Pellet Damage Effect on Accuracy

[Mcameron]

We all know that a pellet with a damaged skirt will effect accuracy, what i wanted to test was exactly how much will it effect your shooting and if it will produce any noticeable effects. bellow is a small study i did to test just that. now i dont have access to a state-o-the-art shooting facility or equipment, but i feel i did a good job of reducing as many variables as possible that would effect the outcome of the results.



Pellet Deformation on Accuracy


Objective:
To determine the effects ( if any) of that of damaged pellets on the accuracy of an air rifle.

Procedure:
1.Fire a course of 5 “Clean” pellets into a standard AR-5 target from bench position
2.Fire another course of pellets into a new AR-5 target this time with “ Damaged” pellets from bench position
3.Repeat steps 1 and 2 until a total of 25 pellets from each group ( or a total of 50 pellets) had been fired
4.Score as accurately as possible all 10 targets using the standard scoring method
5.Calculate the average score for each pellet group
6.Calculate the Standard Deviation for each pellet group
7.Calculate the Percent Change

Equipment:
Gamo BigCat 1200 (stock)
.177 RWS Meisterkulgen (8.2 grain)
AR-5 target @ 10 meters

Data:



Clean Pellet
Score:

33/50
30/50
38/50
36/50
36/50

Avg = 34.6/50
St. Dev. = 2.8



Damaged Pellet
Score:

32/50
35/50
25/50
35/50
29/50
Avg = 31.2
St. Dev. = 3.8



Percent Difference = 9.8%

Conclusion:
From the data obtained, there is a 9.8% reduction in Accuracy when shooting “damaged “ pellets over “clean” pellets.

Given that both sets of shots were performed by the same shooter with no change to equipment, the variables of Shooter and equipment performance are greatly negated and are considered nullified for the purposes of this experiment.





Other:

Example of a Damaged Pellet used for testing



Example of a Clean pellet used for testing









An additional 40 shots were taken at a distance of 30 meters to show the spread of the pellets at a longer distance ***






one thing that i was not expecting was how well the damaged pellets grouped together, i was expecting them to scatter all over the target however they seemed to shoot very consistently and group nicely towards the bottom of the target.

[NB]

I dont think I have ever shot a pellet THAT damaged in a match. Point 1 could you do it again with pellets in a little better condition? Point 2 . Most important (I think) Was it a blind test? Did someone give you the pellets to shoot without you knowing which was which? I believe the test would be TOTALLY void if you knew when you where shooting bad pellets. Unless it was done in a clamped down gun. Great job ! I just thought I would throw in my point of view. P.S. If I ever shot a damaged pellet in a match it would have damage just to the point that I could not see(at a glance) or feel the damage. I do not really inspect all my pellets LOOKING for damage. I have yet to find a pellet in a tin that I would not shot in a match, but am sure it happens. From now on I will be thinking about it more and will be more likly to someday find a bad pellet. Thanks for an interesting post NB.

[Makris D. G.]

While interesting, and a job well done :) the Big Cat is a powerful hunting style springer, not a particularly consistent rifle.
Also, the best course of action when in a match, is to just discard any suspect pellets, the cost is minimal and it is not so much the bad pellet that will effect the shot, as is the moment of doubt while executing the shot.

[NB]

Moment of doubt! its not there when you r shooting a good pellet. Its always there when shooting a bad pellet. And now if I dont check my pellets it will be in my mind. What am i doing messing myself up. Someday when I throw out a bad pellet i will thank you. NB.

[Guest]

"I dont think I have ever shot a pellet THAT damaged in a match. Point 1 could you do it again with pellets in a little better condition?"

the reason i used pellets that were so damaged was to convey the worst possible situation, the damage of the pellets throughout the testing varied from moderate to severe.

"Point 2 . Most important (I think) Was it a blind test? Did someone give you the pellets to shoot without you knowing which was which? I believe the test would be TOTALLY void if you knew when you where shooting bad pellets"

well the thing is, i actually went into this experiment trying to prove that there was no discernible difference between damaged and clean, so if there was any bias shooting, it would not be reflected in the scores of the damaged pellets.

"the Big Cat is a powerful hunting style springer, not a particularly consistent rifle."

while true the Big cat is not an ideal rifle for this experiment, it is the only rifle that i had available that would shoot consistently at 30+ meters, which is actually where i started my experiment with.....when moved to 10 meters, i stuck with the bigcat because my other rifle(IZH61) is clip fed and i feared loading errors with the damaged skirts.

the fact is its not really about the accuracy of the rifle that is important, it is the change in accuracy between pellets that i was looking for.



again, this is not a definitive experiment, a number of factors come into play as im sure you all know. i can also assure you this will not be my last look into this, as of right now i have a few ideas on a bench rig that will eliminate human error.

[Makris D. G.]

