Velocities Hot or Not? With FX STX Superior Liners and Diabolo Heavy Pellets...

[JoeKool]

Hello AirgunNation Peoples ,



This post ain’t about slugs or 100+ yard shooting. It’s about good ol’ Diabolo pellets. Namely, JSB .22 caliber Jumbo Heavy 18.13 grain and JSB .25 caliber King Heavy 33.95 grain. Everybody who’s anybody in the airgun world seems to follow or believe in the commonly known theory that the top most stable velocity for Diabolo pellets is around 860 to 880 fps. It sounds like a skipping record to my ears:



”You can’t shoot Diabolo pellets beyond 880 ft./s or you’ll lose everything”.



”Diabolo pellets lose their stability if shot faster than 880 ft./s”



”Diabolo shaped pellets will begin to wobble and veer out of control if shot beyond a certain speed. All accuracy will be lost”.



”They may be stable at high velocities out to 25 or 30 yards but beyond that they will lose stability”.



You get the point. All of my PCP’s are power tuned to the mid-900’s and I get good groups and out to 75 yards I rarely miss shots on game. I am at least a 90% kill rate. Misses usually are due to the quarry moving, matrix-ing me, wind, or something I did wrong not an effect of a unstable pellet. Never noticed stability issues.



So, since my FX Crown .25, Wildcat MKIII Sniper .25, and Dreamline-Bullpup .22 caliber are easily power adjustable, “click-click” on the adjusters and I am shooting @ 860 to 880 fps, and again “click-click-click” at the mid-900’s. Figured I would test the stability at those different speeds at 50 and 75 yards with some five shot groups.



The PCP’s and the Heavy Diabolo pellets

About the PCP’s

Ideal Speed Tune

Hot Tune

Ideal Speed Tune

Hot Tune

Ideal Speed Tune

Hot Tune

The range, the wind, and the shooting 

Targets, target close ups, and group breakdowns



50 yards (left to right: Crown, Dreamline, Wildcat)

75 yards (left to right: Crown, Dreamline, Wildcat)

Dreamline Bullpup .22

No stability issues here.

No stability issues here.



Wildcat MKIII .25

No stability issues here.

Here on the lower group @ 960 fps I botched one shot high because I forgot my hold over. I mistakenly held 1.5 mils when the holdover was only 1 mil. Messed up what was going to be a fine group! Still, no stability issues here.



Crown .25

No stability issues here.

For the FX Crown, it was one of those not the greatest 75 yard group days. It’s done and I have shot better groups with it, even @ 100 yards. Not the greatest or tightest groups, but they are honest. Maybe my eyes are bad and not as well trained as the next guys, but I see no POI or evidence of a lack of stability between any of the groups. They all seem to be comparable in size??



Conclusion



In my PCP’s I cannot see a difference in performance if shooting at the sacred 860 to 880 fps versus my preferred 950 to 960 fps. What I do see is a gentler recoil per shot and efficiency or shot count increases when shooting on lower power settings. On the higher power level I see flatter trajectories and more energy down range, which I prefer for hunting. Also, like I hinted at above slightly more hold sensitivity. I am not a competitive airgun shooter but I could understand that the gentler recoil of a 860 to 880 fps PCP could make it easier to consistently shoot small groups. But from my airguns and for their uses, “Ideal” velocities versus “Hot” velocities have no edge one over the other. Please share your comments, thoughts, and experiences?



Thanks,



JoeKool

 

[L.Leon]

@JoeKool, thanks for taking the time, really good shooting and very informative, clear and concise... thanks again.

 

[Centercut]

Very good comparison. I think much of the 880 ish folklore comes from the FX ST barrel. Because it only has rifling in the last couple inches, faster than 900 often resulted in less accuracy and stability. Maybe because at higher speed the pellet wouldn’t engage the rifling enough to get the small amount of spin necessary in a diabolo Pellet? Not sure there. 

 

[Bigragu]

Great write up, Joe. You and I have discussed this in the past. I’ve been told to “slow them down” by others before, but I put my ear muffs on to those suggestions, lol. 

