Why is your barrel so short?

Higher volume = longer barrel to match c/b ratio = lower power spring to reach desired power

What's the point of having the higher volume if you put a short barrel. Might as well not have bought the tac41 if you want a barrel that short.

 

I've seen plenty of people run the short barrel and get up to the desired fps/joules for our UK field limits so not sure thats the issue here.

 

Have you checked what spring others are using? I know a lot of people here have ordered the short barrel ssg10 and been surprised by its lack of power, 330 is just too short to use the air efficiently. Just use a harder spring if there's no air leaks.

 

Frankly I'm inept when it comes to M1xx springs, but on my Tac41 with the 510mm barrel, I ordered the stalker piston and a 2.8J rapax spring, but only got it up to 2.2J if I remember correctly. With the stock piston and 2.8J rapax spring it was nearly perfect at 2.8J, but something about the Stalker pistons just needs a stronger spring. I ended up getting a 3J+ Rapax spring and that managed to get it to 2.8J just fine, with some of the included spring guide spacers.

 

Maybe the piston was too lightweighted/too heavy then?

 

I'd tried the heaviest configuration and the lightest configuration when I was troubleshooting mine - it really wouldn't budge much. It's been months since I was toying with it, but IIRC the problem became that the stalker piston, at it's shortest configuration, was a little bit longer than the stock piston. Longer piston means less volume, means less FPS. I had full air seal, tried with and without the airbeak, I just couldn't get it above 2.3j. If this guy is running a similar setup but with a shorter barrel, it's not much of a surprise that he's getting even less.

 

Based on everything you've said it's going to be the cylinder/barrel ratio, up the spring massively or just use a longer barrel (hide it in a suppressor if needed)

I don't see the point of getting a tac41 if your going to use such a high ratio.