Air Gun Home :: View topic - What makes the Marauder (or any PCP) tick?

rsterne · Moderator

I'm sure that eventually someone in the USA will start playing with the Marauder (I can't in Canada).... It has a lot of adjustability built in already.... so what it really needs is someone to simply start shooting and playing with the adjusters and recording shot strings.... It's boring, but you learn a lot.... and it's where I started with my Discovery.... Test all the pellet weights with it stock.... then change one thing and do it all again.... If you find one (middle weight ~18gr?) pellet which works particularly well, you can short cut the process by doing a lot of the testing with just that one pellet.... Change the fill pressures and record the resulting shot strings (I stop at 95% of peak or so).... Then using the "best" fill pressure, change the velocity adjuster and find out what effect that has.... When you find the "best" setting on that, then you try the hammer preload adjuster and find out how that works.... The problem is, of course, that these three adjustments all interact.... It would take a long time to try all the combinations, but once you get a feel for how each affects the performance, you should be able to zero in on two or three settings that produce (different) results that you want.... Wink

If each person that did this testing took the time to record it in Excel and publish the shot strings along with the settings.... it would go a long way towards understanding what makes the Marauder tick.... I've done a lot of this with my Discovery (and homemade PCPs) and I've learned a lot which will PROBABLY apply to the Marauder (or any PCP, for that matter).... What I have found with my experiments follows:

1. The fill pressure range you can use will DEPEND on the other adjustments (and pellet weight).... Higher pressures generally mean more potential power, but fewer shots per fill (from the increased air use).... and also fewer refills per tank (because you have to fill to that higher pressure).... I use a cutoff point of about 95% of the peak velocity on both sides of the shot string.... If you are shooting at short range, you could use 90%.... but the vertical stringing will increase....

2. Increasing hammer strike will move the peak of the shot string to higher pressures.... and vice versa....

3. Opening up the velocity adjuster (which restricts the transfer port) will make the shot string "peakier" (ie shorter) but with more power.... while closing it will flatten the shot string making it longer.... Opening the adjuster will usually move the peak of the shot string to a lower pressure as well (and vice versa), which complicates matters.... Increasing the "flow" from the valve (or ports) even more than what you can get with the velocity adjuster opened up all the way will simply extend these effects....

4. Heavier pellets tend to be more efficient in extracting power from a PCP.... particularly at higher power levels.... Their shot strings tend to peak at lower pressures.... and tend to be longer (more shots within the 95% window)....

I hope that these ideas will guide you in dialing in your Marauder (or other PCP) for your particular use.... PLEASE record and publish your shot strings so that others may benefit.... Shocked

Bob

sniper · Silver Status Member

bob,
i have the chrony, the time, the patience and the ammo.

i need a bigger tank. Crying or Very sad

Midichlorian · Veteran Member

You should take a vacation rsterne.
Come down to my house in Victorville Ca,stay a few days and we can experiment on my Marauder.
Im sure Sniper would come through too. Cool

sniper · Silver Status Member

i think bob posted this thread to taunt us mid. Laughing

since he knows i have a tank and no pump and you have a pump and no tank. Shocked

the only problem is it's an hour and a half each way from my house to yours. Rolling Eyes

broommaster2000 · Moderator

I was thinking, which doesn't happen often, and thought; Technically there isn't a lot of difference in the Marauder and say an Air Arms S400 12 Fpe. The biggest differences are probably the trigger and the valve (apart from dimensions). Now, my Air Arms has a build in anti-tamper and a Marauder doesn't. Over here they're roughly the same price. The Marauder is more powerful but also not as factory tweaked as the S400. Slap a decent scope on the S400 and you can shoot field target matches, and you have a decent chance of winning. You'll definately need to tweak the Marauder.

What I really wonder, if you would buy a rifle to shoot FT @ 12 Fpe with, which would you choose, and why?

(If you're thinking, S400 is my benchmark? Yeah, pretty much.)

rsterne · Moderator

Over here, the limit for FT is 20 FPE.... so you'd have to buy the FAC version of the S400.... and the Marauder wouldn't have to be tuned down very much.... Wink

My guess is the S400 might be higher quality.... but I've never had either gun so can't make a judgement.... Embarassed

Bob

broommaster2000 · Moderator

I might go for a FAC version in the future. But only the older carbine version. I don't like the sidelevers at all. Sure, they work flawless, and they're light to operate but there's nothing like a nice bolt for aesthetics. At least the Marauder has a genuine bolt. Mr. Green

sniper · Silver Status Member

shooting the mrod is VERY centerfire rifle-ish.
to me anyway. Cool

69Hotrod69 · Veteran Member

sniper

I feel for you, I shot about 50 shots today through the chrony refilling to 2000 PSI every five shots, then shot another hundred to sight it in pumping every 25 shots. My shoulders and back are killin me! Crying or Very sad

I do plan on posting my excel graphs when I have time to test the Mrod on the chrony. Should I post them here? or start a new post.

sniper · Silver Status Member

Though it's an old thread it's not overposted on.
post here.

packrat · Senior Member

A fellow named GREG DAVIS, out in Arizona (I think) is reportedly a MRod "wizard" when it comes to performance mods, etc. I know LOTS of guys send their Mrods to him for averything from simple "tune-up" to all out performance guns.....at least that's what I've read..He surely would be one that knows a lot about tuning for max output...
I don't have a link to his website, sorry. Nor do I know how he would feel about sharing "secrets", as it were....simply passing on what I've read of his sterling reputation Mr. Green

spysir · New Member

Is it the shroud that keeps you from being able to have one? Darn easy to remove and it would look different but it is a fine rifle.
Let's call the trigger "a close copy" of the Theoben MFR, pop out what I call the laywer spring (first 100 Marauders did not have it) and the trigger
is as sweet as a $2,000 rig.
Lot's of info on this blog(not mine):
http://avveduti.wordpress.com/2010/04/30/marauder-project-lightening-the-trigger/
click all the Marauder sections.

John