Air Pistol pellet weight.

[Denis]

Please assume 500 fps in this discussion.
Light (pistol figure on tin) pellet weight 0.47 grams.
Heavy (rifle figure on tin) pellet weight 0.53 grams.

Has been said on various websites to ignore this and use heavy pellets in modern pistols as the light ones were for older, slower pistols.

Here's the question, the light pellet is about 12% lighter.
Assuming the velocity is adjusted to the same fps (500) there would be 12% less air used and 12% less felt movement /recoil.
In a game where the trend is to minimise pistol movement, is the light pellet the only way to go?

[Axel]

I have tested both rifle (heavy) and pistol (light) pellets in my Steyr LP10 and didn't notice any difference at all. IMHO, there are no real world difference between high quality brand pellets - they shoot the same and feels the same.

/Axel

[Fred]

Denis,

It is not correct to assume that using a 12% lighter pellet, with gun velocity adjusted accordingly, would result in using 12% less air or feeling 12% less recoil. For the former, think of what happens when the pellet weight is zero, i.e. no pellet. Does the gun therefore use no air? As to recoil, many factors are involved besides pellet weight, so that the felt difference is far less than the difference in projectile weight. Again, think of firing the gun without any pellet.

What I have been told, without any testable proof to back it up, is that the heavier pellets stabilize better in CA and CO2 guns, while the lighter pellets work better in low velocity pneumatics. While I haven't done any testing to verify this - basically I think it would be a waste of time - I have followed this advice. But I can't really say I have noticed any difference.

Fred

[Denis]

What I base my thinking on is something I was taught many years ago, if anyone can put me straight please do.
If you double the weight of something doing the same speed, you double the energy required to drive it. Vice versa.
For every action, there is an equal and opposite reaction.
The argument of using a pellet weighing zero is not a good example, try scoring with it!!

Axel, if you did'nt adjust the velocity back to the same figure they would feel the same. Same energy expelled.

[TomF]

Never mind the physics. If you are shooting at 10m, you can spit just about anything that will fly out of the front, and in most quality guns it will go thru the same hole if the gun is in a machine rest or held to the same point of impact.

My IZH, Morini, Anschutz, and Aeron really dont know what they are blowing out the muzzle. They all will shoot any make, weight, and form of .177 pellet, even placed in backward, mostly thru the same hole at 10m. Anschutz 2002ca and XS-B50 rifles will do the same.

I just wish I was good enough to extract that accuracy and place it in the X-ring.

Your mileage may vary.

Carry on!

[Tony C.]

Denis,

Here is another example why I think your reasoning is incorrect, lets say I'm driving my pickup with a 500lbs. load in the box for 50 miles @ 50mph. and used 5 gallons of gas, if I change the load to 400lbs. and driving at the same distance and speed, will I use 20% less gas? I don't think so, a load reduction of 100lbs. is rather insignificant compare with the weight of the pickup of several thousand lb. which require energy to propel.
By the same resoning, when compress air is expelled to shoot a pellet out of an airgun, most of the recoil energy was absorbed by the mass of the airgun which weight hundred of time heavier than the pellet, a tiny reduction of 12% of a fraction of a gram of pellet weight will had hardly any noticeable effect.

Tony

[Mark Briggs]

Denis,

In answer to your question, I can't feel any difference between shooting H&N Finale Match High Speed and H&N Finale Match Glatt (rifle) pellets from my pistols. These include CM162EI Short, LP-10P (air) and LP-1C (Co2).

What really makes a difference is group testing to find the pellet that works best with your individual pistol. I've found my CM162 and LP10 both prefer heavier pellets, while my LP-1 seems not to have a preference. The end result is that I purchased a case of H&N Finale Match Glatt pellets because they performed the best in all three pistols, and do well in my Walther rifle. Since I've purchased a case lot I don't need to worry about doing group testing for at least another year or two, and that lets me concentrate on shooting.

BTW - I've shot all of my pistols across a chronograph using both light and heavy pellets. My data collected to date reflects a velocity decrease of something like 4-5% when switching from H&N Finale Match High Speed to H&N Finale Match Glatt. They weigh 0.486grams/7.49grains and 0.507grams/7.83grains respectively. This also represents about a 5% change in mass. I haven't seen this same relationship established when testing using JSB Schak pellets weighing approximately 0.535grams/8.25grains, a 10% difference in mass from the High Speeds. In this case I've seen only a 7-8% change in velocity. But I still can't tell which one I'm shooting in the pistol based on perceived recoil. Some day I hope to get good enough to be able to tell the difference based on group size produced when I hand-hold the pistol!

The bottom line is that you're still far further ahead to spend your time training then to worry about the minutae of pellet selection. My experience has proven that even the pellets that group the best from a machine rest don't improve the amount of wobble in my hold!

[Denis]

Thanks for the comments, I think I'll make this my last as velocity point doesn't seem to be taken.

Thanks Mark for your technical data.

Tony C, you forgot to add the weight of the truck into your calculation.
2000+500=2500
2000+400=2400 only a 4% reduction, you have to power both on the trip.
The only thing powered is the pellet. The pistol doesn't travel to the target.

The only point I'm trying to make is that a gun adjusted to shoot heavy and light pellets at the same speed will have approx 12% less felt movement/recoil with the lights.
I'm not saying anything about accuracy.

