Crosman 13xx bottle gun

[Tack Driver 10]

Dry fired the gun from 2000 psi to 1500 psi and got 23 shots.
So should get around 70 shots from 3000 to 1500 psi.

As an experiment swapped in a 14 1/2" Crosman 22 cal barrel.
Want to see what difference the caliber swap makes with all else equal.

07.9  CPHP 882 FPS 13.64 FPE
14.3  CPHP 733 FPS 17.06 FPE

The 17 cal LW barrel is choked so normally cuts velocity by about 20 FPS.
Adding 20 FPS to the 17 cal barrel= 902 FPS 14.27 FPE

Good numbers with both calibers, I think I'll leave it there (for now).

[Tack Driver 10]

The reg on the gun was set at about 1475 psi.
Set up another bottle with a reg pressure of 1200 psi and installed it on the gun.
Left everything the same and was expecting a decent drop in velocity.
Dropped less than 10 FPS with the same sound level, 91.5 dB.

14 1/2" 17 cal LW barrel
7.9 CPHP 877/875 FPS 13.45 FPE

The gun has a stock 13xx hammer that weighs 38 grams.
Made an adjustable 24 gram hammer to further tune the gun.
The poly bumper on the back of the valve limits stem travel to .100".
With this hammer stem travel can be adjusted lower until power drops off.

Wagged the shot count to be 80 shots from 3K down to 1200 psi at this power level.
Should be able to increase it if the new hammer works out.

[Tack Driver 10]

Well.... that hammer didn't work out.
Regrouped and made a new valve bumper from Teflon.
The valve stem protrudes .500" from the back of the valve.
Made this bumper .450" so the stem has .050" of travel.
Same stock 13xx hammer and SSG.

07.9  CPHP 859 FPS 12.94 FPE
07.9  CPHP 855 FPS 12.82 FPE
10.65 BM 763 FPS 13.76 FPE

The word on the street is if you want to succeed then dress for success.
Dressed up the gun with a stock and other items from my collection.
If loving this gun is wrong, I don't want to be right....LOL
Here it is all gussied up.

[Rob M]

very cooll  probably serious efficiency with thaat set up.. ( regged and limited stem travel

[Tack Driver 10]

Sighted the gun in and it's very accurate with 7.9 Crosman CPHPs.
Ran some extra shots to run the reg down from 2K to 1500.
Got 25 shots at the same power as before, 855 FPS 12.82 FPE.

So if the gauge can be trusted, should get 90 shots from 3K to 1200 psi.
Makes it easy to calculate, 10 shots per 1 ci and 5 shots per 100 psi.

With the power set at 12 FPE should get close to 100 shots.
A 13 ci tank at 12 FPE possibly 140 shots.

When I was in the Air Force the saying was, "The job's not finished until the paperwork's done".
Glad I only did one hitch....LOL

The PCP conversion cost me about $100.
$50 for the tank/reg and belleville washers. (ANS Gear, McMaster Carr)
$35 for the drop block, ASA adapter and gauge.
$15 for the SSG.

This is my cost for basic materials assuming you have a 13xx gun (who doesn't) with a steel breech and good barrel..
I'm not factoring my time etc.

[Tack Driver 10]

For all the tree huggers (you know who you are), here's a green version....LOL

[johnbrown]

Where did you buy the drop block?
Can you post a link?

[Tack Driver 10]

Where did you buy the drop block?
Can you post a link?

I made the drop block from basic aluminum stock and an ASA adapter.
Got everything off EBay.

Maybe someone with a CNC setup will make a run of these and sell them.

[Tack Driver 10]

Another option is to use a spent 90 gm CO2 bottle.
Wouldn't be regulated but would fit nicely on a 13xx gun.
Just add a gauge and fill port on the drop block.

Could also be used on a 760, 2100 etc.
Here it is mocked up on a 13xx chassis.

[Tack Driver 10]

Here's the 90 gm bottle drop block, nice little afternoon project.
The bottle screws into the block so no adapter needed, I cut out the middle man....LOL

[Rob M]

Here's the 90 gm bottle drop block, nice little afternoon project.
The bottle screws into the block so no adapter needed, I cut out the middle man....LOL

that actually looks like it belongs there ..

[Tack Driver 10]

Some pics of the drop block.
Mounted the drop block on my test gun.
Just pulled off the pump arm and piston and slid the DB in.
I'll run it as a pumper valve and then tune it like a PCP.
Has a 22 cal 18" Crosman barrel.

[Tack Driver 10]

Ran 12 shots over the chrony to get a baseline, 1500-1250 psi.
14.3 CPHP, 18" Crosman barrel. 160" ports

 635 FPS 12.80 FPE  start 1500 psi
 644 FPS 13.17 FPE
 653 FPS 13.54 FPE  high
 649 FPS 13.37 FPE
 641 FPS 13.04 FPE
 25.4 Monster 510 FPS 14.67 FPE
 642 FPS 13.08 FPE
 640 FPS 13.00 FPE
 635 FPS 12.80 FPE
 635 FPS 12.80 FPE
 634 FPS 12.76 FPE
 630 FPS 12.60 FPE  low, end 1250 psi

Pretty good for a gun setup as a pumper.
Some tuning and mods should help the gun considerably.
Anyone have a WAG as to how many CI are in a 90 gram CO2 bottle?

[Rob M]

90 gram is aout 121 cc, so whatever that is in Ci

[Insanity]

90 gram is aout 121 cc, so whatever that is in Ci

7.38ci.

[Tack Driver 10]

Thank you gentlemen.

The regulated 9 ci bottle has an efficiency of 1.06.
The short 17 cal barrel and low pressure just can't make big power.

I plugged the 90 gram bottle gun values into Lloyds efficiency calculator:
Came out at 1.23 so somewhat better.

[Tack Driver 10]

Pumped the gun to 2000 psi.
Took 2 shots:

14.3 CPHP
733 FPS 17.06 FPE
726 FPS 16.73 FPE

Need to take the gun apart and mod the valve.

In the meantime, why not a 760 bottle rocket?....LOL
Made the drop block before the SB kickoff.

[Rob M]

nicce, a real good fit on the 760

[Tack Driver 10]

It does look like a nice fit for the 760 and 13xx.
The tradeoff is the bottle is unregulated.
A 9 ci regulated bottle can also be used as seen mocked up here.

[Insanity]

I really like these little bottle projects.