TargetTalk

RE: air pistol velocity

Does anyone have any FACTUAL data on this. I figure opinions are like ......

Rover wrote:Does anyone have any FACTUAL data on this.

FACT - changing the velocity will change the accuracy of a given gun/pellet combination.

FACT - A given pellet in two guns of the same type might be more accurate at different velocities in the two guns.

You might not find too much in the way of hard data on this. As you well know, when adjusting the velocity to give the best accuracy the actual velocity readings are pretty meaningless, it's group size that counts.

Check last image and description
http://www.pilkguns.com/mako.htm

David,
I knew from my own testing that group size would change with velocity, but hoped I would be able to spot a trend with more information.

BTW Did you notice in MAKO's testing

http://www.pilkguns.com/mako.htm

the excellent performance of the low priced GECO (now Diabalo Basic) pellets.

Confirms what I've been saying...you need to test them to find the best and not believe someone's hype.

Rover wrote:David,
BTW Did you notice in MAKO's testing

http://www.pilkguns.com/mako.htm

the excellent performance of the low priced GECO (now Diabalo Basic) pellets.

Confirms what I've been saying...you need to test them to find the best and not believe someone's hype.

What I did notice was that in both runs the Vogel Match pellets produced nice groups (I'd be happy shooting with them) for all 3 sizes, 4.49, 4.495 & 4.5.

According to normal pellet testing theory, that shouldn't have happened.

David Levene wrote:
What I did notice was that in both runs the Vogel Match pellets produced nice groups (I'd be happy shooting with them) for all 3 sizes, 4.49, 4.495 & 4.5.

According to normal pellet testing theory, that shouldn't have happened.

2 points to consider - 1) very small group size, n=5 is not enough to gauge variability. and 2) They pellet sizes were a very small range - you'd typically test 4.48 - 4.52 before honing in on the best. So if for example that gun favoured 4.495 then the high and low samples were only 0.005mm different from that - and again very small group size could well be masking what's actually happening.

Rob.

Most of the air pistol manufacturers provide a test group for the pistol. Often they mention the size of pellet that has been used. That should save some of the testing. Then, if it is possible to adjust the muzzle velocity, carry out some carefully controlled tests with the pistol in a suitable "clamp". Small adjustments to the muzzle velocity will make corresponding differing strike position and group sizes. Careful adjustment and analysis will help you to decide which pellet, in your opinion creates the best group size from the "clamp".
There are some thoughts that when the pistol is in the hand, slightly different results are obtained as the reaction of the "recoilless" pistol is minutely dampened when compared to being in the test rig.
The main object of the exercise is to re-assure yourself that you are shooting with the most consistent pellet/muzzle velocity combination. This should be a great boost to your self confidence, but at the same time may actually highlight that if you have eliminated the pellet "error", you will need to look elsewhere for the reasons/causes of the next "bad" shot.
If you take a look at www.tenrings.co.uk you can see some fairly simple results from such an exercise.

Thanks John! That's the kind of stuff I'm looking for. I just wish the groups had more shots in them.

Rover,
The groups were of 10 shots for each test. It was felt that this was a good representative sample and that very little extra data would have been obtained by firing more shots in each sample. There was the added concern that the rig would have to be dismounted to change the cylinder and it might not have been practical to get the best alignment on the target.