700mm Barrel Over 600mm Barrel

[Goldwing]

It's only 34" long OAL in an Impact lol

Then add a moderator and your even longer, not for me

 

[qball]

What are the benefits- pros and cons - to 700mm barrel over the 600mm barrel on an FX Impact M3 .25 caliber shooting pellets only (33.95/34 grain JSB and FX)?

Impact has enough power to not need 700mm barrel to shoot any pellets. Only “advantage” is you can tune the gun to be slightly lower for a few more shots but honestly a waste of money and time. If only shooting pellets it’s better to go with a 500mm barrel so less harmonic and barrel dwell or hold/follow through sensitivity.

 

[MikeAllen]

Shorter barrels require more air to make the same power. Getting the valve closed before the pellet leaves the bore provides better pellet stablility and air efficiency. If you can reach the needed power without the excess air the shorter barrel is an advantage. Over dwelling a short barrel to make power can impact accuracy.

Thanks thane - power isn't the issue. I'm shooting 34 grain pellets at about 875 fps - not trying to shoot pellets at high speeds. I think I have reached a good balance/sweet spot with my setup (600mm barrel) as I am getting tight groups at 45-50 yards with very good ES and SD.

 

[MikeAllen]

Impact has enough power to not need 700mm barrel to shoot any pellets. Only “advantage” is you can tune the gun to be slightly lower for a few more shots but honestly a waste of money and time. If only shooting pellets it’s better to go with a 500mm barrel so less harmonic and barrel dwell or hold/follow through sensitivity.

Thanks qball - I agree - see my reply to thane.

 

[thane]

My M3 shooting .22 works very well with 500mm, preferred setup.

 

[Glem.Chally]

Then add a moderator and your even longer, not for me

Ok so I guess they didn't design it for you. Good to know.

No mods for us up here, so 34 inch OAL isn't a big deal.

 

[Goldwing]

Ok so I guess they didn't design it for you. Good to know.

No mods for us up here, so 34 inch OAL isn't a big deal.

I'm so happy for you Charlie, enjoy the fishing

 

[athlon_oved]

A YouTube video shows a fps test between the 600 and 700mm on a impact. The 700mm was only 10 fps faster.

with the YT vids I've seen you can gain that with the power block

 

[bigHUN]

with the YT vids I've seen you can gain that with the power block

No need to buy always new, just use a little imagination. I can shoot a .25 44 grain with 150 bar on a Reg 1010 fps with a first gen PP and 700 liner.
Back to OP: 600 mm vs 700 mm liner
If you want to shoot a same projectile with a same speed - with 600 mm liner vs 700 mm liner, that will cost you about 12 bar on the Reg.
but
Per say your Reg is @ 130 bar with a .25x700 liner shoots great, you don't touch the Reg just swap the liner to 600 the projectile with tumble.
That is why the longer liner/barrel more friendly with a not 100% perfect tune.
And second advise, when you tune or check your tune, shoot the most longest possible distance you can find, let say 100 yards... 30-40 is too short, you cannot read the POI correctly.