Correct, it is not about absolute but relative accuracy, but my comment was about consistency. A powerful springer will not vibrate identically each time it is shot. But I concede that you still got valid data.

[David M]

Hate to throw a spanner in the works, but unless you carry this test out using
a machine rest the results will be meaning less.
Your undamaged pellet test should be giving you one hole groups.
A quality target pistol in a machine rest with match pellets will shoot a hole not exceeding two pellet diameters 9mm (usually less than 6mm).
If it is greater than this there is something wrong.
Also if the pistol uses a breech with a loading rod (ie Morini) the deformed pellet will be reformed/reshaped in the chamber when loaded.

[vin]

Great work!
I would not have guessed the results for the 30m test.
The 10m test is also interesting.

BTW, this is not true:

I believe the test would be TOTALLY void if you knew when you where shooting bad pellets. Unless it was done in a clamped down gun.

A test may be flawed without it's confidence level going to zero.

[Mcameron]

"Hate to throw a spanner in the works, but unless you carry this test out using
a machine rest the results will be meaning less.
Your undamaged pellet test should be giving you one hole groups. "

well yes, if everything was shot perfectly they should be one hole groups, but like i said before, its not an ideal target rifle and im not an ideal shot...but it isnt crucial for what i have done here to have 1 hole groups....

the fact is, that target for target, the clean pellets are scoring significantly higher than the damaged pellets are

"I would not have guessed the results for the 30m test."

neither did i, i was expecting there to be pellets all over place, especially at that range, but they seemed to group very well( albeit they were a tad off target)....its caused me to think that there might be something interesting going on there...


again, take from this what you will...im not saying that this is definitive, but it sort of gives you an idea of what is going on

[Rover]

I wouldn't put too much stock in anything you've tested because your accuracy really sucks!

At 10 meters you should have one ragged hole. Perhaps not the tiny hole the match guns produce, but still one hole.

The spring guns are difficult because nothing else requires the shooting technique they do.

What you need is a completely relaxed hold, letting the gun go where it pleases. Everything must be exactly as the previous shot.

They drive me nuts, but I still have four of them.

[vin]

Even with convoluting factors the results are interesting, especially the 30m results... hard to argue with them...

[pilkguns]

I have to agree that this not really a valid test. As stated, at 10 meters with a match rifle in a rest with 10 shots you would have one hole, of 8mm or less size.

with scrunched skirst as shown, you would normally still have one hole, of 10mm or less.. (bearing in mind the 10 ring is 9.5 mm)

Match pellets in a high power springer would not do well at longer distances, because they are too light for the speed they are being shot at.

[Mcameron]

I wouldn't put too much stock in anything you've tested because your accuracy really sucks!

i would just like to say, that with the recoil and the ungodly trigger pull, this gun is really difficult to shoot....

i know ideally there would be a one hole group, but the fact is that the scores for the clean pellets were consistently higher...

what i was measuring wasnt the overall accuracy, i was measuring the change in accuracy......so i could have shot 6" groups with clean pellets so long as they were consistent and there is a noticeable difference between the damaged pellets


weather permitting i will give this another go with the rifle i do actually shoot 10 meter with if you would like

[Makris D. G.]

(bearing in mind the 10 ring is 9.5 mm)

Which air rifle discipline uses this target?
I only know the ISSF targets, you seem to have more variations in the US.
Or you mean that a 9,5mm hole is still all 10s, meaning 0,5mm for the 10 ring plus two pellet diameters?

[Spencer]

...Or you mean that a 9,5mm hole is still all 10s, meaning 0,5mm for the 10 ring plus two pellet diameters?

You have answered your own question

[robf]

HW97k springer, sitting position 25m indoors, 6 shots (1st for placement)

when the precision of the group is low, the statistical error becomes too big to draw logical conclusions.

the group doesn't need to be accurate, just precise.

that said, at longer ranges, say at 50m pellet problems become more apparent, but as posted, if they aren't one holing at 10m, something is wrong somewhere to start with.

[vin]

Before you start conducting research, learn how to shoot.

You're putting the cart before the horse

I would have more respect for this statement if it was not posted anonymously.

Vin Livieratos

[Makris D. G.]

Before you start conducting research, learn how to shoot.

You're putting the cart before the horse

I would have more respect for this statement if it was not posted anonymously.

Vin Livieratos

I would still have no respect for a comment that is impolite
and provides no useful input to the discussion.

[vin]

Of course you're right Makris.
I should have said so.
Vin

[GTFS]

The size of the groups of Mcameron is not important but the % size of difference between the groups that is the important thing.

Mcameron’s test shows a 9.8% increase in group size with damaged pellets.

Pilkguns test shows only a 2mm difference between clean pellets groups and damaged pellets groups. But that is a difference of 25%.

I am thinking 10 what are you thinking?

Glen Turner