Tuning an Air Rifle


tuningIn response to an email, here are my thoughts to tuning.

OK I’ll ask the question. Why do you want to waste money?
Many books have been written about this subject with some expert tuners making wild claims of sub 1 minute accuracy and brick busting at 100 yards. Yet that’s not only wistful thinking in a lot of cases but hardly worth spending megger bucks trying to achieve it.

Standard cop-out clause for when you finally wake up to all that money for not a lot of gain?
Bad pellets, poor shooting technique, wrong Met conditions, bad sights, or you just can’t shoot.

Anyway, lets talk power. EVERYONE WANTS POWER.
Lets run the math.
My rifle (a PCP Harrier) using a 21 gn pellet (BC 0.035) , cracks out the barrel at 500 fps generating 11.66 ft.lbs. Within the 12 ft.lb limit in the UK. Above that I’m going to have to register it as a firearm.

Can I help it if the UK limit,
for an air-rifle, is only 12 ft.lbs!?!

Anyway muzzle velocity calculations mean diddly squat as 30 yards away that style of pellet is actually going to smack the bunny at around 9 ft.lbs

Yet if I changed the pellet for one with a higher BC (ballistic coefficient) i.e. a BETTER design, sleeker shape, it’s going to smack that same bunny at just under 11 ft.lbs having lost next to nothing in speed over the same distance. So there is point one. A better design pellet, more aerodynamic, and better balance (Center of Gravity), is MUCH BETTER than piling on the power. That’s a couple of hundred pounds saved on tuning kits. A simple change of pellet.

So why tune at all?
In a spring powered air gun the best reason for tuning is to reduce and smooth out the wild double snap recoil effects. NOTE THE WORD REDUCE! Nothing you can do will EVER kill that snap recoil.  However changing the trigger group to one with a smoother let off, that will probably up the game of a few weekend shooters in seconds.

Math the return.
I’m going to tune like mad now and push your gun to the limit to produce 900 fps at the muzzle. (I mentioned this in the Air weapons and the need for speed). Anyway at the muzzle power (same pellet) pencils out as  38 ft.lbs and at 30 yards 29 ft.lbs.

One seriously dead rabbit eh?
WRONG because the pellet went wild and you missed!
This was caused either by tail flipping from the muzzle exhaust gas, the “near to the speed of sound” turbulence, or the pellet just went “Jeez” and deformed so much it ended up with the flight characteristics of a flying BRICK!

Why tune?
I suppose it’s down to the end-user at the end of the day.
That and how much you believe the hype.

  • Does tuning always work? NO!
  • Would better maintenance help? Probably! [Source]
  • Does it improve accuracy?
    Maybe! but you can do more [Source] & [Source]
    Improving the trigger group usually does but there is no substitute for trigger time i.e. actually shooting the beast.
  • Does it improve POWER? Occasionally.
    Yet if you haven’t got a firearms license for what you now own in the UK, it’s going to get expensive i.e. fines, maybe jail time, definitely a criminal record, possible loss of your job, house, and most importantly your weapon.

That and increased power isn’t a lot of good if you can’t hit shit!

And finally will it make you a better hunter?
Trigger and field time does that for most.
Lots and lots of lovely hours spent shooting.
Personally if think you are capable of more, you should have bought better in the first place. Still for those who can’t afford to upgrade, here’s a question for you. How easy is it to make a silk purse out of a sows ear?

Crap will always be crap only sometimes a bit slicker!
Even if some expert claims (at a price) to be able to make it silk, are you sure it’s worth the hassle?

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2 Responses to Tuning an Air Rifle

  1. equippedcat says:

    How can something which does not work on expanding gas from burning or explosion be a “firearm”? If they wanted to, and could keep a straight face, they could call it a “deadly weapon” or “air weapon” or something like that, but it is not a firearm by the very definition of the term.

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