I spent 6 hours with my MROD .22 and my crony yesterday…
…but a few weeks prior I ran a test to see how it performed from the factory and this is the string it produced in stock form:
Crosman premiers 14.3gr 2600 psi sp
846
856
859
863
869
875
877
882
879
883
886
888
890
891
892
893
880
891
895
891
888
893
890
889
885
885
882
879
884
877
871
871
870
864
866
865
858
857
Now that’s not too shabby for a 40 shot string, and shots 6 through 36 procuced a nice 30 shot string with an ES of 20 with a high fpe of 25.5
If I had any sense, I would have simply left this rifle alone and set myself to the task of working on the barrel for accuracy…but I’ve never been accused of having much sense, so I could not leave “well enough” alone!
I have always been an “energy” junkie when it comes to pcp’s…so I had to see what kind of power I could get out of this thing.
I started out by maxing out the hammer spring preload, opening the TP screw wide open, and the longest valve stroke setting.
I shot a string this way, and it very loud (even with the shroud) due to the TP metering screw being “wide open”. I’m not going to tire my fingers and list all of the six hundred or so pellets I shot through the crony, but I will say that after each string I walked the valve stroke in a 1/2 turn and the difference in fps and ES from 1/2 turn in on the valve stroke to 2.5 turns in on valve stroke were for all intents and purposes negligible, that is the ES only varied slightly, the fps hardly differed and the bell curve climb rate was pretty much the same. One thing that did affect the velocity significantly was when I turned in the metering screw on the TP. All the way in made the rifle very quiet, but it also cut my fps down by an average of 50.
All my strings were shot with a fill pressure of 2700 to 2800 psi.
The best power I was able to achieve through the night was with the following setting:
Hammer spring preload on MAX, valve stroke 3/4 turn in from MAX, TP metering screw 1 turn in from wide open. This string was shot with jsb Jumbo RS 13.43 gr as I ran out of Crosman’s by 1:00 am. I figured they travel around 15 to 18 fps faster than the 14.3 premiers.
SP 2700 EP 1900
966
962
967
969
964
982
987
979
982
977
988
989
986
984
983
983
975
982
978
977
980
972
966
958
962
958
955
948
947
942
That gave me a high of 29.176 fpe (nearly four pounds higher than the factory setting) A ES of 47 over the entire string, but a respectable ES over the “meat” of the curve {20 shots} of 31, and a 15 shot ES of 21 as long as I’m disecting the curve, lol.
Depending on what pellet this barrel likes best (so far it is the 14.3 premiers and 14.3 beeman FT, it hates the JSB’s), I will decide if I want to keep it where it is now, or go back to the lower fps and higher shot count…
I can’t help but wonder what a slightly heavier hammer would do for helping me get into the “meat of the curve” faster…, or perhaps a stiffer hammer spring….????
Honestly, this is time consuming, tedious work, and my hat goes off to the professional tuners who offer us their services. I’d rather spend my time plinking and sighting in scopes…
EDIT: Next time I will play around with a lower fill pressure (2600) and see what I come up with. This would be ideal as it would save on air in the long run anyway.
I hope others will post their numbers on their MRODS as I think I am the first. I search high and low and I have yet to find any “numbers” by anyone…, not even by the Man himself. I looked on his sight, but I can’t find any. I would like to see what Mr. Davis and others have achieved so I have something to aspire towards…Until next time….Oh, and thanks for all your help David!
80 Grit
All Replies
nutshot, on 10 April 2010 – 05:49 PM, said:
No prob Hassan
If you were running a shorter pip than 17mm that would have been your problem . Too short and the action gets all slow and sloppy and consistency got totaly to pot .
