Author Topic: A New Method for Increasing the Efficiency of a PCP - the SSG (Read 373644 times))

rjorge · « **Reply #280 on:** January 10, 2016, 06:38:37 PM »

Bob, you may want to try a peek valve seat on the AT (~.012" of sealing surface works great against the angled poppet).

rsterne · « **Reply #281 on:** January 10, 2016, 08:53:42 PM »

I installed an SSG in my Grouse Gun today.... 2260 PCP Carbine with a 14" barrel and a stock Disco valve and hammer spring.... I used a 2200 spring with 0.90" of preload, which puts it very close to coil bind when cocked....

Previously I got 16 shots with a 2% ES, and 20 shots within 4%, averaging 20 FPE (705 fps with JSB 18.1 gr. heavies), with an efficiency of 1.15 FPE/CI

Now I get 20 shots with a 2% ES and 24 shots with 4%, averaging 21 FPE (722 fps), with an efficiency of 1.50 FPE/CI, an improvement of 30%....

It doesn't seem to matter if the PCP is regulated or not, the SSG can provide big gains in efficiency....

rjorge, that may indeed work on the Hatsan, but would not be a fair test of the SSG....

Bob

Rallyshark · « **Reply #282 on:** January 10, 2016, 09:02:50 PM »

Quote from: rsterne on January 10, 2016, 03:48:14 PM

I pulled the SSG out of the Hatsan this morning, and tried changing the springs for the only stiffer choice I had, using two 1.75" long x 0.051" wire springs.... The rifle could not be cocked as the springs went coil bound.... At the moment I'm out of ideas....

Bob

I was afraid it would come to this

I wish I had more time/tools/parts to try and figure more out. With that being said, I wonder what your setup could do for a lower powered AT-44 at maybe 35fpe in a .22. In my case it would be a no go just for the inability to swap between cylinders and power levels like I currently do, but some one else it could be much better... I wonder what could be done with a cable setup like I_like_irons mentioned too. Either way you've proven it can work. Awesome job just the same Bob!

rsterne · « **Reply #283 on:** January 10, 2016, 09:51:52 PM »

Yep, you can install an SSG in a Hatsan AT-44, and get it to work in the 50 FPE range in .25 cal.... higher than that would need other changes, I think....

Bob

Matt15 · « **Reply #284 on:** January 10, 2016, 10:04:07 PM »

Quote from: rsterne on January 10, 2016, 08:53:42 PM

I installed an SSG in my Grouse Gun today.... 2260 PCP Carbine with a 14" barrel and a stock Disco valve and hammer spring.... I used a 2200 spring with 0.90" of preload, which puts it very close to coil bind when cocked....

Previously I got 16 shots with a 2% ES, and 20 shots within 4%, averaging 20 FPE (705 fps with JSB 18.1 gr. heavies), with an efficiency of 1.15 FPE/CI

Now I get 20 shots with a 2% ES and 24 shots with 4%, averaging 21 FPE (722 fps), with an efficiency of 1.50 FPE/CI, an improvement of 30%....

It doesn't seem to matter if the PCP is regulated or not, the SSG can provide big gains in efficiency....

rjorge, that may indeed work on the Hatsan, but would not be a fair test of the SSG....

Bob

From what I have observed, It seems the SSG does not work if you are trying to get max power. Am I right?

rsterne · « **Reply #285 on:** January 10, 2016, 11:17:59 PM »

I wouldn't say that at all.... My .25 cal Disco/2260, the 2260 regulated HPA, and 2560 regulated HPA all are tuned with the SSG well up on the knee of the curve, just a whisker below maximum possible velocity at that pressure.... In fact, I found I could tune closer to the plateau velocity and still get good efficiency than I could before I fitted the SSG.... The only gun I haven't been able to get to it's previous power level is the Hatsan.... Three of the guns are tuned about 10 fps faster with the SSG, at much better efficiency than without it....

Bob

pllagunos · « **Reply #286 on:** January 10, 2016, 11:19:33 PM »

Bob in the case of an at44 if I install an SSG for a short version @30 fpe, will I loose adjustability in spring preload?

rsterne · « **Reply #287 on:** January 10, 2016, 11:24:21 PM »

Yep, the guide sits in the middle of the block, so you can't slide the allen key through into the hammer any more.... The preload is set by the length of the guide, and the gap between the end of the guide and the hammer can be adjusted with the setscrew in the hammer, but you have to take the gun apart for every adjustment, the way I did it....

You can't make an SSG cartridge and have it removable, like the others we are using, because the hole through the block is only 7/32", and you can't make it larger or you will hit the trigger assembly.... The spring seat is on the front of the block, and I see no way to change that....

Bob

pllagunos · « **Reply #288 on:** January 10, 2016, 11:28:05 PM »

Oh... Even though I will lose adjustability, it is probably worth it since I like to have it at 30fpe all the time, based on yours and others results with the SSG I guess 30 shots at 31fpe is possible for a future project.

rsterne · « **Reply #289 on:** January 10, 2016, 11:36:22 PM »

I would think that 30 shots at 30 FPE should be no problem.... My stock .22 cal AT-44 Short did 30 shots at 31 FPE (18 gr.) within 7% ES, and 23 shots within 4%.... My best tune was 30 shots at 34 FPE within 4% from 190 bar down to 130.... pre SSG....

