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Back Stop

Posted: Wed Jul 29, 2009 9:43 am
by DinerKid
So i recently got a sch 120 barrel for my paintball cannon and while the pbs fit really nicely they still curve like crazy. i found some marbles that fit the barrel well and they are flying straight as an arrow. i want to reuse the marbles cause they are still in fine shape after hitting the cardboard targets i made. right now i am just searching for them on the ground with about a 50% recovery. i would like to make some kind of a backstop to stop to catch them after they hit the cardboard target.

i am looking for

simple
will not cause bounce-back
catches the marbles

i have been thinking of using cloth to absorb the blow but every kind i tested gets pierced by the marble.

any ideas?

Thanks
~DK

Posted: Wed Jul 29, 2009 10:02 am
by jackssmirkingrevenge
Simplest is probably a box full of old newspapers, just replace them as you go along.

Posted: Wed Jul 29, 2009 10:09 am
by DinerKid
well i am shooting about 75-100 yards at a pizza box target so i was looking to make something a bit larger to catch even if i miss.

Posted: Wed Jul 29, 2009 10:33 am
by jackssmirkingrevenge
A large box full of newspapers ;)

Posted: Wed Jul 29, 2009 10:36 am
by DinerKid
i was thinking about possible like a piece of plywood at an angle. looking at the side it would look like a triangle with the plywood as the hypotenuse and some cloth as the base and the target could hang from the vertical part of the triangle. ya get it?

Posted: Wed Jul 29, 2009 10:49 am
by geardog32
maybe a box with the back wall at an angle covered with some sort of rubber mat and then fill the bottom with sand. i would probably just try to find some more durable fabric maybe double layers of jeans. you could gey alot of jean material for cheap if you just go to the thrift store and buy the size 70 jeans.

Posted: Wed Jul 29, 2009 10:59 am
by boyntonstu
A 45* angle over a tub of water?

Posted: Wed Jul 29, 2009 12:01 pm
by Big-E
A big piece of carpeting or multiple layers of heavy material (canvas, heavy dropcloth, etc) make for a great backstop. you must have a means of suspending the material. I use the frame from an old swingset that my kids don't use anymore in my backyard.

Carpeting works best, if the pile of the carpet faces the shooter, it works like a charm.

The fabric or carpet works because it absorbs most of the energy from the projectile. if you make a trough or bin to place under your backstop material, it will catch most of your ammo. also, make sure your backstop only hangs from the top end, and isn't stretched too tight, otherwise it's more likely to make your shots bounce like a trampoline.

I learned this from shooting air rifles at my pellet trap over the years. works good for most homebuilt pneumatics.

Posted: Wed Jul 29, 2009 12:07 pm
by Technician1002
Big-E wrote:A big piece of carpeting or multiple layers of heavy material (canvas, heavy dropcloth, etc) make for a great backstop. you must have a means of suspending the material. I use the frame from an old swingset that my kids don't use anymore in my backyard.

Carpeting works best, if the pile of the carpet faces the shooter, it works like a charm.

The fabric or carpet works because it absorbs most of the energy from the projectile. if you make a trough or bin to place under your backstop material, it will catch most of your ammo. also, make sure your backstop only hangs from the top end, and isn't stretched too tight, otherwise it's more likely to make your shots bounce like a trampoline.

I learned this from shooting air rifles at my pellet trap over the years. works good for most homebuilt pneumatics.
At high velocities it doesn't hold up.. Attached is the results of using a carpet over a sawhorse to catch a rolled up t shirt. This was subsonic at just under 400 FPS. It went right through 2 layers of carpet. The carpet over the sawhorse provided a double layer. It went through both layers. Projectile is about 5.6 oz in weight.
Image

Posted: Wed Jul 29, 2009 12:17 pm
by Big-E
Hence why I said it works for most pneumatics... if you are using a bigger projectile, or high pressure (like most big PCP rifles) it probably won't work well. since he's shooting marbles, it will probably work ok. it works fine for me.

