Tuning Marauder POI shift opinions?

[SqrlHntr]

Merry Christmas all! 
I found this old post (2014) and wondered what the opinions are from the the experienced mrod tuners. Logically it makes some sense, but I have never read or found anything else about this ‘fix’ involving the barrel set screws. To me this would make sense, but I am not as savvy as y’all are. Least not yet! 

 

[Odoyle]

Probably the most common issue is the front air diffuser with o-ring cracked or worn that supposed to center the barrel inside the shroud. Some may even take the next additional step to fill in that gap between the barrel band and shroud to make it rigid.

 

[JamesD.]

The O-ring on the end of blast diffuser is there to squelch down harmonics. 


I'm not sure if a tighter custom band or O-ring mod is necessary at every power level. Free floated seems to work great for me at my lower power levels for pellets. 
I would not mind a good tight cushioned barrel band to test slugs at 30 to 50 yards on higher power levels. Even super high power levels by mods. I think a better band would be required.

 

[triggertreat]

I just put an O-ring inside the front shroud support (Danco #30 from HD). That seems to hold the shroud good for any POI shifts. The breech end of the shroud is a half turn out from being tight. On my other .25 Mrod, I just use an aftermarket Hill shroud support, which has a tight tolerance to the shroud and an O-ring already in place inside for support.

The CF sleeve would certainly stiffen up the barrel more. I would be looking at some expandable foam to fill in any gaps between the barrel and the CF tube.

 

[SqrlHntr]

Y’all are the best. Between the knowledge and desire to help others. major part of why I love air-gunning. 

. I have the Hill band installed and was about to leave it on the shelf. Turns out the o ring at the muzzle end was deformed, replaced both and the breach oring just for good measure, backed off the shroud a little, and things got back to normal, sort of, still more fliers than I care to admit. Put everything down and was about to revert to the stock config when I had a thought. I backed off the set screws in the Hill band and shot a full mag. Must have aligned itself because its back to driving tacks. Set the screws and good to go. 


Again, y’all are the best and the major reason air gunning is so much fun. 

 

[uhfradarwill]

I had a .25 cal Marauder years ago; it drove me crazy.

I did manage to get it to group ok but the location of the groups changed by the minute.

I finally sold it.

Good Luck.

Will

 

[mercado]

Yup me to.. I have 2 marauders years ago..even the .22 came with a awesome barrel both were shooting perfect...then some day 2 months after..It don't matter what I tried pellets simply go everywhere..I think that if crosman charge $100 dollars more a screw the barrels in to the block..like the taipans they could be such a good pcp that I would have kept mine. Aside from the POI shift every thing else on the marauders worked for me..

 

[Xbowsniper]

Nation, 

I've found that every Marauder has some form of shift. It's from the fact that the shroud torqued the barrel. O rings making the shroud semi rigid will help a little, but in the long run, the torque issue is still present.

You can tell if you are going to have a large, or small to negligible shift easily, by doing this test.

Shoot and zero your gun at 30 yards as normal. Carefully unscrew and remove the shroud. Shoot another group aiming at the same place. If the group shifts very little or not at all, you most likely will have little or no shifts due to temperature. If the group moves significantly, you will most likely have issues. My Marauder set up for WFTF PCP field target, had a shift of over 2 inches to the left. The shroud, when screwed back on, torqued the barrel back to where it was. I removed the shroud completely, as I don't care about noise, I care about accuracy, and maintaining that accuracy in all conditions. 

Tom Holland 

Field Target Tech 

Fieldtargettech.com 

 

[Odoyle]

Or cracked barrel shroud stripper spacer and or surrounding O-ring Or both at the end of the barrel.

 

[PumaCarl]

I know this is controversial, but, I completely bedded my synthetic stocked mrod to include the barrel ring. Never had a poi shift. Shoots lights out at 58fpe with no harmonics problems. MkII are stabile out to 120 yards. Not an opinion, a fact for me. I have a lot of experience with the process and it worked really well with the mrod. I have never even bought a case for it. I usually am a fan of free floating but I wanted rugged this time and I got it.