, I have collimated the scope using the very handy rig he described (which I built on my 3D printer. I have installed the front pad, per his instructions, with the pad located as far down and forward as it would fit.
My issue is the placement of the rear pad. When I temporarily place the rear pad in what appears to be it's correct position (lower edge resting on the beveled edge of the receiver sidewall), the point of aim is WAY high. Using a laser bore sighter I measured that the pad needs to be mounted about 0.13" higher in order to bring the point of aim about 2" above the bore sight. This works out to about 130 MOA based on the 3.6" distance between the two mount attachment screws. I confirmed this measurement with POA being about 12" above the bore sight at a wall 326" from the optic. All of this is with the tip of the reticle optically centered to the scope tube. I put a Weaver K4 in the mount and got the same results, so I don't think it's the scope. I've checked the critical dimensions on both pads and the mount vs. the military spec and they are in pretty close agreement, so I don't think the problem is there. I'm going to take this to the range and check my calculations at 25 and 50 yards, but I suspect this will confirm my findings (assuming I can even get POA and POI on the same target at those distances).
Has anyone encountered this issue? I can mount the pad higher but that will put the 1/4" screw very close to the top edge of the receiver sidewall.
The windage is actually pretty good as is, and I can taper the front pad a bit to fix that.
Thanks in advance for any advice.
JD
Information
Warning: This is a relatively older thread
This discussion is older than 360 days. Some information contained in it may no longer be current.