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rsterne · Moderator

The 3000 psi fill is really only dependant on the valve mounting screws from a safety point of view.... The large porting on the valve is a separate issue, and will work with any caliber .25 and up (it's too large for a .22 cal, but that could be supplied on request).... In order to utilize the higher pressure fill, and the large ports, the hammer strike must be increased, and we have done that by a combination of more hammer weight, travel, and using a QB hammer spring....

Sean will be making all these items available (modded valve and new hammer & spring) along with a repeater breech that accepts a .25 (or .30) cal MRod magazine.... along with barrels in both .25 and .30 cal, already chambered, ported, and crowned.... Basically, the intention is to provide all the necessary parts to duplicate my build.... eventually....

I can't remember Sean's website, the best way is to email him.... PM me for his addy....

Bob

renderbrandt · New Member

Thanks Bob,

Sent you a pm.

Seeing the velocities you are creaming out of .30, I would assume cal .25 would scream down the range being lighter and slightly smaller.

I know without testing you could'nt say anything towards accuracy at longer distances 75-150. But I can ask what you expect it would do.
Good enough for competitive shooting?

Regards.

T

rsterne · Moderator

The first one of our .30 cal barrels tested was doing MOA.... In theory a .25 will shoot faster, but since we are in practice limited to ~950 fps, it will more be a matter of how heavy a pellet/bullet you can find that is accurate.... I'm hoping for in the 80 FPE range in .25 cal as a maximum....

Bob

renderbrandt · New Member

MOA is great accuracy!

Just Sub 1k in .25 with 80 FPE is plenty.

Will be interesting to see what grain pellet would yield that at 950fps.
Thanks for your prompt responses Bob, its refreshing.

Regards

T

rsterne · Moderator

At 950 fps, the FPE = twice the pellet weight in grains.... Works for all weights and calibers....

Bob

rsterne · Moderator

After three months of waiting for Airguns of Arizona to come through with my pellets I cancelled the order and got them from Specialty Shooting Sports.... I originally ordered the 50 gr. JSBs from AoA and they (knowing they were incorrect) shipped the 45 gr.... I told them I'd keep those and to ship the 50 gr. when they came in (in a month), and after 2 months I contacted them and they told me JSB didn't ship them.... After chewing them out (again) for not letting me know, they agreed to substitute the Daystate 50 gr. (same pellet but more expensive) when they arrived in 2 weeks.... A month later I called them yet again and found the Daystates hadn't arrived either (and once again they didn't let me know), so I cancelled the order and got them in 3 days from SSS.... Anyway, that is the reason for the lengthy delay in getting back to this project....

I now have the 7-shot converted mags from Lloyd at AirGunLab, and after a bit of tuning to function with my flat faced bolt, they function flawlessly.... I had four pellets to test now, some #1 Buck from Ballistics Products, 44.8 gr. JSBs, 46.4 gr. FX, and 50.2 gr. Daystates.... I weighed 10 of each and they came out at follows:

#1 Buckshot - 39.6 gr.
JSB - 45.2 gr.
FX - 44.8 gr.
Daystate - 49.4 gr.

The #1 Buck were rather inconsistent in diameter, running from 0.294" - 0.302", with most between 0.296"-0.300".... While they were too loose in a 0.308" PB barrel, or the one on my DAQ, they worked perfectly in our new 0.300" barrel, and chambered easily (without the small ones rolling out the muzzle like they did on my DAQ).... The JSB and FX pellets are from all measurements exactly the same.... The previous tins of FX pellets I had weighed 45.3 gr, so it would appear that 44.8 to 45.3 is normal for both brands.... The Daystate pellets are exactly the same length as the FX, and they are availlable under the JSB label as well, I just haven't been able to get any.... The extra weight comes from a thicker waist, they measure 0.257" instead of 0.214".... All the pellets shot into one (large) ragged hole during my indoor Chrony session, although the roundball group was nearly 1/2" OD whereas the others were more like 3/8".... It's very satisfying to see a big hole appear in the paper and then see the rest of the shots go through it, barely enlarging it, even when shooting at only 20'....

