Rifle support for load development

[deer_hunter132]

Dad has a browning A bolt 7 rem mag with the boss "brake".
Last shooting session we determined the Swarovski was bad.
Hes got his old pentax on it that it sported years ago.
We were using a old metal caldwell type sled. The recoil was a bit much on his shoulder after a bit.
Yesterday we started testing hand loads doing a powder ladder of .5gr and seated as long as the magazine would allow, which was about .02 from jam.
Decided to use my tripid. The first 12 shot just as well as we could expect from a tripod and our ability. Shot a couple factory hornady sst loads of the same projectile and they grouped right in line with the others.
Pulled the gun from the tripod to check out the mag spring (weak).
Loaded another 3 at the 59.5gr that did well in the powder test. 1 (3 total) at 2.770 ogive to base. Back in the tripod. Went 2" right and .5" low compared to the first two. Tried 2.760 and 2.720 seating depth at the same charge and two factory loads. The groups are 3" apart left/right. Im wondering if i tightened down the bipod gimble and we were torquing the stock into the barrel to get it on target causing the shift.
I say all of that to ask this; is there a design a welder can duplicate that keeps us from imparting force into the stock/barrel while putting the gun on target and steady and absorbing some recoil?

 

[TaperPin]

I use a rather ordinary traditional front rest and rear bag, but use a PAST shoulder pad to distribute the recoil over a wider area, or on heavy recoiling rifles a bag filled with lead shot can be used. The heavy shot filled bag is easy on scopes because it has a lot of give and doesn’t make the scope bounce back like a lead sled.

The nick name “sissy bag” has been so catchy it seems it’s always been called that. Any fairly long bag roughly 4” across can be used, and even heavy sand works well, but lead shot has always been considered best. The downside is it totally messes up eye relief so you have to work extra hard to keep the visible field of view centered.

If you want to build a basic front rest, the one at the bottom of the catalog page is as simple as it gets - a big nut with welded legs and a section of threaded rod with a flat bar welded to the top. There are cheap front bags for a rest, but a traditional leather bag filled with sand is stable and trouble free.

 

[hereinaz]

I would recommend something like Taper. And, add an extra pad for your shoulder to cut the pain.

Highly recoiling rifles can break scopes and sticks when put into lead sleds.

When you are “absorbing recoil” in some different manner than you shoot in the field, the zero will absolutely change.

My bench zero is a bit different than my tripod zero.

There is significant recoil that happens before the bullet leaves the barrel, and the amount and type of support changes how much and which direction the barrel moves. It does not take much movement at the buttstock to show up on paper.

 

[deer_hunter132]

how far off are we talking, 1in, or 3in?
What if we had a sliding sled like some pro shooters use and the gun is strapped into at the butt end at two points so the stock/barrel arent fighting each other?

 

[hereinaz]

Movement of POI is gonna vary by amount of recoil, weight of the rifle, flex in the stock, and how the rifle is influenced by whatever it is in contact with. Some rifles move less because the action is stiffer, the stock is rigid, and the stock is bedded. Savage Axis for one example are terrible plastic stocks that have way too much flex through the grip area. It flexes under heavy recoil even when shouldered.

I am not familiar with a sliding setup, what I have seen in competition rifles js the weight is in the barrel and stock itself and then the rifle rides in the bags. PRS shooters have bolt on weights for their chassis to balance it and add weight.

Spitballing, you could attach a heavy bar to the forend of the stock to act as a bag rider and weight to slow down the recoil. You could fill the buttstock with lead shot. They will tame recoil on the bench some.

 

[sneaky]

Stop thinking about sleds. They're the worst thing you can use if you care about your setup. Be far better off breaking up your shooting sessions to keep it easier on shoulders.

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