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Tuning Diagnostic Help with Taipan Veteran Long .25

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Just sent an e-mail to Utah Airguns, sharing this information and requesting assistance. Utah set it up for, and I prefer using, the 25.39 grain JSBs but the erratic accuracy is even worse. Dime-size groups to 3+"@ 50 yds, then back again to dime-size, for no reason. I'll try some chrono work with the 25.39s, then wait to hear from Utah. Thanks for all the help and suggestions, Cannonball, I'll try the HST adjust, if all else fails and report back. WM
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WM - I’m confident what I’m telling you is correct as I have 3 Vets and they will all to some extent do the same thing yours is doing when the HST is turned down a considerable amount. My .177 standard is the least affected, the .22 long a little more and my .25 compact sees the most extreme spread of all three when turned down, due to having the highest set regulator pressure. I think your Taipan is fine, it’s your tune that is messed up. If you want to shoot the 25.39’s you will need to reduce your regulator pressure to get the consistency you want. The good news is your shot count should go up as well. I would crank up the HST and shoot a string of the 33.95’s before calling Utah or burning through any more of the 25.39’s.
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Same here, with the varying tolerances to wide swings in hammer spring tension.

Also own 3. 

.20 Vet from Ukraine (was originally a .22 Short). That one is the by far the most tolerant of wide swings. Can win a field target match at just under 20fpe or push 30fpe and still be as consistent as the run rising, ES in the 8-15 range. Reg at OEM and I've never laid eyes on it (likely 125bar). 

.22 Long from Czech, has mostly been my powerhouse so it's always on the high end of hammer tension (reg around 140 right now)

.177 Standard from Czech (originally a .22 Standard but now with a 24inch .177 poly barrel). This is the most recently purchased gun, the one that needed new orings in the regulator. Shot it with the OEM .22 barrel when I received it and ES was in the 40-50 range, no matter where the hammer tension was. After Oring replacement though, it'll have spread in the 25-30fps range down at just under 20fpe, but ES tightens up to the low teens when up around 32fpe. (reg at OEM 125). 

It's really interesting that a specific Vet's regulator is more or less sensitive to hammer spring, b/c theoretically, they should be pretty close in design/specs/tolerances.

Agree with Cannonball, increased hammer tension is the first thing to look at. 
 
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Cannonball,

I do not doubt you one bit, you're the expert on Taipans I needed to hear from. The tune is exactly what Utah Airguns sent, I've touched nothing. They included two 50m targets they shot with JSB 25.39s. I'm interested to hear what they have to say. Might say gun not set up for shooting JSB 33.95s, so, if I chrono some 25.39s, I'll be able to show problem exists with both. Well, think I'm on the road to getting this resolved, one way, or another. I'll keep all posted. Thanks again for your help, WM
 
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Dairyboy,

Sounds like the tune wasn't quite right, I'll air gun back to 250 bar, run several chrony groups with the JSB 25.39s and report findings. Very odd, the gun shoots great, then drifts to inaccuracy, then back to accuracy, frustrating, for sure. Have several thousand JSB 25.39s so best for me to set that tune, don't know, crows here are tough, might just adjust hammer, like Cannonball said, and use the 33.95s. I've been searching for some sort of justification for another .25 purchase, maybe JTS Airacuda or that new Generation 3 Chinese gun (forget the name.) Yeah, that's the ticket, have to find something to use all those JSB 25.39s. Problem solved, WM 
 
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Unfortunately, it seems one has to be skeptical of any tuning done by most dealers. If you are comfortable doing it yourself, that's probably the best option. I've read several threads here lately that involved tuning that was totally messed up by the dealer. Sometimes, I believe they try to take the short cut of simply adjusting the HST. If the adjustment is very small, that might work. If not, you can end up with a tune that's totally out of balance. I'm not sure which is worse, such a lousy job that results from incompetence, or laziness. The Taipan regs are typically very good, and I believe you will find the resolution in tuning. 
 
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Read Bob Sterne's articles about tuning a regulated PCP. You need to tune on the "knee", if you don't know what that means, you need to read the article.

I have a Taipan .25 Standard and had the same problem when I tried turning it down low. Increase the hammer spring until it won't cock, as someone else said, then back it off a little bit. My standard came shooting JSB 25gr at 915fps.

At least try this before sending it back.


 
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When I had my 25 Veteran Standard a few years back (Sold it like a dumb A$$) it loved the 25's right at 880-890. It shot lights out!!!! if I remember I got over 3 magazines before dropping off the reg......This was waaaaay before I learned how to change regs eand work on the rifle.....I bought a 25 long with power plenum used here on AGN, that I am working on and it has been a labor of "Love" bad barrel and other issues, but I think I have a tune for the 34's and I will be heading out this morning to see.

Tony P.
 