I started out with the hammer spring preload set just shy of coil bind, and tested all four pellets at that setting.... The roundball screamed through the Chrony at 1079 fps and 102 FPE, the JSB & FX 45 gr. weren't far behind at 1050 (110 FPE), and the Daystate 50 gr. hit 1015 fps (113 FPE).... The roundball were really just a curiousity, and I had already extensively tested the 45 gr. FX pellets, so I used the Daystate 50 gr. for the rest of the tests.... I reduced the preload a turn at a time, recording all shots within 4% of the peak velocity in each string, as follows:

At 1 turn out on the preload, I got a 7 shot string (1 full clip) averaging 988 fps (107 FPE) with all shots within a 2.8% ES, and the first 6 shots within 1.8%, with an efficiency of 0.92 FPE/CI, pretty decent for over 100 FPE.... At 2 turns out, the shot count with a 4% ES jumped to 10 at 102 FPE, still starting with a 3000 psi fill (ending at 2200) with an efficiency of 0.99 FPE/CI.... At 3 turns out, the fill pressure was 2800 psi, and I got 11 shots at 97 FPE at 1.05 FPE/CI and at 4 turns out, using a 2700 psi fill, I got 11 shots averaging 94 FPE at 1.09 FPE/CI.... Any of these tunes would be very usuable, and selecting the 7-shot sweet spot at the top of the curve would give minimal POI change, even out to 100 yards.... at peak velocities of 940, 960, 980, or 1000 fps (with the 50 gr. Daystates) depending on choice of preload and hence fill pressure....

Testing at longer ranges is problematic at the moment as pressing family matters and travel is going to detract from my target time.... However, with two weights of pellet to choose from, and the ability to fine tune the velocity, I would expect to find at least one combination that proves stellar....

Bob

rsterne · Moderator

I finally had a chance to get the gun out for some long range shooting today.... It is tuned for one 7-shot clip at 107 FPE with the 50 gr. Daystates (988 fps) or 105 FPE with the 46 gr. FX/JSB pellets (1012 fps).... I first shot a 3-shot group with each pellet at 50 yards, and they were all under a quarter, with this being the best....

That measures 1/2" C-T-C.... I then shot a 5-shot group with each pellet at 100 yards.... Here are the targets....

Daystate 50 gr.

JSB 45 gr. (higher aim point)

FX 46 gr.

There was a slight wind swirling around though the trees.... Four of the five shots in each group are within 1.0" - 1.2", and the average group size was under 2" except for the 1 shot I pulled.... I didn't do any tuning of the air stripper, nor did I check to see if the accuracy is any better at a slightly lower velocity.... To be frank, I wasn't shooting at my best in the cold weather, it was just above freezing today, and I know for a fact I pulled the one FX pellet up and to the left.... Overall, I'm very pleased with the groups for a first time out.... I stapled a pellet tin (2.5" D) to the 100 yards support and nailed it first shot.... All three pellets print at very nearly the same POI at 100 yards....

The development work on the .30 cal version is now complete, and it's time to start work on the .25 cal barrel.... This testing certainly proved that the .30 cal barrel Sean and I designed for the .300" head size JSB pellets does the job....

Bob

rsterne · Moderator

Before leaving the .30 cal, I had one more thing I wanted to try.... The bolt on this gun is probeless, you push it forward to seat the pellet, turn the handle down, and then retract it clear of the barrel port.... It occurred to me that if I had an adjustable stop in the "J" slot I could set how far back the bolt retracts, and hence use the nose of the bolt to restrict the barrel port.... Here is a photo of it installed in the breech....

I drilled a 3/32" hole in line with the "J" slot from the back of the breech, then drilled in and tapped the back of it for a 1/2" long 6-32 SHCS.... The screw pushes on a 0.8" long brass pin for the bolt stop, which can be adjusted from fully open to stopping the bolt with the nose virtually at the front of the barrel port.... The screw might have a tendency to back out, so I drilled up from the bottom of the breech, near the back, and installed a 1/4" long piece of 0.095" weedeater line pressed against the adjusting screw by a 6-32 setscrew to provide a "brake" by adding friction so it won't self-adjust.... Everything worked great, so I proceeded to testing it....