Anyone agree? or are we not trying to look for any more technical advances, eg porting, shot compensaters etc. If the aim of the Manufactures is to have nil movement, why not try to do a bit ourselves?
Otherwise, sell the LP10 and buy a FWB 65 as they shot just as good.

[Guest]

But the gun wont shoot the different weight pellets at the same speed.

[Spencer C]

In a game where the trend is to minimise pistol movement, is the light pellet the only way to go?

Has everone else missed the original question?

Spencer C

[Pär Hylander]

.

The only point I'm trying to make is that a gun adjusted to shoot heavy and light pellets at the same speed will have approx 12% less felt movement/recoil with the lights.
I'm not saying anything about accuracy.

Anyone agree? or are we not trying to look for any more technical advances, eg porting, shot compensaters etc. If the aim of the Manufactures is to have nil movement, why not try to do a bit ourselves?
Otherwise, sell the LP10 and buy a FWB 65 as they shot just as good.

If you adjust the amount of released propellant gas the in order to reach tha same V0 for both the light and heavy pellet, the recoil will of course not be the same IMO. I have not analysed if the releationship i linear (eg if 10% heaver pellets create 10% more recoil) , but with those small changes it will probably be close to linear.

I think it is intrestening to have the system (pellet, pistol and shooter) to perform as good as possible. I think that the system might perform better with a pellet that leaves the barrel quicker (higher V0) even if recoil and grouping if tested in a vice is at bit less good, because a a pellet that has left the barrel can not be influenced by movement after the shot is released..... ;-)

[Andy Osborne]

Using a 2.2lb pistol adjusted to shoot both weight of pellet at 500fps.

pellet 1 at 7.48grains

Recoil Impule 0.0166 lb.sec
Recoil Velocity 0.2432 fps
Recoil Energy 0.0020 ft.lbs.

pellet 2 at 7.83 grains

Recoil Impule 0.0174 lb.sec
Recoil Velocity 0.2542 fps
Recoil Energy 0.0021 ft.lbs.

if anyone wants to post real life figures I'll recalculate

Andy

[Mark Briggs]

Hmmm, there have been some very interesting comments and some good theoretical math too! Wish I had access to those recoil equations so I could play with them myself for this and other types of guns. (Hint, hint, Andy! *grin*) It seems that for the pellet weights used there's a 4-5% change in recoil velocity and recoil energy to match the 4-5% change in pellet weight. It looks like Andy's math has proven a linear relationship as originally hypothesized by Denis.

Spencer - your point is well taken. Unfortunately the original question is anything but easy to answer, and this is primarily because of the large number of factors which impact accurate shooting. Pellet weight and any subsequent effect it has on recoil is balanced off against muzzle flip, compensator efficiency, match between any given pellet and the unique barrel bore of every pistol. I tried to summarize these effects by stating that none of them will likely produce a noticeable impact on match scores until the shooter is capable of producing a 10-ring hold and has perfect trigger technique.

Until we achieve near-perfect shooting capabilities we can likely get away with a sub-optimal pellet and not even notice the difference. As an additional case in point I can state that perceived recoil using my LP-10 is substantially less than what's felt with either the LP-1 or CM162. But in my hands I can't make the LP-10 group nearly as tightly as the other two pistols. All three pistols are technically excellent in terms of design and execution. This being the case we have to allow that human factors continue to exert greater influence on match scores than do minor technical points such as pellet weight. I don't think light pellets are "the only way to go", but rather are just one variable that needs to be factored into a multi-variable equation.

Par has made a good point about "barrel time", effectively stating that barrel time should be minimized in order to reduce the ability of shooter error to deflect a pellet before it leaves the barrel. At the same time he also very wisely refers to the "system" which includes not only the pistol and pellet but also the shooter. Once I again I would submit that striking a harmonious balance between these three elements is more important than focusing on only one of them (ie the pellet). If shorter barrel time produces increased muzzle flip which reduces the shooter's ability to "call" the shot then a negative influence is exterted on the shooters psyche; the likely result is reduced shooter confidence. If the same pistol/pellet combination is shot at a lower velocity (and longer barrel time) which allows the shooter to build better confidence in his or her ability then I would wager scores will increase as a factor of confidence, completely nullifying the argument in favour of shorter barrel time.

Yes, these are all good theoretical points, good things to be discussed and contemplated from a comfortable chair in front of the fireplace with a nice glass of brandy. When it comes to standing on the firing line and putting the lead in the X-ring I think we can all agree that ultimately it's the shooter that makes it happen.

[Andy Osborne]

Ok then,

I'll give you the full version that even accounts for some of the recoil due to air movement.

Keep in mind that
Mg*Vg = Mb*Vp + Ma*Va

I = (Mp*Vp+Ma*Va)/7000*g

Vg = g*I/Mg

Eg = Mg*Vg^2/2*g

Where:
Mp = Pellet mass in grains
Vp = Muzzle velocity in fps
Ma = Mass of the air charge used to propel the pellet in grains
Va = Velocity of the propellant in fps
I = Recoil impulse
Mg = Mass of the gun in lbs
Vg = Velocity of the gun in fps
Eg = Energy of the recoiling gun
7000 = Number of grains in a lb
g = 32.2 = acceleration due to gravity in fps

[Mark Briggs]

Oh, most excellent. Thank you, Andy!