SpudFiles

Hi i'm kinda new to this web sight but i have made three pnuematics (not yet posted) so far and would like to make a pnuematic sniper. For ammo i would like to use 1/4" steel slingshot ammo. I already have some designs but do not know what type of barrel and what size to use, maybe copper brakeline or whatever but any help/suggestions would be very helpful. Thanks.

9/32" brakeline is your best bet. That is, if the 1/4" slingshot BBs are actually 1/4." Bring one to the hardware store and pick out the best fitting barrel, it's pretty simple.

Welcome to the forums man. As for the barrel, it doesn't make so much difference as the projectile does. You can have the best barrel in the world, but if you're shooting potatoes, it's not gonna be terribly accurate. A lot of guys on here like to make aerodynamic darts to shoot, and you can use all kinds of barrels for it, but smaller diameter is suggested. There's a coule of how-to posts on how to rifle a pvc barrel, you could do that with a 3/4" ID barrel and use wax slugs, that might work well.

thanks noname but didn't you say that 9/32" brakeline has an i.d. of 6.03mm?

Most slingshot BBs have flat spots on them, so they won't do to well in a pneumatic.

According to the manufacturer, yes. And I do know that that's .237." They should fit in it, if they don't, just get 5/16" brakeline.

BigJon wrote:thanks noname but didn't you say that 9/32" brakeline has an i.d. of 6.03mm?

Actually it's 7.41 mm. There's 2.54 cm to an inch.

5/16ths would be 7.94 mm.

thanks for the help guys. I think I will go with the brakeline, and as for slingshot ammo being partially flat i might just use ball bearings.

i actually did this once......

i reccomend MCmaster. they sell 500 packs of .25 inch steel bearings (polished) that have a .0001 inch tolerance

and, of couse, stainless steel tubing with an ID of .251 inches, and a .0001 inch tolerance. you can only get 2 foot lengths but you shouldnt need any more than that............

Aluminiun poles that are used for fencing are a good way to go, very smooth bore with no seams. I'm not sure about 1/4 inch though, i use a 1/2 inch Aluminium barrel 2 metres long (coupler in the middle) and it has proven to be very accurate with home made projectiles. I think you can even buy 6 metre lengths.

Peace
Scotty

may i suggest one more type of tube for your barrel?

aluminum arrow shafts for they are dead straight, no seams fairly decent length. im not sure on the i-d though so maybe something to research they come in different thickneses so your probably bound to find the right size.

arrow shafts are kinda short though i think and i whant to have more of a long rifle feel to it. But thanks anyway.

Slingshot ammo works great, yeah it has a tiny flat spot, but its an indention and not a protrusion so it doesn't really hurt anything, and they are made to a pretty good tolerance.

As for a barrel I would suggest looking for a place that has the K&S Engineering metal displays that have tubing of different sizes. The Ace and Hobby Lobby near me both have these, and I think I have seen them at other stores as well. Bring some slingshot ammo and find the tube that fits them, I believe it is 9/32" (OD). They come in 3' lengths. The display looks like this:
http://www.ksmetals.com/HobbyMerchandis ... chandisers

Hey thats great because I think they sell that stuff at this hobby shop near my house.

Paaiyan, the brakeline goes by OD, not ID.