Im not one to buy the high end scopes with fine line intersecting cross hairs. Much of my groups aren’t as “tight” as I like due to a dot as the center point on my Monstrum scopes covering up the bullseye, but I know inside my groups are stellar, for the speeds they are going at. 

I posted on another topic the results of a pest kill on my battle against the squirrels, and the results of a barracuda hunter extreme 28 grain traveling at 1001 FPS truly promotes a quick humane death. I see all those you tube vids and vids on here of squirrel hits, and too me, if I see any kicking, jumping, or even a tail twitching post shot, that’s too much movement for me. The 28 grain BHE at that speed I have it at, there is no movement whatsoever post shot. 

No need to jump to a bigger caliber air rifle to have a “more forgiving kill in case the head isn’t hit”. A 22 or 25 caliber, with the right pellet and high high speed, means more energy upon impact.

Remember, there’s benchrest accuracy, and there’s hunting accuracy, and a mix of both. I strive for the mix of both, which is plenty for me.

Thanks for your efforts, KoolJoe

 

[Bigragu]

Oh, yeah, forgot to add-

with high velocities and a good weighty pellet, shot count is lost. 25 to 30 shots is plenty for me! My opinion only- I think shot count myself is over rated. Most of the time, anyway, the manufactures specs given for shot count(and speeds) are all bogus, anyway. With all the available sources out there in the form of tanks, portable 12v compressors, and more and more folks with in home compressors, I don’t know what the big deal is anyway with shot count. From what I’ve seen, PCP’s unregulated are in the 20-25 shots medium power, or 16 if ramped up.

regulated, about 30-36 medium power, or 20-24 ramped up. This is medium power class, ramped up to high power. I’m not including the low power class, the 775-850 FPS for 70 shots in this post. Those are the ones that still have the squirrels twitching post shot, lol

I’ll end with this- if a pcp gun is designed and tuned for EBR and RMAC competitions and the like, then disregard my two posts. I am with Joe on this one. For the utmost in accuracy, then yes, a PCP with a bit of power jolt is not welcome, and shot count is vital. 

 

[JoeKool]

@JoeKool, thanks for taking the time, really good shooting and very informative, clear and concise... thanks again.

I’m not sayin’... But, I’m just sayin’...


You’re welcome!

Very good comparison. I think much of the 880 ish folklore comes from the FX ST barrel. Because it only has rifling in the last couple inches, faster than 900 often resulted in less accuracy and stability. Maybe because at higher speed the pellet wouldn’t engage the rifling enough to get the small amount of spin necessary in a diabolo Pellet? Not sure there.

I agree, much validity in your point. Two additional sub-points, my FX Streamline .22 is tuned to 960 ft./s and is a laser with the OG Smooth Twist Barrel using 18.13’s. Also, I have noticed that lighter weight pellets or different brand pellets don’t handle high velocities well. I acknowledge that what’s true for one isn’t always true for all.

Great write up, Joe. You and I have discussed this in the past. I’ve been told to “slow them down” by others before, but I put my ear muffs on to those suggestions, lol. 

Im not one to buy the high end scopes with fine line intersecting cross hairs. Much of my groups aren’t as “tight” as I like due to a dot as the center point on my Monstrum scopes covering up the bullseye, but I know inside my groups are stellar, for the speeds they are going at. 

I posted on another topic the results of a pest kill on my battle against the squirrels, and the results of a barracuda hunter extreme 28 grain traveling at 1001 FPS truly promotes a quick humane death. I see all those you tube vids and vids on here of squirrel hits, and too me, if I see any kicking, jumping, or even a tail twitching post shot, that’s too much movement for me. The 28 grain BHE at that speed I have it at, there is no movement whatsoever post shot. 

No need to jump to a bigger caliber air rifle to have a “more forgiving kill in case the head isn’t hit”. A 22 or 25 caliber, with the right pellet and high high speed, means more energy upon impact.

