I was a bit quiet recently. But there was a good reason for that… fine tuning my R5. It’s part of fun, part of the game (at least for me). It’s just like with cars – even the coolest latest sport car can be tuned, not just outside but also inside – chip tuning, engine tuning, exhaust tuning, etc. Thanks Lord it’s a bit less complicated with airguns, and waaaay cheaper, LOL! Anyway, long story short – one day I was asked by my buddy from NZ if I’d be willing to take part in Huma kit development for R5. OK, why not? And as a result I was sent a prototype of R5 performance kit (or power kit if you prefer that name) to try in my R5. Of course I was more than happy to try something new… but it was not as simple as I thought! The Prototype kit was not threaded correctly at the connection end (hence the name – prototype). So I was not just testing and playing with new kit, but also tried my machining skills on lathe, with a bit of help from my father in law (who is really good at it… and his shop is quite equipped too). BTW, the thread connection between reg and plenum is not needed at all imho. It was made to remove the whole unit easier from air tube but... it disconnects anyway when you're unscrewing the rear plug, lol! So it should be either ccw thread or... just no thread at all. It's not designed to seal on that thread anyhow.
Small digress here: I really like the way Ed design his airguns (as an overall concept). It’s just SO EASY to work on them and R5 is good example. Changing regulator setting takes just couple of minutes. Of course, I know there are other guns with regulator settings / manometers on the outside, but none of them looks so ascetically good imho. R5 looks like a gun and can be used & treated as a regular field gun. And the new electronic manometer makes that overall look even better. And BTW, when disassembling/assembling R5 be sure to tighten the breech/ hammer block really well, otherwise it can get loose with time (it’s not needed for reg adjustment, but I quite disassembled my R5 when I was playing in a shop). End of digress.
Anyway… after some time spent behind lathe finally I built a hybrid of original plenum and valve (very good valve let me tell) and Huma’s regulator and additional plenum space. I tried many different settings - almost anything between 110 and 130 bar. After fine tuning I could easily get 44grain ammo flying at 900+ fps (about 25-28 shots per fill) with 120, 125 and 130 bar on reg. A 120 bar it required really strong hst, so I decided to set my reg at 125 bar. That way, depending on need, I can get either high power (900 fps) or very efficient shot count at slightly lower muzzle enegry (850 fps, or 260 m/s). But that ‘low energy’ is still close to 100 Joule at the muzzle and 50 Joule down range at 100m. So it’s not ‘low’ by any means.
So as you can see with my new custom setup (it’s really nice feeling to have some parts machined by myself inside my own airgun) I can get quite significant number of shots. Starting from 251 bar it shoots really good up to 125 bar reg setting, than goes up a little bit (+3m/s) which is an usual peak after getting reg pressure, and goes slightly down to 256 m/s at shot #42 (shot at 106 bar). Some would say that it’d be better to stay at #40 as last one, depending on what is your expectation. Still 40 very good shots is quite a serious shot count. As a side note – originally I could get about 30 good shots at 260 m/s (plus 2-3 more usable, just as here) which was also not bad. 10 more shots is not 'day and night' and .30 cal still eats air fast so... get a bigger tank if you plan to get into .30 cal territory! Could that be tuned for even more shots at 260m/s? I guess so. At lower reg pressure setting. But I’ve chosen a compromise of tuning muzzle energy easily between 850 and 910 fps with just one reg setting, just by turning hst. That’s how I want my gun to shoot. And with 285-290 bar fill I could get 50 good shots I guess… I’ll check that when I top my tank up to 300 bar again. I hope Huma can use some of my findings and suggestions for the final R5 kit. And I learned some new skills too
To make the update complete – I practiced some more at the range, but this time I was very picky on ammo. I inspected each pellet for any sign of deformation, scratches, etc. and my best 5 shot groups were 26 and 29 mm across (#1 and #2 from the left in the pic below) and groups I considered ‘average’ were like the #3 (42mm). Of course, I’d love to shoot everything at MOA or better, but it’s surely MOA (1”@100y) capable airgun.
And last but not least… obligatory ‘for fun’ shot with my Fuji. I know it’d be more appropriate for November but hey, this year we have November weather in December here (as you can see):
I know it was a long update but… maybe worth typing. At least enjoy last pic, LOL!