Pushing the envelope . :TX 200

[TonyL]

I know what happened, the piston seal set on fire, the gun exploded and the barrel fell off

Ah, that explains the "wow" due to the acrid stench and the need to call out the fire brigade! Mayhem in Boingerland!

[TonyL]

We have a new sport.. Tony baiting

Cruel but true , I am sure he will be along in a bit to end the misery ��

Yes, I mean, stop it. My suspenders are getting all in a twist (oh shit, the cat's out the bag, now!), er, I mean I can't handle all the suspense!

[Craig-P]

Sorry Tony, couldn’t resist

It’s another huge pat on the back for Nick, basically. It has the cocking effort of my HW30 (possibly even a bit less due to stroke length) and is as easy to shoot as my BSA Cadet.
Ultra quick cycle but also hugely soft without being bouncy. Definitely comparable to the tiny little 30.
There’s absolute minimal sight picture movement. To put that in context, we were watching the pellet flight at 30 yard targets, at 10x mag in wooded areas...
We tried the 20mm (or Mk99 as we called it) in cold conditions, in two very different stocks (including a sporter which was held in by a single bolt), shot it from various positions, with various ammo, in gusting winds and it performed flawlessly - and this is after Nick has banged it over the chrono for a few hundred rounds. I stacked four pellets on top of each other from a fairly informal sitting position at just over 30 yards.
We switched rifles several times (Nicks 20mm against my 21mm) and there was a very noticeable difference between the two. This isn’t rubbishing his 21mm setup, I’ll still be keeping that in mine as it’s rock solid stable and hits what I point it at (despite me taking it out from the house that Sarah heats to around 50degrees). It’s just that this new one is, well - nicer to shoot.

Nick, hats off to you, mate. A job brilliantly done - and thanks again for a great day out.
Best, Craig.

[Shed tuner]

Is this a good time to mention I've been working on a full piston 19mm ? Found a swedish supplier who can make me the spring, OD 17mm, so 0.75mm piston skirt walls. 2.8mm wire guage, will leave the guide with only 0.75mm walls too, but that's fine. Made up a small spacer to extend the cylinder the 20mm needed to gain the extra stroke, and a new forestock bracket to slide the holes back. The cocking arm needs to be custom made, as it will need a kink to clear the bracket and allow for the 115mm stroke...

am I fork ;-)

[Craig-P]

I had the same idea about a set back forend bracket. So yes, it’s a great time to bring it up, mate.

[NickG]

Thanks for the kind words Craig I had a thoroughly enjoyable day to day ,it's nice to get another opinion especially from someone who knows air rifles so well.
Nice one , JB, already been there with the under lever, and have plates made that give extra stroke.
It's all about the spring , if you have a supplier that has 2.8 wire your halfway there.
Only half way mind ��.

[hmangphilly]

We have a new sport.. Tony baiting

Correct

[TonyL]

Cheers for the detailed feedback, Craigy.. Sounds utterly superb to shoot. Comments re quick yet soft cycle and minimal sight picture disturbance all noted. Nick's 21 that came to Neil's shot sublimely, so if your 21 is just like that, this sounds another step, then..

JB - taking things to a newer next there, maybe. Those margins are getting ever tighter, however. It'll be most interesting to see what you make of it.

These tunes are serious re-engineering projects and so far removed from the usual "spit and polish" and drop-a-kit-in tunes most of us are limited to. Almost akin to highly tuned, bespoke race engines. I applaud you, peeps. Well done. That envelope has been well and truly pushed.

[maximus]

Maybe the next step is to make a gas ram, no restriction due to spring wire etc.

[Shed tuner]

Maybe the next step is to make a gas ram, no restriction due to spring wire etc.

that's actually a very good point... the OD and the guide rod are becomming limiting factors. You'd need a thicker piston wall (or rear section) for latching the trigger sear, but there'd be plenty of space to do it.

[NickG]

Been working on hunter carbine this week so cheekily bunged the 20 mm set up in , and it did 11.1 with 8.4 and 11.3 with 7.9, so it works with a short barrel as well happy days. .

[TonyL]

Maybe the next step is to make a gas ram, no restriction due to spring wire etc.

that's actually a very good point... the OD and the guide rod are becomming limiting factors. You'd need a thicker piston wall (or rear section) for latching the trigger sear, but there'd be plenty of space to do it.

My thoughts have also sometimes wandered along on those lines. And there are bespoke gas ram makers out there. A piston without a central rod lends itself more nicely. One of the longer stroke Gamo rifles, if someone could properly rework the trigger unit to improve it, might provide the ideal platform?

[TonyL]

Been working on hunter carbine this week so cheekily bunged the 20 mm set up in , and it did 11.1 with 8.4 and 11.3 with 7.9, so it works with a short barrel as well happy days. .

Very impressive. Superb work, Maestro.

[TonyL]

Knowing that you're not one to rest on your laurels, Nick, have you got any further little tweaks in mind for this project or do you think that's it, onto endurance testing and see how it fares?

[NickG]

Hi Tony, I think it's about there , However 🙄, building one as we speak to test in my target rifle,I am making a steel comp tube ( there is a convenient size available ), the only change in specification is a slightly shorter stroke as the other one made high 11's and I don't need that much, and a shorter stroke may be even better 🤞.Got the comp tube finished need to do the piston now so should have it in the gun by end of next week 🙂