Remember, there’s benchrest accuracy, and there’s hunting accuracy, and a mix of both. I strive for the mix of both, which is plenty for me.

Thanks for your efforts, KoolJoe

Hey... If it ain’t broke...

Oh, yeah, forgot to add-

with high velocities and a good weighty pellet, shot count is lost. 25 to 30 shots is plenty for me! My opinion only- I think shot count myself is over rated. Most of the time, anyway, the manufactures specs given for shot count(and speeds) are all bogus, anyway. With all the available sources out there in the form of tanks, portable 12v compressors, and more and more folks with in home compressors, I don’t know what the big deal is anyway with shot count. From what I’ve seen, PCP’s unregulated are in the 20-25 shots medium power, or 16 if ramped up.

regulated, about 30-36 medium power, or 20-24 ramped up. This is medium power class, ramped up to high power. I’m not including the low power class, the 775-850 FPS for 70 shots in this post. Those are the ones that still have the squirrels twitching post shot, lol

I’ll end with this- if a pcp gun is designed and tuned for EBR and RMAC competitions and the like, then disregard my two posts. I am with Joe on this one. For the utmost in accuracy, then yes, a PCP with a bit of power jolt is not welcome, and shot count is vital.

Basically, you have to work with what you’ve got. Make what you have work until you figure out a better solution, or learn to appreciate the way it is. I prefer airguns that yield about at least 40 shots per fill, so that’s just one of my pre-requisites before I would consider purchasing a PCP. But, could I go out and hunt and fill my game bag with a PCP that yields only 20 shots per fill? YES! I would just have my full 100 or 75 cu/ft carbon fiber bottle on the backseat, and when a fill is required, I’d have to go back to the truck and fill-er-up! No tears shed...



Thanks Bigragu!!

 

[yalel]

Fantastic post again Joe ! Thanks a lot !

do you think that with older version liners the results would be different ?

 

[JoeKool]

Fantastic post again Joe ! Thanks a lot !

do you think that with older version liners the results would be different ?

Thanks, I don’t think there would be a great difference Yalel. With the exception of the WC MKIII, I had and still have the original STX and Slug “A” liners. My PCP’s were accurate with those as well @ high and lower velocities, using these same Heavy Diabolo pellets.

 

[yalel]

I believe that your posts and some other studies on the internet show that velocities around 950 fps are still perfectly fine for pellets in order to remain stable at all relevant distances for airguns. One consideration to keep this approx. 950 as a nice maximum is the fact that the BC of pellets becomes worse above this kind of speed. That is something you would not want right ? When reaching the speed of sound above 1000 fps the sound is loud when the pellet passes the soundbarrier is a loud “ bang”. and stabilisation of the pellet is lost . Lost not so much becuse it goes through the soundbarrier but more when it returns to sub sonic level. All in all Joe’s posting and all other supporting facts going with the approx. 950 fps should from now on fade away the myth of the 860-880 fps max speed for pellets and put it in the 950 fps area !

 

[tor47]

A nice test. Can high velocity also work for the lighter pellets?

 

[JungleShooter]

JoeCool,

Thanks for the helpful test you ran! Great data! Excellent photography!



Maybe someone could run a test with the JSB Express at 950fps.

And some wadcutters and hollow points at 950fps! H&N Crow Magnum?

Please, some more details on the Baracuda Hunter Extreme!



Matthias

 

[JoeKool]

I believe that your posts and some other studies on the internet show that velocities around 950 fps are still perfectly fine for pellets in order to remain stable at all relevant distances for airguns. One consideration to keep this approx. 950 as a nice maximum is the fact that the BC of pellets becomes worse above this kind of speed. That is something you would not want right ? When reaching the speed of sound above 1000 fps the sound is loud when the pellet passes the soundbarrier is a loud “ bang”. and stabilisation of the pellet is lost . Lost not so much becuse it goes through the soundbarrier but more when it returns to sub sonic level. All in all Joe’s posting and all other supporting facts going with the approx. 950 fps should from now on fade away the myth of the 860-880 fps max speed for pellets and put it in the 950 fps area !

