Veteran Standard .177 poly

[Franklink]

A little background on how this gun came to be....

https://www.airgunnation.com/topic/veteran-long-22-rebarrel/#post-1180157

This one is somewhat of a fortunate accident. Friend machined up that 24inch .177 polygonal for me to do some testing in my .22 Long. I was swapping the unchoked .22 LW and the poly .177 back and forth on the Long and trying to be ready for monthly XFT matches with the .22 and, well, I guess I'm something like 0/5 on making the single gun/multiple barrels thing work. On paper it looks great, but swapping back and forth is a pain. So, a .22 coffee Lam Standard came up used on the classifieds and I bought it, with the intent to make a dedicated .177 Veteran and letting the Long stay a dedicated .22 for the MRDs. 

The .22 Long (the "Long Ranger" in the post referenced above) now has the coffee lam stock from the used Standard and the pepper lam from the .22 Long got moved to the .177 Standard. 

Currently the regulator pressure of the .177 Standard is OEM 125bar. With some chrono work I concluded that it'll just barely shoot a tight enough ES @ regular field target legal level of just under 20fpe. Spreads of around 25fps with JSB 10.34s at an average of 920fps with hardly any hammer tension, seems like most of the hammer tension adjustment plug is sticking out the back of the gun-can probably see 4 threads. Ideally it probably needs the regulator down around 100 or maybe 110 for really tight ES as a dedicated sub 20fpe field target gun. BUT I still want to play with it shooting heavy .177s and might even go the other direction with the reg pressure to see how it'll sling the 20.5grain NSAs. Even with 125 bar reg pressure it'll push the 16.2grain JSBs up to 940 but I don't expect it to get the 20.5s moving unless the regulator is up around 150bar. I will eventually find out for sure vs speculating. 

The barrel looks too long for the air tube but it balances surprisingly well, given the 10mm OD barrel and carbon fiber. That CF saves a ton of weight! Total length is 34 inches, and nearly an inch of that is the 3d printed butt pad. Anybody with a complaint about the heft of a Veteran should consider this CF configuration, REALLY cuts down the overall weight. Lots of steel (weight) in those 15mm factory Taipan barrels.

Gun is topped off with an ever-trusty SWFA 20x. 3d printed buttpad from Bryan Samson. UTG front grip being used as a make-shift knee riser. Tube is the Veteran Standard length tube. No plenum addition. OEM hammer spring. 

I had about 30 minutes of daylight last night after work and plopped down on a bumbag to see what it'd do. As cited above, averaging 920fps with JSB 10.34. Shot 9, 10 shot groups at 55 yards from field target position. Not sure if they should be considered 9 shot groups though, cuz the first shot of each group was to make a pellet hole/aim point. The tighter groups were before the light started failing and I could see that .177 pellet hole that I was aiming for. Overall quite pleased with the accuracy. Plenty accurate for field target. Shot from a bench it'd be all pellets touching. 

Gotta love Vets. Properly adjusted trigger is just a perfect two stage feel, take up that first stage and then nice and crisp and predictable on the break. Firing characteristics of airguns aren't often discussed but I feel like that's a large part of why the Vet has a cult following. They're just so dead to shoot. Calm as can be, no bucking bronco with a Veteran (even at higher power they're really docile to shoot). Pellet is gone quick and crosshairs stay right on the impact point through the shot and as the pellet gets where it's going. Just a surreal, thoroughly enjoyable shooting experience. 

Current plan for the .177 Standard VET...

• Eventually do some head to head in the wind with this .177 polygonal barrel versus the one on my USFT. I've always been in awe at how well that poly barrel in the USFT resists the wind so it'll be interesting to see if the same characteristic can be seen from this barrel. It should be a very fair comparison. They're the same length, both have slight choke, can be set up to shoot at identical power levels, both from guns with great triggers and consistent ES. Both barrels like the JSB 10.34. Also curious to know if the BC is any different from one .177 poly to the next, given every other variable being nearly identical. Should be fun.
• Might just compete with it for some of the low power field target matches this summer. 
• Also want to experiment more with the .177 slugger idea. Have a couple boxes of the 20.5grain NSAs and I'm excited for that too, especially after Arzrover's impressive long range results and high BC measurements from a couple weeks back.
• Final configuration will be decided upon by results from above testing. 

