Damaged Skirt Pellet Testing

Thank you for doing that testing, that exact task was on my to do list this summer. I’ve considered making tooling to reform damaged skirts.
Randy

I imagine if you damage the skirts and the head (just a little) the results would be yet another step worse.

I'm thinking of a head scratch that would damage the seal in the barrel.

I suppose it makes sense that, on skirted pellets, if it doesn’t have a 360 sealing ring at the skirt it would be like a damaged crown on the barrel at the moment of exit from barrel.

Makes sense that the damaged skirt pellets get worse accuracy but are not as bad as we would initially suspect. The JSBs are very soft and even with a damaged skirt there is some expansion of the skirt taking place during the shot cycle, especially with springers. What would be interesting is to do a before and after by catching the pellets and comparing how much the skirt re-formed back to normal.

-Marty

Maybe next time see if you can capture some of the damaged skirt pellets in a foam backing if possible and see if they opened up to something closer to round.
Be interesting for sure.
jking

A recent posting by Heinz Reinkemeier at is video of a similar extensive controlled damaged pellet test, specifically for 10m precision shooters. Similar results were obtained.

He has many videos on all phases of precision airgun shooting.

JE

I too have had a bunch of pellets with bent skirts. In the past, I would just toss them in the trash, but the last batch that I got had nearly 10% of the pellets that had small issues at least. I didn't want to toss 50 pellets in a tin, so I have been firing them lately at the cans on my range, and I didn't notice a remarkable difference in the performance...especially not to justify throwing the pellets away. I did a test myself of "good" pellets versus those with bent skirts at 50 yards. Here is a video of the test:

Just to note, here are the pellets with good skirts:


Here are the pellets with bent skirts that I shot:


Here is a picture of the final results:


I got a very slightly better center-to-center grouping from the bent pellets than the good pellets. I got 1.125" spread on the good pellets, and 1.0625" on the bent pellets. The most notable thing is that the POI was pretty consistently shifted low and to the right.

Believe it or not, I didn't notice a remarkable difference in the velocity between the bent pellets and the "good" ones. I expected the velocity to be lower with the bent skirts, and that wasn't the case.

I wouldn't want to shoot these at a competition, especially at the BenchRest, but for plinking, they may through off your POI a bit, but there is no reason to trash these if you are just shooting for your own pleasure. I thought they would be WAY off, but this is not the case.

I hope that this is interesting to my airgunning brothers and sisters.

Cheers!

Jonathan

The concentricity of the head to the skirt IMO is the random flier issue. For the competitions we evaluate and some weigh. I head size for big competitions. There is a new product about to be tested that allows you to check the concentricity of pellets. There was one posted on AGN back (https://www.airgunnation.com/thread...pellets-by-weight.1275719/page-6#post-1375207) a few months ago. The idea was refined and implemented into one-off machined carbide pieces that the tolerances check to .0000 so cross your fingers and stay tuned.

Accuracy is all that matters no matter what your shooting activity is. Throw out the stupid damaged pellets.

darylm said:

Accuracy is all that matters no matter what your shooting activity is. Throw out the stupid damaged pellets.

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I guess you missed my original comment. I used to throw away my pellets that had deformed skirts. I recently started shooting them for practice sessions since I had so many, and saw a minimal difference in accuracy. This is why I ran the test, as @Sqwirlfugger57 did. You can see the pellets clearly before and the accuracy after shooting. They were jacked up before shooting, and somehow managed to group about the same. The POI changed, but that is up for discussion.

jking said:

Maybe next time see if you can capture some of the damaged skirt pellets in a foam backing if possible and see if they opened up to something closer to round.
Be interesting for sure.

Click to expand...

This is definitely the missing piece of data in this experiment. I feel pretty strongly that the skirts will be "fixed" by the pressure and rifling. The pellets consistently gave right at 26FPE whether the skirts were perfect or deformed.

Sqwirlfugger57 said:

I also want to retry the test with pellets like H&N and CPs to see how harder skirts react in the same scenario.

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I shoot H&N Baracuda in competition for one reason is because I never get the skirt issues that I do with JSB. Perhaps I will deform some on purpose and see what happens.

I forgot to mention. On shot #7 on my "Good" pellets, and shot #8 on my "bent skirt" pellets were obviously "fliers" from the point of the gun. The gun sounded weird for each of those shots, and it never does that. The only thing that I can figure is that some moisture started freezing in my gun for those shots. It was 20F at the time of shooting, and at that point my gun was outside for the better part of 30 minutes so this is the only thing that makes sense. This gun really never has fliers.

Anyway, I thought I should mention that.

Another issue that's relevant is your damaged pellets, once they've been extruded through your barrel will be deformed yet-again. I imagine much of your damage will be erased by this process. Perhaps if you fire them at slow velocity into a gelatin you could check to see the extent to which your pellets are "corrected" via the barrel extrusion.

I had this thought because I had a garden hose reel explode -- I did not winterize it properly. It exploded at an o-ring junction, with some relatively thin stamped steel. The steel was badly deformed. I wasn't sure if I could get it back into shape. After a little hammering on it with a brass mallet, to get the rough shape correct, to my surprise the internal stresses of the steel forced the entire thing into its original shape.

SkeeterHawk said:

I guess you missed my original comment. I used to throw away my pellets that had deformed skirts. I recently started shooting them for practice sessions since I had so many, and saw a minimal difference in accuracy. This is why I ran the test, as @Sqwirlfugger57 did. You can see the pellets clearly before and the accuracy after shooting. They were jacked up before shooting, and somehow managed to group about the same. The POI changed, but that is up for discussion.


This is definitely the missing piece of data in this experiment. I feel pretty strongly that the skirts will be "fixed" by the pressure and rifling. The pellets consistently gave right at 26FPE whether the skirts were perfect or deformed.


I shoot H&N Baracuda in competition for one reason is because I never get the skirt issues that I do with JSB. Perhaps I will deform some on purpose and see what happens.

Click to expand...

If you have that many bent pellets then you need to get them from a different distributor.

This has come up many more times than I can count or find the posts... (grin)

However, one thought I have always had, but never tested and nobody testing bent skirts has addressed is:

Drum Roll...

Does the actual pressure make any difference in opening up the skirt and making it fly straight or is even the lowest pressure simply enough to open up the skirt, say with a 12fpe or less gun? This may be pellet dependent and may depend on the alloys/or none present in the lead of any given pellet. Pure lead being softer, I would venture to say that those pellets will flare the skirt with less pressure, but then again I am just guessing. (smile)

Just a thought for this discussion..

Sqwirlfugger57 said:

View attachment 270930

Got bored and decided to run a quick test to see the effects of damaged skirts on accuracy. I was honestly a little surprised with the results.

Undamaged Pellets Groups:

View attachment 270927

The picture above shows two seperate 10x shot groups taken at 30m. The group on the left is just 10 pellets pulled at random from the tin and sent down range. The group measured 0.395" CTC.

The group on the right is with 10 pellets pulled from the tin but each skirt was examined for any defects. If none were found, they were sent towards the target. That group measured 0.318". Pretty solid improvement if you ask me.

Damaged Pellets Group:

View attachment 270928

Here is where it gets interesting for me though. Picture #3 was 10 shots with more than just a little skirt damage. You can get a rough idea of what these pellets looked like from the first picture. One of these pellets had both sides of the skirt literally touching in the center. I was expecting an 1.5"+ from this group. What I got was 0.621".... I can live with that any day of the week.

I guess what I learned is that I shouldn't waste "bad" pellets. I wouldn't use them for hunting or in a match but for plinking? All day.

Click to expand...

Interesting Test! Appreciate the time to share it with us.