SpudFiles

Hey, I'm looking to build a pneumatic sniper rifle, most likely sprinkler valve, w/ sch 40 pvc. What's the best type of ammo to use ( what will go the farthest ). All I'm trying to do is hit targets.

What size is your barrel?

i dont know, i want to find out what projectile would fly the farthest, then I'll get a barrel to fit it.

Nails with the heads grinded off or BB's seem to work fine.

what kind of barrel would i use for that? brakeline, where can I get brakeline?

You’re probably going to want to get .177/4.5mm darts/bolts from Daisy.
Edit: never mind, there made by Marksman. airgun darts

Just get a bb gun if you plan on using pellets.

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wow those dart things look like i would want a few...... if you have a 3/4 inch barrel, try arrows with a wad behind them.... makes for a big gun but hey, i can stick them into trees with my spudder.....

I just felt like reminding you guys that there's no such thing as a sniper rifle; sniper is a job description.
(and "sniper's rifle" tends to include alot of things that you wouldn't think of as the stereotypical "sniper's rifle"... heck, as most deer hunting with firearms is essentially sniping (well, you don't run 'em down, do you?), an iron-sighted shotgun would count. As a "sniper's rifle"... at least if it was rifled.)

Instead, what you guys are building are <i>precision guns</i>.
Gun because they arn't rifled - although gun generaly means a crew-served weapon... so I geuss we call 'em "precision spudguns".

Semantics aside, aerodynamical stable objects are what you want to use in a smoothbore. This includes darts and projectiles with a pocket in the back.

what does a pocket in the back do for a projectile?

Hollowing out the back moves the center of mass forwards (where it'd balance on your finger) while not effecting the center of pressure (where the air resistance pushes).

This generally results in the COM being in front of the COP... meaning that the projectile will be stable.

Such projectiles can be designed with the help of COM-P - just treat the pocket area as a cylinder and multiply the density by 1-(InsideDiameter/OD)^2.

Last time I checked the “pocket” was so that the back would expand from the forces behind it and the round would bite rifling better, like on the Minie ball.
Edit:
Oh, okay. That makes more sense.
It took me to long to find that link…

"Sniper rifle is a term most frequently applied to rifles used by military or law enforcement to ensure accurate placement of shots at greater ranges than other small arms. A typical sniper rifle is built for optimal levels of accuracy, fitted with a telescopic sight and chambered for a military centrefire cartridge. The term is often used in the media to describe any type of accurised firearm fitted with a telescopic sight that is employed against human targets." - wikipedia

Yea, there's such thing as a sniper rifle.

Yep, sniper’s rifles exist; my favorite would have to be the Colt 1885, or the Remington No.1 Falling block in .50-110…

But what you’re making is most likely going to be neither rifled nor accurate enough to suit the needs of a sharpshooter.