MP-17, Mini Prod 17 cal build

[Tack Driver 10]

This build will be a Prod based gun but in 17 cal with a mini me 9 ci bottle.
Quite frankly it could very well be, "The Prod Yo momma warned you about"....LOL

Had most of the parts except the breech and attaching parts.
Ordered them on Monday morning and received them today.
That must be some kind of a record, at least for me.

Started making parts earlier this week so got a good head start.
Here it is mocked up with a few rough edges.
Should get to refine it over the next few days.
Stay tuned for all the gory details.

[ranchibi]

Ron, that looks like a Prod on HGH! Looking forward to seeing it completed!

[FuzzyGrub]

Substantial drop block there!     

[Tack Driver 10]

Substantial drop block there!   

This block is 5/16" taller than the AirMega gun.
It looks bigger since it hasn't been finished.
Might use Birchwood aluminum black on it when done. (black is slimming)
Here it is after I had my way with it this morning.

[FuzzyGrub]

I meant in a good, heavy duty, way.   Looks like it would hold that bottle very secure.

[Tack Driver 10]

I meant in a good, heavy duty, way.   Looks like it would hold that bottle very secure.

Gotcha, it does look long but no real way to get around it and have the rail on the bottom.
The goal is to keep the gun under 36" long, less than 5 pounds and balanced at the trigger.
Right now it weighs 4 1/2 pounds and only missing the PA so shouldn't be a problem.
With a wood stock should be right at 5 pounds soaking wet.

The 9 ci bottle is 148 cc, about 50% more volume than the AirMega tube.
It got 48 22 cal shots at 900 FPS so this one should get 100+ in 17 cal.
Has the same sling shot hammer as that gun.
Might be able to get it together this weekend for initial testing.

[Tack Driver 10]

Time to address the elephant in the room, aka the barrel.
Have a 14 1/2" LW barrel but need to add the o-ring inside the leade.

The conventional approach is to cut off the leade at the TP and rework it.
I would loose about 3/8" in length in the process.
Decided to trim the end .030", cut in the gland and press on a brass sleeve.
Just had to drill the TP, 1/4"countersink and probe port.
Most of the fine LW work remains intact.

Here it is:

[Tack Driver 10]

Made the rest of the parts and put the gun together.
Held 2500 psi rock solid overnight.
Should get to do some initial velocity tests today.

Specs:
14 1/2" 17 cal LW barrel
.140" ports, valve, TP, barrel
SSH 2400 spring
Ninja Pro V2 regulator 1400 psi
Tippmann 9 ci, 148 cc reservoir
45 cc plenum
4 lb 10 oz weight
36" length

[JimD]

Looks Great!

[screwwork]

Looking good, I’m looking forward to seeing how she shots and power range you get out it.

[bear air]

Great work Ron. I love what you did on this one and the airmega one as well. Excellent craftsmanship.

[Tack Driver 10]

Thanks guys, this has been a fun build.

Ran the gun over the chrony yesterday.
Started with the light 2400 hammer spring.
Power was too low at around 750 FPS with 7.9 CPHPs.
Put in a heavier spring and power went up to 870 FPs.
Going to leave it there for now.
Only takes 6 1/2 lbs to cock the gun, 4 oz trigger pull.
May try a heavier hammer spring later.

CPHP 7.9
870 FPS 13.30 FPE

Barracuda Hunter Extreme 9.57
820 FPS 14.29 FPE

Barracuda Match 10.65
796 FPS 15 FPE

Just under 80 dB on the sound meter at 3'.

[FuzzyGrub]

FWIW: My crosman 12" 1720T LW barrels really like the JSB/AA 10.3g at 800fps, right about where you are at.   

[Tack Driver 10]

FWIW: My crosman 12" 1720T LW barrels really like the JSB/AA 10.3g at 800fps, right about where you are at. 

I figured the high 800s would be a good place to start.
Need to see how accurate it is there.

I single loaded the previous pellets for the velocity test.
Now need to address the other elephant in the room.

The Prod breech only accepts 22 cal mags specific to the Prod.
In order to use 17 cal mags, Mrod mags need to be modified and the breech shimmed.
The Mrod mags are taller and narrower than Prod mags.
Need to shave .030" off the bottom of the mag and shim the breech .040".
The 17 cal bolt from the Fortitude is a drop in, p/n ME-104.

Milled the bottom and made a shim from plastic laminate, aka Formica.
Glued the shim to the breech with Dow Corning 3145 MIL spec RTV.
Sharpie to the rescue to match the breech....LOL

Although this is 17 cal, 22 and 25 cal versions are just a barrel, bolt and mag swap away.
Up next, sight in and initial accuracy testing.

[Tack Driver 10]

Put a scope on the gun, loaded 2 mags with CPHPs and sighted in at 15 yards.
First shot was 3" high and to the left, adjusted scope and the remaining 9 shots grouped well.
Next took 10 shots at a can on the fence post at 20 yards.

I can tell this gun is going to be a shooter.
Will stretch out the distance when we get a calm day.

[Tack Driver 10]

Tried an experiment after reading about the Mrod with a peek striker.
Naturally I had to have one for my very own....LOL
Threaded a piece of 1/4" peek 1/4-28 and screwed it in the hammer.
Gained about .060" hammer travel in the process.
Added a black Delrin spacer to the spring to make up the difference plus some.

Chrony numbers, 2 turns CCW on the PA:

CPHP 7.9
945 FPS 15.66 FPE (+2.36)

CPUM 10.5
865 FPS 17.44 FPE (NT)

Barracuda Hunter Extreme 9.57
908 FPS 17.50 FPE (+3.21)

Barracuda Match 10.65
875 FPS 18.10 FPE +(3.10)

Uses a little more air but puts the heavy pellets in the upper 800s.
From 3000-1400 psi should get about 90 vs 107 shots.
Will make a good squirrel gun out to 50+ yards.
Need to put the target out at 60 yards and see what this gun will do.

[Tack Driver 10]

Tuned the gun for 880 FPS with 7.9 CPHPs.
Still sighted in at 20 yards.
Was going to shoot some targets at 30 yards but......
Cut out the middle man and went out to 60 yards.
Didn't intend this gun to be a 60 yard gun but let's go there.
Want to avoid a severe case of FONK (Fear of Not Knowing)....LOL

CPHPs, BHEs, CPUMs all were about 1.4" CtC.
Surprising to see the Crosman brown box domes bring up the rear at 2.65".
Next up H&N FTT, Barracuda Match and JSB Exact.

[TF89]

Awesome,  nice work, looks like a keeper.

[TF89]

I and  quite a number of us feel the prod is a perfect platform for .177 and don't understand why crosman hasn't  made a version in that caliber. I converted one, not like you as yours is just bada.. 

[Tack Driver 10]

I and  quite a number of us feel the prod is a perfect platform for .177 and don't understand why crosman hasn't  made a version in that caliber. I converted one, not like you as yours is just bada..

I thought the same thing.
Even without the bottle a 17 cal Prod just makes sense.