Edit: forgot to add shot count info. I started with gun filled to just under 250 bar and ended with it just under 150 bar, so call it 245 bar to 145 bar. 90 shots. Probably another good 20 shots before getting below reg pressure of 125. Not that efficient when compared to my Vet Short @ 20 fpe (either .22 or .20). But again, I think with a lower regular pressure on a dedicated 20fpe tune and the shot count would go up to around 140 shots per fill @ 20fpe. 

 

[Motorhead]

Nice !! Loving those TAIPAN's !!!

 

[Matt247365]

Nice work!

Love seeing all the different Taipan DIYs people are coming up with.

 

[Franklink]

FINALLY found some time to play with this project.

With how well they will shoot when pushed fast enough, the intent was to shoot the 20.5gr NSA slugs, so bumped the regulator to 145-150. Yeah that's high. Arzrover let me shoot some 20.5s out of his gun and they really are amazing, but man it takes some oomph to push them, that's why I went so high on the reg.

Also opened up the regulator while I was there to see how the 70D orings are doing. They've been in for a couple months and aren't the slightest bit chewed up so left them.

Went to the chrono and the fastest I can push the 20.5s is 712. And FPS was all over the place, 300fps spreads. Lots of pressure to get the bolt closed on those long slender slugs. SOOOO much bearing surface. And some felt tighter than others, and the tightest were the low fps shots. I've seen that when I've tried to play the slug game before, with .22s.

Needless to say, the 20.5s are not for this barrel, and probably not even for this gun. I'm as high as I'm comfortable with on the regulator pressure and am against the heavy truck spring.

Decided to step down in projectile weight and see what I had there. The 15grain NSAs are doing 975, very consistently. Gets 40 shots from 250 to 140 bar and then fps drops down past the 25fps spread that I like to be within. That shot count is with a Vet Standard length tube and no plenum.

Also put some 12.5 NSA through the gun while in this HP config. 1065fps there, also consistent. I didn't get a shot count above reg pressure with the 12.5s.

Also thought I better do some accuracy testing.

This first one is from 40 yards and the 15gr NSAs, mostly getting on paper and adjusting the scope. I was shooting at pellet holes and could get a couple to overlap with the previous hole but sometimes not-typical of my experience with slugs. At 35-40 yards, my simple accuracy expectation is that holes should be at least touching, when I make good shots. And it wasn't always doing that with the 15gr slugs.

Moved on out to 95 yards after that. Two groups of 10 shots each. Slug typical ho-hum, 2-3moa accuracy.

Decided to throw some 12.5s down to 95 yards too. Again, typical less than impressive slug accuracy. I've now shot the 12.5s from 870 to almost 1070 and had similar results. Decent, but not amazing accuracy.

Finally, concluded that I better shoot some test groups from my "Long Ranger." Figured I at least owed it to the experiment to see if my baseline for long range accuracy could do any better than the .177 slugs in the same conditions. Havent shot the .22 Vet Long since the last XFT match, which I think was end of April. These are the first and only 20 shots. Two ten shot groups at 95 yards, just like with the slugs. I remembered the clicks a bit wrong on the first group and it was a bit high on the paper, took some clicks off for the second group. Top group is from a known good batch of pellets. Bottom group is from one of the worst batches I've shot. Had the typical bad flyer and another two not so bad flyers from the bad batch.

Conclusion: The .177 heavy slug experiment has not converted me to slugs. If I could push the 20.5s fast enough and if this particular barrel liked them I might be willing to switch over to them for my long range uses. Until I find a slug that'll outshoot the MRDs, I'll stick with the MRDs. Especially when the MRD groups are half again what the slug groups are.