Your carpet isn't exactly hanging there in your pic, it's more like it's crammed into that sawhorse. your backstop should be able to "swing" a little bit to further absorb the projectile's energy, and redirect it towards the ground.

another solution would be to add more layers.

Another idea would be to use a big bale of cardboard. they work awesome! most of the indoor archery ranges I used to frequent used this method.

the cardboard should be stacked in flat layers, pressed, and strapped together tightly.

When I worked in retail, several of my jobs required me to bale cardboard, they had a big hydraulic compactor that would press the cardboard in bales, then you would use wire or steel strapping to tie the bales. the result was quite heavy and dense. If one of those bales tipped and fell on you, it was all over! we needed hand trucks to move them.

Now, if you are very serious about developing power, do what they do at outdoor shooting ranges, and use an earthen backstop. a few meters of hard packed dirt will stop just about anything.

Posted: Wed Jul 29, 2009 12:30 pm
by Technician1002
Big-E wrote:Hence why I said it works for most pneumatics... if you are using a bigger projectile, or high pressure (like most big PCP rifles) it probably won't work well. since he's shooting marbles, it will probably work ok. it works fine for me.

Your carpet isn't exactly hanging there in your pic, it's more like it's crammed into that sawhorse. your backstop should be able to "swing" a little bit to further absorb the projectile's energy, and redirect it towards the ground.

another solution would be to add more layers.

Another idea would be to use a big bale of cardboard. they work awesome! most of the indoor archery ranges I used to frequent used this method.

the cardboard should be stacked in flat layers, pressed, and strapped together tightly.

When I worked in retail, several of my jobs required me to bale cardboard, they had a big hydraulic compactor that would press the cardboard in bales, then you would use wire or steel strapping to tie the bales. the result was quite heavy and dense.
The carpet was draped over the sawhorse. The sawhorse behind it was there to brace it. The impact broke off 2 legs of the rear sawhorse and knocked the front sawhorse over. The shirt continued and hit the bucket in the background that is against sandbags.

I used the carpet to protect the bucket as it was getting beat to death.

Posted: Wed Jul 29, 2009 12:34 pm
by Big-E
You sir, definitely should have used an earthen backstop :D

I take it the t-shirt was rolled up and rubber banded.

Edit: I appreciate this topic, as I feel it is often the most overlooked aspect of spudgunning. It only took one accidental hole in my shed to make me reconsider my backstop design.

Posted: Wed Jul 29, 2009 12:41 pm
by boyntonstu
Big-E wrote:You sir, definitely should have used an earthen backstop :D

I take it the t-shirt was rolled up and rubber banded.

Edit: I appreciate this topic, as I feel it is often the most overlooked aspect of spudgunning. It only took one accidental hole in my shed to make me reconsider my backstop design.
AFAICR Mythbusters proved that a few inches of water will protect you from rifle fire.

Besides being clean, the marbles will be easy to see and to recover from water.


Splash height velocity calculation?

BoyntonStu

Posted: Wed Jul 29, 2009 12:47 pm
by Technician1002
Big-E wrote:You sir, definitely should have used an earthen backstop :D

I take it the t-shirt was rolled up and rubber banded.
The sandbags worked well, but were becoming a pile of sand as the bags broke.

For reloading and re testing, instead of rubber bands, I tied it with mason line.

Behind the sandbags is the woodpile. I didn't get any through that. I did have one ricochet and fly over the fence into the neighbors yard. I didn't always hit the bucket dead center.. :D
Besides being clean, the marbles will be easy to see and to recover from water.
Having water stand upright is the problem.. :D If using a cheap container, it gets holes.

Posted: Wed Jul 29, 2009 1:26 pm
by boyntonstu
Having water stand upright is the problem.. :D If using a cheap container, it gets holes.

I wrote a 45* and a tub of water beneath.

No holes unless you shoot low.

OTOH Place the water tub into a hole in the ground and shoot away!

BoyntonStu