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elh0102,

Yeah, I got that same impression, really bad when you pay Dealer an extra fee for tuning and still messed up. One member even commented his tune was so bad the "proof of accuracy" targets included with his gun could not possibly have been fired from it. Looking at the 50m "proof of accuracy" targets, that were included with my gun, seems all is well, maybe they tested when gun was in accuracy mode, prior to drifting out. WM

P.S. DAR Generation 3 is the name I forgot.
 
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Mike,

Earned point for Accuracy, as you first spotted HS adjust, as likely problem. Thank you, sir. No plans to send her back, I'll rebuild myself, if needed. Agree that tune is first place to start. Thanks for tip on Bob Sterne, plan to follow up on that. WM

Tony P,

Will be interested to see chrony results from 25.39s. Good luck with your testing. WM
 
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I do not own a Taipan (yet) but the hammer spring adjustment suggested (turn it all the way up then back off 1/4 turn) seems unusual. Possibly very good advice but unusual. I just turn it up until velocity stops going up then go a little more and see if it helps accuracy. A more cautious approach would be to just increase the hammer spring a little - like 1/4 turn - and see if velocity increases. It it does, you know that it is too low for the regulator setting.

My P35 came with too low a hammer spring setting for the regulator but it exhibited itself by making the first shot velocity significantly low. After that shot, it would settle down and give a decent (teens) ES. After I turned it up as described above, it keeps all the shots within a teens to low 20s ES.

I also like to shoot groups as I do the tuning to gather information on what it likes.
 
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Just completed three 10-shot groups, over chrony, of JSB 25.39. Results:

Group #1 Median 918.45 ES 22.1 SD 5.184

Group #2 Median 916.55 ES 10 SD 3.008

Group #3 Median 933.6 ES 34.4 SD 8.96

Here's Group #3 @ 50 yards, not very impressive. No word from Utah Airguns, might be closed for Holy Week. 
IMG_20220413_153142.1649880089.jpg
 
 
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Just completed three 10-shot groups, over chrony, of JSB 25.39. Results:

Group #1 Median 918.45 ES 22.1 SD 5.184

Group #2 Median 916.55 ES 10 SD 3.008

Group #3 Median 933.6 ES 34.4 SD 8.96

Here's Group #3 @ 50 yards, not very impressive. No word from Utah Airguns, might be closed for Holy Week. 
IMG_20220413_153142.1649880089.jpg
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Did you increase the hammer spring tension until it wouldn’t cock and then back it off? The reason I am asking is those speeds are at least 100 FPS slow assuming the rifle is operating properly and the regulator is still set to factory specs. If you didn’t do this, please give it a try and see what happens. You will need to shoot the 34 grain pellets, the 25.4’s will group terrible over 1,000 FPS. The 34 grain pellets should be shooting right at the speed you are currently shooting the 25.4’s at after the hammer spring adjustment. If you have questions or need help, send me a PM and I’ll give you my cell number so you won’t be waiting on a response. 
 
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Cannonball,

After last post I aired up gun, turned HS in about 1 1/2 turns till no cocking, then back in a 1/4. Loaded 33.95 grain and let fly. Reset scope from 25.39 and this is the result. You, Sir, know of what you speak. Didn't use chrony, but they're hot. Pity the crow on the receiving end of these. I owe you big time, awarding an accuracy point just doesn't seem enough, but will have to suffice. Thank you very much for your help, WM
IMG_20220413_171726.1649885563.jpg

 
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Glad to hear you got it resolved. That group looks MUCH better. Although I'd still be curious to see an ES. 

It sounds like the higher reg pressure of the .25 Vets might be a bit less tolerant of varying hammer pressure than the .22s that I have dealt with. I've always felt like the .22 Vets are much more accepting of varying hammer spring tension than lots of other PCP designs. 

There's also the fact that the gun is new. I personally feel that there is a regulator break in period. The 4 or 5 regulated guns that I reviewed for Airguns of Arizona, as well as all the regulated guns that I have purchased, all lost a couple FPE but gained in consistency (lower ES) as the shot count through the gun increased. 
 
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Franklink,

Yeah, that group is 5 (33.95 grain) JSBs @ 50 yards very similar to the accuracy of my Veteran Standard .22. What a relief to have that .25 performing like it should. I think you're correct, the .25s are less tolerant of varying HS pressures than .22s. Hope this thread helps others who might be in the same predicament. Thanks again for all your help, WM
 
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I’m glad it’s shooting like a Taipan now. You can get it to group just as well or better with the 25.4’s but the regulator will need to be turned down to achieve this. I do agree with Franklin that the regulator will settle in some after time and get more consistent but not enough to shoot the lighter pellets well. The .25 compact is perfect out of the box using them if you ever decide to buy another or trade yours in for something else.
 
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