Air Arms S410

[Missed-Em]

I recently purchased a AA S410 Carbine as "new/old stock" from a dealer although there are indications (burred screws and light wear marks) it's been into previously.  Any way it's a beautiful rifle and quite accurate but has a couple problems I need help with.  First here are the details:  AA S410, no velocity adjuster, not moderated, 22 cal, and hand pumped from 150 Bar to 190 Bar (ain't doing that again!).
Here is the 20 shot string:
Bar 190  1 - 631.5     Bar 175 11 - 659.8
             2 - 645.9                  12 - Err
             3 - 646.8                  13 - 666.7
             4 - 639.7                  14 - 670.5
             5 - 648.7                  15 - 670.5
             6 - 651.2                  16 - 676.2
             7 - 645.8                  17 - 673.1
             8 - 666.3                  18 - 676.2
             9 - 654.8                  19 - 676.0
            10 - 654.7                 20 - 676.1  End Bar 160

When I fire it I feel a strong air release at the magazine.

So, first I feel I should get around 900 fps and second the air pressure goes down so rapidly I feel I won't get as many shots per fill as it's capable of. Second, what velocity and shot count do you get with your S410?

So........... Where do I go from here?  I've done minor mods on other AR's but this one appears to be more complex.  How do I approach diagnosing the problem(s) and how difficult the fixes?

Thanks - Steve

[LDP]

What pellets are you using? If it has no power adjuster you probably have the non fac model and if its been opened up who ever opened it was probably trying to get fac power level from a non fac. Based on the string you are filling it to high for the pre load it currently has.

 If you set it to 12 fpe it will get allot of shots. Im guessing on what I have seen posted but I believe in the neighborhood of 50.

[garczar6]

Steve at Pomona can install a power adjuster. My '03 410 .22 is currently set to avg. 840fps w/15.9's for 35 shots. You may need a FAC hammer spring also. About 13bux on ebay.

[Missed-Em]

Should have noted in op that it is an FAC model and that I'm using the 15.9 gr. pellets.

[Jking]

Steve, it sounds like your breech O-ring is bad or missing. That would explain the blast of air around the magazine and the loss of power. I haven't had to change one in my S510 yet so I'm not sure how difficult they are.
Jimmy

[dhc8guru]

I have an S510 FAC super lite carbine in .22. I don't think the 419 and 510 are mechanically much different. I shoot mine with the power set just below the half power mark. At this setting, if I recall gives me around 650 fps on the Crony. I'm shooting FT's at 30yrds in the backyard, so no need for full power. I fill to 190 bar and refill at 140 bar. It is consistently gives me 70 shots from the 50 bar of air. I read that you get less shots out of the .177 then the .22 but I don't know why this is.
Don't know if this info helps but going by what I see from my S510, I would say something is probably off on your gun. I would send it in and have someone go through it. I have owned mine for a few years and after shooting it a few 1000 rounds, I have never had an issue.

[BigTinBoat]

When I fire it I feel a strong air release at the magazine.

This could be just the air out the shroud vents. I thought the breech seal was bad on my 510 when I first got it, but then realized there are holes in the end of the shroud there

[LDP]

When I fire it I feel a strong air release at the magazine.

This could be just the air out the shroud vents. I thought the breech seal was bad on my 510 when I first got it, but then realized there are holes in the end of the shroud there

Thats what I was thinking to but he says its not moderated. I guess this is REALLY OLD new stock I dont know when they started putting shrouds and power wheels on as standard equipment. So if it is not shrouded it seems the o-ring is probably bad. I would expect to see a shot string that had more ES than the one posted plus he says its very accurate. Every post I have seen about bad barrel o-rings always have accuracy issues as part of the problem and I would expect it would be caused by wild velocity numbers that jump around.

[Missed-Em]

Ok, more info - This 410 has a shroud (The barrel appears to be inset several inches inside the shroud).  By no moderator I meant no "can" on the end.  The comment on the age may be pertinent, how do I determine age on this rifle?

I checked out a YouTube vid on disassembly and appears dueable but it's a shame on a rifle of this quality that mods are required.

Steve

[LDP]

If the shroud has holes at the reciever end then most likely the air you feel is coming from those holes. I dont think you would have such a stable string if the o-ring was bad and had air blowing by or stellar accuracy. I could be wrong but to me both of those show the low velocity is caused by another problem. You are certain you have the FAC model? If you do have the FAC I guess its possible the previous owner set it up to shoot on low power. You could pull it apart and check the hammer to see if it has the non fac hammer.

[Jking]

Single load a pellet in the gun and drape some tissue paper over the breech but keep it away from the holes in the shroud. Fire the gun and see if the tissue paper stay in place undisturbed or is blown off.
Jimmy