.357/9mm marauder build

[rsterne]

Not sure how you figure that a 1/2" OD is "pretty close" to yours, but whatever.... When you ask advice and then ignore it, you shouldn't be too surprised when no further advice is offered.... Good luck with your build, and stay safe....

Bob

[shorty]

Ordered some pellets and they should arrive on Wednesday.
JSB Match Diabolo Exact, .35 Cal, 81.02 Grains, Domed, 100ct    
Air Venturi 9mm, 67 Grains, Round Ball, 200ct
Air Venturi .356 Cal, 95 Grains, Hollowpoint, 100ct    

Can't wait to try out some real ammo. The gun is really loud with the shroud off. Don't want the neighbors to be bothered so I have been working on making new baffles. The gun has a fast sharp high pitched pop. Almost like those kids cap guns.

I guess I will start working on the single shot tray too as the pellets won't be here till Wednesday.

I did shoot three more times today with the homemade slugs. No recharging from yesterday with a starting PSI of 2800 and I shot 2 yesterday and 3 today with an ending pressure of approximately 2600 psi. Today numbers were 495/510/509.

So far that's 5 shots using approximately 200 psi at an average fpe of 70. Not bad at all.

[shorty]

10 new baffles made along with end cap today. Now that makes a big difference. Shot once and still hit 506 fps with 124 homemade slugs at 70 fpe and sounded like the .22 at 40 fpe.

Shroud didn't come flying off so I guess alignment was Ok. Made baffles out of steel and plastic at .41" and drilled end cap at .45". Boy I am happy the shroud didn't fly off from a terrible clip.

[shorty]

Travis's comments about 50 to 100 psi to launch these .357's at a good click made me think about the air usage I did with the homemade slugs.  At 200 psi for 5 shots is only 40 psi.

Seems like (atleast with the homemade slugs) the flow is not there with the pressure just yet.

Well, hopefully that will change. I opened the valve exit to .18" and opened the steel transfer sleeve to .171" (biggest I can go with stock orings).


Edited for safety concerns.....

[shorty]

Figured I would let everyone know "who's interested" the "almost" final results of the build. I just can't leave a never ending story and there's absolutely no one else that understands this kind of addiction beside you guys (really).

Everything in a nutshell:
Valve throat-.25"
Valve exit port-.19"
TP-.19"
Barrel port - .19"
Increased "stock" hammer weight- pretty cool design, it goes on the inside of the hammer and double used as a spring guide.
Increased hammer travel- Thanks Pakprotector, set screw installed and recessed as hammer throw adjustment.
Modified bolt probe-sleeved with 2 orings
Barrel-16.5" .357/9mm barrel sleeve from numrich.
Baffles- 10 new baffles
shroud end cap- opened to .45"
Single shot tray-made from delrin.

Total cost $30. My labor and lathe work-free.Hrs to complete- 10.To do it again, not gonna happen.

JSB 35 cal 81.3 are the most accurate. At 22 yards it is a 1 holer. Air venturi 95 grain hollow point are around .25 CTC and 66 grain round ball are similar.

For the power and over 300 rounds fired so far (.357 gets expensive):
Since I like the JSB's the most, 672-703-650 for 18 shots from 3000 psi to 1800 psi. Beautiful curve. 2nd shot is 688fps starting at 3000 psi and hangs around 690 to 703 for 12 shots. Then falls hard around 2200 psi to 1800psi. Peak is at around 2600 psi.


It wasn't until I did the hammer weight increases along with hammer travel that the numbers started moving the power up. Thanks to Rstern and the great data from port size vs caliber/fpe and hammer weight/energy charts/data. This kind of information made my .357 "almost" hit my goal.


So where does this leave me at? A 22 marauder can be converted to a .357 fairly easy with great accuracy and 90fpe max "my current configuration". It can also be converted back to .22 cal with removing a bolt sleeve and replacing the barrel to the original .22 barrel.

Almost forgot:
Sound--It is as loud "slightly louder" as my .22 when fully maxed out when I was testing it at 53 fpe. So I would guess it as as loud as a stock .25 maxed out. No neighbors complained yet and no police men arrived yet. It kind of reminds me of when everyone says that hitting the target is louder. That really is the case now when your punching holes through your wood fence because your standard .22 backstop aint working as good.

Thanks for listening/reading guys. There's really no one else that understands our crazyness. Even though I said goodbye,you guys a a group of guys/gals that i can only share my obsession with.