Arca Rail placement on fiberglass stock

It's either the long Memorial Day weekend or no one has relevant responses.

Considering the variables, you might enjoy pursuing this question on your own... then fill us in.

I did Sable,
My results were I had the most stability with the ARCA mounted on the two swivel studs. Then I mounted the ARCA just forward of the front receiver screw. The reticle was kind of drifty. Not good.
To my surprise, near the receiver screw gave me the best groups. Even though its more reticle drift. Out near the end of the stock where it was more stable they were the worst. With plenty of vertical. This was tested at 717 yards on three different days with the same results. The stock is a A-5 McMillan.

The rear of the rifle is supported with my elbow resting on a sandbag on my thigh. I sit in a chair . I have very good stability in that position. I'm testing this Rifle to replicate in the field hunting positions. If I have time to do more testing I'm going to try to determine why I'm getting more vertical with the ARCA on the end of the stock forearm yet I have less reticle movement in that position. I lean on a rifle pretty hard to control the recoil of the Rifle. I may be inducing flex in the stock with the ARCA in that position. We'll see.

Good explanation, thanks!

When I was testing a bunch of these on various rifles, the set up was held by a tripod, all Really Right Stuff originally. The intention was to shoot from a ground blind while seated but with the rifle on the tripod with either rails or plates clamped by the Really Right Stuff SOAR PT-Scout pan-tilt head.

Each plate was mounted at the balance point of the rifle then held by the clamp. This has worked for several years from field positions to ground blinds. The only drawback to me is their pricing, it's really over the top.

The point I see in your explanation is not just the rail position but the seated position and a sand bag. A mild, stressed position will affect the shape of the group on the target. Lots of variables between the mounting/support and your body position.

Best of luck with the testing!

This is great stuff! I am about to mount ARCA rails to a couple of hunting rifles, and this has really been my biggest delay, deciding to mount forward or at the balance point.

I hope others chime in with there experiences as well. Thanks for the info!

Placement in front of the bottom metal has worked well for me in combination with the RRS Anvil-30 head.