Bob

match · « **Reply #290 on:** January 10, 2016, 11:46:07 PM »

bob - is your Grouse Gun regulated? and is it a full length 2260 tube?

I am in the process of doing a build like that 2260 14.5 inch .22 cal.

What kind of spring and preload did you use on the final tune?

Rallyshark · « **Reply #291 on:** January 11, 2016, 12:04:41 AM »

Quote from: pllagunos on January 10, 2016, 11:28:05 PM

Oh... Even though I will lose adjustability, it is probably worth it since I like to have it at 30fpe all the time, based on yours and others results with the SSG I guess 30 shots at 31fpe is possible for a future project.

FYI, I'm getting around 35 shots at 33fpe(JSB 18.1) with my AT-44 long. I have modified the valve/ports and have regulator

That is a more expensive solution if you don't have a regulator though. The SSG would be far more cost effective.

Rallyshark · « **Reply #292 on:** January 11, 2016, 12:08:51 AM »

Okay Bob, I think I have a plausible solution for the AT-44, but this mod would definitely be more in your ballpark than mine. Prepare yourself for another bad Paint diagram

I didn't put it in the diagram, but I'm sure it wouldn't be that hard to figure out a way to keep the modified hammer stationary for pre-load adjustment. The part of the hammer that strikes the valve is not attached to the other part. It moves freely after the rear part hits the stop screws. What do you think?

pllagunos · « **Reply #293 on:** January 11, 2016, 01:17:13 AM »

Actually I have 3 holes plugged mine but the best I can get is 29 shots at 30fpe (18.1) with a 42fps ES, when I said that with the SSG I would like to get 30 shots I meant with a tighter ES...

rsterne · « **Reply #294 on:** January 11, 2016, 01:43:03 AM »

match.... My Grouse Gun is unregulated, the reservoir is a bit longer than a 2260 now, I replaced it with a cut-down Disco tube.... It uses a PRod hammer and trigger assembly and a skeleton stock.... Here is a photo when it had the 2260 tube.... If I had the SSG a couple of years ago, I wouldn't have bothered with the slightly bigger reservoir.... It is 2000 psi fill, and 1200 psi refill....

Rallyshark.... so a 2-piece hammer ala Daystate "slingshot", only different?.... *LOL*.... With theirs, the outer part hits the valve and stops and in inner section carries on to open the valve.... Either way, you are losing a lot more energy to the part that stops than with the SSG....

bob

Matt15 · « **Reply #295 on:** January 11, 2016, 08:40:05 AM »

Quote from: rsterne on January 10, 2016, 11:17:59 PM

I wouldn't say that at all.... My .25 cal Disco/2260, the 2260 regulated HPA, and 2560 regulated HPA all are tuned with the SSG well up on the knee of the curve, just a whisker below maximum possible velocity at that pressure.... In fact, I found I could tune closer to the plateau velocity and still get good efficiency than I could before I fitted the SSG.... The only gun I haven't been able to get to it's previous power level is the Hatsan.... Three of the guns are tuned about 10 fps faster with the SSG, at much better efficiency than without it....

Bob

Okay. Thanks! That is good to know!!

Tom SC · « **Reply #296 on:** January 11, 2016, 08:50:58 AM »

Bob, thankyou thankyou !
I added the SSG to my gen2 .177 Marauder,with a little mod to the stock it fit nicely.
Previously I was running with a regulator at 875fps. for 35 shots and wasting a lot of air from hammer bounce.
This SSG is made with a screw which I polished the rounded head, added a plastic sleeve around the screw. The hard rubber bumper is something a plumber would recognize, it's just a faucet seal I had a few of around in the shop. Lubed inside the hammer and screw head with molly grease.
I set the stock hammer freeplay gap where I thought it should be. This gave 944 fps. with 10.3gr. pellets. Then adjusted the velocity down with the TP adjuster to 877 fps.
I ran a short string of 21 shots over the chrony (I'm real low on pellets) averaged 877 fps. and .6% ES. the report is super short and quiet. Shot cycle is surprisingly smooth. After 56 shots I'm still on the reg. Thats a 3000 fill down to 2200 psi. woohoo

and it didn't cost me a dime!

match · « **Reply #297 on:** January 11, 2016, 10:48:53 AM »

Bob - for your Grouse Gun did you try a heavier spring or did you stop with the 2200 (what is the spec on that 6# 2.5 inch?)

rsterne · « **Reply #298 on:** January 11, 2016, 04:39:58 PM »

I didn't need any more power, so I didn't try a heavier spring.... The 2200 spring is 2.25" long (once set), made from 0.035" wire with 19 coils, and is just under 7 lb/in.... It goes coil bound at 0.70" so has about 1.5" of travel.... and a maximum force of just over 10 lbs.... For the Disco, I would think a 2.5" long version, with a slightly longer rear cap, would give more flexibility for more power.... but you might need a couple thou bigger wire as well, because the rate goes down as you increase the length....

Bob

Sfttailrdr46 · « **Reply #299 on:** January 11, 2016, 08:10:15 PM »

Will the SSG work with the WAR no bounce hammer

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A New Method for Increasing the Efficiency of a PCP - the SSG

Author Topic: A New Method for Increasing the Efficiency of a PCP - the SSG (Read 373644 times))