Nick
a lesson to be learned tho nutty lads thinking a shoter pip will give u a better gun m8
Mam,
So if the striker is too short, it will not allow the valve to open properly on each shot? Question: What would cause this “pip” to be too short in my tuning process??? In other words, should not the stock config be sufficient? Thanks
Well 80, I think what happens is that the the shorter the striker, the less
pressure the spring is applying to the hammer on the end of the stroke
when the hammer is making contact with the valve.. This means the
spring may not push the hammer all the way through the valve opening
cycle… The hammer would be disconnecting from the hammer spring so
to speak and would be relying on momentum alone to open the air
valve. On a Rapid the pip/striker is not adjustable. If we are fortunate,
we can find a custom pip maker to make any size we want but, as you can
tell from what Nick and Dave G. have to say, shortening the striker to gain
more hammer momentum does not always work…. Sometimes what
makes sense in the head does not translate to the gun…I posted that just
to give you some mental notes while tuning just in case you start to see
your consistency fall away…The only way to know for sure it to try
several different positions as you have been doing. That is a very nice
tuning feature on the Marauder that the Rapid owner do not have… We
have to pull the gun apart to make that adjustment… Just more FYI…
nutshot, on 10 April 2010 – 05:49 PM, said:
No prob Hassan
If you were running a shorter pip than 17mm that would have been your problem . Too short and the action gets all slow and sloppy and consistency got totaly to pot .
Nick
a lesson to be learned tho nutty lads thinking a shoter pip will give u a better gun m8
Mam,
So if the striker is too short, it will not allow the valve to open properly on each shot? Question: What would cause this “pip” to be too short in my tuning process??? In other words, should not the stock config be sufficient? Thanks
While tuning keep this in mind…. I got this from the Rapid Forum.. A hammer pip is equivalent to the hammer striker on the Marauder… This guy was having problems with shot consistency.
nutshot, on 10 April 2010 – 05:49 PM, said:
No prob Hassan
If you were running a shorter pip than 17mm that would have been your problem . Too short and the action gets all slow and sloppy and consistency got totaly to pot .
Nick
a lesson to be learned tho nutty lads thinking a shoter pip will give u a better gun m8
consistent shots @ 24FPE and a higher shot count… I’ll post some results
when I get it into the Falcon… Will be 3-4wks because they have to custom
cut it to fit the Falcon air tube….
Okay, so I will be able to get a good 50 consistant shots out of one fill. That would be very nice!
Also, if you have any suggestions for any other “tweeks” for my MROD…I will be “dismembering” it next week…For starters I am going to polish the inside of the tube where the hammer rides…
May as well polish the bore and crown while you are at it….
I am not positive about the actual shot count but what ever it is, it will be
consistent… I have seen the results that Vincent posted and they were
great… I have not seen any from anyone that bought the regulator yet…
http://www.network54.com/Forum/79537/message/1265507755/initial+results+marauder+regulator+project-
consistent shots @ 24FPE and a higher shot count… I’ll post some results
when I get it into the Falcon… Will be 3-4wks because they have to custom
cut it to fit the Falcon air tube….
Okay, so I will be able to get a good 50 consistant shots out of one fill. That would be very nice!
Also, if you have any suggestions for any other “tweeks” for my MROD…I will be “dismembering” it next week…For starters I am going to polish the inside of the tube where the hammer rides…
The regulator will give you the ability to fill to 3,000psi and give you more
consistent shots @ 24FPE and a higher shot count… I’ll post some results
when I get it into the Falcon… Will be 3-4wks because they have to custom
cut it to fit the Falcon air tube….
saying. 😉
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Yeah, I hear you Mam…I probably would have been testing with 3k had I had that in my scuba tank. 2800 was all I had. when I shim the spring for preload…I will surely start from 3,000. If I decide to make this a 24fpe rifle (original setting) I will tune it to a 2600 start pressure for sure.
I also just ordered a regulator from Vincent…. I am putting it in a Beeman
Falcon instead of a Marauder but I think it would do really well if you are
thinking about 24FPE… Just check to make sure it is shooting accurate at
what ever speed you decide you like… I dropped my EDgun and Rapid to
880ishFPS with JSB 18.1gr to get them to do sub 1″ groups at 100yds….