Well, every PCP and barrel has potential to perform differently. The ones in my collection using Heavy JSB’s have no problems shooting @ 900 to 975. Stable as the dining table! The BC’s are better, it’s apparent on impact. But the scientific’s of what’s happening in the pellets flight is the last thing on my mind when in the field. I am more concerned with can I hit my target and humanly put it down. Just not a blind believer in something until I see it for myself. 860 to 880 ft./s is a sweet velocity to shoot pellets at but its not the absolute limit in which they can perform well. Been shooting successfully at these mid-900 ft./s velocities for years.

A nice test. Can high velocity also work for the lighter pellets?

I have not in my personal experience had great luck with very light pellets at high 900ish velocities. I think they have trouble bucking the oncoming wind vs heavier diabolo pellets. 860 to 880 ft./s may be better for those ones. But, testing them yourself is the truest way to find out. Some .177 Diabolo’s can cut through the air at blazing speed and remain accurate and stable.

JoeCool,

Thanks for the helpful test you ran! Great data! Excellent photography!

Maybe someone could run a test with the JSB Express at 950fps.

And some wadcutters and hollow points at 950fps! H&N Crow Magnum?

Please, some more details on the Baracuda Hunter Extreme!

Matthias

Thanks Matthias!



Shape, weight, design, and barrel characteristics probably are the primary factors if a given Diabolo pellet can handle the a speed. Haven’t tested everything out there. But, I can say H&N Sniper Magnums, and Domed Barracudas performed on par with JSB Heavies.

 

[intenseaty22]

That’s some serious power, accuracy, and shooting. Glad you shared. It’s one reason I don’t think I need a .30. If a .25 is giving me almost as much power as a stock .30. My Cricket shoots the 34s at 925ish and at 45 yards it holds an excellent group. Surprisingly accurate with 26gr Polymags as well at 995fps!

At some point during my Wildcat ordeal I tuned the gun such that it was shooting the JSB 8.44gr pellets at around 975fps. At 30 yards it was a pin hole, no joke, 8 shots into a pin hole. So, the speed thing was debunked for me at that moment. Problem was, that tune didn’t keep. It strayed off the next time and was a different POI and throwing flyers. In either case that’s just too hot for my little suburban yard. But would have made for a hell of a contender. 

 

[bandg]

I shoot a lot of AA 7.33 Falcons because several of my guns like them a lot. Upper 900's are no problem in those that will shoot that fast. Over 1000 has been very accurate in several. IMO it depends entirely on the pellet/gun combination and may be related to harmonics as much as anything else.

 

[Quad82]

Another very nice write-up. I enjoy seeing your shot target pictures and that my MK3 tunes almost match yours to a T. So I feel I did well. I did drop mine down to 910 for the 34s. I like the higher shot count for shooting strings or off the bench. But even 1 (16 shot) mag is enough for a squirrel hunt for me. That doesn’t mean I don’t fill my pockets with extra mags! Our limit is 5, so that gives me enough extra shots for a coon, crow or whatever I decide to take a poke at. I remember when I was a kid and my dad let me start using a 22 rimefire. The 5 squirrel limit was the same back then. I was given 5 shells for the day. Be it shotgun or 22. I believe that is what made me try to take only good shots. 

 

[Ranchibi]

Excellent write up by Joe as usual! I also found that my RAW LRT’s poly barrel likes speed as I de-tuned mine to shoot 18gr @ 950fps accurately. Saw a video where an Airgun Depot guy had success shooting a RAW .22 using 18gr @ 1050fps @ 100yds accurately. Shows speed and accuracy is barrel dependent for the most part all things being equal. Good time to be an Airgunner!

 

[JoeKool]

That’s some serious power, accuracy, and shooting. Glad you shared. It’s one reason I don’t think I need a .30. If a .25 is giving me almost as much power as a stock .30. My Cricket shoots the 34s at 925ish and at 45 yards it holds an excellent group. Surprisingly accurate with 26gr Polymags as well at 995fps!

