Rear Bag Settling Tricks?

[CharlieNC]

The butt is straight and parallel to the forend, sliding it back and forth gives no vertical change looking through the scope. A quick calculation shows the settling is only around .01inch to yield 2 moa. Such little deviation is why I'm able to squeeze the bottom of the bag, and not really feeling movement, and restore the elevation. I was able to tamp 3 filling spouts of sand into it and will shoot next week to assess. Worst case I will squeeze bag to restore, as this is less disruptive than loosing position to adjust the bipod.

 

[Alex Wheeler]

Lots of ways to do it. I have used heavy sand in the front and shot some very good aggs. Tom's lg tracks like crazy with heavy sand in the rear bag. So I know we can certainly be successful with many types of fill.

 

[Alex Wheeler]

Well then, if it truly settling you need to pack it. Drive with it in your trunk for a week....

 

[mikeeg02]

It may look ridiculous. But have you considered putting a ratchet strap around it and sinching it up some? If the bag itself is truly settling and squeezing it works?

You may be the laughing stock of the range, but who cares if it works .

 

[CharlieNC]

It may look ridiculous. But have you considered putting a ratchet strap around it and sinching it up some? If the bag itself is truly settling and squeezing it works?

You may be the laughing stock of the range, but who cares if it works .

That could be argued to be adjustable, which I think would violate rules. But I'm always open, having built the bipod I and a few friends use.

 

[johara1]

If the muzzles is going down the butt is going up... too much sand in the bag. If the muzzles is going up the butt is going down..... I never saw a hard bag work yet...... Jim

 

[mikeeg02]

That could be argued to be adjustable, which I think would violate rules. But I'm always open, having built the bipod I and a few friends use.

I didn't think about that. Good point

 

[bpmoss1]

Its probably not the bag but the surface its on. Off the bench we dont see that kind of movement and the bags dont have to be filled like a rock either. Most times the ears are filled too much and squeeze the butt up and out of the bag. If you have to pound the stock into the bag take sand out of the ears. Most the time the ears will be soft and when you push the stock into them they tighten up. Ears guide the stock left and right, the bag is the vertical unless the ears are filled too much.

I agree with this. My minigator has a little slope and my stock is flat and doesn't quite sit flush on stitches. I pound the stock in and before I know it it's not flush again and I believe it's causing me issues. I'm going to take a little out of the base, hoping it will stay settled, then double check that ears are right.

 

[BoydAllen]

I agree with this. My minigator has a little slope and my stock is flat and doesn't quite sit flush on stitches. I pound the stock in and before I know it it's not flush again and I believe it's causing me issues. I'm going to take a little out of the base, hoping it will stay settled, then double check that ears are right.

Or you could double stick tape a spacer to the toe of your stock so that it fits your bag better. My experiments have shown me that if one is shooting a rifle loose, making slight or no contact, a certain level of bag fill is desirable. On the other hand when a rifle is held and shouldered it is much less critical. The fill that is holding your stock up in the ears are the ears, unless you "deflate" the base so much that it allows the angle between them to increase. The unfortunate part about some ears, the ones that are just made of cordura, is that the only thing that gives them shape and stability is their degree of fill. It can happen that when you take enough out of them to let the stock come down to reliably contact the stitches that a necessary degree of guidance is lost. I believe that this is why you are seeing various slide enhancing materials installed as facings for leather ears. The leather is better able to take a set, and not be so dependent on its fill level for maintaining its shape.

 

[CharlieNC]

I agree with this. My minigator has a little slope and my stock is flat and doesn't quite sit flush on stitches. I pound the stock in and before I know it it's not flush again and I believe it's causing me issues. I'm going to take a little out of the base, hoping it will stay settled, then double check that ears are right.

Call Protektor and discuss the particulars of your stock with them, and they can build you a custom fit bag for a very reasonable price. Get a flat top to match your flat stock, and proper ear spacing.

 

[johara1]

now all the info. is there, if you were using a bag made for a short range stock that had draft in it. A flat top works and leather tracks better but you guys shoot in the rain. Leather doesn't work to good wet. the slick material they use works good and the weather won't bother it. Jim

 

[Joe R]

When shooting a Ftr match my rear Protektor bag tends to settle quite a bit, as in several MOA. I have continued to add sand over time and it will not pack any more. For storage I insert a board where the stock rides between the ears, and hammer it down; but this has not helped. To continually adjust the bipod during a match is distracting, and it is easier to squeeze the bag to restore proper elevation. I have read someone added a little cement and water for packing, but I worry this may result in too hard with little buffering. Any suggestions?

