I've been working on trying to help the guys who bought Walther 1250 Dominators
that are finding it a pain to fill to 4500psi each time to get a reasonable shot count
and also to address the very heavy trigger that they all suffer from.

What I came up with is to convert it over to 22ci, 3000psi HPA and to do the 850s
trigger mod on it.
Both these things have worked out well and have made the rifle more user friendly.
although I have had to sacrifice a bit of the shot count to get it where it needs to be.

We wanted to keep it at 30fpe and provide at least 50 full power shots per fill to
keep it in the hunting category.
Heres the first string off the gun after the tune.
I'm excited, I think if I decrease the regulated pressure a tiny bit more (keeping it
at just over 30fpe) we will end up with 60 shots at full power. Or just leave it
like this
I am going to leave it like this for now though and wear it in a bit. 

Rifle	HPA 850HP in .22
Pellet	JSB Jumbo
Weight	15.9
Shot #	FPS	Dev From Avg	Stats
1	937.9	0.4	Max	940.1
2	940.1	1.8	Min	936.7
3	938	0.3	Average	938.3
4	937.1	1.2	Standard Deviation	1.3
5	936.7	1.6	Extreme Spread	3.4
6	940	1.7	Energy	31.1
7	939.5	1.2	Average Deviation	1.1
8	936.8	1.5
9	937.9	0.4
10	939.1	0.8
Rifle	HPA 850HP in .22
Pellet	JSB Jumbo
Weight	15.9
Shot #	FPS	Dev From Avg	Stats
11	940.1	1.8	Max	940.3
12	940.3	2.0	Min	933.9
13	940	1.7	Average	938.3
14	939.7	1.4	Standard Deviation	2.1
15	938.8	0.5	Extreme Spread	6.4
16	937.7	0.6	Energy	31.1
17	936.5	1.8	Average Deviation	1.7
18	933.9	4.4
19	936.7	1.6
20	939.3	1.0
Rifle	HPA 850HP in .22
Pellet	JSB Jumbo
Weight	15.9
Shot #	FPS	Dev From Avg	Stats
21	940.2	1.1	Max	941.4
22	941.4	2.3	Min	936.2
23	939.7	0.6	Average	939.1
24	938.3	0.8	Standard Deviation	1.9
25	936.2	2.9	Extreme Spread	5.2
26	937	2.1	Energy	31.1
27	937	2.1	Average Deviation	1.6
28	940.1	1.0
29	939.7	0.6
30	941.3	2.2
Rifle	HPA 850HP in .22
Pellet	JSB Jumbo
Weight	15.9
Shot #	FPS	Dev From Avg	Stats
31	938.1	0.1	Max	940.2
32	939.9	1.9	Min	935.1
33	937.3	0.7	Average	938.0
34	938.2	0.2	Standard Deviation	1.5
35	939	1.0	Extreme Spread	5.1
36	936.7	1.3	Energy	31.1
37	935.1	2.9	Average Deviation	1.1
38	937.8	0.2
39	938	0.0
40	940.2	2.2
Rifle	HPA 850HP in .22
Pellet	JSB Jumbo
Weight	15.9
Shot #	FPS	Dev From Avg	Stats
41	936.7	1.2	Max	937.4
42	937.4	1.9	Min	933.1
43	936.9	1.4	Average	935.5
44	935.4	0.1	Standard Deviation	1.4
45	933.1	2.4	Extreme Spread	4.3
46	936.7	1.2	Energy	30.9
47	934.5	1.0	Average Deviation	1.1
48	935	0.5
49	935.3	0.2
50	934.16	1.4

Roald

The 850 Store

you can improve the trigger on the 850

We have a pretty good mod for that now too. It makes it a true 2 stage very crisp
let off. Not a target trigger mind you, but a very good hunting trigger for sure.

The 850 Store

that is some nice power and 50 shots i think is more then enough, how are you able to get such little spread in the FPS, good work and great stuff keep it up .

Thanks Jovan, the regulator is really sweet. Almost zero bleed up too..
I'm wondering if its partially the valve thats regulating too, helping it
stay so flat. 
Well I'll put about 4000 pellets through it and see how it holds up.
I'm using Van's Airhog regulators, they really handle high pressures
very well. 

The 850 Store