Having your rear bag move is really hard on tracking.

B

Boyd Allen

Active member
Yes I am aware that my thread title is an entirely obvious statement, but it got you this far, so it can't be all bad. Now, as Paul Harvey used to say, "The rest of the story".

Day before yesterday I returned to the range that I wrote of in my thread about LT 32 and columns. This time I took my four legged "portable" shooting bench, that I had not shot off of before. It was a really pretty day, and I learned a lot. One thing was that my rear bag tends to skate around. I was able to get a better fix on this because I had set up so that the inside edge of the base of my standard Edgewood rear bag was exactly flush with the square edged side of the bench. It felt perfectly flush at its widest point. Starting from there made it easy to feel slight bag shifts by feeling with the side of my thumb. Of course there was the evidence in the scope that something was moving, but this helped pin the problem down. So, not that I had proven to myself that at least part of my problem was bag movement, the next question became what to do about it. Reaching way back into the dim past, I remembered something that someone posted about using sanding screen between the bottom of the bag, and the bench, so I located a hardware store that carries full 8 1/2 x 11 sheets of various grits, and bought a sheet of 150, the coarsest that they stocked. Next step, a return to the range, with the same bench, for a test. After I do, I'll let you know if it worked. The surface that my bag sits on is the face of a piece of 2x12 (nominal)Douglas Fir dimension lumber, as it came from the mill. Comments? Suggestions? I am really trying to come up with something that I can also use on a concrete bench, otherwise I would just glue a sheet of 80 grit to the bench, where the bag sits.
 
You could figure out what's making the bag move and work on that. Another idea is to become a "bag squeezer". Bag squeezers don't care if their bag moves a bit.

If the sanding screen doesn't hold it I don't think anything will short of sticky.
 
Well, as far as having a bag slide in recoil of the rifle all I can say is I have been there done that and got the t-shirt to prove it. I will have to say St louis Benchrest club has some of the slickest bench tops I have ever shot off of. When I am there I make it standard procedure when I set up to pore water on the bench where the bag goes and set the bag ontop of it, This works well. Now that they have mandatory superfeet use there, I also wet the area under the superfeet. This makes things just sit still.

I have a Bumble bee bag that has leather ears and they like to stick to the rifle, and the bag wants to slid in recoil. I found a couple of fixes for this, One is I lay a microfiber towel over the ears, and apply a coat of powder wax, or baby powder with cornstarch, (It has to have corn starch.) and this will remindy the problem. I also use a high grade automotive wax, and wax my stock. You will find if the stock is slick it will have less tendancy to move the bags.

As far as wood benches you may find that rubber sticks better to it, and you may want to try one of the rubber donuts that goes under the bag, the company that makes the Mr. "D's" sighter cam makes a rubber donut.

I have also found that how a rifle is in tune will affect how the gun recoils.

Hope this give you a few ideas, and help you out.
 
82Boy,

When you say you "wet" the area under the super feet what EXACTLY do you mean? Do you rinse the bench off and dry it or do you leave it wet? I tried using super feet on my Farley yesterday and I was spraying all over the target. Removed the super feet and got back to "normal". Any advice would help because I'd like to be able to use the feet on our old, pockmarked concrete benches.

I don't seem to have the same problem as Boyd with the rear bag on our concrete benches. Maybe they're rough enough that my bag doesn't slide!?!

Dennis
 
Rubber matting

Soft rubber mats work great get two Glue one to the bag and the other one you lay on the bench.when the soft rubber will stick to its self solid and the other side on the bench you leave it big enough to run the length of the bench. I think this will steady things up for you also if it gets dirty and you notice slip just rinse the rubber off and it is back to new. You can also take it every were and use it on every kind of bench
 
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Boyd Allen said:
... my rear bag tends to skate around. Comments? Suggestions? I am really trying to come up with something that I can also use on a concrete bench, otherwise I would just glue a sheet of 80 grit to the bench, where the bag sits.
Click to expand...

Boyd: Here's a remedy for benches that have uneven and sometimes slick surfaces.

For my Protecktor Model bags, I use their "Bag Stabilizer": http://webpm.fatcow.com/ProtektorModel/index.php?main_page=product_info&cPath=9&products_id=252 .

For my Edgewood bag, I use the "Dead Bottom" [no picture available but is almost identical to the Protektor]. http://www.edgebag.com/catalog.html#newpricing

Both are made of a suede type material that prevents sliding, and both are adjustable for height by adding or reducing sand.

While normally on hand for their usual inventory of bag sizes, dimensions can also be customized upon request. :)
 
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Pretty sure the NBRSA allows the Dunrud spacer - I forget as time slips. Good as any, and better than most is the sand ring Francis mentioned.
 
As Wilbur said, the Dunrud is legal. I checked, but I also tested mine to see how the bag reacted when I rocked it while on the Dunrud, and did not like what I saw. I have a custom Otto ring on the way from Protektor, sized to fit my Edgewood bag...good price. The issue of tracking is related to shooting free recoil, without ones hand on the bag. I had heard of the sanding screen, so I decided to try it. I know that there are a number of ways to solve this problem, and the main reason for posting it is that I thought that some would come up that would be useful to all of us. One thing that I may do, purely for research, is to build a spacer that is designed to be clamped down to the bench, and which secures the bag in a manner that would not be legal, just to see if I can see any difference on the target, or in my scope on tracking. I does not take much bag movement to screw up tracking, and I have always, possibly mistakenly, thought that it was in the ears of the rear bag. If it turns out that it was in the whole bag moving so little that I did not see it, then this will end up being a big deal, because that can be more easily fixed. Ultimately, whether I am currently competing of not, I would like anything that I do to fit within the rules. Thanks for all of the responses, and keep them coming.