I ran the adjuster in all the way, filled the gun to 3000 psi, and fired two shots.... turned the screw out a turn and fired two more, and repeated until the stop pin was flush with the end of the shot and therefore having no effect.... The purple stepped line on the graph above shows the results.... 310 fps, 550 fps, 740 fps, 870 fps, 950 fps, 980 fps, and just over 1000 fps.... There was no change in velocity for the last turn, it was the same completely clear of the "J" slot or 1 turn (0.032") in.... I turned the screw in 2 turns from maximum and backed off the hammer spring preload a turn (the measurements on the graph, eg. 0.337", are the preload, which moves 0.042" per turn) and shot a string.... My goal was two 7-shot magazines (ie 14 shots) at the highest possible FPE level within a 4% ES.... I played around with a few settings, and three of the 14 shot combinations are on the graph above.... It took the adjuster screw turned in 2.5 to 3.0 turns to get my 14 shot strings, and I ended up with the following:

86.6 FPE average at 1.08 FPE/CI
84.0 FPE average at 1.14 FPE/CI
82.7 FPE average at 1.18 FPE/CI

With the gun set for a single 7 shot string (1 magazine) at maximum FPE, it shoots 101.2 FPE at 0.90 FPE/CI with all the shots within 17 fps (1.7% ES).... All these strings are with the JSB 45.2 gr. pellets, the FPE levels are slightly higher with the 49.4 gr. Daystate pellets, averaging 107 FPE over 7 shots.... I have no doubt that by turning the velocity adjuster in more I could achieve more shots at less power, but two full magazines at 83-87 FPE is a good compromise.... I'm very pleased with the way the .30 cal version of this gun turned out.... When time permits, I will be getting on with fitting a .25 cal barrel to see what can be achieved when set up as a quarterbore....

Bob

rsterne · Moderator

I got a chance to machine the .25 cal barrel and install it yesterday.... I reamed the chamber with a reamer I made myself (thanks Sean for the guidance).... I cut the chamber in the TJ's .25 ACP liner (14" twist) to fit both pellets and bullets, and it should handle anything that will fit in an MRod magazine.... I then machined the O-ring groove and barrel port, using an oblong port measuring 3/16" x 1/4" which has the same area as the 7/32" transfer port I used for the .30 cal version.... I removed the .30 cal barrel, installed the new .25 cal in the breech and started testing....

I cranked the RVA to just shy of coil bind, left the screw that adjusts the bolt in the wide open position, filled the gun to 3000 psi and tried a few shots with different pellets / bullets to find out the maximum the gun could deliver, with the following results....

Just as the .30 cal exceeded my expectations, so did the .25 cal.... The maximum power is down about 16 FPE compared to shooting simlilar weight pellets in the .30 cal version, as could be expected.... I then proceeded to shoot some strings, and I found out that with the 52.7 gr. RN bullets I have to run the RVA nearly at coil bind (in fact just 1/2 turn out) to get the best string with a 3000 psi fill at maximum power.... Here are the results of testing with those bullets.... The bullets were unsized, and I think the variations in diameter as cast are causing the shot to shot variations in the strings....

When I turned in the velocity adjusting screw (which causes the nose of the bolt to partially block the barrel port) I found that I had to back the RVA out 1 turn to get the best strings.... Here is a summary of the averages for each string shown on the graph....

Maximum: 894 fps (93.5 FPE) for 9 shots at 0.80 FPE/CI
3 turns in: 856 fps (85.8 FPE) for 12 shots at 1.02 FPE/CI
4 turns in: 827 fps (80.1 FPE) for 15 shots at 1.04 FPE/CI
5 turns in: 779 fps (71.1 FPE) for 17 shots at 1.07 FPE/CI
6 turns in: 712 fps (59.3 FPE) for 21 shots at 1.15 FPE/CI

I didn't test the gun with the velocity adjuster in 7 turns.... It wouldn't have been in the 300 fps range like it was with the .30 cal because the oblong barrel port would not have been as completely blocked by the nose of the bolt, and I didn't care about velocities below 700 fps anyway.... In the next post I'll tell you what happened when I switched to the JSB Kings....

Bob

rsterne · Moderator

Now that the initial testing was done with the cast bullets, it was time to try out the .25 cal Disco Double with my favourite pellet, the 25.4 gr. JSB King.... I left the gun tuned the way it was at the end of the bullet testing, which was about 60 FPE.... I expected I would have to reduce the hammer spring preload with going to half the weight pellet, and that was exactly the case.... Here are the results.... The green line is the way the gun was set for the last test (also a green line) with the bullets.... You can see that it pretty much started on the top of the bell-curve, I had to turn the RVA out 2-3 more turns to move the shot string over....

