Crosman 13xx bottle gun

[Tack Driver 10]

Had a spare 1377 gun and with all the chatter about pcp guns decided to convert it.
Made a drop block and slid it into the tube.
Left the rest of the gun stock and pumped the bottle to 2000 PSI, regged at 1500.
Wasn't sure how the gun would respond but it fires just like a pumper.
Got 22 shots from 2000 psi to 1500 psi.
Too late to run it over the chrony last night though.

[Rob M]

very compact , i like it !

[Killercrow]

I like it too! I'll be waiting for chrony results.
Meanwhile I'll post a 1377 you might like.

[Spooner]

that is AWESOME!!! 

[Tack Driver 10]

The "short and sassy" (SS) gun has a 17 cal 12" LW barrel, measures 23".
The Ratcatcher (top gun) makes 750 FPS in 22 cal with a 14" LW barrel so should get around 850ish FPS???
May need some tuning but I'm going to run it as is to get a baseline.
Hopefully rain and clouds should clear out later today for chrony test.

[Killercrow]

The best I could ever get from a 2240 and regulated 850psi air, was like 840 fps, 24" barrel.

[lizzie]

Moving thread to the Darkside

[JimD]

Very interesting.  I have a 1377 gathering dust and no 177 PCP. 

[Tack Driver 10]

JimD....Tons of options modding a gun like this.
If you want to use a 13 ci tank, just machine a 2100 tube to fit the 13xx frame.
more here:
https://www.gatewaytoairguns.org/GTA/index.php?topic=155629.msg155718495#top

So ran the gun over the chrony wih 7.9 CPHPs:
1 shot 17 cal 11" LW barrel, .134 port, reg 1450 psi
650 FPS 07.41 FPE

The 11" barrel choke is extremly tight and kept getting errors.
Possibly bits of pellets?

3 shots 17 cal 14.5" LW barrel, oval port, reg 1450 with 7.9 CPHPs:
1. 722
2. 717
3. 719 average 9.07 FPE
The 14.5" barrel was fine with no errors.

Ran a 10.65 g Barracuda Match pellet
664 FPS 10.42 FPE

The pumper valve has the Teflon check in it etc and reduced volume so mostly stock.
Next need to take the gun apart and modify the valve to take advantage of the 3" plenum.
An SSG and power adjuster are also needed.

[Killercrow]

What are you using for exhaust/transfer port? Is it custom or still original?

I'm really curious what sort of numbers you would get from a 21" barrel.

[Tack Driver 10]

The valve and transfer port are .157".

I don't have a 21" barrel but put a 24" barrel on the gun.
This is a non choked Crosman barrel.
The LW choke usually takes about 20 FPS off.

CPHP 7.9= 793 FPS 11.03 FPE
BM  10.65=717 FPS 12.15 FPE

[Rob M]

very good numbers.. with the 24 incher, and the front of the 1377 valve opened up , im thinking the sky is the limit.

[Killercrow]

By the look of things, I think simply opening up the ports will help performance a lot. Then play with a hammer spring adjuster to out it where you want it.

I know it's not the same thing... But I have a 1400 doing 900+fps in 177, the thing is I have no way of knowing what sort of pressure I'm playing with.

Not sure if you're after max power or what...

[Tack Driver 10]

I'm really beginning to love this gun.
Why I love this gun so much that I made the valve opening in the shape of a heart....LOL
Isn't that special?

But seriously folks:
Took the gun apart and modified the valve.
It had a big spacer in it that restricted the volume.
Took the stem and cut a goove in it for an external spring and clip.
Added a poly bumper to the back of the valve to limit stem travel to .090".
Put the gun back together with the same back end for now.

Ran it over the chrony and believe me Cleveland has nothing on this gun because it's rocking out with the band.

14.5" LW barrel, reg 1450
945 FPS 15.66 FPE with 7.9 CPHPs
885 FPS 18.52 FPE  with 10.65 BMs

24" Crosman barrel, reg 1450
1030 FPS 18.61 FPE with 7.9 CPHPs
958 FPS 21.70 FPE with 10.65 BMs

The gun is VERY LOUD (93.7 dB) as expected so need to tune it for power and shot count.

[Rob M]

yes , that thing is cooking now !!

[Killercrow]

That is awesome!
Are the exhaust ports still the same size or did you open it up?

By the way... I'm borrowing your external spring idea

[Tack Driver 10]

That is awesome!
Are the exhaust ports still the same size or did you open it up?

By the way... I'm borrowing your external spring idea

The ports are the same as before.
Only change was to gut and open the front of the valve.
Sadly it's now just a shell of what it once was....LOL

[Tack Driver 10]

I know what you're thinking.
How much power would a 24" Crosman 22 cal barrel make?

Swapped one in from one of my pumpers, .135" barrel port.
The barrel port is a little small but it is what it is.
Since I'm expecting explosive power used the Grenade bolt to help tame this beasty boy....LOL
Still just as loud at 93.6 dB.

Ran 3 shots with different pellets:

14.3 CPHP 926 FPS 27.22 FPE
25.4 JSB Monster 748 FPS 31.55 FPE
34 JSB Beast 641 FPS 31.01 FPE

[Killercrow]

Nice! That's pretty good power for a 1377 haha.
I need to get me a pump and a bottle...

[Tack Driver 10]

Time to get serious and tune this gun.
Put the 17 cal 14" LW barrel back on.
Took the stock off and installed an SSG, now it's a pistola.

Tried a 2300 spring too soft, hammer had too much bounce.
A 13xx spring works really good with the 13xx hammer.
Was able to adjust the hammer free flight from 800- 900+ FPS.
Settled on 900 FPS 14.21 FPE for now to see what the shot count is.
That's about what a hot 2100 pumped 15 times makes.
Thinking should get 22 shots per 500 psi or 66 shots from 3000-1500psi.

At one point I'd like to drop the reg pressure down to around 1200 psi.