What are the largest diameter .177 pellets

[hmangphilly]

https://photos.app.goo.gl/tpdLyAwW6voL8ua5A

Thanks Lawrence .
What does this show ?

I see grooves formed by the lands in both the skirt and the head .
I do not see any sign of contact to the bore in the section between these grooves .
This is the part of the pellet that is believed to be blown out to make a seal with the bore . Not happening on this pellet , which looks like it has only been pushed / rodded through a barrel .

Ok found a couple pics of a fired and retrieved from down range pellet , i'll have to get help posting the images , but check the portion of pellet that is believed to be blown outwards and drag along the wall of the bore ......

[Lol Moore]

It shows a pellet that has been fired and clearly shows what was mentioned by chris and nurek...i.e. the pellet skirt expanding

No mention of the pellet sealing in the grooves, just expanding...not sure how you can say that pellet has been merely rodded?

Try this one for size

https://photos.app.goo.gl/zvz5gW6sVvQyGapw8

I followed your threads on the other channel with great interest but I think you have maybe read too much into the statements in this thread, I agree with almost all the conclusions you came to and admire the way you got there.

I was messing with barrel lead in shape after I had read the article where the photos came from.

[32:1]

I cant copy and paste Al's pic so heres a link, its the AGF on a thread called barrel polishing with solvo or something like that

https://www./community/index.php?att...dr-jpg.122248/




Chris

[hmangphilly]

It shows a pellet that has been fired and clearly shows what was mentioned by chris and nurek...i.e. the pellet skirt expanding

No mention of the pellet sealing in the grooves, just expanding...not sure how you can say that pellet has been merely rodded?

Try this one for size

https://photos.app.goo.gl/zvz5gW6sVvQyGapw8

I followed your threads on the other channel with great interest but I think you have maybe read too much into the statements in this thread, I agree with almost all the conclusions you came to and admire the way you got there.

I was messing with barrel lead in shape after I had read the article where the photos came from.

You could be right Lawrence .

I've just re-read my thread on the other site .

You're also correct in that i cant possibly tell that the pictured pellet has not been fired .
If it has then hats off to the contributor for capturing the pellet in such condition .

[bucketboy]

It a simple matter of physics, you need to apply a energy to get the pellet up to speed. The faster you want the pellet to go the more energy is required. Even at 12fte the amount of force required to push the pellet up to speed in the length of the barrel is not inconsiderable.

I takes very little effort to flatten the skirt of a pellet between your fingers, it takes much more effort to stop the air coming out ot the barrel by clamping your thumb over the end (don’t, it hurts) it stands to reason that if the discharge of air hitting the back of the pellet is enough to do damage to your thumb it’s enough to do damage to the pellet.

Bb

[Lol Moore]

You could be right Lawrence .

I've just re-read my thread on the other site .

You're also correct in that i cant possibly tell that the pictured pellet has not been fired .
If it has then hats off to the contributor for capturing the pellet in such condition .

Phillip....my name is Lol....confusing in this day of text speak I know

I think we are interpreting the picture differently, its two of the same type pellet, to my eye the skirt of the "fired" pellet has indeed expanded (it looks more rounded) as you say a very good job of capturing has been done. If you cover the bottom quarter of the skirt and just look at the top portion of the skirt it does look different.

This was not intended to join into the debate about whether pellets sealed completely in the grooves of rifling, it just shows that the pellet skirt deforms (as stated by a few on here) and as such the deformation will effect the pellet flight, which is ultimately what counts.

Before all your testing I believed that sealing was probably the case - not so sure now.

I agree there appears to be no evidence on this picture of "sealing".

Anyway, the article is by Hector Medina in the states, he writes some really interesting stuff (as do you ), here is the article:

https://www.ctcustomairguns.com/hect...to-the-rifling

The bit that caught my eye and set me off messing with breeches was this:

Careful experiments have shown that pellets DO DEFORM upon firing. And one of my preferred methods of choosing the best possible pellet for a barrel involves soft-capturing fired pellets and measuring how much they expand at the waist or the column. The more they expand, the less are we in control of the final shape of the pellet once we have pulled the trigger.
Once the pellet starts to move, depending on how the chamber was machined (or not), the head engages the rifling before the skirt and this also exerts a TORSIONAL stress on the waist or the column. At times, this stress may be enough to deform the pellet substantially, in most cases it is not, but it is still mentioned here to point out to problematic barrels that, in reality, need only to have their chambers fitted to the pellet the shooter wants to use.

Great believer in the importance of the skirt - how good do these Qiang Yuan bad boys look

https://photos.app.goo.gl/QXwKC4TaERJgQKxA6

One or two tiny nicks in there but easily fixable on the pellet tin lid with a rub

[RobF]

Phillip....my name is Lol....confusing in this day of text speak I know

I think we are interpreting the picture differently, its two of the same type pellet, to my eye the skirt of the "fired" pellet has indeed expanded (it looks more rounded) as you say a very good job of capturing has been done. If you cover the bottom quarter of the skirt and just look at the top portion of the skirt it does look different.

