Veteran "jacked up tune"

Jump to latest Follow Reply
F

Franklink

Member
Sep 3, 2017
4,687
2
5,969
AZ, United States
My little Vet Short was purchased new from R&L back when they stocked them. Ukraine vintage so came with CZ barrel, BEFORE all the confusion about LW vs CZ. With OEM barrel I almost always had it shooting right under 20fpe with JSB 13.43gr and loved it. 

Machinist friend converted it to .20 about 8 months ago. Read here if interested in details on that: https://www.airgunnation.com/topic/veteran-short-20/?referrer=1

Got the chronograph out today and decided to run some over it with the .20 just to kinda make sure it's still where I think it is. 

68 shots, starting pressure of 238 bar and ending pressure of 128 bar (Sekhmet digital gauge so not just guessing)

Lo = 791.3

Hi = 806.7

Ave = 799.2

ES = 15.39

SD = 4.35

With JSB 13.73 gr so average FPE of 19.48. 

It's pretty common to read comments where folks make it sound like a sin to just turn down the hammer tension without adjusting the regulator......well.....I'm a sinner. But I'm also pretty dang happy with this Vet's performance (accuracy/shot count/etc) at 20 fpe, whether it's got the .22 or the .20 barrel on it. 

A little chairgun fun for those turning red in the face at my blasphemous, no-touchy on the reg, tune......

with a 30 yard zero, the 806.7fps pellet (fastest) will impact at -8.29 inches at 75 yards, the 791.3 (slowest) will impact at -8.73, also at 75 yards. So that's a difference of 0.44 inches. In other words, taking operator and wind out and bum pellets, and whatever other excuses, all 68 shots would hit within 0.44 inches, vertically, of one another. Just sharing a bit of perspective about jacked up tunes.

It's fun to obsess over single digit spreads, and tinker and tune and fiddle till we get there, but how many of us are actually good enough to put this particularly low weight, low bc, low energy pellet within 0.44 inches at 75 yards anyway, Better BC, heavier, and higher FPE simply push out the distance to where a 19fps extreme spread doesn't make any real world difference over a 9fps extreme spread.
 
Frank, Thanks for sharing your tune👍



I'm a sinner too 😇

One of my .22 shorties is set at 870FPS with 18gr JSBs. 50 shots per fill. 30fpe.

In the other I run 14.35gr JSBs at 870 for 70 shots. 24fpe.

The 14.35s are effected by the wind a little more but when it's calm I can print some small groups at 75 yards.

Squirrels are easy with the lighter pellets (heart shots) and I love how quiet it is with the Tatsu.
 
Upvote 0
Frank, you didn't mention the maximum fps possible at your current reg setting, so your tune might not be as "jacked" as you think. It seems the general belief is, 96-97% of max is usually a well balanced tune, generally allowing the smallest ES and most consistent behavior as it shoots through and below the reg set point. But as you demonstrate, single digit ES is not necessary for very good accuracy at reasonable distances. I almost never shoot beyond 50 yards, using standard power .22 and .177. And I'm pretty sure that I've had ES numbers of 15 or so, with no practical degradation of accuracy. At the moment, my rifles are probably in that "balanced" area of tune, and luckily demonstrate very consistent numbers. But, I think you are right, it's not the Holy Grail that many folks say is necessary for good accuracy. Every element of tuning, rifle and pellet preparation, and shooting technique become more critical as the distance is stretched, or, if competition is at the highest level. Like most of us, I don't shoot at extreme distances, and I sure don't compete at a high level, so I'm not going to be compulsive about the numbers. If the rifle is competent to hit the targets I generally shoot, assuming I do my part, then I'm happy. 

Ed
 
Upvote 0
Hi Ed. The max energy output I've never gotten out it was 33fpe with JSB25.39. Cranked down on hammer tension till it would just barely cock. 

Interesting thing on the reg pressure, I was told by R&L that the ones he was selling usually came with reg pressure of 120 bar. I don't have a reg tester so don't know for sure but I've shot it down to 85 bar and still had all shots within about 25fps. Its been a while and it was with the .22 barrel but, from memory, there was a gradual increase in fps around 105 bar-up about 10fps over the highest "on the reg shots" and then it came back down to the same fps as regged shots until about 85 bar where it drops off in fps enough to start noticing low pellet strikes. 
 
