Air Gun Home :: View topic - 22xx repeater breach MOD-B, Marauder magazine

dogon1013 · Member

This is a continuation from a previous thread in which I started designing a tube magazine repeater breach, here: http://www.airgunhome.com/agforum/viewtopic.php?t=4079

basically, the spring loaded tube mag did not work well for all types of pellets. So I bought a marauder magazine, which still won't fit all length of pellets (I might have a fix for that though). But at least any shape will work.

I found out why crosman/benjamin went with the o-ring in the barrel, instead of the probe. the stock 2240 o-ring in the bolt is actually larger than the whole in the magazine. It still works, but the o-ring may wear out quickly, as it drags thru the magazine.

Here are some pictures of the latest prototype, still made from printed plastic. I plan on shortening it when making it out of aluminum. The magazine will easily fall out if the bolt is not holding it in, and the bolt handle is just a bolt, but it does work. This breach does have the ability to add a built in shroud, just like the M-rod.

Constructive criticism is welcomed.

rsterne · Moderator

If it functions OK you are obviously on the right track.... The breech looks very high, especially when you consider the barrel line is already raised.... I guess you are using a Weaver/Picatinny rail on the top which saves cutting dovetails.... but with medium rings (the most commonly available) won't the scope clear the top of the magazine by a lot?....

The higher the scope, the shorter the "point blank range" for any given pellet and kill zone size.... so it's always best to keep the scope as close to the boreline as possible.... I would think lowering the top of the breech to the point where a scope will just clear the magazine when set in medium rings would be best....

Bob

fritz · Silver Status Member

Bob said it.

Why not just purchase a Mrod breach from Crosman. They would likely be happy to part with one for a fee.

rsterne · Moderator

AirGunEric · Site Admin

Crosman of late, has not been able to provide service parts for their new products for well over a year after a rifle is released- so things like a Marauder breech might be some time before they become available.

Crap- I'm still waiting for a SuperStreak tube to show up at my door, what- 2 years since the rifle came to market?

dogon1013 · Member

Exactly,

Even on crosmans website, it says that parts for the M-rod are not available yet. I also believe the marauder tube may be larger in diameter than the 2240 tube but I don't have any confirmation on this. If anyone has a marauder, could you measure the tube diameter, and the shroud diameter.

the height of the breach is pretty much set by the magazine size. there has to be some meat under the magazine. The plastic breach is rather flexible so I used the aluminum picatinny rail to help stiffen it. It would also be swappable for a dovetail rail. The top of the breach has to clear the shroud too, and leave room for the band.

Another option would be to cut the dovetail directly into the breach, like on the M-rod. But all the pictures of the M-rods with scopes show them with very high rings anyway in order to clear the magazine, so I just thought bolting on the rail would be simpler than having to get extra high rings.

It would not be too hard to cut a dovetial into the breach, and still leave the mounting holes for the picatinny rail. This is probably what I will do, sinc it is the best of both worlds.

dogon1013 · Member

Off topic, but it has been bothering me for a while.

Which spelling of breach/breech is correct in this case.
Turns out it is breech with 2 E's
http://www.wsu.edu/~brians/errors/breach.html

rsterne · Moderator

It's hard to tell exactly from your photos, but it looks like your breech is only about 1/8" below the top of the magazine.... In the pictures on the Crosman website, you can see that the magazine sticks out more than the top row of pellets above the breech.... so I'm guessing the top of the breech is at least 1/4" lower than yours....

The Marauder tube is over 1" OD while the Disco / 22XX tube is 7/8" OD....

Bob

dogon1013 · Member

Here is a good view of the marauder with magazine.

it looks like the top of the breech is slightly above the top of the number ring in the magazine.

It's hard to see in my pics, but if the rail is removed, the top of my breech is in line with the top of the number ring. so the top of my breech may be slightly lower than the marauders. (assume the picatinny rail is remived, and a dovetail is cut into the breech). I think the smaller 2240 tube makes the breech look bigger than it does on the M-rod.

1" OD is also what someone else posted about the M-rod main tube on another board, same person said the shroud is 7/8" (same as 2240's main tube).

PS anyone have good dimensions on the dovetail rail?

dogon1013 · Member

here is the latest picture of a possible production model.

I found some dovetail dimensions mentioned here: http://www.airgunbbs.com/forums/showthread.php?t=93137 and used that to make the dovetail cut into the breech. A picatinny rail or some sort of riser could still be bolted to the top, or you just use the built in dovetail.

I did the shroud attachment simpler. It's just a bored hole in the breech that the tube slides into. this is much simpler than the external threads with o-ring on a protrusion in the M-rod breech. The barrel band would actually help attach the shroud to the breech, and an o-ring could still be used if needed.

rsterne · Moderator

Looks nice.... How are you going to fasten down the rear of the breech with the bolt protruding through the back of the breech?.... Shocked

If you make the shroud attachment an integral part of the breech what happens if you don't want (or in Canada, can't use) one?.... The Marauder can't be imported because of the shroud/silencer.... and I can't imagine everyone thinking about one of your breeches would want a shroud.... The number of 22XXs I've seen without a shroud far outnumber the ones with.... Rolling Eyes

I would think that the simplest breech/bolt assembly you can make that will allow you to use a Marauder magazine on a 22XX (or for that matter a 13XX, no reason it can't fit both).... would bring the biggest potential market.... Wink

Bob

dogon1013 · Member

the rear of the breech is fastened while the bolt is out, then you install the bolt (the cam pin is removable). I also left out that rinky-dink tiny screw that crosman uses. Why they did that is beyond me. So the only thing attaching the breech is that rear screw, and the barrel band.

A non-shrouded version is simple. just need to add a small filler plug that just extends out to the barrel band. Or simpler yet, just don't bore the large shroud hole, and use a smaller hole in the barrel band.

I have yet to see an aftermarket integral shroud and breech for the 22xx's available. Maybe that is why most are unshrouded. The external barrel mounted shrouds are questionably legal at best (you could mount one to a firearm). building it into the breech is definitely legal (crosman/benjamin proved that by selling the marauder).

I'm really just shrouding it so I do not annoy the neighbors. this will probably be a made to order part anyway. I doubt I could keep up with more than that.

now I gotta see if we have any 1.5" aluminum at work tomorrow and see if I can get something built before Christmas (I doubt it, but maybe).

rsterne · Moderator

dogon1013 · Member

I looked at some pictures of the other models ( 2250/2260) and noticed the forend would probably interfere with my barrel band. I should be getting a 2260 soon so I can look at that one. The 1300 series may be more difficult...I'll probably have to get one of those too and take a look at it.

a non-shrouded version is no problem, like I said before. it should also be easy enough to add the hole for that little screw too. I don't know how sturdy that would be with only the little screw, and the rear screw. A special barrel band would probably be necessary. That should also be no problem to make. All these extras just cost more time and money, that's why I am trying to keep it as simple as possible.

Don't get me wrong, I do plan on selling some of these breeches (sometime) and I want to make it as universal as possible for all models. I'm just not sure yet how many I can make at a time. I'm only focusing on the 2240 because that is what I have in front of me right now.

Alstone · Moderator & Site Supporter

I just saw this on the DFG airgun forum, thought it might be of intrest to you, It's a auto load breech for a 2240, seems to work resonably well. It's made by a guy call "Jezx".

Al