This was not intended to join into the debate about whether pellets sealed completely in the grooves of rifling, it just shows that the pellet skirt deforms (as stated by a few on here) and as such the deformation will effect the pellet flight, which is ultimately what counts.

Before all your testing I believed that sealing was probably the case - not so sure now.

I agree there appears to be no evidence on this picture of "sealing".

Anyway, the article is by Hector Medina in the states, he writes some really interesting stuff (as do you ), here is the article:

https://www.ctcustomairguns.com/hect...to-the-rifling

The bit that caught my eye and set me off messing with breeches was this:

Careful experiments have shown that pellets DO DEFORM upon firing. And one of my preferred methods of choosing the best possible pellet for a barrel involves soft-capturing fired pellets and measuring how much they expand at the waist or the column. The more they expand, the less are we in control of the final shape of the pellet once we have pulled the trigger.
Once the pellet starts to move, depending on how the chamber was machined (or not), the head engages the rifling before the skirt and this also exerts a TORSIONAL stress on the waist or the column. At times, this stress may be enough to deform the pellet substantially, in most cases it is not, but it is still mentioned here to point out to problematic barrels that, in reality, need only to have their chambers fitted to the pellet the shooter wants to use.

Great believer in the importance of the skirt - how good do these Qiang Yuan bad boys look

https://photos.app.goo.gl/QXwKC4TaERJgQKxA6

One or two tiny nicks in there but easily fixable on the pellet tin lid with a rub

This bell shaping has been shown before. Unfortunately I believe it's caused by the rapid decelleration of the pellet. I don't know that though but capturing pellets at short range which went from 800fps to zero in a few feet caused showed enough force was still present about 2 feet in to imprint the texture of one of the baffle materials significantly in the head of the pellet in the lead. (it was a unique material at that depth so it was obvious where it came from).

Kevin Lewis did some experiments on this and found the bell shape was not so visible in pellets in flight.

One day I hope to be able to capture pellets at around 300 yards when they have considerably less energy to deform. If there's an obvious difference in shape between them and those captured by whatever method at short range then we could deduce it's the distance vs the method of capture which causes the shape and not the air pressure. If there isn't then it may hold true. Certainly at 50m there's a lot of energy left to do this but pellets we've captured don't always show bell shaping.

I might add that often people look for experiments in airgunning and draw a single conclusion that suits their theory after the experiment rather than listing other possibilities which don't.

Anyway Phil asked me to stick these up... he knows what they're from... I don't. To me there doesn't seem to be an equal expansion of the skirt. Dunno if it was indented deliberately, on or before impact, either.

[bucketboy]

If deceleration of the pellet from 800pfs to zero in two feet shows deformation of the head of the pellet then accelerating it from zero to 800fps in 16” must deform the skirt more.

Bb

[TenMetrePeter]

If deceleration of the pellet from 800pfs to zero in two feet shows deformation of the head of the pellet then accelerating it from zero to 800fps in 16” must deform the skirt more.

Bb

not to mention zero to 48,000 rpm in the same distance.
(Assuming 800 fps and 1 in 12 rifling)

[Rich]

If deceleration of the pellet from 800pfs to zero in two feet shows deformation of the head of the pellet then accelerating it from zero to 800fps in 16” must deform the skirt more.

Bb

Yup.

Force = mass x acceleration.

[Lol Moore]

....."Kevin Lewis did some experiments on this and found the bell shape was not so visible in pellets in flight."

https://photos.app.goo.gl/zvz5gW6sVvQyGapw8

Looks bell like to me.

As the original statements were not qualified i.e. the pellets bell from a low power pcp, then this picture surely proves that deformation of the skirt can occur in the barrel, wether it does for us low power pcp shooters is another matter.

Springer, PCP, low power, high power, breech shape, regulator/hammer balance, rifling or lack of, choke or lack of, pellet hardness, pellets sized.....lots of varibles that should all be included in any experiments if you want a definative answer.

From what I have READ I think belling can occur, as you have observed though not in every scenario.

The Cardews did a shed load of work on this (chapter 18 of Trigger to Target) as have several other American chaps I am yet to see one come to the conclusion that skirt deformation/expansion/belling of some kind does not occur, that aside from rifling marks.

I dont know how Hector caught his pellets but the Cardews used jelly - Lemon flavour I believe

[RobF]

If deceleration of the pellet from 800pfs to zero in two feet shows deformation of the head of the pellet then accelerating it from zero to 800fps in 16” must deform the skirt more.

Bb

Not necessarily. Think of a car. If you do 0-60 in 5 secs and 60-0 in 5 nothing happens. But drive it into a load of soft air bags that do the same deceleration and you will see compression on the front.

In addition stretch isn’t the same as compression and certain shapes are better one way than another. Think like a submarine. Very good at withstanding huge pressure from outside, from inside not so much.