Bench set up or technique problem?

1

10ring

Member
I'm very new to benchrest shooting and noticed something that doesn't seem right but I don't know how to fix it.

After I align front rest and rear bag with the target I place the rifle in the bags and moderately pound the rear of the stock into the rear bag. Then I get behind the rifle and do some fine tuning to line up the rifle with the target. I slide the rifle back and forth a few times looking for up and down tracking and end up with the front of the stock touching the stop post. Here's where it gets weird. If I dry fire in this position the crosshair jumps up about 3/10 moa and stays there. If I slide the rifle back and forth stopping at the stop post the crosshair is on target. Pull the trigger to dry fire and the crosshair jumps up again.

What is allowing the rifle to move slightly when the trigger is pulled.
 
10ring said:
I slide the rifle back and forth a few times looking for up and down tracking and end up with the front of the stock touching the stop post. Here's where it gets weird. If I dry fire in this position the crosshair jumps up about 3/10 moa and stays there. If I slide the rifle back and forth stopping at the stop post the crosshair is on target. Pull the trigger to dry fire and the crosshair jumps up again.

What is allowing the rifle to move slightly when the trigger is pulled.
Click to expand...

I'm not an expert, but I'll take a shot at this. Your rifle is probably moving backwards when you dry fire. (Any backward movement will raise the crosshair.) If so, why is it moving backward? Maybe your trigger pull is enough to cause that. Are you using a 2 oz trigger? If so, are you barely touching it when you dry fire?

Alternatively, maybe the sudden extension of the firing pin spring exerts enough force on the stop post to cause the rifle to recoil?

Regardless, see if the rifle moved away from the stop post after you dry fire.
 
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Bags?

Try not pounding your stock down into the rear bag so hard. But I'm saying this without knowing what your rest and bag set up is. I use Edgewood bags, I have the base packed super tight. On the ears I try to keep them soft but filled enough that when I press the stock between the ears, the bottom of the stock doesn't contact the top of the bottom bag, just maybe 1/16" gap or less under it... On my front bags I keep it filled but fairly soft, I use a lot of side tension on the forearm to give me a fair amount of drag but not grabby tight. When I dry fire nothing moves. After a shot when I go back to the front pin, I'm within 1/4" of my original point of aim. It took me a long time to get things set up correctly with a lot of help from veteran BR shooters. Jack at Edgewood was a great help getting me what I needed.

Thanks,
Scott
 
There’s more than one way to skin a cat. What you are doing or attempting to do goes counter to the way I do it. You say you are very new to Bench Rest shooting. Have you tried changing your approach to shooting? Have you tried to shoot without the front rifle stop on the rest? You are obviously not shooting a straight line or non drop stock. One final and minute amount of elevation can be gained by removal of that front stop and by shouldering the rifle slightly forward to get back down to on target. I said there is more than one way to skin that cat and mine is to shoot a softer rear bag and to squeeze it to lower the crosshair even more.
 
All of the above is good advice. Here's a couple other things to try and see if it changes things. I would suggest trying #1 before doing anything else.

1- Instead of dry firing, put a case with a fired primer in the chamber.
2- If the stop is a hard material, wrap something soft around it....a piece of foam, etc.

Let us know what you find, ok? -Al
 
Al Nyhus said:
All of the above is good advice. Here's a couple other things to try and see if it changes things. I would suggest trying #1 before doing anything else.

1- Instead of dry firing, put a case with a fired primer in the chamber.
2- If the stop is a hard material, wrap something soft around it....a piece of foam, etc.

Let us know what you find, ok? -Al
Click to expand...

What Al suggested, find a piece of plastic and make it small enough to fit the primer pocket flush with the top of the brass. This will absorb the firing pin fall.
 
Al Nyhus said:
All of the above is good advice. Here's a couple other things to try and see if it changes things. I would suggest trying #1 before doing anything else.

1- Instead of dry firing, put a case with a fired primer in the chamber.
2- If the stop is a hard material, wrap something soft around it....a piece of foam, etc.

Let us know what you find, ok? -Al
Click to expand...

Tony Boyer puts the fuzzy side of stick-on Velcro on his stop. I read his book, …. I put the Velcro on my stops, maybe more consistent bump in. It didn’t hurt.

Lots of good ideas given here. You might try varying the distance to the front stop. Front bag squeeze can affect. And I’ll echo a light trigger is important. I pull the trigger with my finger print, seems I can get it consistent.
 
Bump rifle into both front and rear bags. Slide rifle fore and aft.

I'd be more concerned how the rifle shoots instead of fretting about dry firing.

Later
Dave
 
Thanks for all the excellent tips! The trigger is a Bix&Andy - probably about 1 once.

My set up is a SEB NIO front rest with original bag and moderate fill. I bought it used so I don't know what the fill material is. The rear bag is an Edgewood original that I just got. I may not have had enough fill in it. The front stop post is a hard plastic so putting some fuzzy velcro might help isolate. (I've been reading Tony Boyer's book and I remember him saying he put a piece of velcro on the post but it didn't click)

I'll let you know what seems to help.

Thanks -- Todd
 
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