Upvote 0
Frank, you're over 30% off the max at your current reg set point, and that probably explains the manner in which it behaves as it comes off reg. I guess I have 2 thoughts. If it's shooting to your satisfaction, there's nothing wrong with leaving it as is. If you're looking for something to do one day, you could back down the reg and probably achieve a greater shot count within the sweet spot of accuracy, might be a bit quieter too. More of a fun project if you like tinkering, certainly not necessary.
 
Upvote 0
As elh0102 eluded to, a “jacked up tune” is not 100% accuracy related. I would rather shoot 850fps at -30% of max at 100b than 850fps -60% of max at 120b. A jacked up tune can be shot count, gun harmonics and sound related. Taipans hide it all well because they are tanks. I went from 120 to 140b and added a heavier spring for slugs and the gun felt the same. Couldn’t even tell. Amazing, but the gun is a brick.
 
Upvote 0
@vetmx, just curious, do you happen to remember what the max fpe you could get with the oem hammer spring? (Hoping youve got data for a .22 Long but also curious regardless of caliber).

Pretty sure I could get more oomph out of my Vet Long but I really like the ease of cocking and shot count with factory hammer spring.

And yes, Taipan's hide a jacked up tune quite well. None of that "harmonics" stuff going on here, even if regulator and hammer tension aren't perfectly "balanced." 
 
Upvote 0
You’ll have to forgive me because I am not a fpe guy and not a fan of doing backwards math when guys throw out fpe numbers. My vet standard when I got it, 2017 I think, would shoot a 18.1 at 930fps with the stock spring maxed out. Upon throwing in a heavier spring, it’s true max at 120b+ or - was 945fps. I’m guessing that the stock HS would have been capable of producing a max speed if the reg was set at 110b. I also believe that Taipan already knows those numbers but installs a spring that’s softer to keep the gun butter smooth but not so soft that it’s at its peak in the accuracy zone for pellets. It still gives you wiggle room but doesn’t let you too close to the plateau we’re we shouldn’t be anyway. Maybe a trade secret for sweet shooting guns at the time seeing as how an 18.1 was a heavy pellet in .22 in 2017. Hope this info helps. Oh, I also haven’t done any mods to my porting or valve.
 
Upvote 0
Having a Taipan VL.25, and wanting to increase reduce FPS for barn shooting, I may become a sinner too.
Click to expand...

I sin every time I take my Dreamtac to my dads. He lives in a neighborhood so I drop down from a 18.1 to a 14.3 pellet. I turn my TP wheel down and my HS wheel to 1 instead of 4. It’s a temporary thing and I may not be getting the most out of the gun but it works for those temporary situations. The ranges are fairly close so like Franklink mentioned, I’m not too concerned about my ES. I never even ran that setting across the chronograph because I want to protect me from myself.
 
Upvote 0
IMG_20201107_11199.1616265728.jpg



 
Upvote 0
Frank, you're over 30% off the max at your current reg set point, and that probably explains the manner in which it behaves as it comes off reg.

If you're looking for something to do one day, you could back down the reg and probably achieve a greater shot count within the sweet spot of accuracy, might be a bit quieter, too.
Click to expand...



Ed,

I was just curious about the gun getting quieter....

So, what you mean is to basically lower the REG while maintaining the HST setting, which will close the 30% gap below max. to say 5%, producing a lower ES.

Won't this lower the OP's overall power even further?

(Which of course usually results in a quieter gun.)


Or am I thinking this wrong? I thought(!) that the 30% below max. is actually a quite effective way to quiet the gun.



Matthias
 
Upvote 0
At 30% below max, the air plenum is (relatively) over pressurized, so your air consumption is a probably bit more than would be the case at a lower pressure. And you're correct, a lower reg set point, at the same HST will yield lower velocity. I don't think you would see a significant difference in either air consumption or sound, assuming you kept the same velocity, thus requiring a higher HST. The advantage would be a higher on-reg, consistent shot count, probably a smaller ES. But again, none of this is critical of you're satisfied with overall performance. As others have said, for the use to which most of us put our air rifles, a 15-20 fps ES is not noticed in practical accuracy. 
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu