Under the Hood Of A Benjamin Trail - XL .22

[Gene_SC]

Early this afternoon I received a Benjamin Trail-XL .22 in for a GRT-III trigger and tune. There was an issue with the gun that warranted the customer to call Crosman for a replacement. But I do have some pictures and information for everyone. First off it has the same O/D piston as the Crosman NPSS and Remington NPSS air guns. Yes the seal is a huge seal along with a very heavy and machined piston. The gas ram is the same size in diameter of haft and tube as the Crosman NPSS. Thegas ram has an overall length of 12". The Benjamin NP .22 9" overall length of piston. The Crosman and Reimington NPSS is 8.5" overall length. The Benjamin Trail XL looks to be a decent build. But there are still some issues with the gas ram fitting into the piston. I will show you a picture of what I am talking about. The gas ram being so long really needs a bushing to support it when it is compressed into the piston. I mentioned it with the Benjamin Trail NP where I made a bushing for the gas ram so it would fit into the piston without any chaffing on the gas ram housing.

This gun was basically brand new. I want to warn you guys who own a Benjamin Trail XL .22 that the pivot pin on the bottom front of barrel breech had worked it's way out some. This will be a hazard not only to your stock but you if that pin comes all the way out when cocking the gun. I also have a picture of it as well.

The nipple on the end of piston that holds the seal is a small size, so a standard seal I/D will work without any modification. I found that the Walther Falcon Mag seal will work just fine. OEM seal and the Falcon seal are the same O/D.

The picture of the seal was not a good one but it had multiple slicesonthe outer edge. A good indication that the tube needed de-burring.

[longislandhunter]

Enjoyed the post Gene....  I will check my pivot pin next time I take the rifle out.  

Jeff

[wahoowad]

Gene_SC - 4/12/2010  5:11 PM  

But there are sill some issues with the gas ram fitting into the piston. I will show you a picture of what I am talking about. The gas ram being so long really needs a bushing to support it when it is compressed into the piston. I mentioned it with the Benjamin Trail NP where I made a bushing for the gas ram so it would fit into the piston without any chaffing on the gas ram housing.

Thanks Gene. I have a new NP XL in the mail as we speak. I guess I don't quite follow what you are saying in the above part of your quote. How/where do you recommend this bushing be added to the gas ram? Is it hitting something?

Thanks !

[shadow]

The bushing slides over the ram where the ram meet's the ID of the piston. It removes any play beyween the OD of the ram and ID of the piston. Note the rub mark in the pic of the gas ram this has been rubbing on the ID of the piston. The bushing eliminates this rubbing and possable canting of the ram. Ed

[Gene_SC]

There are two rams and the lower one has custom bushing installed. Arrow pointing to bushing.. Without the bushing I have found that in the Benji Trail NP and XL the ram will rub inside the piston. It is a stress point.

[bigbadwulff]

Second set of pics are much better

[Gene_SC]

Photography is not one of my talents... I just do not do well with cameras, newer TV', VCR', or even figuering out how to reset my trip odomenter on the car and the worst one of all is these new cell phones... I am lucky to even be able to dial a number... Fingers hit two numbers all the time and I end up talking to strangers and recording... hehe So do not expet high end pictures from me... Macro??? what is a Macro?

But I do well playing with air guns...

[geewhiz380]

Lately i been getting funny phones calls i knew it had to have been someone here ,now i know it was u Gene hehehehe .....jorge

[rocker1]

i understand the bushing i can see where it would stabalize the ram, how did you determine the length? and how is it attached to the gas tube is it a press fit??

[Gene_SC]

David, I just guestimated what length to make it. 1" is the length. Yes it is a press fit and I had to compensate for the expansion of the bushing. I did use a tiny dab of glue just for extra insurance. But she will not come off unless it is cut off. I used delrin on the two that I have done. On my next one I am going to use teflon.

[Gene_SC]

LOL Jorge, I thought that was you...

[wahoowad]

Gene,

What is your opinion on the usefulness of piston buttoning for the Trail XL piston? I saw some wear marks on mine - were you concerned with any wear marks on the piston you inspected? What I am reading about piston buttons makes me think they might be useful for the Trail. I wish I had inspected the amount of play before I sent it back for replacement.

[Gene_SC]

The tolerances are much closer on the NPSS piston and chamber than many of the springers that I have seen. I would see no advantage to it nor room.

[wahoowad]

Thanks for your input! So is a very light coating of moly grease applied to the wear marks a sufficient long term lubricant to help with whatever contact occurs? Obviously contact occurs - hence the wear.

I have never removed a piston that had moly applied (only removed the piston with factory mystery grease) but I would think a thin moly coating would quickly rub off. Here are some shots of my wear marks. I will polish these areas on my new piston after shooting it a bit and seeing where the contact points appear. I suspect they will be in the same areas which for my piston were the top and bottom, with the bottom having more possibly due to gravity allowing it to ride?