22 synrod with my 40cc plenum regulator - looking for a 40/40 tune

[shorty]

Started messing around with the synrod22 again while I wait for funding on the 32 cal conversion on the 25 synrod.

I pulled out the smaller 22 reg and popped in the 25 cal reg that I added a spacer to it so it can achieve a 40cc plenum. HPA side should be around 170cc's now.

It's pulling 38fpe at 1700 psi and just about 40 fpe (39 and change) at 1850 psi.

I am thinking of getting some heavier pellets to try and get a 40/40 tune on the 22synrod. Too bad those 25.39's don't shoot well out of my barrel but if any of you guys are having any "good" luck with anything 25 grain and larger out of your 22 synrod, let me know. Mine only seems to like the 21.14's and the FTT 14.66's.

More to come this weekend.

[rsterne]

Should be possible.... I can get 54 shots at 37 FPE with my 2260 HPA (23.8" LW barrel) from a 13 CI tank (213 cc) regulated at 1600 psi.... 960 fps with JSB 18.1 gr....

Bob

[shorty]

That is encouraging.

 Sure seems like a big difference going from 15/20cc's to 38/40cc's on the plenum so far. Nearly 110fps difference using 21.14's.

In my head I am saying set the reg to 1100 psi and hit well over 2.0 efficiency at 25fpe but, my ego says max that thing out at 40 fpe for the most shots cause no one has done that with a 22synrod yet.

I guess we will see how it goes.

[rsterne]

Regardless of what some people have said over the years.... I didn't just pull 1 cc per FPE out of thin air.... Up to that plenum volume real gains in power and efficiency take place.... You still get gains above that, but they are much less dramatic.... and on a tube gun in particular aren't worth giving up the HP reservoir volume....

Bob

[PCPhack]

There's a reason that I ended up putting the .30 Huma in my .22 synrod.

[triggertreat]

Wishing you good luck on the .22 Synrod build.  My view is that if it isn't accurate, what's the point.  Hopefully it will be for you.  I tried a more substantial power tune on my .25 cal and it was a flop in accuracy at ~77 FPE so I brought it back down to ~56 FPE and wow is it accurate now.

[shorty]

I guess those reg's just ain't liking me for some reason. They were great when new. Reg was leaking and creeping. I just have the worse luck repairing them and then re-setting properly.

Oh well, another repair kit and in the mean time I put the stock gauge port in.

The cool thing was what Bob mentioned " the 1cc per fpe rule of thumb" It stands tall as I left the hammer spring adjustment the same and at 1850psi "without reg" was still just a smudge under 40 fpe.

So I guess this project is on hold for now.

[shorty]

So the reg thing fell through and just plugged away with non-regulated. Got the 40/40 with a large ES. Shooting 21.14's. 3000 psi to just over 1500 psi.

Shot #   FPS   FPE
1   880   36.4
2   881   36.4
3   889   37.1
4   896   37.7
5   911   39.0
6   920   39.7
7   924   40.1
8   934   41.0
9   940   41.5
10   937   41.2
11   929   40.5
12   933   40.9
13   936   41.1
14   952   42.6
15   949   42.3
16   946   42.0
17   954   42.7
18   933   40.9
19   956   42.9
20   953   42.6
21   946   42.0
22   955   42.8
23   960   43.3
24   962   43.5
25   946   42.0
26   935   41.0
27   940   41.5
28   925   40.2
29   936   41.1
30   920   39.7
31   945   41.9
32   940   41.5
33   938   41.3
34   933   40.9
35   920   39.7
36   916   39.4
37   905   38.5
38   902   38.2
39   896   37.7
40   880   36.4

[shorty]

.168" porting through and through with dual wire hammer spring and STOCK HAMMER. Throat is at .25".

[triggertreat]

Nice power out of a .22.  I see 27 shots within a 3.95% ES averaging 41.7 FPE starting at shot 7 and ending at shot 34.


