CRAZY SHOT STRING....???? GET ALOAD OF THIS.

[bmazz007]

Thanks for that spread sheet.

Does that seam a little light in power? It doesn't much better than a stock spring.

Bill

[GadgetX]

Will do less preload as possible.  Pumping now scuba only at 2300 i will be going in and out, checking your tips..


I feel like a ping pong ball..

Bill

Ouch 2300 !!   Bill, the last string still seemed wrong.  I was getting 24 shots on the #10 spring at WO.

I'm sure Bob or Doug will figure it out, I of no help.

Mike

[bmazz007]

Preload set On 1 turn in everything else the same. Standard deviation is 13.52 avg 810 

809.....3050
800
808
829
825..........2800
829
813
822..........2600
825
805..........2500
811
807
802..........2350
796
789
785...........2100


  ??

that looks pretty good.  You found the balance point with your hammer force and this string is a pretty good string with almost all shots within 4% of max speed.  I'd move stroke about 1 to 2 turns in and test; you'll lose a little energy, but you'll broaden your shot string and move the peak to the right.

Here's your data, plotted:  https://docs.google.com/spreadsheet/ccc?key=0Auo5v-jZ9NUjdG1PTnpQWWtrWUVSTzJNRm5GR1kwUUE&usp=sharing  (what pellet weight are you using?  you can correct it in the spreadsheet...)

Crow mags 26.23

[sperho]

Crow mags 26.23

Peak energy of 40 fpe (spreadsheet revised).  Seems within manufacturing variance of these guns and is quite a smack, still.  Like Bob said, lower ES is more important than peak speed for shot-to-shot placement consistency on a target...

[sperho]

I was getting 24 shots on the #10 spring at WO.

At what energy?

[bmazz007]

This seams a little weak in comparison to others. I was hoping for upper 40s at least with around 20 shots a little disappointing. I may try another turn on the preload and see where that take me.

[sperho]

It'll take you to fewer shots at a little higher power, with the peak shifted to the left, or no left side of the "hill".  Post the numbers or create another table in that spreasheet and you can compare the data and plots side by side.

[bmazz007]

Ok heading out right now running out of light,,

[GadgetX]

JSB Exacts 25.4 gr. 

#10 Spring Wide open.   
H=0, P=7, V=4.5   
(FPS)   ~ Pressure
890.0   3000
886.8   
881.0   2800
889.1   
888.8   2600
885.2   
881.7   
875.9   
869.0   2400
860.4   
857.4   
849.5   2200
841.9   
834.1   
827.4   
821.9   2000
817.5   
808.6   
802.8   1800
787.0   
775.7   
772.6   1600
769.9   
757.6   
752.0   1500
   

I ended up that day with this.

#10 Sping   
H=0, P=6, V=4.5   
(FPS)   ~ Pressure
796.5   3000
819.8   
827.9   
832.6   
847.4   2800
852.1   
856.0   
853.7   
862.1   
866.6   2600
865.0   
869.6   
866.8   
870.8   
868.7   
868.6   
868.1   
864.8   2400
859.4   
847.7   
849.9   2200
836.8   
833.7   
829.9   
821.1   2000
815.5   
809.6   
802.7   1800
792.6   
790.0   
785.3   
780.1   1500

My final tune was this.

#10 Hammer Spring, v=4.25, p=7, h=0  JSB 25.4 gr pellets temp is about 59 f.  From 3000 psi down to 2200 psi, gauge is hard to read, maybe 2100 psi.  3 clips.

842.6
845.6
850.9
855.5
858.7
861.7
869.7
867.3
872.1
878.5
881.1
876.7
877.4
871.8
873.2
866.1
868.5
866.8
865.1
860.5
856.0
852.1
849.7
843.2

Mike
   
   

[sperho]

My final tune was this.

#10 Hammer Spring, v=4.25, p=7, h=0  JSB 25.4 gr pellets temp is about 59 f.  From 3000 psi down to 2200 psi, gauge is hard to read, maybe 2100 psi.  3 clips.

842.6
845.6
850.9
855.5
858.7
861.7
869.7
867.3
872.1
878.5
881.1
876.7
877.4
871.8
873.2
866.1
868.5
866.8
865.1
860.5
856.0
852.1
849.7
843.2

Mike
   
   

Plotted (2nd tab on the above spreadsheet I made for bmazz): 

https://docs.google.com/spreadsheet/ccc?key=0Auo5v-jZ9NUjdG1PTnpQWWtrWUVSTzJNRm5GR1kwUUE&usp=sharing

You guys clearly have different guns (porting?)...

[bmazz007]

Here is my Final for the day...The preload is 2  open stroke and valve on 4.5 I started this time with only 3000 psi (No biggy)  26.23GN  standard deviation is 25.37 avg fps 808
   

16 shots

838....3000
831.2
825
828......2650
827
825
819.....2500
812
810............2400
804
797
784
773
765
758...........2000

[bmazz007]

Mike your gun blows mine out of the water....Mine not worthy

[sperho]

Spreadsheet update with latest data.  Was I right or was I right?  I'd do what I suggested (1-2 turns in on the stroke), back the preload off again and leave it alone for awhile and then make a decision...

[bmazz007]

Spencer your awesome...Unfortunately I am a little disappointed in this rifle It seems week in to most I have seen on you tube ect.....I may return it to PA



Bill

[sperho]

I'd exchange it and give another .25 a shot (no pun intended)...  Yours does appear to get a little winded early.

[bmazz007]

I am changing stock spring as we speak its going back..

Bill

[GadgetX]

Mike your gun blows mine out of the water....Mine not worthy

Not my intention to brag, but a week or so the experts here were helping me and when all was done I was very happy.  I'm sure folks here were getting tired of me, but I really appreciated them!  I shot nearly 1400 pellets that week.  Four fills of 2 scuba tanks (88cf).

Don't lose the faith !!

Mike

[bmazz007]

Its going back.. I have tried over a week I went through almost 2 tanks and 1000 pellets. Its a bit of an air hog and seems to be short winded yeha it has power for 8  shots after that if falls on its face.


I already swapped the spring and set it to stock settings. I am sending PA a message now.

Bill

[rsterne]

I was hoping for upper 40s at least with around 20 shots

My grandfather used to say "If wishes were horses, we'd all be riding".... Your expectations (ie hopes) are not reasonable for an MRod with stock porting, IMO, and from the results I have seen on the GTA.... Mid 40s for 16 shots is typical.... You don't seem to be prepared to accept that.... and because of that another MRod will likely disappoint you as well....

Bob

[bmazz007]

I was hoping for upper 40s at least with around 20 shots

My grandfather used to say "If wishes were horses, we'd all be riding".... Your expectations (ie hopes) are not reasonable for an MRod with stock porting, IMO, and from the results I have seen on the GTA.... Mid 40s for 16 shots is typical.... You don't seem to be prepared to accept that.... and because of that another MRod will likely disappoint you as well....

Bob

Believe me I don't want to send it back,but from what i have been reading my gun is lower than most its barley 40 ft pounds with a 10 spring and at the end of 16 shots I am under 2000 psi If i fill it to 3100 or 3150 i will be at 2000 at best. I dont know if ill do an Mrod again My first one had a leak from the factory my first fill it was hissing would not hold air. Now I am on my second one. I am not sure what to do right now. May be a Evanix or Hatan.. Dont know maybe I will buy a tuned Marauder ..

Bill