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

[BigTinBoat]

... At just under 12 FPE, I got 2.12 FPE/CI, which is 7.7 barcc/FPE....

Bob,
What kinda of ES are you getting at that level? When I de-tuned my gun reg'd at 1500 (and shooting 20fpe)the ES doubled when shooting it that low.

[rsterne]

I honestly didn't pay any attention.... I shot 30 shots through the Chrony and only wrote down the average.... If you are just plinking at 532 fps, that would imply close range, so does it really matter?.... I guess it would if you were building a gun for 10M competition, but otherwise, even a 10% ES would be insignificant for minute of pop-can.... The 250 shots, on the other hand would be pretty KEWL!....

For that string, I was working with a gap of about 1/4".... If the ES was important, I would use less preload and/or a weaker spring and way less gap....

Bob

[BigTinBoat]

.. If you are just plinking at 532 fps, that would imply close range, so does it really matter?....

I guess not, sorry I asked. You guys are the best, thanks! Imoutahere

[rsterne]

Nothing wrong with the question, just not something I considered important enough to bother recording.... Didn't mean to be arrogant.... 

Bob

[moorepower]

And another in .22 and all of these are internal SSG not getting anywhere near spring bind or hard to cock.
ated: 01/12/16 06:04 PM
Description:
Notes 1: bone stock marauder .22 with SSG
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 14.30
Temp: N/A °F
BP: N/A inHg
#          FPS  FT-LBS      PF
58    881      24.65    12.60
57    889      25.10    12.71
56    889      25.10    12.71
55    895      25.44    12.80
54    882      24.71    12.61
53    886      24.93    12.67
52    889      25.10    12.71
51    883      24.76    12.63
50    881      24.65    12.60
49    890      25.16    12.73
48    896      25.50    12.81
47    894      25.38    12.78
46    895      25.44    12.80
45    891      25.21    12.74
44    904      25.95    12.93
43    892      25.27    12.76
42    904      25.95    12.93
41    895      25.44    12.80
40    905      26.01    12.94
39    894      25.38    12.78
38    899      25.67    12.86
37    892      25.27    12.76
36    911      26.36    13.03
35    908      26.18    12.98
34    911      26.36    13.03
33    909      26.24    13.00
32    891      25.21    12.74
31    897      25.55    12.83
30    907      26.13    12.97
29    900      25.72    12.87
28    912      26.41    13.04
27    914      26.53    13.07
26    898      25.61    12.84
25    895      25.44    12.80
24    891      25.21    12.74
23    898      25.61    12.84
22    911      26.36    13.03
21    913      26.47    13.06
20    895      25.44    12.80
19    900      25.72    12.87
18    891      25.21    12.74
17    911      26.36    13.03
16    901      25.78    12.88
15    907      26.13    12.97
14    903      25.90    12.91
13    887      24.99    12.68
12    918      26.76    13.13
11    906      26.07    12.96
10    899      25.67    12.86
9    899      25.67    12.86
8    896      25.50    12.81
7    900      25.72    12.87
6    894      25.38    12.78
5    893      25.33    12.77
4    896      25.50    12.81
3    882      24.71    12.61
2    888      25.04    12.70
1    ERROR 10
Average: 897.5 FPS
SD: 9.2 FPS
Min: 881 FPS
Max: 918 FPS
Spread: 37 FPS
Shot/sec: 0.1
True MV: 898 FPS
Group Size (in): 0.00

.       That looks like an all day sucker. Wow

[rsterne]

I wish Travis would post his starting and ending pressures.... Nice loonnngggg string for sure....

Bob

[oldpro]

Bob I should and will from now on but almost ALL the mrod tunes are from 2800 to 1800psi give or take 50psi,  its the sweet spot on the Mrod valve in stock format. Ps woke up with one *(&^ of a headache lol.(inside joke)

[rsterne]

Assuming that was the pressure drop (1000 psi = 69 bar) on that string, on a stock 215 cc (13.1 CI) MRod tube, that works out to a total of 905 cc of air.... You had 58 shots averaging 898 fps (25.6 FPE) which is a total of 1485 FPE.... That gives an efficiency of 1.64 FPE/CI.... Crosman, are you listening?.... 

Bob

[cclingma]

I have my doubts as to whether Crosman is listening, but as a owner and lover of a exceptionally air hoggish .25 Mrod, I'm listening for sure.  That many shots per fill would explode the fun factor of the .25 while reducing the wear on my hand pump and I.  The external home brew SSG looks awesome/cheap/gratifying/reversable but WAR all internal is looking too good to resist for me.  If I try to set the hook of airgunning on someone I'll likely use my .25 marauder as the bait with its accuracy, repeater action, and authoritative 40FPE smack.  The internal SSG wouldn't require any explanation or cautions when passing around to friends and family to start their airgun addiction.  Crosman can reimburse me for such promotion later.

Mr Bob, thanks for sharing this nifty mod with the community!

[oldpro]

I sold all my first run of the Sterne SSG(30) and Im building more now. This will be fun to see people using this tec. and posting results. Cant wait to see some strings. Crosman you just keep doing what your doing LOL I need the work

[Sfttailrdr46]

I sold all my first run of the Sterne SSG(30) and Im building more now. This will be fun to see people using this tec. and posting results. Cant wait to see some strings. Crosman you just keep doing what your doing LOL I need the work

I was going to wait to start the mods on my marauder so now I will just need to get the War valve that much sooner and start my mods sooner and skip the wood stock for a little longer

[PBguns]

This thread is beyond sticky worthy.......mods?

