Airgun World – Summer 2019

http://www.airgunshooting.co.uk AIRGUN WORLD 55

I

’ll be honest, I’ve never attempted much in the
way of DIY when it comes to my airguns. So
when Terry asked me to take a look at the
converted rifle that had been sent in by the guys

at Pneumatic Ballistics I was rather intrigued.

Needless to say I took the rifle apart and

examined exactly what the guys at PB had

done to it, and I was rather impressed to say

the least. They’d also sent me a complete

breech/bolt kit so I could see the bits they’d

actually replaced, and the whole process looks

extremely easy to perform.

AIRGUN DIY

ARE YOU CONVERTED?

Dave Barham takes a look at a couple of DIY

conversion kits for the SMK QB78 rifle.

»

CO2 CONVERSION KIT £49.99

This is probably the easiest and quickest conversion that you could

ever make to an SMK rifle! Simply unscrew and remove the CO2 cap

from the rifle’s reservoir, then replace it with the Pneumatic

Ballistics conversion cap – making sure the new cap is screwed

down tight.

On the end of the PB conversion cap is a fill port, which you can

connect to an air supply to charge the reservoir. PB recommend a

working pressure of 100 Bar and specify that the reservoir should

not be filled to more than 150 Bar. Filling the rifle over 100 Bar

might well cause severe malfunction, so please don’t stray from the

instructions - and PB’s repair experts will know if you’ve done this, I

assure you. The rifle can easily be used with CO2, again by simply

refitting the original SMK cap if you require.

The SMK with the new breech and magazine fitted.

The conversion from CO2 to air is as

simple as replacing the cap!

SAFE WORKING PRESSURE!

The working pressure of this conversion is

100 Bar, and you can use a stirrup pump

or compressor to fill the rifle instead of the

bottle, if you wish. However, the operating

pressure it set for a reason – go above 100

Bar and you risk locking up the exhaust

valve and damaging the rifle.

The working pressure of CO2 cartridges

varies from manufacturer to manufacturer,

and, of course, is governed by ambient

temperatures as well as how many shots are

being fired continuously; the more you shoot

with CO2 the lower the temperature in the

air reservoir. As a rule, though, the working

pressure of CO2 is between 60 and 75 Bar.

I tested this rifle twice by filling it to 100

Bar, then rattling off a load of shots through

my chronograph with QYS Streamlined 8.48g

.177 pellets, taking ten-shot averages as I

went. These were the best results I achieved.

0-10 Shots – 582fps, 6.38 ft.lbs.

10-20 Shots – 559fps, 5.89 ft.lbs.

20-30 Shots – 524fps, 5.17 ft.lbs.

30-40 Shots – 434fps, 3.55 ft.lbs.

40-50 Shots – 236fps, 1.05 ft.lbs.