Here is summary of the averages for the shot strings in the above graph....

Maximum: 1162 fps (76.2 FPE) for 7 shots at 0.65 FPE/CI (all supersonic)
4 turns out on RVA: 1097 fps (67.8 FPE) for 12 shots at 0.77 FPE/CI (just subsonic)
5 turns in on velocity screw: 991 fps (55.4 FPE) for 18 shots at 1.09 FPE/CI
6 turns in: 922 fps (47.9 FPE) for 19 shots at 1.03 FPE/CI

There are a few useful shots missing on the last string, backing the RVA out to 4 turns out like in the other strings (it was at 3) would have dropped the velocity slighty, added shots, and increased the efficiency.... Tunes in between any of these can be obtained by using adjustments finer than a full turn, of course.... One thing that I was very pleased about was how tight the groups were with the Kings.... I'm used to seeing ragged holes at 20' even when I'm not taking my time and just shooting through the Chrony, but here is what I was getting for 8 shots.... Yep, that's just a 1/4" hole!....

When I was doing the Chrony work with the bullets I was using up some unsized bullets I had that had very uneven bases, bent by the sprue cutter.... The groups were unacceptable, even for Chrony work inside at 20'....

When I was done with the Chrony testing I switched to the last batch of .25 ACP bullets I cast (some 46.4 gr Hollowpoints) and ran an 8-shot magazine through to see if they were any better....

While not as tight as the Kings, this group is consistent with what I usually see with good pellets while doing my Chrony work inside, and usually means I can expect to be able to cover the group with a dime at 25 yards when I move outside.... It certainly proved to me, once again, how important it is to have as perfect and square a base as possible on a bullet.... It just makes sense, it causes the same problems as a bad crown on the muzzle, right?....

One of the things that amazed me during the testing of the JSB Kings was how much I had to restrict the flow to get the velocities in the sub-1000 fps range.... At 5 turns in on the velocity adjusting screw, the nose of the bolt is blocking 0.16" of the 0.25" long barrel port.... leaving just half of a 3/16" hole available for the air to flow through to drive the pellet.... That is basically the same area as a stock 0.134" Crosman barrel port.... AMAZING !!!

Bob

rsterne · Moderator

I threaded the muzzle for the Hatsan air stripper and installed the carbon fibre shroud and stripper.... The accuracy seems unchanged inside at 20', but it's pretty hard to distinguish small changes at such close range.... I tried some Daystate Rangemaster 36 gr. pellets as well, which were pretty dismal in my Hatsan, and they shot nearly as tight as the JSBs, so it looks like the warning on the box about being intended for unchoked barrels may have merit.... I tested them at 950 fps (72 FPE) and they can be tuned both up and down from there.... so definitely worth invetigating....

Bob

rsterne · Moderator

Today I tried several different tunes for the JSB Kings around the 55 FPE level.... The plan was to try adjusting the hammer preload weaker (and drop the fill and refill pressures) while opening up the barrel port by backing out the velocity adjusting screw.... I wasn't fussy about getting exactly the same velocities with each tune, I recorded all the shots within a 4% ES (~40 fps), and all the shots were between 965 fps and 1018, so the strings were within about 15 fps for the peak velocity.... I backed off the hammer spring preload a turn, dropped the fill pressure 200 psi, and opened up the barrel port to keep roughly the same velocity for each string.... Here are the results....

The numbers on the legend are the number of turns in from maximum power on the bolt travel (barrel port restriction) and the hammer spring preload, measured from the lock nut to the end of the adjuster (bigger distances mean less preload).... The -5T and 0.358" curve started at 3000 psi, and the last string shot, (-2T and 0.568") started at only 2000 psi.... I know it's a bit hard to see, with all the lines on top of each other, and the curves look silly with the drastically expanded vertical scale.... but here are my conslusions....

1. There was little to choose from for the efficiency.... All the strings were between 1.02 - 1.10 FPE/CI, with no real trend apparent.... The differences may have been more due to some strings being a few fps faster, or missing a shot or two on the front end of the string because the starting pressure I used wasn't quite high enough....

2. As the pressure range dropped and I compensated by opening up the porting to keep the same power, the shot strings got shorter and more curved.... The range of pressure between the ends decreased.... Once again, it is apparent that wide open ports can develop good power at low pressures, but the price you pay is a low shot count.... You can equate big ports to a hot cam in a racing engine.... More power for a given pressure, but a narrow power band....

