Author Topic: .22 Mrod slug shooter tuning help  (Read 503 times)

Dairyboy

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.22 Mrod slug shooter tuning help
« on: February 01, 2018, 09:23:34 AM »
Hey Bob,

Trying to get my tune where I want it on my slug shooting .22 Mrod. I've tried a few from NSA and the 23gr slugs shoot great! Shooting at 880-900fps showed great accuracy at 55yds from a standard Crosman barrel. So here's where I'm at on equipment:

SS valve with .140 ports through to the barrel.
26gram MDS hammer
Aluminum airtube from JSAR

So reason I mentioned that I don't want to fill over 3000psi with it. Here's what I'm getting at the moment. Stock hammer spring with about 3turns CW from full CCW. Efficiency at 1.23 isn't bad but wonder if I can stretch out the string by opening ports. I don't have enough of the 23gr slugs to test a full chrony string as they were just a sample. They run right at 100fps slower than the 18s on this tune. Will this be a hard string to beat? The tinkerer in me says I can do better but I guess it's hard to guess just how much better.

Created: 01-28-2018 04:44:56 PM
Description: .22 Synrod SS valve
Notes 1: 3000psi-2400psi
Notes 2: 26gr MDS hammer
Distance to Chrono (FT): 3.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 18.130
Altitude (FT): 0.0
Temp: 45 °F
BP: 30.37 inHG
Shots
#     FPS        FT-LBS     PF
17    979        38.59      17.75     
16    981        38.75      17.79     
15    986        39.14      17.88     
14    990        39.46      17.95     
13    960        37.11      17.40     
12    992        39.62      17.98     
11    993        39.70      18.00     
10    1000       40.26      18.13     
9     993        39.70      18.00     
8     1004       40.59      18.20     
7     1003       40.51      18.18     
6     1007       40.83      18.26     
5     997        40.02      18.08     
4     986        39.14      17.88     
3     990        39.46      17.95     
2     985        39.06      17.86     
1     962        37.26      17.44     
Average: 988.71
StdDev: 13.09
Min: 960
Max: 1007
Spread: 47
True MV: 989.04
Shots/sec: 0.09
Group Size (IN): 0.00


I appreciate any advice you can give me.

Dillon


  • Outlook, WA
John 3:16

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Dairyboy

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Re: .22 Mrod slug shooter tuning help
« Reply #1 on: February 01, 2018, 04:28:11 PM »
I've been thinking alot about this today and realize I might not have worded my question the best. What I'm looking for is to expand my pressure range from 600psi to 1000psi.
  • Outlook, WA
John 3:16

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.177 TJ barreled Huma regulated LW airtube
.22/.30 WARP COBRA

rsterne

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Re: .22 Mrod slug shooter tuning help
« Reply #2 on: February 01, 2018, 04:46:01 PM »
Bigger ports in an unregulated PCP tend to narrow up the pressure range for a given ES.... I don't know if that applies to the SS Valve, Travis would be the guy to ask....

Bob
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Dairyboy

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Re: .22 Mrod slug shooter tuning help
« Reply #3 on: February 01, 2018, 06:02:25 PM »
Thanks Bob, I now thought I remembered you saying you opened ports and got more useable pressure (Chief) I however now read it again and saw you did that but also upped the power alot more. More to think about for sure. Thanks Bob!
  • Outlook, WA
John 3:16

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.177 TJ barreled Huma regulated LW airtube
.22/.30 WARP COBRA

grumpy

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Re: .22 Mrod slug shooter tuning help
« Reply #4 on: February 02, 2018, 09:09:18 AM »
I don't think that's to shabby a string.
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Dairyboy

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Re: .22 Mrod slug shooter tuning help
« Reply #5 on: February 10, 2018, 06:47:40 PM »
Thanks Dave! I didn't think it was too bad either.

I got some beasts in yesterday and will be testing them tomorrow
  • Outlook, WA
John 3:16

.177 Nova Freedom
.177 TJ barreled Huma regulated LW airtube
.22/.30 WARP COBRA