Again, I am just saying…lol
It’s funny you say that. I think so far it prefers the premiers…I want to try a few other pellets to find out for sure. My plan is to find out what pellet it prefers…perhaps send the barrel to someone qualified to “accurize” it (that is a little beyond my capability), or perhaps come off this hip—which I really don’t want to do—and buy a LW barrel for it, then after I have found the “pellet”, adjust my fps for that specific pellet.
As for the regulator…I thought about that…, but if I decide to return it to factory settings I will not go that route as you can see from the first crony I did, it looks like it is dam near a regulated rifle already 😯
No doubt the reg will help if I decide to extract the most fpe possible out of it. I’d like to see how it turns out for you and your falcon…can’t wait to read the post 😎
Also FYI. The .25cal Marauder has an operating psi of 3,000psi… I’m just
saying. 😉
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Yeah, I hear you Mam…I probably would have been testing with 3k had I had that in my scuba tank. 2800 was all I had. when I shim the spring for preload…I will surely start from 3,000. If I decide to make this a 24fpe rifle (original setting) I will tune it to a 2600 start pressure for sure.
I also just ordered a regulator from Vincent…. I am putting it in a Beeman
Falcon instead of a Marauder but I think it would do really well if you are
thinking about 24FPE… Just check to make sure it is shooting accurate at
what ever speed you decide you like… I dropped my EDgun and Rapid to
880ishFPS with JSB 18.1gr to get them to do sub 1″ groups at 100yds….
Again, I am just saying…lol
option 80 GRIT
Yes, I think you are right. I will try this before I change the spring. Another MROD owner bought a different spring at Ace Hardware and he got 34 fpe from kodiaks for a nice 20 shot string with a es in the 20’s.
Also FYI. The .25cal Marauder has an operating psi of 3,000psi… I’m just
saying. 😉
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Yeah, I hear you Mam…I probably would have been testing with 3k had I had that in my scuba tank. 2800 was all I had. when I shim the spring for preload…I will surely start from 3,000. If I decide to make this a 24fpe rifle (original setting) I will tune it to a 2600 start pressure for sure.
Good work 80! These are very good airrifles. I like my 25. The shot count is terrible at just 16 rounds, (2 magazines). But then again it is a .25 putting out a solid 48-50 FPE. 😀
That 2nd shot string looks good as it is..but a heavier hmr. spring I think would get to the “meat of the curve” as you put it, a little quicker.
Packrat,
If you look in your owners manual it will tell you why and how you can adjust your rifle.
It was suggested to me by a gentleman who is very knowledgeable on this rifle to start adjusting from the settings I mentioned, and to work the valve stroke in a 1/2 turn at a time until you desired fps starts to fall off (although I think it would be best to work your valve stroke a 1/4 turn at a time rather than 1/2). Once it starts to fall off, turn it back out to return fps to the previous level. Then start working your TP metering screw back in a 1/4 turn at a time until fps starts to drop again. This is how I arrived at my current setting. I was hoping the transfer port metering screw would give me more “shot count” while it was in a bit as oppossed to “wide open”, but I did not notice much difference in shot count…I still have alot more testing to do on this rifle…I need more time, and energy for it 😆 I will continue to post my findings.
option 80 GRIT
Yes, I think you are right. I will try this before I change the spring. Another MROD owner bought a different spring at Ace Hardware and he got 34 fpe from kodiaks for a nice 20 shot string with a es in the 20’s.
Also FYI. The .25cal Marauder has an operating psi of 3,000psi… I’m just
saying. 😉
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option 80 GRIT
Yes, I think you are right. I will try this before I change the spring. Another MROD owner bought a different spring at Ace Hardware and he got 34 fpe from kodiaks for a nice 20 shot string with a es in the 20’s.
Shimming the back side of the hammer spring with washers could be an
option 80 GRIT
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Got it! Thanks for all your FYI’s mam, they are much appreciated.