3. All these tunes used about 50 psi per shot from the 250 cc Disco Double reservoir.... in fact the range was narrow, between 48-52 psi per shot.... Each vertical line on the graph therefore represents about 50 psi.... With the ports wide open, I was able to get 1000 fps (55 FPE) from only 1700 psi, which is pretty amazing, IMO....

4. The longest shot string was at about 2800 psi fill pressure, and ran 18 shots, but it was missing 1-2 shots off the front end of the string, and peaked at over 57 FPE.... I feel that with some fine tuning, I can achieve 20 shots at 55 FPE average from a fill, within a 4% ES.... I can already get 13 shots within a 2% ES, and 17 shots within a 3% ES, averaging closer to 56 FPE with the Kings....

While the purpose of this gun was to achieve a higher power level using cast bullets, I'm very pleased with the flexibility demonstrated to shoot JSB Kings at 1000 fps with a good shot count.... and once again I was provided with the opportunity to learn more about PCP tuning....

Bob

rsterne · Moderator

My new Boattail bullet mold arrived a couple of days ago and I cast some bullets yesterday.... The new .300 cal bullets came out at 70.4 gr. and they function perfectly in the modded MRod magazines....

Here is what they look like....

Since these bullets are a lot heavier than the 50 gr. JSB pellets the gun was built for, I maxed out the hammer spring preload and the velocity adjuster and ran a string.... It peaked at 114 FPE and averaged 837 fps (110 FPE) for 9 shots.... so a little bit more hammer strike is required to get the maximum from one 7-shot clip.... I'm hoping to fix that issue by replacing the valve poppet with one made from PEEK which is a harder material and takes less energy to break loose from the seat.... I shot a couple of other strings with the velocity adjuster run in a bit (which restricts the barrel port with the nose of the bolt), and here are the test results....

The last string was two full clips (14 shots) averaging 86 FPE at an efficiency of 1.11 FPE/CI, which is the same energy as I got with the 50 gr. pellets when the gun was set for 14 shots at fractionally better efficiency.... The way I see it, the best use for these bullets will be with the gun adjusted for a single clip at maximum power.... The bullets were all going into ragged holes between 3/8" and 1/2" OD during Chrony testing, which is pretty good for cast bullets.... Proper accuracy testing will have to wait until the spring, however....

Bob

rsterne · Moderator

Well you knew I had to do it !!! .... My .30 cal Disco Double is one of the best documented guns I have, and with the new 70 gr. bullets it's now limited out on performance due to insufficient hammer strike.... or rather it WAS, until today when I made a new poppet out of PEEK for it.... All I can say is WOW !!!

Before I tore the gun apart, I made some measurements of valve lift, using an O-ring on the rear cocking shaft.... This is an easy procedure, you slide the O-ring up against the adjusting screw on the RVA, cock the gun, fire it, and measure the gap.... Voila!, instant measurement of how far the valve opened.... I set the preload to maximum (as near coil bind as will safely cock), opened the bolt stop to maximum (this gun has the ability to choke off the barrel port with the bolt nose), loaded a 50 gr. JSB, and checked the valve lift at 2800 psi and again at 2000.... I did 2 shots to confirm the measurement, and I was pleased that they were the same within 0.001" or so.... I then repeated the test with no pellet loaded (open bore), and then I moved the bolt nose forward with the adjuster to close off the barrel port, loaded a pellet to block the bore even more, and did another set of lift measurements.... These three conditions change the flow around the head of the poppet, from "normal" to as much flow as possible (barrel at atmospheric with no pellet), to virtually no flow where the pressure on both sides of the poppet is nearly the launch pressure (the velocity drops to about 200 fps, you can see the pellet arc through the air to the backstop).... This gives us a way to somewhat quantify the aerodynamic drag trying to close the poppet, relative to the major closing force, which is the air pressure acting on the 5/32" valve stem.... Anyway, I then tore apart the gun and made a new poppet out of PEEK, reassembled it, and repeated the tests.... Here are the lift measurements....