Charlie,
I've had the same issues with my rear bag, I can feel your pain. If you can squeeze the bag with your hand you definitely do not have enough sand in there. The way I solved the problem was to use heavy sand, then when I thought is was full I proceeded to insert a long screwdriver jab it in there and then filling the hole with more sand. The process took well over an hour and I was amazed how much more sand I managed to squeeze in my "full" bag. The thing about the heavy sand is that it doesn't pack and flows like water to fill the hole left by the screwdriver.

The trick is to use a good funnel and thin tube to shove the sand in there. Now my DR bag does feel like concrete and it weighs in at 25 pounds. The other trick under the "stability of platform" heading is to use a donut under the bag so the bag has an even surface to rest on.

Like Average Joe said press the butt of the rifle between the ears to make a "track". Also make sure the bag top is slippery and that the butt slides smoothly. If it doesn't a little Armor All helps a lot (that I learned from Alex).
Good luck

Joe

 

[coldboreshot]

CharlieNC, Its my understanding you use a Protector rear bag? One of the issues I've had with these is the type of leather used in the construction. It tends to be a little soft which, every time you continue to fill, it keeps stretching the leather. This is why for the most part, your bag keeps settling beyond your preference. Look into Edgewood bags. They are a bit on the pricey side but they are built a little more durable with double layers of leather where necessary. No matter what design rear bag you have, there will always be a degree of settle. I agree with the other responders, don't overfill. Don't turn your bag into a rock.

 

[CharlieNC]

I don't think this will be totally eliminated, since the top of the bag only settles a few hundredths of an inch to cause several moa movement at the target. And I rest my head on the cheek rest between shots, which exacerbates the situation.

 

[dannyjbiggs]

Don't pack 'em too hard boyz . I don't know about BR, but the F-Class ICFRA rule on bag hardness is as follows:

F2.8 The contents of front and rear bags will be a dry, finely (less than 5 mm) divided substance such as, but not limited to sand, gravel, or grain, packed loosely enough so that the bag will be visibly deformed by pressure of the range officer's fingers.

(Underline is my emphasis .) And, don't count on a big 300-pound RO coming over to kneel down and press on your bag...they are all nice and trim fellows as I recall!

Not to worry though if you're not going to the upcoming World Championships .

Dan

 

[CharlieNC]

Danny I'm just hoping to make a decent showing at the State championship this year!

 

[Joe R]

Don't pack 'em too hard boyz . I don't know about BR, but the F-Class ICFRA rule on bag hardness is as follows:

F2.8 The contents of front and rear bags will be a dry, finely (less than 5 mm) divided substance such as, but not limited to sand, gravel, or grain, packed loosely enough so that the bag will be visibly deformed by pressure of the range officer's fingers.

(Underline is my emphasis .) And, don't count on a big 300-pound RO coming over to kneel down and press on your bag...they are all nice and trim fellows as I recall!

Not to worry though if you're not going to the upcoming World Championships .

Dan

Dan,
I went to Berger SWN in February hoping to learn some wind reading tips from Mid. Well... it turned out that the high point of the trip for me was when you critiqued of my equipment. In five minutes you gave 3 really valuable tips. I have implemented all 3 and they have made a difference where it really matters; on the scorecard. That alone made the trip from Houston to Phoenix worth it for me and for that I thank you.

Kindest regards,

Joe

 

[CharlieNC]

Well I "resolved" this in a different manner. The bag is hard and it was only possible to add minutely more sand; as mentioned by Coldbore the problem was not lack of packing but the stretching / elasticity of the leather. And my calculations showed the top of the bag only fell on the order of .02 - .04 inches to cause several moa change in poa. Since the butt of the stock was parallel with the fore-end I decided to add a 1.5 degree taper; a modest angle that would not cause a significant change in poi upon recoil, while allowing vertical adjustment when aligning for the following shot. My move to action was confirmed when researching Ftr stock designs and seeing Cerus utilizes a 2.5 degree. Upon the first shots yesterday it was apparent that this was a near-perfect angle to achieve that compromise, shooting 5X on 5 shots. The ease of vertical adjustment, without the disruption of tweaking the bipod or rear bag, led to much better focus on the target on my part. Tomorrow's match will be the acid test!

 

[kvd]

How did the match turn out with the revelation mentioned above? Dealing with some rear bag movement issues of my own and curious to know how things worked out.

Ken

 

[CharlieNC]

Ken it worked out well, shot best score this year. Instead of fidgeting with bipod or bag adjustments during the string of fire, simply slide the rifle slightly to tune the elevation. The 1.5 degree was just right.