Air Rifle Tuning Kits

Weihrauch HW99s customer tune

As well as making fitted guide sets and short stroke extensions, I also service spring rifles.

After posting an advert for my drop in tuning kits on the airgun forum, a member contact me to ask if I could service his 99 for him. We met yesterday, talked guns for a bit and I learnt what it was about the gun he didn’t like.
Usually, the 99 is a sweet little gun straight out of the box, especially in .22! So I was surprised to hear the list of things he just wasn’t happy with.

I gave the rifle a test when I got home last night and saw what he meant. Now, I stripped mine down the day I bought it and started tinkering, so its probably not fair to compare a stock gun to what I’ve been using for months, but blooming eck! What a racket!

Lets start with the trigger. It was too long a reach, the first stage was silly and it was very creepy. The gun went off with a helluva TWANG! with quite a bit of recoil to match.

Mission accepted!

On stripping the gun I could see one problem immediately. The piston had scuff marks where high points were rubbing along the cylinder. This is never a good thing, so I skimmed the tiniest amount off on the lathe and then polished it with emery until it was all lovely and smooth. The spring itself looked ok, so it was degrease and a quick clean of the ends before refitting. Next job was to cut some thin plastic to make a piston sleeve, this was fitted in with some lithium moly grease and one of my kits.

The kit itself comprises of a delrin spring guide which is shorter than stock, with a long top hat and slip washer. This keeps the spring supported along its whole length when cocked, and allows it to unwind without hindrance on firing. Another thin coating of moly on the piston and the gun went back together.

Before fitting the Rekord trigger I brought the blade back a few mil, shortening the first stage and adjusted out the creep. After it was all together I also adjusted the trigger weight to my preferred setting, hopefully the owner will like it that way, although that’s easy to change if not.

I had also been asked to fit one of my barrel sleeves, which I did, and even if I say so myself, the end result really does look the business!

The gun is firing superbly now. No twang, a nudge straight back for recoil and it feels altogether faster.
oh, and I re-parallaxed the scope too!