Marauder Project – .22 Tuning (Part 3)   2 comments

Greetings All,

It appears as thought the provided manual is not consistent perhaps. My previous findings seem to hold true. Instead of resetting everything to zero and starting over, I decided to continue my testing from yesterday evening. I received a call regarding an issue at work (I am on call this week), so I was not able to finish.

I believe I am at a stopping point regarding the .22 Marauder after today’s tune. I reviewed my settings from yesterday and decided I would try decreasing the hammer stroke and see if I could get the fps to drop just a bit. I am about out of pellets to test, so I reviewed ChairGun Pro and it gives the following numbers. For Barracuda Match pellets, 800 fps for 30 fpe. For JSB Exact Heavy (18 grain), 866.2 for 30 fpe. I only had about 14-15 JSB Exacts, so I decided to used the JSB Heavy for testing.

Abbreviations are the same as before. HS = Hammer Spring; Sk = Hammer Stroke

Starting pressure: 2600 psi 873; I decreased the hammer stroke (Sk) one turn clockwise. 849, SK = +1/4 ccw, 872, SK = -1/4; 854, (~2550 psi), 856, 855, Err, 848, (~2500 psi), 854, 860, 858, 865, 865 (duplicate), (~2200 psi), 859, 854, 848, 847, (~2000 psi), 846, 836, 834, 828, (~1900 psi).

    High – 873, Low – 828, Average – 854, Extreme Spread – 45, Standard Deviation – 10 TOTAL – 26 shots

If the last three shots are removed and the two high shots removed, this might give a preview of the current settings. This gives a better feel for a sting from 2600 – 2000 psi.

    High – 866, Low – 846, Average – 855, Extreme Spread – 20; Standard Deviation – 5 TOTAL – 21 shots

To see where the fill pressure is (should be at around 2600 psi), I filled the gun to 2800 psi.
Here is the shot string:

804, 812, 825, 807, 809, 847, (~2700 psi), 833, 828, 844, (~2600 psi), 847, 846, 840, 854, (~2500 psi), 855, 860, 851, 861, (~2400 psi), 862, 862 (duplicate), 626 (loaded two pellets), 865, (~2300), 865, 864, 856, (~2200 psi), 862, 853, 858, 856, (~2050), Err, 840 (~2000 psi), 835

To see if it was any better this time, I deleted the shots before 2700psi and the 626.

    High – 865, Low – 828; Average – 851, Extreme Spread – 37; Standard Deviation – 10 TOTAL – 25 shots (24 if keep above 2000 psi)

Summary: [Beginning from extreme left]
HS – 7 1/4 turns
Sk – 8 1/2 turns
MS – 3 3/4 – 4 turns out

Of course each rifle is different and your results may vary.

I believe I have it as close as I am going to get it without a regulator. Of course I could be wrong, but it seems that from shot to shot the FPS is close. I can fill the gun to 2600 psi and get 20 fairly consistent shots in the 30 foot pounds of energy range. This should be adequate for removing groundhogs at 80 – 100 yards.
If you have other suggestions, please let me know.

I hope these series of tests are able to help someone. However, it seems that my gun differs from the manual (not sure why) and I am no gunsmith or expert of any kind regarding air rifles. At any rate, perhaps the tests can be of some help to some individual.

Next: tuning the .177 Marauder, Hawke SR Scope, and other items.

Until next time… same bat time and same bat channel.



Posted April 20, 2010 by avv604 in Marauder

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2 responses to “Marauder Project – .22 Tuning (Part 3)

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  1. Hi Jeff – I’m trying to figure out your final net adjustments starting from max out? Being you picked up from yesterday it’s a bit much to follow. The string looks good.

    If your moving onto the .177…. this Crosman Blog should save you loads of time. I was going to try some setting to see how well it would work in .22.
    Copy paste the link and scroll down to “YOUR MILEAGE MAY VARY”

    This is what I was talking about yesterday of having preset numbers to work with. Let me know what you think after you read it and check the assorted settings.

    • Greetings Bob,

      You are correct, I have covered quite a bit of ground. I will reply with a concise overview of my settings.

      Thank you sir for the posting link. I have fiddled a bit with the settings, but I will need to really document everything I have done. So I will basically starting over. šŸ™‚

      Thanks again,

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