Pellet choice

[Axel]

ps
all the pointed and hollow pointed pellet ideas are flawed,mainly down to consecutivity,unless the point or hollow point are exactly the same ie centeral each pellet will pull to one side either horizontally or vertically differently
i spent a lot of money and time working this out through a lot of guns ,ending in working out that most of the adds in mags are talking sh1t,round nose are the way forward unless your target/close up pest controling then flat nose is best

Thanks for that advice!

Got to get me some AA/JSB ASAP

[Andy.I]

Axel

With respect to your question regarding de-leading / re-leading: you don't mention whether you are using a springer or a PCP, but from a previous post of yours which mentions dieseling, I suspect you may be using a springer. This may explain what you have experienced.

PCP's tend to perform better with squeaky-clean bores, while a freshly cleaned springer barrel will noticeably lose power and accuracy after cleaning until a considerable number of pellets have been put through it.

Also, something you might like to experiment with is pellet size. JSB / Air Arms pellets, for example, are available in different die size, which refers to the diameter of the pellet's head, and is usually shown on a label on the tin. Many PCPs showed a marked preference for a specific die size. Springers in my experience however, are less sensitive to head size and more sensitive to skirt size. You can demonstrate this with a freshly cleaned springer barrel, by taking a pellet, placing it skirt-down on the lid of the pellet tin and polishing the skirt with some considerable downwards finger pressure, which expands the skirt. This will result in an increase in velocity close to or equal to the velocity you got before cleaning.

[Axel]

Hi Andy
Yes, you're right, it's a springer (Weihrauch HW97 KT). I have noticed that some pellets(Crosman Destroyers and H&N Field Target Trophy) are a looser fit when inserting into the breach. Weihrauch don't specify the exact diameter of pellet to use. What is the science angle here? I can see that a tighter pellet will provide a better seal, but will a tighter pellet slow down due to the increased friction in the barrel? As you say, experimentation with different sizes is the best answer!

Cheers

Axel

[leadpig]

Hi Andy
Yes, you're right, it's a springer (Weihrauch HW97 KT). I have noticed that some pellets(Crosman Destroyers and H&N Field Target Trophy) are a looser fit when inserting into the breach. Weihrauch don't specify the exact diameter of pellet to use. What is the science angle here? I can see that a tighter pellet will provide a better seal, but will a tighter pellet slow down due to the increased friction in the barrel? As you say, experimentation with different sizes is the best answer!

Cheers

Axel

i have always found a snug fit to be best,to loose and you get flyers,but you dont want to be hamering them in either
as said some brands of pellet can have 3 different sizes so it will be trial and error
my 97kt was .22 so cant help you there

[Andy.I]

Hi Andy
Yes, you're right, it's a springer (Weihrauch HW97 KT). I have noticed that some pellets(Crosman Destroyers and H&N Field Target Trophy) are a looser fit when inserting into the breach. Weihrauch don't specify the exact diameter of pellet to use. What is the science angle here? I can see that a tighter pellet will provide a better seal, but will a tighter pellet slow down due to the increased friction in the barrel? As you say, experimentation with different sizes is the best answer!

Cheers

Axel

The science angle is complex and what I write below is very much a simplification.

A PCP works with the pellet accelerating (relatively) gently up the barrel while a springer relies on a small blast of extremely high pressure air "spitting" the pellet. The skirts of pellets fired from a springer can be seen to have been inflated by the piston pressure, causing them to grip the radius of the breech, allowing the pressure to build up until it (the skirt) suddenly yields, resulting in extremely high initial acceleration. Conversely, skirts of pellets fired from a PCP tend to be undeformed, except of course by the barrel's rifling.

You need to fire the pellets into material which will gently decelerate them to see this. Once fired, both springer and PCP-fired pellets exhibit approximately the same barrel friction.

This is the reason you can get very short barreled springers while PCPs tend to have longer barrels.

To go back to the subject of barrel leading, I have observed that PCPs tend to suffer from lead build-up much more than springers. I remember somebody bringing a BSA R-10 to me to investigate why it was so inaccurate and I discovered that the lead build-up was so bad it was hard to discern that the barrel was rifled! However, as to why springers are so sensitive to de-leading (suffering from power loss) while PCPs prefer a perfectly clean barrel (and become inaccurate when leaded) is still very much a mystery - if anybody has any idea please educate me!

[Sidebyside]

- if anybody has any idea please educate me!

Wouldn't take on that job

[Axel]

The science angle is complex and what I write below is very much a simplification.

A PCP works with the pellet accelerating (relatively) gently up the barrel while a springer relies on a small blast of extremely high pressure air "spitting" the pellet. The skirts of pellets fired from a springer can be seen to have been inflated by the piston pressure, causing them to grip the radius of the breech, allowing the pressure to build up until it (the skirt) suddenly yields, resulting in extremely high initial acceleration. Conversely, skirts of pellets fired from a PCP tend to be undeformed, except of course by the barrel's rifling.

You need to fire the pellets into material which will gently decelerate them to see this. Once fired, both springer and PCP-fired pellets exhibit approximately the same barrel friction.

This is the reason you can get very short barreled springers while PCPs tend to have longer barrels.

To go back to the subject of barrel leading, I have observed that PCPs tend to suffer from lead build-up much more than springers. I remember somebody bringing a BSA R-10 to me to investigate why it was so inaccurate and I discovered that the lead build-up was so bad it was hard to discern that the barrel was rifled! However, as to why springers are so sensitive to de-leading (suffering from power loss) while PCPs prefer a perfectly clean barrel (and become inaccurate when leaded) is still very much a mystery - if anybody has any idea please educate me!

Fascinating info, Andy. Thanks!

[Axel]

Wouldn't take on that job

Ha ha

[Axel]

Sorry to go slightly off topic here, but:

How often should my barrels (one springer rifle and a pneumatic postol) be cleaned? There are bore cleaning pellets on the market, anyone had any experience with these? Other than that, is best to rely on pull throughs?

[Andy.I]

Sorry to go slightly off topic here, but:

How often should my barrels (one springer rifle and a pneumatic postol) be cleaned? There are bore cleaning pellets on the market, anyone had any experience with these? Other than that, is best to rely on pull throughs?

My suggestions are:

- For a spring just pull a dry patch through a couple of times every thousand-or-so pellets.

- For a pneumatic thorough clean with patches and solvent every few hundred pellets. I tend to use lighter fuel, although I'm sure somebody will crawl out of the hedge and tell me that it's dangerously inflammable! However, I don't think it really matters what you use as long as you don't spill anything nasty on seals and you don't spill it and light up.

[Axel]

although I'm sure somebody will crawl out of the hedge and tell me that it's dangerously inflammable!

OK! I'll put me fag out before I start then!

Thanks for the advice Andy.