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Pellet skirt width


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On the subject of heavier vs lighter pellets, I noticed a lighter pellet with a 5.55 skirt flew lower than a heavier pellet with a 5.52 skirt.

 

Obviously the wider skirt is a tighter fit but why the variation in skirt widths? What are the pros and cons of a wider or narrower skirt?

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Probably just the different tolerances on the die used to make the pellets, this is why you should try and buy in batches so your getting consistency.

 

Also different barrels also like different sizes again due to the tolerance on the barrel.

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Did you measure these skirt sizes .? Or are you taking the label as reference ?

As usualy the label on the tin referres to the head diameter not skirt .

Ive donr quite a bit of work on different skirt diameters in the past .

Specifically with bisley magnums in .177 .and found that a wider skirt was more relevant to good groups than the head size .

 

If you think about it the last part of the pellet to leave the barrel is the skirt and it needs to let go evenly and true .its very important to accuracy .

The main function of the skirt is to obturate into the rifeling of the barrel making a air resistant seal so air doesnt get infront of the pellet reducing efficiency .

This is one of the reasins why jsb mde pellets tend to make more energy than other brands of pellet in a lot of guns .the skirt is thin and made of soft lead .so its obturation is very effective

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Did you measure these skirt sizes .? Or are you taking the label as reference ?

As usualy the label on the tin referres to the head diameter not skirt .

Ive donr quite a bit of work on different skirt diameters in the past .

Specifically with bisley magnums in .177 .and found that a wider skirt was more relevant to good groups than the head size .

 

If you think about it the last part of the pellet to leave the barrel is the skirt and it needs to let go evenly and true .its very important to accuracy .

The main function of the skirt is to obturate into the rifeling of the barrel making a air resistant seal so air doesnt get infront of the pellet reducing efficiency .

This is one of the reasins why jsb mde pellets tend to make more energy than other brands of pellet in a lot of guns .the skirt is thin and made of soft lead .so its obturation is very effective

 

 

Bought a tin of JSB exact............sold as 4.53mm head size..............load of cods.......the head size on my micrometer were all 4.50...

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Bought a tin of JSB exact............sold as 4.53mm head size..............load of cods.......the head size on my micrometer were all 4.50...

 

There is a reason that target air pellets (RWS, JSB, that Chinese brand) have lines that are extremely expensive, but are basically machined to perfection.

 

Not that it matters a damn unless you are shooting at World Cup standard.

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There is a reason that target air pellets (RWS, JSB, that Chinese brand) have lines that are extremely expensive, but are basically machined to perfection.

 

Not that it matters a damn unless you are shooting at World Cup standard.

 

These are an example:

 

https://rws-munition.de/en/rws-sportshooting-area/rws-sport-ammunition/rws-air-gun-pellets-for-sport-shooters.html#!12/196/0

 

Each pellet is packed individually so there are no deformities arising from transport.

 

 

 

Also, I remember using a batch of pellets that were a couple of years old, and the skirts seemed to have shrunk on them; over the half the batch didn't fit the breach properly. Think they were H&N

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Skirts should be wider than head by about 0.04mm and as you seat it into barrel, it is resized to barrel width and helps forms a good seal on firing.

 

If you look at something like a H&N Grizzly, these are 0.250 at best (airgun 25cal) and fall through my barrel as it is 0.254 (rifle 25cal) and as they have no appreciable skirt will not seal.

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When you consider that lead expands at nearly half the rate that Mercury does, you gotta realise that measuring or moaning about tiny variations in pellet sizes is akin to peeing into the wind - it's going to come back and embarrass you. Any tiny variations will be sorted when hit by 2-3000 psi of air.

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It's the head size that is quoted on the tins not the skirt size, and as such it isn't blown into shape by the air pressure. The deformation of pellet skirts is in my opinion, unless really bad, has little effect unless the pellet has a harder alloy (think from what I can remember Accupels are one example and Defiants). Head size effects some barrels more than others, one that was especially notable were the older BSA .25 cal.

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  • 2 months later...

On the subject of heavier vs lighter pellets, I noticed a lighter pellet with a 5.55 skirt flew lower than a heavier pellet with a 5.52 skirt.

 

Obviously the wider skirt is a tighter fit but why the variation in skirt widths? What are the pros and cons of a wider or narrower skirt?

 

You simply need to find what works best for your rifle/quarry.

 

My Falcon prefers 5.51, but my old Airsporter, which really is a .22, favours as big as I can get.

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