View Full Version : S400 pressure ??

23-05-2004, 08:02 PM
Hiya all,

Just bought a S400K in .177 second hand.
Can anyone tell me the recomended fill pressure, how many shots I should get and what pressure I can go down to before it starts to affect performance???

Many thanks....Gumbob

SWAT Strachan
23-05-2004, 08:06 PM
Well according to the Air Arms user manual, the fill pressure should be 190 bar. Mind you, people do say to vary that pressure downwards to see if it helps the power curve. That should give you about 40 consistent shots, maybe a few more. As for the lowest pressure, fill it once you hit about 100-110 bar. Get as low as 60 and it'll start venting. If it does, cock the rifle before filling.

I'm too lazy for all that jazz, I just fill to 190 and be done with it :D.

23-05-2004, 08:37 PM
I used to fill to 190 I only fill to 175 now and can shoot a full HFT or FT course with no loss in rifle accurcy

23-05-2004, 08:43 PM
As above, fill to 175Bar and get approx 60 full power shots, fill pressure is down to aroun 100Bar after 60 shots.

Shed tuner
23-05-2004, 09:05 PM
My carbine worked best filled to the full 190BAR, the classic seems to prefer a smite less....

These are .177, things will be different in .22 ;)

Darren Petts
23-05-2004, 09:41 PM
My carbine was perfect on a full fill. Right at the start of the flat part of the curve. Got 56 shots within 15 fps of each other.

24-05-2004, 05:12 AM
Thanks for the info, its all much appreciated.
Looks like its a case of triar and error (pity I dont have a crono:( )

Thanks again...Gumbob

24-05-2004, 08:55 AM
Zero the rifle at say 40yds, refill to 190Bar, and left off numerous shots at the same zero point & note where the best grouping is. If they are all the same apart from when the power drops off, your optimum fill pressure will be 190Bar, if it starts low or high then the fill will be lower. (e.g. if the zero moves after say 10 shots, then approx 175Bar is the optimum).

24-05-2004, 04:54 PM
Thanks Davestate.
Common sense I suppose but logic was never my strong point:(

Cheers... Gumbob

24-05-2004, 08:22 PM
Tests from Biggles - click the links below..



Dan :cool:

24-05-2004, 09:06 PM
Cheers Geordie for hosting those - look OK.

In case it wasn't clear from the pdf's, these were done using an AA400 carbine and Air Arms Field in 4.51 pellets. Chrono was a Target Tronics PM1. Gun had very recently been checked for 'legality' and reset by Air Arms (had been a little 'hot' from new !).

On the graph, the 'x' scale is shot number and 'y' is fps muzzle velocity. Red line is a sort of average/trend.

On the table the 1st column is shot number, 2nd = pressure (read approx from rifle's guage), 3rd = measured muzzle fps, 4th = muzzle FPe using usual maths, 5th = 10 shot rolling average and final = change in average.

Hope this is of interest.

Was (VERY) boring doing the chrono work but certainly helped improve my confidence in the gun and knowledge of what to expect from it.