So where does that leave me with the .177 polygonal Veteran project? Well, it's going to get a regulator pressure down around 90 or 100 and a new smaller transfer port and be a dedicated sub20fpe field target gun. It spent some time under 20fpe and does really well with JSB 10.34s, that was with regulator around 125. I think it'll really shine with an appropriately sized transfer port and lower regulator pressure. From the shot count I was getting with the high reg pressure and huge dual transfer ports, I conservatively expect to get 150 shots with those two changes.

 

[Franklink]

I've had some more learning experiences with this project and wanting to make an update, in case it can help somebody else in some way.

Lots of what I'll share in this post is knowledge passed on by who I consider my airgun mentor. He's always willing to impart knowledge and humors me in my machining requests. I of course pay him for the machining, but still often feel like I'm taking advantage of his gracious ways. So, credit to him, where it's more than due (name withheld to prevent him from being inundated with machining requests).

So, two OEM Veteran characteristics were keeping me from attaining a tight extreme spread in the sub 20fpe .177 project.

• the OEM Veteran dual transfer port configuration is simply too big for a low power .177
• the OEM Veteran reg pressure of 125 bar was a bit too high (the two OEM Vet regs that I have personally laid eyes on have had "125 bar" written on them with marker).

Transfer port and "flow"
The left-most elongated, dual port is OEM.
The center was machined by the aforementioned airgun mentor/guru at 75% of .20
He also made the smallest tp here, at 75% of .177 (on the right).

The smallest one (on the right) is what I put in the .177 polygonal Vet project a few days ago, more on that in a minute.

We were surprised to learn that the valve porting is actually smaller in area than the dual transfer ports. So, despite the huge and seemingly wide open transfer port, the air is actually constricted at the point where it exits the valve (directly underneath the transfer port when the gun is assembled.

Here is a photo of the front section of an OEM Vet valve, illustrating that exit port. OEM poppet is also shown here.

And for somebody going the opposite direction (of where I'm at now wanting a 20fpe/.177) and really wanting BIG power from a Vet, there's really not much meat on either side of that exit port on the brass valve to be opening it up much.

Generally PCPs power output and efficiency and shot cycle characteristics and consistency, etc are the cumulative effect of the balance between the pressure (regulated or otherwise), the porting, the valve return spring, and the net effect of the hammer strike (hammer strike can be further broken down into the stroke, the hammer spring tension, and the weight/mass of the hammer, etc). My basic understanding is that an oversized port (for a given desired power level from the specific weight of the intended pellet) has a detrimental effect, not only on consistency, but efficiency. And the opposite is true too, a transfer port properly sized to the desired power (in this case a relatively small tp) can act as a sort of regulator, assisting in a tighter ES and less air wasting. Well, after putting the 75% of .177 transfer port in the Vet poly I'm seeing a tighter ES and seemingly less air waste. More on that in a minute, first......

Regulator
The OEM pressure of 125 bar was simply too much for the desired 20fpe in .177. I had the hammer tension almost zero to get it down to 20fpe and was not on the ubiquitously discussed (ad nauseum sometimes) "knee." Having played with the OEM Vet regulators a bit, taking careful measurements, I feel like a have a rudimentary grasp of their output pressures, based on how they're adjusted. Furthermore, I found a youtube video where he had captioned that the output pressure of a Vet reg is 120-155 bar. I'd link it if I could find it right now, but it was Spanish speaking and mostly a disassembly guide, the guy knows his way around the Vets though. I was hoping he was wrong but found out there's not much in the adjustment range that would allow less than 120 bar. They can go the other way quite a bit, but the adjustment collar bottoms out not very far from the oem 125 bar (less compression on the belleville washers = less output pressure and more compression = higher output pressure). So, I bottomed out the collar and was hoping for 100-110 bar. The aforementioned airgun guru told me that toying with the bellevilles further could be attempted to get pressure even lower, perhaps swapping out a similar thickness flat washer for one of the curved ones, or maybe even omitting a washer. I don't think I'll go down that road as I'm getting tired of the tinkering and just want to shoot and enjoy the gun. Also, I'm happy with consistency now.

