104 Shots.. Finally Chrono'd .25 cal MROD w/ hill Valve, spring, hammer etc..

[Rosco]

Finally got around to getting this up on my Chrony.. Plenty of spring tension back and forth to play with but I wanted to see where it was at.. Seemed like it would never run out of air.. but here are the results.. 104 shots with 7 Errors the Chrony missed so total of 97 shots captured avg 737fps wtih 25.39 JSB avg 30fpe..

Filled to 2900psi shot down to 1100 psi

Hi 753: Low 636: Avg 737



Thoughts?

#1 644

#2 636

#3 654

#4 644

#5 650

#6 649

#7 649

#8 660

#9 653

#10 656

#11 675

#12 680

#13 677

#14 677

#15 676

#16 679

#17 683

#18 687

#19 688

#20 682

#21 689

#22 690

#23 688

#24 687

#25 696

#26 689

#27 701

#28 696

#29 698

#30 694

#31 706

#32 703

#33 708

#34 709

#35 713

#36 718

#37 713

#38 718

#39 721

#40 721

#41 725

#42 722

#43 728

#44 735

#45 728

#46 730

#47 734

#48 735

#49 733

#50 730

#51 733

#52 737

#53 736

#54 737

#55 744

#56 740

#57 752

#58 743

#59 743

#60 745

#61 741

#62 743

#63 742

#64 744

#65 740

#66 753

#67 747

#68 748

#69 745

#70 744

#71 736

#72 744

#73 744

#74 735

#75 748

#76 749

#77 744

#78 749

#79 744

#80 745

#81 746

#82 747

#83 737

#84 743

#85 745

#86 740

#87 737

#88 738

#89 736

#90 726

#91 730

#92 722

#93 723

#94 717

#95 701

#96 700

#97 693

 

[crittahitta]

That is amazing. But after really looking at your chrony numbers maybe you should try lowering your starting psi down from 2900 to say 2600 or 2700 and maybe you will only get 80 shots but it will all be in the 700 fps range. Otherwise you have a 100 fps spread. Just a thought. But either way great job.

 

[Rosco]

I agree - My AV tank is regulated to 2900 and wanted to see the full curve of the string on my "max fill" but going foward I can save the Air! 

 

[AirNGasman]

So a good fifty-shot power-band.

 

[Rosco]

I'll take it.. but I do have a Huma Regulator with gauge port to put in but not sure what the string would do.. same shots more consistent, more shots more consistent, less shots more consistent??... would lose volume with the Reg in so not sure .

 

[addertooth]

I would go with a huma regulator set to 1400 PSI, leave your hammer where it is.

I want more FPE, so I am tuned for 40 FPE with a hill valve, lightweight hammer, Huma regulator (set to 1800 PSI), barrel ported, bolt recontoured, and TSS spring....and get 42 shots within an extreme spread of 1.8 percent from the fastest shot in the string to the slowest shot in the string. Fill to 3000 PSI, fire to 1800 PSI. This is also with the JSB exact king 25.39 grain pellets (unsorted). The general rule is 2 percent variation equals about 1 inch of vertical error at 100 yards.

You achieve about 1.8 percent variation from shot number 59 to shot 82, with a peak velocity of 749 FPS at shot 78. For a total of 24 shots of 30 FPE within 1.8 percent variation in velocity. A rather good result without a regulator, but you could achieve much more shots within the margin of 1.8 percent with a regulator at 30 FPE. I would guess in the ballpark of 60 shots.

Just my 2 cents, but I suspect I am spot on. 

 

[Michael]

Nice job

 

[Michael]

So a good fifty-shot power-band.

I agree. But that is an awful lots of shots from 2900-1100 psi. Nice work @tpk1975 aint tinkering fun!

 

[shorty]

TPK,

Looking good there chief. I recently pulled my Huma from my 22synrod because I like the power and I can never get it from leaking (the reg). Here's one of the last string I did using 21.14's.

With a well tuned gun at a regulated pressure of 1500/1600psi you should expect 50 shots using 18.13's for 30 fpe from a 3000psi fill with an ES of less than 3%. Or a 25fpe tune using 14.66's for just over 100 shots.

Last string I did:

3000psi fill and Just under 1600psi end.

Stock valve mildly modified (nothing special) Average of 40fpe and just over 8%ES. She will do over 60fpe with 25.39's.(NO regulator).

 

[shorty]

Ooops.Sorry. I missed that it was a 25 cal instead of a 22. Sorry

 

[shorty]

I made a table of what to expect from a modified marauder (22cal and 25cal). Most and all the modifications are with all the stock parts of the marauder. Nothing was purchased. What I usually say, if you bought stuff to get power and efficiency, this is the least you should expect since everything I did can be done in the garage with the STOCK INTERNALS (except for the .22" porting on the .25 cal).

If you do not get close to this, then ask your supplier of the parts "why can shorty get those numbers and I can't".

 

[Rosco]

I would go with a huma regulator set to 1400 PSI, leave your hammer where it is.

I want more FPE, so I am tuned for 40 FPE with a hill valve, lightweight hammer, Huma regulator (set to 1800 PSI), barrel ported, bolt recontoured, and TSS spring....and get 42 shots within an extreme spread of 1.8 percent from the fastest shot in the string to the slowest shot in the string. Fill to 3000 PSI, fire to 1800 PSI. This is also with the JSB exact king 25.39 grain pellets (unsorted). The general rule is 2 percent variation equals about 1 inch of vertical error at 100 yards.

You achieve about 1.8 percent variation from shot number 59 to shot 82, with a peak velocity of 749 FPS at shot 78. For a total of 24 shots of 30 FPE within 1.8 percent variation in velocity. A rather good result without a regulator, but you could achieve much more shots within the margin of 1.8 percent with a regulator at 30 FPE. I would guess in the ballpark of 60 shots.

Just my 2 cents, but I suspect I am spot on.

Good info and probably my next project after seeing these results... looking for a weekend that is two days too long so I can tackle it.. 

 

[shorty]

Videos to back it up:

https://youtu.be/Dp7n_E11zzs

https://youtu.be/6VSGUvxuKzU

https://youtu.be/RQI0EHym1EM



No BS here....!!!!!

 

[Rosco]

Nice Shorty. I haven't done any porting on the Maraduer.. Just changed out the internals, nothing in the tube is stock anymore. 

 

[crittahitta]

Where did you guys get the info on how to work on the prod?

 

[Rosco]

Where did you guys get the info on how to work on the prod?

Its the rifle but tuned the pistol too.. got the info on vendor sites, forums like AGN and GTA.. just ask a question and someone will chime in. Youtube has a #@% of stuff on MRODs and PRODs some good some not so good.. take it all in.