At some point during my Wildcat ordeal I tuned the gun such that it was shooting the JSB 8.44gr pellets at around 975fps. At 30 yards it was a pin hole, no joke, 8 shots into a pin hole. So, the speed thing was debunked for me at that moment. Problem was, that tune didn’t keep. It strayed off the next time and was a different POI and throwing flyers. In either case that’s just too hot for my little suburban yard. But would have made for a hell of a contender.

Thanks intenseaty22!


None of my airguns where not without a problem or two, I’m just thankful that I was able to figure thinks out the majority of the time.


Happy air-gunning man!



Joe

I shoot a lot of AA 7.33 Falcons because several of my guns like them a lot. Upper 900's are no problem in those that will shoot that fast. Over 1000 has been very accurate in several. IMO it depends entirely on the pellet/gun combination and may be related to harmonics as much as anything else.

Many pellet/barrel combos can do just fine shooting 900 to 1000 fps. Not all, but many.. A good harmonic balanced tune and some quality ammo and people would be surprised.



Appreciate ya!

Another very nice write-up. I enjoy seeing your shot target pictures and that my MK3 tunes almost match yours to a T. So I feel I did well. I did drop mine down to 910 for the 34s. I like the higher shot count for shooting strings or off the bench. But even 1 (16 shot) mag is enough for a squirrel hunt for me. That doesn’t mean I don’t fill my pockets with extra mags! Our limit is 5, so that gives me enough extra shots for a coon, crow or whatever I decide to take a poke at. I remember when I was a kid and my dad let me start using a 22 rimefire. The 5 squirrel limit was the same back then. I was given 5 shells for the day. Be it shotgun or 22. I believe that is what made me try to take only good shots.

I has a similar childhood. Dad was like, you like the way I cook rabbit?? Well, go get us a few. The Wildcat MKIII is a great platform, really like mine, and no doubt more power requires more air.



Thank you,



Joe

Excellent write up by Joe as usual! I also found that my RAW LRT’s poly barrel likes speed as I de-tuned mine to shoot 18gr @ 950fps accurately. Saw a video where an Airgun Depot guy had success shooting a RAW .22 using 18gr @ 1050fps @ 100yds accurately. Shows speed and accuracy is barrel dependent for the most part all things being equal. Good time to be an Airgunner!

GOOD TIME TO BE A AIR-GUNNER!!


Have you made any post about your RAW? If so I missed them. I would be exited for a RAW bull-pup if they released one!




Keep doing your airgun thing buddy! 




KoolJoe

 

[Ranchibi]

Joe, I did a very brief one on GTA awhile back as the action is the same as all the HMx LRT's so it would have been redundant, most of it was on the new Chassis which just makes it lighter and AR furniture interchangeable. Basic simple guns nothing much to elaborate on that already has been said! Keep up the excellent mods and tunes for your awesome FX guns! Luv reading and learning anything PCP related and you do a great job of explaining all details and steps clearly, just like a book, my kind of learning!

 

[Khornet]

My Air Arms S500 .177 won't tolerate high speeds. 900 and up, whatever the projectile, is fair to poor at 30 yds. Once I stopped filling to 175-200 bar and used about 125, and closed the TP to about 50%, I began getting sub-0.4" 5-shot groups with my preferred hunting pellet, AA 10.3, at about 870 fps.

 

[bandg]

My Air Arms S500 .177 won't tolerate high speeds. 900 and up, whatever the projectile, is fair to poor at 30 yds. Once I stopped filling to 175-200 bar and used about 125, and closed the TP to about 50%, I began getting sub-0.4" 5-shot groups with my preferred hunting pellet, AA 10.3, at about 870 fps.

Seems some rifles will and some won't. Is it spin (too much or not enough), harmonics (more in some rifles as power rises compared to others) or a velocity limit factor? Seems if some rifles shoot accurately near (or above) 1000 fps with a given pellet then it could not be the latter for that same pellet in any rifle. Some specific to individual gun combination of barrel harmonics and spin may be the answer in many cases.