Plenum
A good deal came up on the classifieds for a plenum and I was curious what effect that addition to the plenum volume would have on a low power tune, and figured I could always put it on one of the higher fpe producing Vets if it didn't work on the .177. So I bought it.

I posted a question on GTA about what happens with too much plenum volume in this low power scenario and had a few mixed responses. Some comments suggested that too low of a power output doesn't use enough air for the plenum to refresh on each shot, requiring multiple shots from the same air in the plenum, descending in fps, until enough is used for it to open and accept air from the tube again. I did not run into that problem, as this gun is now VERY consistent.

Results
Here is what the tube and barrel lengths come out to in current config with the plenum addition.

I've run various strings over the chrono now, using the 10.34grain JSBs. I've done a couple 20 shot string at various pressures, and also did a full string from 250-100 bar and the ES for each of those experiments has been 12-16fps (when I stop above 120 bar). The ES prior to the smaller tp and the reduced reg pressure was optimistically 25fps, but more realistically was probably in the 25-35 range as the fps was not very consistent.

The reg pressure, with the adjustment collar all the way extended, is 120, just as the guy in the youtube video stated. Once the gauge drops below 120 the spread opens up a bit, not much, but the fps drops 3-5fps lower than it is at any of the shots taken above 120bar. Shots can be taken all the way down to 100 bar and still be within reasonable ES for a hunting gun (30-35fps) before they drop off the cliff between 95 and 100 bar. So, all those shots below 120 bar are technically, "off the reg" but still usable for hunting or plinking.

So, it'll now shoot 112 shots, average 932fps with the JSB 10.34, from 250-120 bar, while maintaining all shots within an ES of 15. Another 28 shots are possible, taking the pressure down to just under 100 bar, but opening up the spread to 35fps for a total of 140 shots.

The max it can do now, even with heavy slugs and pellets, is 26fpe. So the tp and reg pressure reductions effectively neutered the gun as it would do 32 or so fpe prior to these changes. I'm trading max power output for an increase in efficiency and consistency and reduction in air usage, and I'm okay with that.

The .177 Standard poly is now my quietest airgun. The slightest little pffffft is heard when the trigger is pulled, and then WHACK when the pellet gets to the target. Just a dream to shoot. Last night it got dark on me and I wasn't done shooting so I put a light on my pellet trap. I was only at 30 yards since the irrigated pasture out back was muddy and I didn't want to wallow around in the mud. Something about that light shining on the white paper brought in the bugs, mostly mosquitos. But it was tons of fun to follow the bugs around on that paper and obliterate them. So, the gun is capable of popping mosquitoes from 30 yards. Although I had some wind switching around from two different thunderstorms trying to build up to the east and the west. Need to shoot it in less wind to truly assess accuracy.

And the annoying jamming that was happening with the huge oem transfer port and some of the .177 projectiles? Not happening anymore. They're loading like butter (mostly, I can feel the 12.5grain NSA slugs bump over the TP but it's not jamming).

In the way of air usage, and for comparison.....
(all of these numbers are for shots taken above reg pressure, all three will shoot past reg pressure and still be consistent enough for hunting/plinking, also, different sized volumes on each of the airtubes)
Vet Standard poly (.177) does 112 shots at 20fpe is a total of 2240fpe (shots from 250-120). 1.16bar per shot
Vet Short (.20) does 90 shots at 20fpe for a combined 1800fpe (shots from 250-125) 1.39bar per shot
Vet Long (.22) does 45 shots at 45 fpe for a combined 1800fpe (shots from 250-140) 2.44 bar per shot

I'll shoot it like this for awhile, and it may just live as a high volume shooter as a low power .177.

 

[douger]

very very nice gun lotta nice stuff you did. great job

 

[Gear_Junkie]

Great post and info - THANK YOU!