Tuning the Benjamin Marauder

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Replacement MROD arrived today. Looked like it shipped better the the first one, no apparent defects, but oddly the fill cap was loose in the box. Barrel looked centered in the barrel band slightly better then rifle #1. 

Mount the optics and filled up the rifle. Well this time I filled to 3000 psi on my hand pump, I'm filling the majority of air with my SCUBA tank and topping off with the hand pump. The rifle gauge showed 2900 psi. My first MRODs gauge showed 3000 psi and the pump showed 2800 psi, so I was filling according to the previous rifles gauge to 3000psi. 

I zeroed the the scope as best I could guesstimate as the target looked like I was shooting with a shotgun. 

Changed targets and and proceeded to start shooting 10 shot groups to see if the rifle would settle down. I did notice with the first rifle the groups tightened up a little after around 100 pellets. 

I would say say rifle #2 is shooting even worse then rifle #1 after 170 shots. This was my last 50 shots, did this on one fill over a chrono just to see what's what. This was absolutely horrible at 20 yards. First rifle was shooting 1 1/4"-1 1/2" @ 20yds. This is off the bench. :(

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Glad you got your gun and already shooting!! Marauder gauges tend to be junk, and I always go by my tank gauges. I was tired of bad gauges, so I bought a bunch from mcmaster carr and they are all spot on with my tank gauges.

I would highly recommend cleaning the barrel if you didn't already do that!! You also need to try different pellets until you find the one that shoots the best. Not to be rude, but I would never expect any marauder to shoot well out of the box. Those that shoot great out of the box are few and far between. Since you had the chrony out, what did your shot string look like? That will tell alot!!
 
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First rifle did shoot noticeably better then this one right out of the box. Wasted a lot of pellets on the first rifle with the JSBs shooting best out of the previous rifle, the JSB's did not shoot as well out of the new rifle. 

I haven't cleaned the barrel, I wanted to start bone stock right of of the box just like I did I with the first rifle. I eventually did clean the barrel on the first rifle, but all things being equal right out of the box this one is shooting even worse then the first one I had. 

I am posting via an iPad and don't have any way to do a shot string spread sheet, but my first shot was 833.0 fps, shot 50 was 830.3 fps, high was 875.0, low 828.1 which oddly was shot 3. 

JSB 18.1
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Just wanted to update my post, I'm not going to post anything further about this rifle in this thread as I don't want to hijack this thread, but after talking with AJ, we finally narrowed down what was causing the accuracy issue. An oversized bore, I have no rifling engagement on the heads of the pellet, just the skirt. And knowing is half the battle. 👍

Thanks AJ, you are a gentleman and a scholar, your time and knowledge is greatly appreciated. 
 
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Here is a 50 yard 5 shot group:
After all the mods I did on my Marauder I wanted to really see if it shot as well as my Cricket. So I have been competing these two rifles for the last several weekends. Two weeks ago the Marauder won out with this 5 shot groupings. I actually stacked the first four pellets but had one drift to the left. One of the few days we have had no wind in the desert.
 
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At the time of that group, I had a Hawke sport HD 3-12. I currently have an Aeon 6-24 that I used at extreme bench rest. I placed 20th 1st time out competing with the "pro" class in the 25 meter. Not sure why there was no Sportsman class or I believe I would have been in the top 5. 

I would like to take the credit for shooting but I will confess I believe it's really the rifle. This rifle has been mod-ed and tuned optimally, all I did was pull the trigger, the rifle did everything else. The skill of the shooter is playing the wind, judging the distance, and most importantly, not impeding the rifle. I am still amazed at the accuracy of these pcp rifles and still get a "kick" out shooting these guns.

I would love to see an accomplished shooter such as AJ shoot one of his tuned Marauders against the "high end" rifles at Extreme Benchrest!!!!! I don't think people would be snubbing their nose at the Marauder any longer!
Aaron, accomadations would be on me!!!!!! I'll even buy the beer!!!!!!!!
 
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First, excellent article!

I tried a little tuning on my Gen 2 Marauder .22 and ended up returning to "Out of the box" settings. Other than that, all I did was spend a lot of time on the barrel. Needed a good, solid cleaning. Since then, haven't done anything but shoot.

Local gun range was fascinated when I brought in an Air Rifle to shoot with the black gun crowd. At the range, zero wind, at 25 yards, I routinely get quarter sized 10 shot groups. And remember, I'm a lousy shot. It is scoped with a 4-14 FFP scope, but still, the gun is much more accurate than I ever will be with factory settings.

I have tried a couple different pellets, but so far the best is the Crosman 14.3 grain Dome. The hollow points and every other pellet I've tried opens up quite a bit.

The one adjustment I'd like to make is to the hammer spring. When cocking the gun, pulling that bolt back takes effort. I jealously watch the FX Videos where the side lever cocking seems effortless. Is there anything I can do for that, or is the heavy bolt pull just part of the design and that's all?

Many thanks.

 
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