Concrete shooting bench

N

Nupes

Regular
EE Expired
Rating - 0%
0   0   0
Location
Ontario, Canada
Hi, I want to talk my shooting range into building at least one concrete style shooting bench. The old wooden benches are starting to show their age and sag and move around. Its frustrating to shoot accurately when someone 5 feet away leans on the long benches and your POA moves.

So my questions are: In Southern Ontario we got frost heave. How would one secure a concrete block based bench in these conditions? Is a deep footing and excavation required down 3/4 feet? Is there a way to do it using metal poles as anchors? Anybody have some photos/drawings of something that has worked well in similar conditions?

I would like a first build to be successful so that it serves as inspiriation to convert more stations in the future. There are a lot of old fogies at our club who lob rounds down range and consider hitting a pie plate at 50 yards as "good'nuff" so this is somewht of a hard sell to begin with, but many of us with BR rifles and such like nice tiny bug sized groups and its hard when your fighting a rickity rack bench on your set up.
 
Where are you going to set it up
On Dirt
On cement floor / pad

My club has made some 3 leg metal bases (welded) with a cement slab on top
Some only with a plywood top
2 guys can drag them across a cement floor

One range has a fixed one on a 5x 6 ft slab --3 legs with cement slab on top

Slab on the ground stops mud / grass under it from growing

3 legs will never rock even if not level (as long as legs are far enough apart)
 
Depending on soil composition to prevent heaving you may have to go down really far or not far at all for footing, 3/4 minus (class "a") base topped with a thin layer of 1/4 minus gravel (rock dust) works well. I known in most spots here on PEI the soil is very loose and can heave a fair bit but with about 18" of tamped class "a" you see very little movement at least when I put in stone walls or walkways. Hope this helps somewhat but again soil comp. is key.
 
Are there specific dimensions of surface area and height for benchrest shooting and if so where can I find them? I have been asked to build some. The only ones I have seen were at Raton (pictured) at the 1000 yard range. The top was all cement. The one thing I did not have was a tape measure, I should have put something in the pic so I could scale but I was there to shoot prone and did not have time.

I have the steel posts, cross pipe, and re-bar. Just need dimensions.

pgw012b-1_zps932c26c8.jpg


pgw011b_zps17f159db.jpg
 
If it doesn't ever have to be moved. Make the three legs out of a sono tube (sp?) make the leg and the footing as one. Auger a hole 3-4ft down and put the tube in. Fill it with concrete right to the height of the table then set the top on.
 
Don't worry about a foundation, make a pad and sit it on the ground. A foundation or deep footings is no guarantee it won't move.

There are different reasons for frost heave, and it depends on the soil (the difference of a few kilometres, or even a few hundred meters can mean the difference between huge heave or no heave). If the soil is sandy and well drained, then generally it isn't frost susceptible, and it won't move anyway. If soils are a silty sand and well drained, they also tend not to move. Certain types of silty and clay soils, combined with wet soil conditions, can have extreme frost heave, and for light structures, a deep foundation won't make any difference.

In some cases, it is useless to go down below frost level because the frost will just grab your foundation and lift it anyway. I have seen attached brick garages raise OVER 4" relative to the house (yes, measured, I could stick my fist in the gap between the bricks on the garage and the house). Yet in the spring, these garages settled right back down and the gaps disappeared. It happened year after year. (This was happening to various degrees on hundreds of new homes !!!)

What was happening? The frost grabbed one or both sides of the the garage foundation and lifted it. The house foundation was OK, because of heat loss through the basement, didn't allow the frost to grab the foundation. Solution was to dig it up and install several layers of heavy polyethylene along the foundation so the frozen soil couldn't grab the foundation. The multiple layers of plastic allowed slippage so the soil could move without grabbing the foundation.

Side effect of the garages after being repaired, was the garage floors stayed put, but the driveways heaved up so they were 2" above the garage floor in the winter, and 2" below the garage floor in the summer.
 
Last edited:
Heave happens but it won't impact your shooting like someone putting their weight on the other end of a wooden bench. Its a seasonal thing and may give you an inch or two movement between seasons but in any given day your bench will work just fine.

Your best bet is to build a 4" reinforced slab on grade over 4 inches of compacted gravel (that'll minimize heave). Sink anchor bolts in the slab and fasten the bench pictured in the above post to it. You'll have a rock solid shooting rest.

If a slab base is not what you want to do, sinking your metal legs 4 ft into ground should give you sufficient penetration of the frost line. Fasten your concrete top to the legs. You could consider using a system of threaded anchor bolts in the bench with two nuts at each of the leg attachments to allow you to fine tune the bench height/level.
 
Last edited:
more information

Here is another link http://benchrestforum.ca/index.php?topic=181.0 thanks to the guys at benchrest.ca for the help, and mike ratigans book also has designs in it.


but before you jump in get a sheet of OSB or plywood and make a template of one of the patterns.

then flip the plywood over and make another pattern and place it on a talbe with the end sticking out so you can

EFFECTIVELY GET BEHIND THE GUN and place both shooting rear bags and front rest (or tripod) onto the template in order to judge the design chosen.

You may quickly see that getting your belly into the curvature of the design is the most effective. i am not good with words but once you see the limitations of the other designs you will quickly see how comfortable getting into place can be. Also if you place the other loading blocks ammo cases and stuff in the bench you then get a feel for thegood, bad and plain ugly in some designs. i will still try to get the measurements from someone this weekend. We tested 6 designs a few years back and we liked the curved sideplates with a longer back end. Some of the ones tested like in colorado at the firewalker are just downright wrong and do not function at all.

later Jeff
 
We have them at the range I shoot at. I'm a little shorter then most of the guys so I end up having to stuff my foot under my butt to shoot so height is a critical factor when building them. Ours also have concrete seats and they are mighty cold most of the time!
 
Drayton Valley had some really nice seats made (for a range) and maybe the guy that built them can post a pic, down in southern alberta


Jeff
 
Thanks for all the replies folks, lots of good information to mull over. Double thanks for the link to the PDF, thats some solid info. I think I will be looking at the steel pipe legs and the versatility in being able to move it around if needed. I figure if the legs get enough of the packrete type fine stone base under it, it should be fine, and of course 3 legs wont wobble. Worse case scenario will be that it might require re leveling once in a while which I think could be done easily with a car jack and a 2X4. Thanks for the input here.
 
Ok seeing as there is already a thread on this

I was talking about making a shooting bench like the one shown, an my friend thinks he will be able to shoot just as good off a picnic table.

Is this so? Ahaha
 
dastt said:
Ok seeing as there is already a thread on this

I was talking about making a shooting bench like the one shown, an my friend thinks he will be able to shoot just as good off a picnic table.

Is this so? Ahaha
Click to expand...
Your friend is probably one of those folks who can shoot a dime sized group in 20 mph wind off the hood of a pickup truck while the engines running. Aside from this, I have a 32X scope which magnifies every little movement and have found that the more solid your base is and the better you support, it makes a world of difference in the bench rest game.
 
You must log in or register to reply here.
Back
Top Bottom