Frustrated with my .22 cal Marauder

Jump to latest Follow Reply
AJ I actually like the idea you used with set screws, that will also allow you to center the shroud or possibly align it with the scope better. If the barrel band is slightly off center the shroud can easily be aligned by using the set screws. With a solid sleeve if you remove the barrel band it will allow the shroud to move and then you have to make sure it is in exactly the same position when you re install the barrel band. I have noticed without the shroud on the gun that the barrel is not centered inside the barrel band so I can see how there would be accuracy problems with these being rubber mounted. Of course the shim centers it but it was just an observation I made with the shroud removed, my barrels points slightly to the left. I really like the set screw idea, Neil.
 
Upvote 0
Hi AJ – I preformed the suggested test as shown below. The target numbers 10, 11, 12, 13, 14, 15 and last 9 were shot in that order. You should exclude 10 as I shoot down from 3000psi to 2400psi as shown on the rifle’s gauge then I shot target 10 and then I refilled it to 2400psi as shown on the tank’s gage, which I believe to be more accurate, the rifles gauge registered somewhat higher. All the other targets were shot starting at the same pressure. I shot over a crono and if you are unable read the results off the target the data excluding target #10 showed velocities: HI = 860, LO = 849, AVE = 855, ES = 11 AND SD = 2.



Here are the rings I machined for the barrel band. Note the grove on the O.D. that the o-ring in the barrel band snaps into and keeps it from slipping out. The I.D. & O.D of the rings are a slip or slight interference fit so there is no movement in the barrel band. I liked the delrin ring better because it doesn’t leave marks on the shroud like the aluminum ring does.



This was the result using the barrel band and before I made the latest mods. The black marker was sighting in.



JPC - I get the same thing if I over fill past 2800. Put I shoot between 2800 and 1800 if I fill to 3000 my groups open way up.
You said "I never found anything consistent as long as I stayed between 3000 psig and 1900 psig." I hope you meant inconsistent.
Once I get these groups to settle down I can start playing with the other adjustments to tune things in. I don't know if I'll ever get one hole groups from this Marauder like I do with the HW 100. I'm not looking forward to breaking in another barrel but I might need to get one on order.

Shoot Straight - Jay
 
Upvote 0
Neil, the set screw band does work well to allow you to keep the scope centered and slightly adjust.

Kill, based on your target and numbers, I would assume that your tune is what is causing poi change over a whole shot string. I am basing that on the graph data in your first post going along with this data. Groups seemed consistent and poi stayed when shooting every group from 2400psi. When shooting down from 2800 psi, you don't see poi change till the middle and end of the shot string? Shoot from 2800psi down to 1800psi over the chrony. Then post the whole string.
 
Upvote 0
Jay - No, I meant "consistent". When tethered to a regulated bottle I was able to select different pressures and shoot many times at a selected pressure. As long as I stayed within the pressure range noted before, I did not find one pressure setting that consistently gave good POI accuracy over another pressure setting.
 
Upvote 0
AJ it is also great for people who do not own a lathe, they can do the modification very easily and will not have to rely on someone making a sleeve for their barrel band, great idea! Because I use the lathe all day long I automatically think about making something permanent on the lathe, I never even gave set screws a thought because of the adjust-ability of them, but having tried the bushing I know that the shroud can be in a slightly different position in reference to the scope each time you remove the barrel band so it makes it easier to center it to the scope than having to sight in the scope every time you remove the barrel band. Of course you could always mark a reference point on the parts to make sure they go back in exactly the same position, but I do like the simplicity of the set screws, Neil.
 
Upvote 0
Jay - Since I own two .22 FX rifles that approach or can slightly exceed 30 FPE, I am not too concerned about maximizing velocities in my .22 Marauder. In fact I wanted a compromise between velocity and shot count. With JSB 18.1's, I get an honest 40 shots at an average of 810 ft/sec, all well within ±3%. I fiddled and fiddled with manual iterations of fine-tuning the hammer spring to hammer throw and velocity screw settings until I got what I was looking for. I did the same with my .25 Marauder and came up with an great shot count of 40 in that rifle with JSB Kings at 820 ft/sec (again well within ±3%), working between 3100/3150 psig to 2000 psig.

My next step with the .22 Marauder is to slow it down to 700 ft/sec with JSB 18.1's and then if I can maintain accuracy, try shooting the rifle in F&T, since that is where I won it. :<))
 
Upvote 0
I shot that string this evening and I was surprised to find it quite a bit different from the one I first posted. So I checked my notes and it looks as though I may have changed some settings back in Nov 2013. I should admit that I haven’t shot the Marauder as often since I got the HW 100 – I’m probably a bit spoiled now.

But at this time it is what it is and here's the chart and target. I started the fill at 3000 psi and I shoot down to 1750 where it was sounding like it was getting to low. The groups are not too bad for this M-Rod – it would be nice to get them to look like the ones on the bottom shot with the HW 100. I know that is a lot more rifle, but one can hope.



 
Upvote 0
Kill, thanks for posting that data!! That confirms my thoughts that your tune is the issue and nothing else. By your group sizes, your barrel isn't very good. To save time, I would get an aftermarket barrel machined for a marauder. Will cost more than a crosman barrel, but you won't have to play the lottery. I bought 9 crosman barrels before I got a good one.

One piece of advice for tuning. Leave the VMS wide open and tune with the spring and striker. The VMS may cause some turbulance and effect velocity, but it doesn't change how much air is used per shot. So, you may slow down fps with the vms, but wasting air. Hence the low shot counts regardless off tune level. The stock valves are rather inefficient and need opened up to breath. Even if you want a lower power tune, the gun needs to breath for efficiency sake.
 
