Speed of pellet Vs. ACCURACY!

[darticus]

My LP 10 and LP 1 shoot a pellet at about 540 ft/ sec. My Daisy 777 shoots at about 360 ft/sec. All three can hit the bull without a problem.I can see the pellet in travel from the Daisy and its very accurate. Is it better to be faster????

[pgfaini]

I don't know if pellet speed contributes to their accuracy, but I doubt your Daisy will, from a vise, put ten shots through a .25" hole from 10m., the way your Steyr's will.
Paul

[Richard H]

Its called lock time, with all things being equal a faster lock time is theoretically better (before the flames fly read the words). The less time the projectile stays in the gun after you pull the trigger the less influence you have on it. Unfortunately you can introduce other problems when you focus stricly on reduceing lock time, it has to be balanced with other factors.

[WaltherWill]

You don't have to worry about it with air rifles and pistols but .22 lr target ammos are ALL sub-sonic. Now under the sound barrier, I don't know what differences in speed would cause.

[pgfaini]

Its called lock time, with all things being equal a faster lock time is theoretically better (before the flames fly read the words). The less time the projectile stays in the gun after you pull the trigger the less influence you have on it. Unfortunately you can introduce other problems when you focus stricly on reduceing lock time, it has to be balanced with other factors.

Actually, it's called barrel time. Lock time is the time it takes from the trigger release, for a mainspring to fire the primer in a cartridge gun, or open the valve in a pneumatic. Ex: A Martini action with its light striker and heavy mainspring, has a much faster lock time than an old Sharps, with its heavy outside hammer. This, along with barrel time, reduces the effect of muzzle sway on accuracy.

Paul

[Fransms]

Yes, for sure speed has an effect on accuracy!!

That is why you get the speed measured when selecting pellets at e.g. H&N in Germany.

Actually, my LP10 did loose around 25 m/per second (close to 85 feet/second) and that did a big difference, maybe only in my head, but when I had it recalibrated, I found the accuracy to be back on track!!

So, if you sellect pellets, do not mess with the speed after the selection!!

[Hemmers]

I imagine it also depends whether the speed causes the air flow around the pellet to be laminar or turbulent flow. Different pellets with differently shaped heads/cross-sections that cause the air to be parted in different ways are, as noted above, going to have different optimum speeds, above and below which they could de-stabilise in flight.

[aurorapolice02_11]

25 m/s had much effect on accuracy and hardly enough to be noticed when shooting.

[David M]

Reading these posts it is fairly obvious that some of you have done no real testing of airpistols for accuracy or velocity.

I am only talking standard target air pellets here, the flat nosed shuttlecock shaped variety. There are two basic weights in these pellets (commonly known as rifle and pistol) and they are available in sizes from 4.48 to 4.51 mm (not all sizes in all brands).

First you match the weight of pellet to your pistol. Early spring and pump pistols use the lighter pistol pellets (as they don't have the energy to shoot the heavier pellet well). Pre compressed air pistols and CO2 pistols can use either weight but to get the best out of the pistol you must then alter the velocity to match the weight (the heavier pellet needs more power).

Now with reference to pre compressed air pistols only (99% of all pistols at World Cups), most pistols come out of the factory set between 150-160 m/s. The adjustment range of these pistols is usually between 130-165 m/s (adjusted by the compression of the hammer spring).

Testing is done in a machine rest with a chronograph, set up indoors with replaceable targets. Start with the light pellets, and shoot groups with all the sizes of pellets, to find the best group and best velocity MAD. This will give you a guide as to barrel diameter. You can also try (if you can strip the pistol to gain a rear inline access) pushing pellets down the barrel to feel resistance, fit and high or loose spots. Although, this is best left for the experts.

Repeat the above with the heavy pellets, noting group, MAD and velocity difference between pellets of the same diameter but different weight. I have found velocity differences of between 4-9 m/s (light to heavy).

Having selected the best choice so far for barrel fit and group (should be about 5.5 - 6mm group), now try varying the velocity up and down to see if the group changes with nodal variation (vibration frequency of the barrel). I found that small velocity changes can vary the group, in fact you may find more than one sweet spot or node between the highest and lowest velocity’s.

Remember that the higher velocities need more air, and this may alter the group between a full tank and a near empty tank (allow for at least 80-90 shots).

So my own results, a Morini 162 ei with a small tank, I shoot a R10 pistol pellet (4.49mm) at 144m/s, the machine group after three shots, the hole in the target will support a unfired pellet and stop it falling thru the hole.

To finish, use fresh shinny pellets (old dull pellets are hard and oxidized) and when you have found your best pellet buy 12 months supply of the same batch number. Next year, service your airpistol and re-test.

[David M]

One other thing I forgot to mention, Darticus, your Daisy shooting at 360 f/s might not have sufficent velocity for the electronic target. It may tear the backing strip badly. trapping pellets and jam the paper roll.

[bryan]

Hi david, so if the pellet is not making a clean hole in the std paper target, you are saying it wont register correctly on the electronic targets.
does it come up with an error, or does it give the wrong result?

I am using a spring gun fwb mod 65, that sometimes rips the target, big strip the size of the hole or more, push the flap back to see where the pellet hit! so this would be a problem.
it has a new spring, but old piston ring, not original though. using rifle pellets still. will check velocity. what is acceptable for electronics, what is the best outcome for mod 65.
will get a new piston ring, old one may be fine? and try some pistol pellets.

also found if you hold it tighter, it makes a better hole, doesnt rip as often.


also, are ca pistol regulators adjustable like rifle ones, if so dont touch it!

regards
bryan

[RobStubbs]

Hi david, so if the pellet is not making a clean hole in the std paper target, you are saying it wont register correctly on the electronic targets.
does it come up with an error, or does it give the wrong result?

To the best of my knowledge the electronics won't tell you there's a problem, you will just see ragged 'tears' and you may get equipment failures due to jamming. This is for Suis Ascor and I experienced such problems when my LP10 went under powered (although I don't recall any machine failures).

With the LP10 (and I imagine most others) you can turn up the velocity but you need to do so carefully with a chrono and make sure you don't lose accuracy. I returned mine for servicing after it dropped pressure a couple of times, just in case anything was wearing our.

Rob.

[bryan]

well crono said 130 mps with 4.49 rifle pellets, 130 with 4.5 pistol pellets, 120 with yellow top 4.5 rifle.
may be faster with 4.49 pistol pellets. expect it would.

what is normal for a mod 65?

no rest to check accuracy yet!

electronic targets, if the paper backer doesnt roll down, and you hit the last hole, you can get some odd results! if you rip target expect some odd results? might have to test it out!

bryan

[Spencer]

well crono said 130 mps with 4.49 rifle pellets, 130 with 4.5 pistol pellets, 120 with yellow top 4.5 rifle.

electronic targets, if the paper backer doesnt roll down, and you hit the last hole, you can get some odd results! if you rip target expect some odd results? might have to test it out!

bryan

Bryan,

at 130mps you should not be experiencing any tearing of the target with target pellets - what brand of targets are you using?

The 'problems' encountered with 10m electronic targets are invariably due to low velocity pellets causing a tear in the black target strip that then causes a jam in the feed system. Mis-feed of the strip can also arise from greasy material on the rubber roller (unusual, but can happen).
Effective range staff keep an eye on the feed of the strip.

As an aside, the constructing authority people for the Sydney Olympic range were going to run the 10m paper strips behind the target backstop to keep things looking 'neat'- we needed to see the strips so that we knew they were moving between shots.

Spencer

[bryan]

Targets? vapa ones?

since replacing the main spring it is tearing less, and getting better, but still not as good as a ca type pistol. I was suprised with the result, maybe it is the crono I used? maybe run a ca one through it to see what it reads.


I am keen to try it out at sydney some time, but rather not get there to find it is a problem.
I am more worried about shooting a snow ball, at least with paper targets it is gone pretty quick! lol

bryan

[John Ariani]

David M - when you post, you always do it in style.(not dissimiliar to the way you compete) Thank you for all that info. You've covered everything needed to know for inexperienced AP users, who like me, are always searching for some miraculous pellet speed that will 'guarentee' tens!!!!! There really are no questions left after reading all you had to say.
Now - if you could set out a post that details exactly what you are thinking/focusing on in those three to five seconds prior to shot realease (AP) and make it as clear as your 'velocity/accuracy' post - I'd be very content!!!!!!

[shadow]

Could we extend this topic to the 22LR? Is there an ideal fps for a free pistol? I have read with interest that CCI has a new ammo called Select Precision - 1,200 FPS and advertised for "The choice for competition shooters. At 1200 fps, this load was developed with reliability and accuracy, both key elements in competitive shooting. "

Any comments on 1,200 fps??

[Tim Conrad]

1200 fps will not work on electronic targets at 50 ft (NCAA Rifle, for example). Should not be a problem at 50 meters as the bullet will be subsonic by the time it hits the target. The lower speed 'sporter' airguns did not cause any scoring problems or unusual tearing on 10 meter electronic targets at the American Legion championship finals last year. The original Federal UM1 was slightly supersonic and shot quite well out of several guns, particularly Barcelona in '92.

Test it. If it works, use it.

Full disclosure: I'm the Technical Rep for Megalink Targets in the U.S.

[Stonewall]

I shoot .22 lr RWS HVHP in several rifles . This lot cronographs in my CIL 190 -model 64 at 1265 and groups as well as old Tenx.
In theory this should be a problem but it works.
Glenn

[Tim Conrad]

That's really the ultimate test. If it works, use it.

At 50 meters, we try to get 5-6 mm center to center, or under 12 mm outside to outside. For a ten shot group. I'm not a believer in 5 shot groups for ammo test. Other than old Federal UM1/1000A (slightly over 1100 fps), we've not seen any fast ammo that shoots well. For NCAA Rifle, the fast stuff doesn't register properly at 50 ft on electronic, no matter how well it groups.

Compressed air guns seem to run close to 600 fps, at least at our altitude, 6000 ft. With the right pellets, we can put ten shots in a target and still pick up a pellet with the fuzz around the edge of the hole. Under 0.5 mm center to center. Sometimes takes a while to find the right pellet, and a few guns never can do it. When it takes a 599 or 600 in prone or 399/400 (wm Air rifle) to win a gold medal, every little bit counts.

For ordinary shooters like me, it isn't that critical, although I did lose the iron aggregate at the State Prone Championship by a plugger. Had more X's, one point behind the winner. Would better ammo have helped ? Depending on where I broke the shot, might have made matters worse.