As you can see, the PEEK valve had about a third more lift at 2800 psi, with the same hammer strike, so it is obviously a LOT easier to unstick from the seat.... There can no longer be ANY doubt of that.... The lift of the PEEK valve at 2000 psi was limited by the physical room between the face of the hammer and the back of the valve, which is 0.162".... You can also see that compared to the "normal" case of firing a pellet, with no load (and therefore a bigger pressure difference across the head of the poppet) the lift is slightly less.... while with the barrel nearly blocked (and therefore very little pressure difference across the head of the poppet) the lift is slightly greater.... That difference in lift is due to the aerodynamic drag across the head of the poppet, which shows up as a pressure difference between the valve housing and the exhaust port, which in turn increases the closing force during the valve cycle.... The differences are smaller with the PEEK valve, likely because the head is a smaller OD.... Here are the two poppets....

You wll notice that the Disco poppet, which has seen maybe 500-1000 pellets during testing, is pretty badly pounded.... While it is not extruded like the one in my Hayabusa was (which had a larger throat), it would appear that 3000 psi on a 1/4" throat is really more than it should see.... The ID of the Disco valve, BTW, was bored out to 5/8" ID so there is lots of room for flow around the head.... When I made the new PEEK poppet, I made the OD the same size as the valve spring.... The stem is made from 5/32" drill rod with the end threaded 8-32 for 1/4" of length and then the stem is slimmed behind that to 7/64", the same as I did on the Disco stem.... The PEEK valve head is drilled and tapped 8-32 and glued onto the stem with medium viscosity CA glue before final finishing.... Thanks, Lloyd, for the idea of threading it on for extra strength !!! ....

Of course my testing didn't finish with just measuring the lift, I had to see if the new PEEK valve increased the performance.... Well, the first thing I noticed was that the gun was louder and a lot thirstier for air.... My SCUBA tank was down to 2800 psi, but that was enough to drive a 50 gr. JSB at 1033 fps (119 FPE) compared to a previous best of 1011.... The 70 gr. Boattail, which I could only get to 852 fps yesterday screamed across the Chrony at 918 fpr (131 FPE).... I'm sure those numbers will increase further at 3000 psi.... I then started backing off the preload, with the pressure in the SCUBA tank gradually dropping, and it was obvious that even with the heavy, 70 gr. bullets, the gun, rather than being limited by hammer strike, was operating on the velocity plateau for the pressure available.... I had to back the preload down 5 turns before the velocity started to drop significantly.... At 6 turns out, the velocity pretty much matched the way the gun shot with the Disco poppet at maximum preload, starting at 830 fps and climbing gradually.... There is one problem, however.... The gun is suffering from a LOT of air robbing hammer bounce.... It appears that the PEEK valve is so easy to open that the returning hammer is burping it a couple of times, even at velocities where I was getting a decent string yesterday....

My ShoeBox is currently chugging away topping up my SCUBA tank, so further testing will have to wait.... I'm guessing that I'll have to use a shorter, stiffer hammer spring to get rid of virtually all of the preload to eliminate the hammer bounce.... I know that something will work, because my Hayabusa doesn't have this issue, nor does Sean's .30 cal QB.... It looks like a whole new learning curve is required to find the best combinations to work with the new PEEK valve.... There can be no question, however, that by using this material for the poppet (or seat) you can immediately reduce the hammer strike required for a given pressure and valve throat size.... Can lighter hammers be in my future?.... certainly the gun just got a whole lot easier to cock....

Bob

rsterne · Moderator

I had a chance tonight to find out how the .30 cal Disco Double responds to hammer spring preload with the new PEEK valve.... Previously there wasn't any point as the gun couldn't reach its maximum potential as the hammer strike was the limiting factor, not the porting.... With the new valve, and tethering the gun at 3000 psi, I could now explore the guns power curve.... Here it is, plotted for both 50 gr. pellets and 70 gr. bullets....

You can see the same velocity plateau as the gun maxes out as you get on a regulated PCP, where additional hammer strike just wastes air.... The "knee" of the curve is where the plateau starts, and there is no point in running more hammer spring preload than that.... This occurs at about 4 turns out from coil bind with the pellets and 3 turns out with the bullets.... Going past that point gains only about 20 fps and doubles the amount of air used.... Even at that setting, the first shot will basically be the fastest, normal unregulated bell-curves start just below the knee of the curve.... at maybe about 5 turns out with the bullets and 6 turns out with the pellets....

The absolute maximum values obtained with this gun were 117 FPE with the 50 gr. pellets and 135 FPE with the 70 gr. bullets....

Bob