Air Arms 410SL / 510 Regulator Installation

Got an Audrius Reg from CygnusX that he had imported via mule (mother in law).

Work is very nice

I’ve never had this rifle apart, have messed with the stock and other stuff but the gun has been in one piece since I got it in 2007 so all this was new to me.

After dry firing to empty the tank I loosened the two set screw’s on the barrel band.

That allows it to slide right off

This uncover’s two pin wrench hole’s in the fill valve assembly. I expected the fill end to unscrew but the entire tube unscrewed which ended up being a good thing.

Because it exposed this little peice I wasnt expecting.

Brass tube with a small hole in the end that I hadnt seen in any of the other 410 installation pic’s – appear’s to be a basic attempt at regulation but get’s in the way of the real reg I want to install.

Checked the T.W CHamber’s site (http://www.gunspares.co.uk/ great resource for Schematics and spares) and discovered that it is called the “firing pot” (PW175). It’s on the AA510 page as that is what the 410 Side Lever is called in the UK.

http://www.gunspares.co.uk/

Removed the gauge and loosened a small set screw which retained the pot in place.

I had hoped just to remove it, but it holds the valve return spring…..

The spring is retained by only a small portion of the “pot”, the extra is just an empty space so I chucked it in the lathe and parted the excess of.

This shows after parting and you can see the part that the spring is held up agaisnt

I faced off down to that shelf t get a much shorter pot.

That gave enough room for the regulators included spacer.

This is a string I shot before installation. 2900 PSI, JSB Exact’s

Shot fps ft/lbs
1 915 29.57
2 920 29.89
3 926 30.28
4 938 31.07
5 934 30.81
6 943 31.40
7 939 31.14
8 943 31.40
9 937 31.01
10 936 30.94
11 940 31.20
12 934 30.81
13 929 30.48
14 928 30.41
15 928 30.41
16 926 30.28
17 923 30.09
18 918 29.76
19 914 29.50
20 909 29.18
21 910 29.24
22 907 29.05
23 902 28.73
24 896 28.35
25 894 28.22
26 890 27.97
27 888 27.85
28 883 27.53
29 879 27.29
30 875 27.04

Unfortunatly the gauge o-ring had not been placed in the recess when it was installed so it was crushed and I couldn’t re-use it. Took my air compressor’s auto drain apart to find an o-ring that would work – but its still got an audible leak until the Hardware store opens.

This is string with regulator installed with a leak so I’d expect more shot’s. Same fill and pellet.

Shot fps ft/lbs
1 882 27.47
2 887 27.78
3 884 27.60
4 885 27.66
5 891 28.04
6 890 27.97
7 888 27.85
8 892 28.10
9 889 27.91
10 890 27.97
11 889 27.91
12 892 28.10
13 892 28.10
14 891 28.04
15 886 27.72
16 891 28.04
17 892 28.10
18 892 28.10
19 890 27.97
20 891 28.04
21 892 28.10
22 889 27.91
23 890 27.97
24 887 27.78
25 877 27.16
26 865 26.42
27 860 26.12
28 852 25.63
29 845 25.22
30 841 24.98

Seems to drop off the regulator around shot 25.

Chart of both results, unregged in Red, regged in Green.

Once I get a replacement gauge block o-ring I’ll do a new string which I expect to be a bit longer.

I’m happy with the string so will likely drill the vent hole in the air reservoir at some point (and possibly duracoat the tube as I’m sick of wiping it down after shooting).