I here on the reg.  The rebuild kit should get you going again.

[shorty]

Yea. There was some thing going on the marauder forum about 30 shots at 38fpe that bothered me for a long time. Ofcourse I said not possible but, the numbers don't lie using a stock modified valve with a stock weight hammer.

[triggertreat]

Yes, I remember that thread, but didn't pay much attention to it at the time.  I am curious about the accuracy at that speed.  I could only take the 21.14gr to 850 fps when I use to shoot them in my unmodified .22 before I got the HF barrel.  Now I can't shoot the 21.14gr at all unless I reinstall the OEM barrel.

[shorty]

Not sure about accuracy either but I can tell you that the STOCK barrel has been re-choked "wedding band method" and a target crown placed on it.

[rsterne]

31 shots within 4% ES.... You need that or less to get the 1/2" at 50 yard maximum you said is acceptable to you....

bob

[shorty]

I did mention that in the 32 cal build.

 I know the ES was large on the 40/40 just done without the reg with a large ES but I am still having dumb problems with my regs. Sure wish I had that reg in but from that string, I am not sure it's possible to get the 40/40 with the reg in it now.

Maybe with a 25 grain or slightly bigger would do the trick.

Although,
Are you sure you need a 4% ES to get 1/2" groups at 50 yards ? Been thinking about that all day and ran numbers with chairgun. See table and please correct if incorrect. It looks like around 5.7% ES is acceptable for a .25" CTC unless I plugged the numbers wrong.

[rsterne]

According to the Vertical Stringing widget in ChairGun, with a 940 fps average and a BC of 0.040, and +- 19 fps (4% ES) the difference between the high and low is 0.40" at 50 yards.... That is within your 1/2" goal, but only if the gun shoots 0.1" CTC at that range.... The way I see it, the difference in drop between the fastest and slowest shot IS the CTC distance, right?.... If you divide that by 2, you are getting the distance from the center of the group, not the total dispersion.... Check it with the ChairGun widget (you can find it in the Toolbox menu)....

My point was that you sure aren't going to get it with an 8% ES like in your string.... I wouldn't call that string a "usable" 40 shot string at 50 yards.... but everyone may have a different opinion on that.... At 25 yards, then yeah, the stringing with an 8% ES would likely be within the "normal" group size for a decent gun.... On the other hand, at 100 yards, realistically you need less than a 2% ES....

Bob

[shorty]

Oohh I don't like doing this but,

All I am doing is just adjusting the hammer spring without any HT throw adjustment for fine tuning (literally just turning the HS adjuster-that's it). It's just an adjustment of the HS 1/2 turn back or forward at full pressure and then running a string.

Here's at 4.5 turn on the hammer spring using those 21.14's:
1   996   46.6
2   995   46.5
3   997   46.7
4   1003   47.2
5   1000   47.0
6   1002   47.1
7   1003   47.2
8   1006   47.5
9   1001   47.0
10   997   46.7
11   997   46.7
12   997   46.7
13   996   46.6
14   991   46.1
15   984   45.5
16   980   45.1
17   974   44.5
18   970   44.2
19   968   44.0
20   964   43.6

4.17% ES.

Also had to verify cocking effort. I have my 18lbs per in spring at 1.8" length (oohhh holy carp it's an 18lb per inch spring) at 4.5 turns which puts it at a max cocking effort of 12.25 lbs with .1" free flight.
Please verify your max cocking effort before replying and seeing how far you can go below pressure before you get a machine gun full dump.

Hook me up with some heavies to achieve a reasonable fps of 850/875fps and the efficiency would go through the roof along with a 50 fpe tune due to the mass.

It's still the basic Mrod valve with just the exit port drilled to .168" and the throat to .25".

If there are any 40+ tunes on the 22synrod platform I would love to see them for comparison. The only thing close was dairyboys using the SS valve with 20 shots at 45 fpe using 25.39's.