Boyd
 
I wonder if

your problem with your rear bag moving is not with the gun but with the shooter. Could it be that you are "shouldering " the rear bag and moving it while running the gun back into battery. I only say this because I have discovered myself doing the same thing.

Lawrence
 
Not sure what you meant about the 2x12 fir board...is this what the bench top is made of...or some kind of spacer to get the right elevation?
Either way, the wider the plank, the more tendency it has to cup.....check it's flatness with a staight-edge. There is probably so much gap from the board cupping, that there is little surface contact.
I used to get that problem with the rear bag moving, I've used standard protector bags with suede donuts, a mini-gator, and a gator bag. Since I have been using the Gator (which I glued 1/16" neoprene anti-slip sheet to the bottom- the Gator does not have a "built-in" donut like the mini-gator) bag movement problems went away.
 
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Yes, the top is made of a couple of 2x12s with a couple of 2x4s on either side, and cross pieces underneath. It looks pretty flat, but I will do the straight edge test, and it it fails, I have a 4" belt sander that I can flatten it with. Ordinarily, I would have made the top from multiple layers (2 or 3) of 3/4" ply but this was a prototype that has a different shape, an experiment, that has been waiting for some time to be shot off of. The thought was to sit more squarely behind the rifle. What I have found so far is that by bringing the butt closer to the center of my chest, that the aluminum butt plate is whacking my collar bone more than I like, which has resulted in an adjustment of body position. The whole thing is a work in progress, investigating better ways to sit behind the rifle, as well as how to manage a portable bench so that it moves the least when adjusting the front rest for windage and elevation. I have made some progress, and I have some more ideas to try.
 
I have had this problem for a long time

I decided a couple of year ago it is caused by having to drape my body over my rifle's buttstock while shooting. I find that if I don't pay close attention to the issue I will pull the bag toward me on every shot. I became convinced that, because of my body's configuration, draping over the rifle is the issue. I believe it comes from sitting beside the rifle instead of behind it. Most bench designs do not lend themselves to sitting behind one's rifle. So, what to do? One solution might be to design a bench top that allows one to sit behind their rifle, cut it out of 1/2" plywood and carry it with one when traveling. Rather or not folks would allow one to use it is a question and this is a good time and place to air it I think. Now, many people won't have this problem but my "Yorkshire Build" does not lend itself to sitting beside my rifle when I shoot Benchrest. Many benches are TOO LONG to allow one to sit behind one's rifle, even if one were to carry a bench top that works for them.
 
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Pete,
Here is the top of my portable bench. Notice the design. You can sit directly behind the rifle.
 

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Once upon a time I tried the Dunrud spacer. It was too mushy, so it was returned. The same with the shelf or tool box liner.

Mushy is OK for maybe sighting in a hunting rifle or bench rest plinking.

It's definitely not good for competitive Benchrest matches when you're trying to put bullets through the same hole or hit a 1/16" dot at 100 yards. A .001" movement at the bench is magnified on target.

The sand-filled bag stabilizer fills in bench imperfections on its bottom side and levels off the rear bag on its top side. It can also double as a spacer for height adjustment. If set up properly, it's rock solid. :)
 
82boy said:
I have a Bumble bee bag that has leather ears and they like to stick to the rifle, and the bag wants to slid in recoil. I found a couple of fixes for this, One is I lay a microfiber towel over the ears, and apply a coat of powder wax, or baby powder with cornstarch, (It has to have corn starch.) and this will remedy the problem. I also use a high grade automotive wax, and wax my stock. You will find if the stock is slick it will have less tendency to move the bags.
Click to expand...

Patrick: You might try Cordura ears and stock tape as a substitute for all the items listed above. Those two complimentary surfaces are very slick and maintenance is almost nonexistent. :)
 
DeltaBravo said:
82Boy, When you say you "wet" the area under the super feet what EXACTLY do you mean? Dennis
Click to expand...

I taker a bottle of watter with me to the line, I pore a puddle on the bench. take my hand rubb it around the needed area, and nock it off the table and set my bag and super feet on the wet spot.
 
abintx said:
Patrick: You might try Cordura ears and stock tape as a substitute for all the items listed above. Those two complimentary surfaces are very slick and maintenance is almost nonexistent. :)
Click to expand...

I have tried them, and believe it or not stock tape made the problem worse. I find that stock tape has a life span of about 1 year from when you put it on the rifle. I have tried both the teflon, and the clear, and I find the teflon stuff last a bit longer. It seams like the tape gets soft, and then the bags starts grabbing it, and I have found that when it gets old, it actulay grabs the stock worse than if there is no tape at all. Ontop of that the tape does add weight, and heck it not the most attractive thing around. I dont like Cordura ears on a bag, they are just too "lively" for me. That is why all my rear bags have leather ears. I do not like the heavy leather that protektor uses on the bumble bee bags, as it just wants to grab. I found that using a microfiber towel is the best thing to do. I was suprised when I shot the IBS 600 Nataionals last year that Richard Schatz did the same thing, but he put it on his leather front bag.
 
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