Upvote 0
Update - I added 3 set screws to the stock barrel band. 4-40 x 3/16 with plastic tips and reinstalled. I made an attempt to adjust the screw to hold the shroud where it normally wanted to float - and lightly tightened them down. and then shot a string of groups.

Neil - As I suspected, and I think you might agree, I don't see much difference between these groups and the target shot in the post of 25 Apl.

Next thing to do is to polish the hammer and inside of the main tube and install the O-rings for a Bstaley tune. I just picked up a 1.00 ball hone so I'm thinking I might start that tomorrow.





 
Upvote 0
I watched Teds Marauder pistol review the other day. In it he commented on Gen 1 Mrod 22 only shooting several copper coated pellets well. Might be something to look into. 

I did the Bstaley mod and had to polish the openings in the air tube as the sharp edges were clipping my orings. Also don't get the super hard orings as they don't have enough give to be installed. I did very minimal tuning, only added a little more spring preload, adjusted the hammer and opened the tiny screw in the side. It gave me spread from 840 to 800 fps over 16 shots with 25.39 gr. JSB Kings. Im sure I could improve on my current setup, but I have a super flat 12 shot group between 3rd and 14th shots. I get free HPA and just shoot around the house so more tuning is not high on my list.
 
Upvote 0
Locking the barrel and shroud will only change the way the gun shoots if the problem lies in those areas, if you have another issue then it will not fix it. A lot of the people I have helped with their shroud problems have found the shims give them a more consistent POI, but this alone will not make a bad shooter into a good shooter, Like AJ mentioned it may be in the tune, Neil.
 
Upvote 0
Dan - Thanks for the copper pellet idea. I have tried those and I got some good results. I now have just about every higher quality .22 cal pellet available and many of the lesser quality. I found a few pellets that grouped better than the rest - AOA, Crow Mags and JSB.

So I Disassembled the rifle and de-burred the cutouts and holes on the inner of the tube with a diamond burr and a Dremal and then using the 600 grit ball hone, I honed the first 6 inches of the breach end of the tube.




Then I polished the hammer and the end of the striker that makes contact with the valve stem working up to 600 grit sandpaper. And polished the end of the springs.

 
Upvote 0
Update - I reassembled with a BStaley Tune - 3 #211 O-rings from True Value. I'm not sure if they are the 70 shore ones as they were not labeled so. I shot some strings and this is the best I could get with the hammer spring set at 6 and the hammer throw set at 2 and the valve full open.



I'm not pleased with the results - 690 down to 630 between 3000 and 2400 psi. Dan 25 - if I could get up to the mid 800, were you at, I'd be pleased.

I don't think the hammer is getting deep enough into the O-rings and if I increases the hammer throw any more the hammer striker may make too much contact with the valve that the hammer may not make contact with the O-rings at all - defeating the tune.

I think I need more spring rate or perhaps the O-rings are 90 shore. I just received my order from the O-ring Store so I have some 70 shore O-rings in there - I could try that as well.
 
Upvote 0
"Killzone"Update - I reassembled with a BStaley Tune - 3 #211 O-rings from True Value. I'm not sure if they are the 70 shore ones as they were not labeled so. I shot some strings and this is the best I could get with the hammer spring set at 6 and the hammer throw set at 2 and the valve full open.



I'm not pleased with the results - 690 down to 630 between 3000 and 2400 psi. Dan 25 - if I could get up to the mid 800, were you at, I'd be pleased.

I don't think the hammer is getting deep enough into the O-rings and if I increases the hammer throw any more the hammer striker may make too much contact with the valve that the hammer may not make contact with the O-rings at all - defeating the tune.

I think I need more spring rate or perhaps the O-rings are 90 shore. I just received my order from the O-ring Store so I have some 70 shore O-rings in there - I could try that as well.


My 16 shot string starts at about 830, climbs to 840 the falls off to 800 with 25 cal JSB Kings. I had to add a little more preload on the hammer spring and extended the striker to make up for the thickness of the O-rings. You should be able to get the velocity up with the striker adjustment. I just followed the youtube video posted by the kid with the sniffles. Shot a few groups for velocity, adjusted the hammer and added more spring preload. Got the velocity where I wanted it and said good enough for me. I'm sure I could improve on the shot count as others have got my tune beat. What I like about the Bstaley mod is my 3rd to 14th shots are +/- 3 fps and the limiting factor on accuracy is my ability, not the gun.

This is the vid I followed. I am sure there are others.

https://www.youtube.com/watch?v=flIxgQXC3r8


Click to expand...
 
Upvote 0
Hi npunk - Thanks for the response. Keep in mind that if you adjust the hammer throw to around 2 turns then you may find that the striker may be hitting the valve before the hammer hits the O-rings and you may here the valve start burping. This is an indication that a spring with a higher spring rate or stiffer spring is necessary.

Hi Dan - thanks for the link - I've seen that video. I started out using 3 O-rings I purchased from a local True Value hardware store that had an 1/8" dia cross section but I didn't know if they were 70 or 90 in shore (hardness). The above shows the results. I replaced them with 4 o-ring of 3/32" dia cross section that are known to be 70 shore and I got very similar results. So it seems I need to look for a stronger spring.

It's interesting that you are having good results with your BStaley O-ring Tune as some of the forums have said that the .25 cal Marauders don't usually do well with it.
Thanks for the info - Jay
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu