Anyone with impact.25 cal 600mm slug liner?

Yes there are differences in the length of the barrel. The 600 mm barrel handles lighter slugs, and won't generate as high an fps. The 700 mm barrel has more length to spin heavier slugs faster and with a slighter higher fps. Both liners are accurate, it just depends on the slug weight used.

I have a slug liner in .25 600mm.

Cant say for slugs so much but testing will be tomorrow. What I can say is that slug liner with pellets is much beter than with pellet liner. 

I also belive that people buy 700 due more power but as per my experiance with pellets, with my 600 I was the same as 700 and in many case even better.

I have made mods like, mk2 valve housing, brass inlet elogated port, pellet probe mod, external plenum 45cc, hamer weight, derlin c3 bumper ... and with all of that mods just on chrono 34.7 grain 1000fps on 140bar easy as that.

Hope weather improves so I can test nsa 34.7gn on 100m and more and will keep u posted.

I got the 700 liner cuz I wanted to shoot long ranges and it has that extra 10% power factor. So, will get me out a little further and shoot heavier slugs. The slugs shoot fine at lower velocities I made the mistake of not checking my velocities on the chrony often enough and got a really nice tune at 740fps. It was sub MOA at 100yards but the pellets started keyholing at 150. So I had to do it over again.

Accuracy with the slugs depends on your tune as they are can group sub MOA when it's right but 2MOA when it's not. Tuning takes a fare bit of time and patients and of course lots of slugs. Then when you change power levels, reg pressure, projectile types or weights you have to tune all over again.