HomeBuilt Airgun — Done!
Finally finished my homebuilt project.
17 inch .357 barrel. 22 cubic inch tank.
This will be the first of 3 or 4 guns. I have 4 more barrels, two .25 cal, one .22, and one .223.
Now I gotta learn Anodizing.
Not quite Buba B’s quality! He’s a tough act to follow!
Mark
All Replies
justforfun:
Yah, got it off EBAY about 4 weeks ago. It went cheep because it is so big and was 3 phase powered. It had a 7.5 horsepower 3400 RPM motor. I remotered it with a 5 Horsepower 1750 RPM single phase motor. Now insted of 9 CFM it only kickes out 4.5 CFM, but thats plenty for me.
I do a lot of fooling around with valves. Having “easy” air, shortens the design, build, test cycle.
Mark
MM123522 is that the monster you got off Ebay?
Must be nice. 🙂
Roy S.
You lucky Devil. Good work keep us apprised.
All:
Finally got decent power. 65 grain round ball @ 885 FPS for 112 FPE. I think i’ll stop here – enough power for me. At 800+ feet per second, it should shoot fairly flat out to 55 yards. Blows through the first 2 by 4, and 3/4 of the way through the second 2 by 4. Plenty of recoil with 65 grain round ball. Shot a 158 grain .357 bullet, LOTS of recoil!
All the power is in the valve. My normal valve has a .173 inch diameter orface. No matter how I tried, I could not develop enough power, even with a .200 hole. Finaly uped the orface to .234 inch, but that required a heavier spring. Went from an 18 pound (compressed) spring to a 24 pound spring. The gun Is a little hard to cock now, and thats what is limiting my quest for power. I need a gun thats fun to shoot, not a thumb buster to cock!
After installing the 24 pound spring the edges of the trigger mechanism started rounding off under the stress. The trigger/ sear were made of air hardening tool steel (unhardened). So I heat treated them so they would be strong (went to rockwell 45 hardness – yah, I got a hardness tester and a heat treat oven too!).
I got 3 tins of 77 grain pellets comming from Pyramid Air, that should raise the energy a notch.
I got so caught up in just making this thing work that I omitted the safety. Now I am considering making a large notch in the frame that would accept the cocking knob. The “safety” would be leaving the breach open, and locked open by dropping the cocking knob into the notch in the frame. It’s a quick and easy solution, What do you guys think?
The last picture is of my compressor. It sure helps out when developing new valves! If you need to empty the tank to modify the valve , You dont have to pump for an hour. The compressor is Huge, it’s chest high. It lives in the garage, and I have two scuba tanks to transfer the HPA to the basement.
Mark
justforfun:
The length of the tube is 25 inches from the valve adaptor to the end cap. Nice and short and light for the woods!
I am having better luck with my valves. Got it up to 820 FPS — low 90’s FPE.
Mark
Shadoh:
The trigger mechanism has two springs along each side of the hammer release lever (sear) and wrapped around the pivot pin. They rotate the the hammer release lever back up when cocking.
The air force type release didnt behave well with higher spring forces. Sometimes it wouldnt release. It would hang, then the gun would fire if you tap the gun on the side. I was using an aluminum hammer with the airforce type sliding release. The aluminum was too soft for a sliding release. Lots of trial and error!
Mark
Mark, I have a question.
What length did you make the frame tube overall?
Thanks
Roy S.
Nice man, I love the simple trigger mech. What resets the trigger after firing? Is there a return spring of some sort thats not in the drawing? You could still add a safety to that set up easily if you desired.
sorry didnt see this post until now….catch me on msn pm me for details i hate spilling my email adress publicly
lets chat
400 gram is crazy…there should be no need for it, 100-150 is all you should need, especially with stronger spring in there.
heck im running 150 gram in my 457 pushing 600 fpe, something is up with your valve….but chat me and ill do my best to help you out
Beautiful job Marc,
I like the trigger config.
Something to be proud of…..
Mark, sure have enjoyed your build posts. Sure can learn allot from what you have done and then posted.
Thank
Roy S.
Blackops:
Thanks for the info! Now that I know it can be done , I’ll try harder.
My numbers are crapy. I’m getting 765 Fps — about 85 FPE.
Blows through a 2 by 4 with no problem, But there should be a lot more power available.
I love the feel of this gun! The barrel is cut thin, and the the 22 cubic inch tank is light weight. The home designed/built trigger worked out really well. The trigger pull does not change much with increased spring pressure, and it cocks smoothly!
I built a new valve this afternoon (from scratch), but no improvement in velocity. Dam!
The hole through my breach is .5 inch diameter. Do you remember what yours was??
Mark
Grats MM looking forward to seeing the tuning of your new gun!
400 Gram hammer 😯 wholly crap!
If I remember correctly I was getting 950 fps with 60 grain Eun Jins, a stock Condor valve 120’sh gram hammer, 17″ 9mm barrel, 3,000 PSI fill. I was getting very near your numbers with a stock talon valve.
I never was able to get a shroud to work worth a crud on the .308 or 9mm be cool to see if you can work something out that takes the BARK out of the 9mm.
Cygnus ought to be able to get your valve working in the scary range!
Really looking forward to seeing how you sort your gun out.
Jim.
REVISED TRIGGER
The upper part (sear?) drops away cleanly to let the hammer fall.
Mark
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SUCCESS!!!!!!
Just recieved my 77 grain eun jin 9mm pellets in the mail.
Somehow they develop more power than the round balls
I just shot one over the chrony — 935 FPS for 150 FPE. Huge recoil!
There is no way I’am gonna quiet this thing down!
The round balls must not seal in the barrel as well as the pellets.??
Round balls are .350 diameter and pellets are .361. The barrel is .357 to the outside of the rifleing.
Shot a 158 GRAIN BULLET @ 730 fps FOR 183 fpe !!!!!!!!!!!
The gun only weighs 4.5 pounds – that might explain the large recoil.
This gun has exceeded all my expectations!
In the spring I’ll evaluate it for accuracy.
Got no Idea what I’ll do with this gun (too powerfull and too loud for the area where I shoot).
Mark