Airgun guru

If you have an airgun problem that no one else can help with, why not write to our Airgun Guru. He will meditate on your problem and then answer your question on this page...

If you have an airgun problem that no one else can help with, why not write to our Airgun Guru. He will meditate on your problem and then answer your question on this page. Write to: airgunguru@archant.co.uk

Recent FAQs:

A QUESTION OF CALIBRE

Are .177 spring guns fitted with more powerful springs than the same model in .22 calibre. And if so why?
George Davis via email

In terms of output (power) versus input (cocking effort), a .22 calibre spring-powered air rifle is more efficient than a .177. So, all things being equal, to achieve the same power as a .22, a .177 calibre spring rifle requires a pokier mainspring. There are exceptions, however. Some manufacturers change the internal set-up of certain models, such as the size of the transfer port, so that each calibre can run the same mainspring.

MODERATE ACCURACY?

Do moderators affect the performance of your airgun in terms of accuracy and power?
Seamus Stuart

No. In fact, a properly-fitted silencer can often improve a rifles accuracy, by dissipating all the turbulent air from around the pellet before it begins its flightpath, and reducing muzzle flip. However, an incorrectly fitted silencer may cause the pellets to clip the internals and that will result in poor accuracy.

STRIPPER OR NOT?

How does an air stripper work? Is it worth fitting one to my hunting rifle?
Ben Jones, Powys

Air strippers, as theyre called, work by diverting away all the dirty, turbulent air from around the pellet when it leaves the muzzle of the barrel. In theory, this means the pellet begins its flightpath to the target in very clean, turbulent-free air the perfect start for a perfect shot. In practise, you need to experiment a bit, because what may suit one rifle may not suit the next. Lots of things come into play, like the calibre, muzzle choke, pellet speed and the air source itself. If youre a hunter, I wouldnt worry too much about it. Simply fit one of the silencers with built in baffle systems like the Prestige deciBlocker which will help stabilise the pellet when it exits the muzzle and enters the silencers diffusion chamber. If youre into competition shooting, a stripper is certainly worth investing in although it might take months to find the optimum position. Moving the stripper 1 mm closer to, or further from, the muzzle can actually make all the difference in the world at the target.

IS LIGHT FANTASTIC?

If I use a lighter .22 pellet than usual, would that give the pellet a higher velocity and flatter trajectory?
S. Pembury, Dorset

Technically, yes although there are lots of ifs and buts. While switching to a lighter .22 pellet may increase the projectiles velocity and, therefore, flatten its down-range trajectory it could still reduce the rifles power. Confused? Well, imagine your .22 rifle records a velocity of 580 f.p.s. with 14.5-grain pellets. Thats a muzzle energy of 10.8 ft. lbs. Switching to a lighter, 11.9-grain pellet, the rifle now records a velocity of 630 f.p.s.. Thats a full 50 f.p.s. faster... except the rifles muzzle energy now equates to just 10.5 ft. lbs.

A good rule of thumb is that a spring-powered rifle will benefit, both power- and velocity-wise, from a lighter round. A precharged pneumatic will probably show a slight reduction in overall power, though, as these types of air rifles work more efficiently with heavier ammo. Another thing worth remembering is that although lighter, higher-speed pellets give a flatter trajectory, they also run out of puff much more quickly down-range. If youre hunting, you certainly dont want too light a pellet.

TO CLEAN OR NOT TO CLEAN

How often should I clean my rifles barrel, if at all?
Terry McLaughlin

Some shooters say never, some say every few hundred rounds. To be honest, I fall into the only when its needed camp. And when is it needed? Easy answer: when you think your rifles not shooting as accurately as it used to, and you cant put it down to any obvious reasons (such as loose stock screws etc.). However, if youre changing to non-lead ammo, like Prometheus Sn1, then Id definitely recommend you scrub out your bore to remove all traces of lead. Use a bore cleaning rod, first with a phosphor bronze brush treated with a bore-cleaning solution, and then polish out the rifling with clean rags and a buffing mop. The bores clean once the rags come out spotless after a pass-through. There are a few points to note, however. Firstly, always clean in the direction the pellet travels. On PCP rifles, this will likely mean you cant use a rod, so use a pull-through wire instead. Secondly, youll probably find the initial shots from a clean barrel go significantly higher than usual, so your zero will be way out. Dont be too hasty to adjust your sights, however. After a hundred shots or so, the barrel is likely to lead back in and your combo will shoot as it did before it was scrubbed.

TIGHT FIT

Does tighter rifling on a barrel slow the pellet down more than less tight rifling?
Martin Freeman via email

Pellet fit in the barrel particularly the breech is an important factor in determining a rifles performance. Springpowered rifles, where the pellet/bore relationship is too tight, tend to perform quite erratically. The piston bounces on a cushion of high pressure air which, besides making the rifle jumpy, also causes all the lubricant in the air chamber to burn uncontrollably and return poor shot-to-shot consistency. With a PCP, a tight-fitting pellet can improve air efficiency, but the downside is that the extra-deep depressions the rifling makes on the pellets skirt and head can cause excessive in-flight friction, resulting in a poor down-range performance.

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