.30 Benjamin Marauder Conversion

[Joe Shooter]

I am about to embark on a .30 Marauder build, utilizing Mountain Airguns .30 Marauder conversion kit along with the Cothran Powerhouse valve w/.180 TP. I am wondering if any of you that have done this build and can provide me with the precise or approximate tuning adjustments for that configuration?

 

[Dairyboy]

I've done the conversion however with Hill valve. You will love it!

 

[Wager]

Im very interested in the Cothran valve. Will probably just end up getting one to see how they do in the Mrod. Not a hole lot on the net about them.

 

[Joe Shooter]

Do a search for the Powerhouse valve on some of the airgun forums, you'll see quite a few people using it. I do know that when modding a Marauder with a stronger valve such as that, it needs to be tuned correctly to maximize power as well as achieve best accuracy. I am looking for some numbers, if anyone has them, of what the hammer and valve adjustments might be, and anything else that might be needed to make this mod efficient.

 

[oldmanblue]

I've done one. 28"TJ barrel, Dons valve. Your tp is a key tuning item. 1180fps with a .230tp using JSB pellets with poor accuracy. Redid at .180tp shooting at 910fps and excellent accuracy at 50 yards. Also did a j slot in the breech to pull the probe back out of the way after loading. This helps for almost 100fps when your pushing that much air. Also the port in the barrel is slotted for more area. Dons valve doesn't require a monster hammer spring hit and my sweet spot is around 2600psi. Good string on the gta in regards to your question.

 

[Joe Shooter]

Thanks for that input Oldmanblue. I plan to keep the stock hammer spring. I am curious as any adjustment of the hammer spring preload adjuster as well as the valve metering screw; did you need to do anything with those to obtain accuracy with the upgraded valve?

 

[oldmanblue]

If you go to Dons valve you lose the metering of the stock valve. Stock spring will do fine. Each setup is different so you will need to tune for yours.

 

[Wager]

Just got off the phone with Don Cothran, super nice guy, more then willing to answer an question you mite have. Unfortunately he no loner sells the marauder valve himself because of the deal he has with Travis over at wicked air rifles. He does still sell valves for all the other guns he advertises for but if you want a Cothran marauder valve you'll have to wait for Travis to start selling them.

 

[Joe Shooter]

I actually just spoke to Don also, 10 minutes prior to you posting this, and he informed me of the same thing. I just called Travis as well, no answer, left him a voicemail to give me a call.

 

[Wager]

Hry he said he had to get a hold of one other guy about the valve, kinda figured it was you.

 

[Wager]

Hopefully Travis won't take to long to getting around to selling the valves. I wish I would have bit the bullet and picked some up a year ago.

 

[Guest]

I see Dons valves on WARS website and On the GTA I see hes doing some good testin.

 

[Wager]

Thanks Tim, I didn't think they be up so fast.

 

[Guest]

No problem I keep checking in to see when their new Cobra gun will be up for sale. Then i will have the Trio!

 

[Joe Shooter]

Travis doesn't give any specifics on the valve. Don offered the valve with two different TP sizes, as well as $60 cheaper!

 

[Wager]

I figured Travis would up the price a bit but yeah i'm wondering about the transfer ports as well. Would also like to know the weight of his new hammer. I'll try to get a hold of him Monday and find out.

 

[Joe Shooter]

I just text Travis and he replied. He has the Cothran valve with both transfer port sizes that Don offered - .180 and .250.