Marauder Rifle .22: Should I go for more mods to get power, or start all over?

[FlexWagtail]

Update: How did I trash my P-rod?

I decided to tinker with my P-rod before going all in on revalving my M-rod weve been talking about — since a Hill kit for the P-rod is cheaper.The tinkering seems to have completely screwed the gun up before I even got to Hill's valving and springs.Here’s the deal:
I was screwing with installing a larger transfer port I had, shot it some, and then changed back to stock — all just for grins.The results was that the gun literally went from shooting 1/2” (or less) at 25 yards EVERY TIME to shotgunning pellets at 10 yards. Really, like 2” at 10 yards bad.Here’s what I’ve done:

1) Checked for clipping, on stripper and TKOmoderator – none

2) Changed scopes for comparison – same results.

3) Cleaned barrel, shot with shroud cap instead of moderator. Still bad.

4) Complete disassembly and cleaning, including removing barrel and checking to see all grub screws are set and tight. Looks and feels solid.

5) Checked barrel bracket. all good. floating free – no friction.

6) Shot multiple groups with shroud — and then without. Even shooting it naked, I got the same bad results at 10 yds! Whaa???

7) Checked and triple-checked to see that the transfer port is set cleanly and orings are good. Its all there, best I can tell.

8) Ran over chrony through most of this. Velocities are stable.

9) Used CP 14.3’s as I always have. I Have not dinked with pellets. The 14.3s are what the gun has always liked.

The barrel is set firmly in the reciever. The scopes are fine. No clipping I can see. I’m literally mystified. I MUST have done something while screwing with swaping transfer ports, but I can’t imagine what.

At this point, the gun is useless. No fun to plink with, cause It can’t even reliably hit a bottle at 25 yards. Hunting is out of the question.

This all started when I substituted a stock transfer port with a drilled .111 port, just for grins. CP 14.3 Velocities went from 640 to just over 800. The accuracy problems started with predictable uneveness at high velocity. I tuned it back a little, but accuracy was still going south. So, since I’m intending to order a Hill P-rod vavle kit, I changed back to the stock port so I could keep the gun handy during the time it would take to get the kit.

Now its a mess. Can’t hit poop.

Thanks for reading. Any ideas?

 

[Jayman07770]

I had the same issue before while re-assembling my M&P-rods. Don't know if it's related to your guns inaccuracy but I'll share my experience. The Marauder breech doesn't go completely square when you bolt it down. I don't have a torque wrench so I usually snug the 4 breech bolts than 1/8 turn crisscross follow by another 1/8 turn. This helps the transfer to be 90 degrees with valve and barrel. My next investment will be a screwdriver torque wrench. 

 

[Wager]

Hey bud,
Im pretty sure I know whats wrong. The pellets aren't being pushed far anuff into the barrel by the probe passed the transfer port, so part of the skirt is still above the tp. When fired it bends the skirt in on that side and accuracy go's out the wind. Take the breach off the air tube, and try resetting your barrel as far back as you can with the mag in and then make so you can still get the mag in and out. You may have to slightly move the shroud threads forward. Then put a pellet in and try setting it all the way with the bolt as you watch it through the transfer port hole to make sure it fully passes. If more room is still needed you can also grind down one side of the catch bolt that is on the bottem side of the probe. But you shouldn't have to. If you need some pics of this pm me your number.
Hope this helps.

 

[FlexWagtail]

Wager and Jaymann,

Took the P-rod apart to act on your advice with no results, sadly.

The barrel is well seated, the barrel port is aligned center with the reciever hole, and there is no pellet skirt showing, only probe. I reset it anyway, just for giggles. No motion I can detect. I'm convinced she's good there.

I've been criss-cross rotating bolts to tighten down the reciever on the tube every time. All good there. It is aligned and solid.

Kept the gun naked with no shroud or stripper and shot three groups of 8 at 12 yards.

The first two groups sprayed at 1.5", which is horrible.

The third group I shot hand feeding pellets instead of using mag. was a little better at about an inch, which is only slightly less horrible.

Thinking I'll just sell the thing, except I cannot hand off this gun to somebody in this condition in good conscience. I wonder what the heck is going on? A barrel doesn't just go bad? Steel beats lead, right? Its hardly worth mailing it to a tuner. For that money I can just buy a MM HFB and start all over. I hate to give up on this, but I'm out of ideas. I can't be the first guy this happened to. Annoying. But hey, its a hobby.

 

[Wager]

Do the pellets chamber smoothly or is it a little rough to close the bolt pushing a pellet in?

 

[Wager]

Im thinking the oring at the beginning of the barrel ether got blown out or cut some how. If not that then when you put the drilled out transfer port in it ether put a bur in the barrel or the transfer ports are sticking to far through the barrel and are clipping the pellets themselves.

 

[Ric-1]

.

Who does custom work on Marauder Pistols?????????

I have a Marauder pistol that averages 650 FPS w/ 14.3 gr pellet. That about 13.5 FPE. I want closer to 900 FPS if possible. 

My problem is I am in my 70's and would prefer having it done professionally. My eyes and finger can't do detailed work like a young man. 


.

 

[addertooth]

FlexWagTail,
​Just for giggles, could you try some H&N Field Target Trophy or JSB Exact King pellets out in your gun before you declare it broken. I have seen a gun change it's pellet preference rather dramatically when modified. Also, if you drilled your barrel to match your transfer port, was it properly de-burred in side and out?

 

[FlexWagtail]

Gentleman, excellent sleuthing so far. 

Today's update. 

1. I had some jjsb 18.1s on hand and shot them with slightly improved but still poor reults
2. The O ring "looks" OK upon pulling and inspecting, but I just ordered some so I will replace
3. the chambering action "feels" OK. No huge difference I remember from past but it's not smooth as butter, so maybe we're on to something. 
4. "Burrs" Hmmm. Now My gears are turning and here's why. When I installed the custom port I felt like it was just a shave high. Seemed like the receiver just didn't want to seat cleanly. We're talking thousands here. But I tightened down anyway and shot it. seemed a little off enough that I disassembled and shaved the port very slightly with a dremel. 
   [/LIST=1]
   This is is about the point where things went south. Gun shooting too fast, and even tuning down was predictably wasting air. Not as accurate as before but not crazy bad yet. This is when I went back to stock and lost it.
   
   I can't imagine an aluminum port buffered by o rings could deform the barrel by tightening too much?? But maybe?? I've cleaned it and no sign of burr in there but maybe???
   
   Whats the solution? Should I go aggressive with some JB paste?

 

[Wager]

So rhat was where my thinking was taking me. The sholder of the barrel isn't very thick so if your transfer port was slightly to long and made of a metal when you tighten it down you have a good chance of deformation. That being said, it doesn't take much of a bur to really through accuracy off ether. And lead pellets are so soft if your feeling any roughness/resistance theres a very good chance that pellet is getting messed up.fully chamber a pellet then use a cleaning rod to gently push it back out the chamber and see what it looks like. It wouldn't hurt to slug the barrel as well and see what that pellet looks like as well.

 

[Wager]

O I keep forgetting to mention this! For your tight Mrod barrel you mite want to try gamo... red fire I think there called. They have the ploy sharp tip on them. There is a chance I just got a weird batch but the head size was way small. To the point you could barely make out the grooves from the rifling. I think its worth a try anyways.