What are the largest diameter .177 pellets

[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

[TenMetrePeter]

just shoot straight up, wait, then catch it in your hat

[Lol Moore]

just shoot straight up, wait, then catch it in your hat

Just looking at that, way too complicated for me to calculate but Googling bullets seems they would come down at around 300ft/s, so about 1.5fpe for a run of the mill pellet.....like firing it 300 yards and catching maybe Rob

Would need an awfully big hat though

[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.

[RobF]

Just looking at that, way too complicated for me to calculate but Googling bullets seems they would come down at around 300ft/s, so about 1.5fpe for a run of the mill pellet.....like firing it 300 yards and catching maybe Rob

Would need an awfully big hat though

Yeh I’m not about to try and catch a pellet at 300 yds even at 1.5 ft-lb because something that has the weight of 1.5 lb being dropped a foot but the frontal area of a blunt 6” nail is still going to smart a bit.

I’ll see if we can get it into something soft and deep.

[Lol Moore]

Yeh I’m not about to try and catch a pellet at 300 yds even at 1.5 ft-lb because something that has the weight of 1.5 lb being dropped a foot but the frontal area of a blunt 6” nail is still going to smart a bit.

I’ll see if we can get it into something soft and deep.

Mmmmm soft and deep?.

Dont airsoft guys shoot each oher every week at these power levels.....bonkers

On the observed deformation of pellets that have been caught, my first instinct is for any belling to have happened at capture is unlikely without lots of other damage...what I mean is the head stops and the skirt carries on enough to deform it outwards...there is very little weight in the skirt in comparison to the main body/head of a pellet so the skirt in isolation would carry little momentum.

Surely much more likely belling occurs in the breech area where rapid acceleration and heat are applied.

Now the nub, would it not be more likely for belling to happen with a pellet that seals well at the breech area, and does this mean that pellet shoots better because of that, or would a poorly sealing and so less belled pellet shoot better because its less deformed?

I was curious so just roughly cut the skirt off a JSB exact and weighed the two parts, skirt weight 2.7gr, head 5.8gr.

[RobF]

Have a watch of the slow motion vids of pellets hitting things. You’ll see the skirt carry on like it is unaware the head has it anything. It acts almost like a liquid.

[bucketboy]

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.

.

Wrong, push the car from 0-60 in 5 seconds and the rear bumper will show sings of compression.

Bb

[RobF]

Wrong, push the car from 0-60 in 5 seconds and the rear bumper will show sings of compression.

Bb

True, but we're not pushing the just the bumper when we accelerate a pellet. The tail is the wider part of a pellet, not a head, the tail offers the resistance not the head. If anything you could argue by the same theory the skirt should stretch as it's fired as the head pulls the pellet away from the skirt.

Have a look at this :

https://www.youtube.com/watch?v=K4FK_GiFBCg

At 1.40 you can see a pellet deforming as it hits something. Despite the poor quality you can see how there isn't an obvious bell shaping compared to when it hits. Then skip to 2.50 when the pellet is split by a razor and you can see straight edges of the tail. It's not belled pretty clearly. Yet when it hits something solid at 3:00 it bells again.

[RobF]

Kev had to drop the speed down to capture pellets well...

https://photosbykev.deviantart.com/a...ning-135418637

https://orig00.deviantart.net/f11a/f...y_kevlewis.jpg

No belling, but then it's only 85 fps so inconclusive.

https://www.telegraph.co.uk/news/pic....html?image=15

Not sure what speed that is. But you can see belling on other pellets when they have hit more solid targets.

[bucketboy]

Kev had to drop the speed down to capture pellets well...

https://photosbykev.deviantart.com/a...ning-135418637

https://orig00.deviantart.net/f11a/f...y_kevlewis.jpg

No belling, but then it's only 85 fps so inconclusive.

https://www.telegraph.co.uk/news/pic....html?image=15

Not sure what speed that is. But you can see belling on other pellets when they have hit more solid targets.

Seriously, this is a wind up surely?

A pellet traveling at 85fps has 100 times less energy that one traveling at 850fps, it takes 100 times less energy to get it to 85fte, little wonder the pellet shows no sign of belling.

I don’t know what pellets you use but every pellet I have seen the skirt has less material than the head.
Also, the only way a pellet can stretch is if it is sucked out of the barrel, dont know of any vacuum airguns.

Bb

[Lol Moore]

True, but we're not pushing the just the bumper when we accelerate a pellet. The tail is the wider part of a pellet, not a head, the tail offers the resistance not the head. If anything you could argue by the same theory the skirt should stretch as it's fired as the head pulls the pellet away from the skirt.

Have a look at this :

https://www.youtube.com/watch?v=K4FK_GiFBCg

At 1.40 you can see a pellet deforming as it hits something. Despite the poor quality you can see how there isn't an obvious bell shaping compared to when it hits. Then skip to 2.50 when the pellet is split by a razor and you can see straight edges of the tail. It's not belled pretty clearly. Yet when it hits something solid at 3:00 it bells again.

Nice find, some very cool images.

But back to the photos I linked, the pellet that is claimed to have been shot and to my eye shows some skirt belling has no visible head damage so if it belled at impact it must have been stopped in some way that was gentle enough to reduce head deformation, unlike the ones which are shown stopped and the skirt bells in that moment, but at he same time the head is destroyed!

Also doesn't explain the pellet shown in flight that has clearly been belled in the barrel ...albeit probably at high energy levels.

Its all so interesting but academic, as target precision/accuacy is what counts, it would be nice to know which factors effect that in rifle/pellet combo's....this may be part of that jigsaw but other than machining the breech and lead in to suit the pellet I am not sure how we could use the knowledge?

[ballisticboy]

Just looking at that, way too complicated for me to calculate but Googling bullets seems they would come down at around 300ft/s, so about 1.5fpe for a run of the mill pellet.....like firing it 300 yards and catching maybe Rob

Would need an awfully big hat though

Vertical fire is a standard method for testing large calibre (105 to 155mm) shells when you don't want to damage the front of the shell since when it comes back down it comes back down backwards. The shells land in soft ground which decelerates the shell slower than the shell accelerates in the barrel Thus any deformation at the front of the shell or internally has been caused by the barrel acceleration, not the shell being stopped. The landing point is calculated before firing based on measured wind so that the shell lands in the range when the gun is pointed slightly upwind. The calculation does not always work though and shells have been known to land on the other side of the main road. The tops of the buildings on the range have a very thick roof.
If you measure the wind you could fire your airgun slightly upwind and then catch the pellet in a bath of water or something as it come back down backwards but I wouldn't like to be the one to try it as it may take more than a few goes to get it right.
The Cardews photographed pellets in flight with distorted flares about 30 years ago.

[RobF]

Seriously, this is a wind up surely?

A pellet traveling at 85fps has 100 times less energy that one traveling at 850fps, it takes 100 times less energy to get it to 85fte, little wonder the pellet shows no sign of belling.

I don’t know what pellets you use but every pellet I have seen the skirt has less material than the head.
Also, the only way a pellet can stretch is if it is sucked out of the barrel, dont know of any vacuum airguns.

Bb

Well we know pellets can stretch because we've measured them. The tail gets swaged along the rifling. It only happens to the parts in contact with the rifling, not all the tail, because now we know pellets don't seal completely (in pcp's anyway).

I'll see if I can capture one as Ballisticboy suggests.