Search found 70 matches

by RBurke83
Sat Jun 27, 2015 11:42 pm
Forum: Pneumatic Cannons
Topic: Bolt Action Bullpup .45 cal (NEW VIDEOS)
Replies: 27
Views: 15233

Re: Homemade Big Bore .545 cal Airgun (Update Damage Pics)

Really nice gun, I'm assuming you screw on to the Schrader valve instead of using a check valve? Also, do you screw the barrel assembly onto the breech each shot or does it slide in? Thanks, beautiful work !
by RBurke83
Thu May 09, 2013 2:12 pm
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Thanks Kilash! I used a muzzle energy calculator on a different site entering just muzzle velocity and projectile weight and I think it came up with 115ft/lbs so your calculation is probably right on the money. It has a piston valve which is almost air tight while being very low friction, currently ...
by RBurke83
Thu May 09, 2013 1:42 pm
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Its .55 inch ID, ty
by RBurke83
Thu May 09, 2013 12:32 pm
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Barrel is 42 inches.
by RBurke83
Thu May 09, 2013 11:57 am
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Thanks! I kind of assumed there was something else going on that I wasn't accounting for. Math has never been my strong suit, but at your leisure could you tell me what energy performance you would anticipate from my launcher? Chamber Vol. is 18.7 cubic inches Barrel Vol. is 6.7 cubic inches Initial...
by RBurke83
Wed May 08, 2013 8:16 pm
Forum: Pneumatic Cannons
Topic: Basic Nerf Cannon Help
Replies: 44
Views: 8971

You probably want something like this: http://www.spudfiles.com/forums/simple-cannon-t24849.html QEVs are dirt cheap online: http://www.spudfiles.com/forums/semi-auto-valve-for-under-20-t23626.html Since NERF darts need so little air per shot, you could probably realistically make a semi auto witho...
by RBurke83
Mon May 06, 2013 3:33 pm
Forum: Pneumatic Cannons
Topic: Piston+Return Spring performance?
Replies: 3
Views: 1195

Well, honestly I wasn't sure. I was thinking about a spring which could act as a piston sealing aide and also as a bumper, which I guess at 2-500 psi doesn't have to be extremely stiff, I'm just trying to find a happy medium between reliable valve sealing and not closing prematurely.
by RBurke83
Mon May 06, 2013 11:59 am
Forum: Pneumatic Cannons
Topic: Piston+Return Spring performance?
Replies: 3
Views: 1195

Piston+Return Spring performance?

I am designing a new launcher based on my experiences with my first piston launcher, and my design necessitates a chamber-side fill port with a multishot capacity, ideally 3 200+psi shots. I'm just wondering if anyone who has developed a piston with a return spring has noticed any notable performanc...
by RBurke83
Thu May 02, 2013 1:28 pm
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

I suppose a ballistic pendulum would simply mirror the muzzle energy calculator?
by RBurke83
Thu May 02, 2013 11:35 am
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Thanks, I bookmarked that thread. From what I took from it was, Faster, Harder, Longer....hehe Debbie Does Dallas could teach shooters quite a bit about target damage. Seriously though, I suppose the best judge of terminal performance is depth and diameter of penetration into a uniform substance.?
by RBurke83
Thu May 02, 2013 10:54 am
Forum: General How-To & Discussion
Topic: Interpreting Muzzle Energy?
Replies: 15
Views: 4056

Interpreting Muzzle Energy?

Hey guys, I searched for an answer to this query, but didn't find any definitive answer. So I use a muzzle energy calculator for my launcher, which for specificity is a standard piston pneumatic, muzzle velocity is approximately 580 fps with an approximately 160grain projectile. Seems easy, plug it ...
by RBurke83
Tue Apr 30, 2013 8:02 pm
Forum: Pneumatic Cannons
Topic: Help with my valve/design choice
Replies: 30
Views: 8423

Copper has the advantage of being easily soldered to other copper parts, steel on the other hand, can be brazed, but most often thought of as a welding material. I would prefer steel seamless tubing over almost any other material, but it is not readily available where I live like copper, and I haven...
by RBurke83
Tue Apr 30, 2013 5:08 pm
Forum: Miniature Guns
Topic: carbon fibre pen gun build log
Replies: 64
Views: 18653

weapon?! Looks like a modded writing instrument to me :wink:
by RBurke83
Tue Apr 30, 2013 10:21 am
Forum: Miniature Guns
Topic: carbon fibre pen gun build log
Replies: 64
Views: 18653

I don't want to get caught up in a bidding war with you Brian 8) ... Jack was the all metal version constructed for a customer? Would you forsee any US Customs issues shipping to the US?
by RBurke83
Tue Apr 30, 2013 8:44 am
Forum: Pneumatic Cannons
Topic: Help with my valve/design choice
Replies: 30
Views: 8423

You will have to purchase a pump which suits the intended pressures. For self contained shooting without pumping, you are entering the territory of PCP commercial airguns. These guns typically have a chamber containing enormous pressures, measured in 1000's of psi's. A trade off could be a chamber d...