[southern gun]

OLDPRO any work on a drop in for the disco

[oldpro]

 Disco and Prod are in the works

[southern gun]

Thanks Will be waiting with shovel to dig up mason jars!!

[Motorhead]

Did a Theoben Rapid MK II in .22 cal today .... reverse floating type again with head of stop rod traveling forward into hammers "removed" kinetic striker bore.
Results were absolutely as expected   

[wasatch]

Did a Theoben Rapid MK II in .22 cal today .... reverse floating type again with head of stop rod traveling forward into hammers "removed" kinetic striker bore.
Results were absolutely as expected   

Up late? 

Thanks for posting your write up about TM SSG. 

Found this, looks like an SSG in a pumper in 2006:
http://www.network54.com/Forum/275684/thread/1160273704/A+hammer+for+knock-open+valve.

Edit: But why in a pumper?

[rsterne]

Looks like a combination of the SSG and NBH.... Nothing new under the sun !!!

Bob

[rsterne]

With all the interest in the SSG, various other similar ideas have been brought forward over the past weeks.... The first thing mentioned was using a short, stiff spring, with a gap (negative preload) which I first saw done by Lloyd Sikes a few years back.... It turns out that Harry Fuller used that idea a decade ago in his Excalibre.... While there is a similarity with the SSG, in that there is indeed a gap, without the stop on the guide no preload can occur on the spring, which is the key to the operation of the SSG.... Recently, a photo has surfaced of a hammer made by a "Val" also about a decade ago, which looks like this.... (mentioned in post #722 above)....



The spring guide, as you can see, indeed has a stop on it, so that there is no preload on the hammer when it hits the valve stem, allowing it to rebound and force the plastic leaves apart, "arresting oscillating motion of the hammer after striking the valve".... I have read the thread, and there is only one mention of the stop on the guide, I think it likely that all the interest was in the hammer design, and in fact there was a large drawing, immediately above this photo, that didn't even show the spring.... My guess is that a large part of the effectiveness was due to stopping the spring, and it wasn't even recognized at the time, it was simply necessary for the hammer not to stick inside the tube.... Certainly, there does not appear to be any adjustment for either the preload, or the gap (as used in the SSG concept), nor are either mentioned in the thread about Val's Hammer....

http://www.network54.com/Forum/275684/thread/1160273704/last-1160356195/View+Thread

My point is this.... There is nothing new under the sun.... Very little has yet to be "invented".... I was very careful not to claim that I "invented" the SSG, because I knew if I did there would be those who would make it their goal in life to disprove that claim.... My development of the SSG was, however, done independently, from concept (emulating a gas ram with a spring) to reality, in my first application in the Grizzly, last year.... I am delighted that the GTA has provided a venue for the explosive growth and interest in the SSG to occur in this thread.... A GTA member recently used the term "Pioneered the SSG" to describe what I did, and I think that is a very accurate description of what I have done (am doing).... He said....

The word pioneered was chosen for a reason, there are so many inventions that don't have any practical purpose or don't actually function as the inventor intended.  Pioneered says, the work was done, (and) it was so successful that it allowed other(s) to follow and benefit.

So far, two individuals have asked my permission to use the SSG concept commercially, which I have freely given, on a non-exclusive basis, with the only request that my contribution to it's development be acknowledged, and they have graciously complied.... I wish them the very best in their implementations of the SSG....

Bob

[rsterne]

Another interesting device has just been compared to the SSG.... The transfer bar used in the Crosman Challenger 2009.... It consists of a rod in a separate housing, located between the hammer and the valve.... I think it's only purpose is to move the hammer back relative to the valve, while transferring the strike, but others disagree.... Certainly Crosman never touted it as an anti-bounce device.... It would appear from the drawing on the Crosman website that it is spring-loaded against the valve stem, and the rear of the rod is impacted by the (adjustable) striker on the hammer.... Page 5 on this webpage....

http://www.crosman.com/pdf/manuals/CH2009%20EVP%20&%20PL%201.pdf?source=pepperjam&publisherId=43737&clickId=1540836582

The circlip on the shaft would just be to keep the parts together on assembly, it does not touch the spring, that is the other side of the hammer, as on the PRod (which shares the same hammer/striker assembly).... If anyone has a Challenger, perhaps they can look at it and let us know if the hammer at rest sits against the end of the transfer bar, or is there a gap between the back of the transfer bar and the striker?.... That would be the key to whether or not it has any action similar to the SSG.... I know already there is no spring guide, or stop on such a spring guide, in the Challenger, because I have used numerous Challenger hammers, springs, and RVAs myself.... Another thing that would be good to know is how far back the transfer bar can move while compressing the spring on it, before it hits the housing.... It is possible if that distance is very small (eg. 0.020") that would completely debounce the hammer by absorbing the recoil of the valve stem into the transfer block (assuming it is bolted into the gun) instead of transferring the energy back into the hammer.... This would work in a similar way (though differently applied) to the wishbone in the Hatsans that prevents the hammer from being thrown back against the spring....

It may be just one more way to skin a cat (debounce a hammer), or it may just transfer the hammer strike to the valve.... Either way, it has little to do with the way the SSG works....

Bob