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Post by hairy apple on Oct 19, 2009 23:16:36 GMT -5
After seeing the photos of the PAK38 on here I have been interested in building something like it. I just thought it was a really cool idea, both for use and for a cool field prop or event objective. Seeing how I do US impressions, I was looking at a M3 37mm A/T gun. It's a small size for moving around easy, and looks pretty easy to build the shield. It had been an idea for the future, nothing I was planning or working on until I got this little trailer for free a few weeks ago. It just screamed "turn me into an AT gun" when I saw it. I have a few questions about breach loading. I've seen a few systems that are breach loaded and really want to do it, but I have no idea what is done to allow this. I'm interested if anyone has made a breach load anything and could help me out with some detailed photos and a little help. Once I start the project I'll make a thread and take a lot of photos. It should be fun!
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Oct 19, 2009 23:35:44 GMT -5
I made a breach loading 90 mm recoiless rifle which I still have. Essentially I used a CO2 adapter with a sealed expansion chamber leading into a two inch section of pipe that housed a Nerf Rocket. It is set off with a large ball valve. The length of the tube is not enough to provide sufficient range for it to do much but when inserted into the launch tube (Slide and twist to lock into place) It adds 2 and a half feet of two inch tubing which provides ooodles of oooomph. It fires the nerf rockets 130 yards quite consistently. Essentially the build components become the shell. You could make perhaps four or five of them and they could be ready ammo for your at gun.
An easier set up would be the 40mm mosscart shells but they simply don't provide the power. I love the trailer. It should work well as a base onto which to build your cannon. Do you know anyone who welds?
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Post by hairy apple on Oct 19, 2009 23:46:58 GMT -5
I weld pretty good. I have a friend who was a welder in the air force though, chances are he'll be helping with some of this. I'm not sure I totally understand what you're talking about with the breach loading recoiless rifle. Do you have any photos of it? Basicly this is going to be a huge potato gun powered by an expansion chamber and Co2. Nerft rockets and foam golf balls will be my ammo of choice.
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Adler69
Master sergeant
Legio Patria Nostra
Posts: 2,859
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Post by Adler69 on Oct 20, 2009 0:15:10 GMT -5
On a breach loading recoilless rifle the breach is hinged and you you have to swing the breach open , load up a round close the breach back up , aim and fire the round goes off and the shell casing is blown out the back of the breach. They are awesome , i fired the M67 a whole lot of times , as well as the Carl Gustaf M2 recoilless rifle.
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kalbs
Master sergeant
Posts: 1,142
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Post by kalbs on Oct 20, 2009 0:15:12 GMT -5
I guess for the price ($,500) why not buy a model M3 37mm from here?: users.multipro.com/brentandloriann/OLD%20index.htmLooks like he will sell Pak 36's soon too. I notice your trailer has a spring suspension which was not on either origional AT guns. I'm all for building custom stuff but I would rather start from scratch
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Post by hairy apple on Oct 20, 2009 0:29:08 GMT -5
Whoa, that it is way cool, but I don't have an extra $5000 laying around. I realize the trailer isn't going to allow for a spot on M3, but it's better then buying axle parts I don't have. I had planned to start from scratch, however having been laid off I don't have the money to do a project like this without using what I have laying around. This will be a start, maybe someday I'll make a more detailed one, but for now, this will do fine.
I understand how a real breach loading recoiless rifle works, I'm trying to figure out how to make a C02 powered air cannon have a breach loader that won't leak pressure or blow open or apart when fired.
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kalbs
Master sergeant
Posts: 1,142
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Post by kalbs on Oct 20, 2009 1:06:50 GMT -5
Hmmm... Something cheaper and easier is in order then: I see Large tube PVC tubes lobbing bags of white powder and bb's...
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Oct 20, 2009 21:46:56 GMT -5
The trailer is actually pretty elaborate with a wishbone suspension and coil springs rather than a simple leaf spring set up. It could be a great foundation for any of a number of great props.
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Post by zbear on Oct 20, 2009 22:05:48 GMT -5
can your welder do an interupted thread? I had designed one out of pvc. Basically a portion of the threads are removed from the breech and the breech block so when they are lined up you only need a quarter turn or half a turn to lock it. don't knopw how to draw it up online but it is basically how a realy breech block works
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biged
Master sergeant
Posts: 468
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Post by biged on Oct 21, 2009 5:05:00 GMT -5
"Tubing" goes by measurement of Outside Diameter or OD. "Pipe" goes by measurement of Inside Diameter or ID. For a sliding breach, you want an ID and OD with play of 1/16th of an inch. Which will yield a 1/32 gap around the circumference. This is where sourced material quality/accuracy is critical. For a Locking breach, an easy solution is a ball valve albeit expensive. Open the valve and insert projectile. Push the projectile forward to T-coupling. A 2-inch ball valve runs around $70, 3-inch is $100. Fastenal.com sells the ball valves, also see your local plumbing distributor. There are thousands of examples of breach loaders on the www.spudfiles.com, do a search for "Breach loading". Here is a reference chart of PVC ID/OD's. www.spudfiles.com/pvc_pipe_info.phpFor steel pipe/tubing you will have to visit your local steel shop or welding supply house. Plumbing retailers are another excellent source for pipe. Remember: A M3 37mm is a direct fire gun, so at high(er) pressure your shot will be deadly at close range. ///ed///
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Post by hairy apple on Oct 21, 2009 22:14:31 GMT -5
Awesome, exactly what I was looking for. The ball valve is a great idea. I dont' intend to fire it at people... honestly, it's probally going to be mostly a prop or game objective, but I wanted to make it function as well just for fun. Maybe for games where we bring out the truck, have something to counter it. Thank you for the links and ideas.
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Oct 23, 2009 17:19:15 GMT -5
I actually think a howitzer would be more practical for game play. It would still serve as a nice objective and since it would be used for indirect, plunging, type fire would be less likely to get someone hurt. A Pack howitzer or 105mm (slightly under scale) could work nicely on your trailer. You could fire tennis balls like Big Ed does with his howitzer or insert Talc powder and a styro cup of BBs for a rain down effect Ed fires 3 tennis balls at a time or smoke grenades or glow sticks and the effects are amazing. He is remarkably accurate and hurls things very very long ranges. In the past we have literally used indirect fire by radio to support distant troops in the field.
Because your trailer is functional and reasonably stout you could build the air source into the gun itself (Perhaps build it into the recoil tube) and have a ready gas source. With longer, seperate and spreadable trailer legs and a lunette hitch you'd end up looking pretty cool.
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deacon
Private 1st Class
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Post by deacon on Oct 23, 2009 18:16:37 GMT -5
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Post by hairy apple on Oct 23, 2009 18:37:09 GMT -5
Yeah, either one would work. The main reason I was thinking of the M3 was it's size, it looks like a rather small gun. Also, for a lot of our non ww2 games we have used a truck for a "tank" and it would be cool to have something to counter the truck with like this. I'm still in the dreaming/stripping the trailer down phase. Once I really start planning I'll start looking at a for sure design. Right now I've been thinking that since I have a pretty stout little frame, I'd include a small electric compressor and car battery for pressurizing the gun. Also I was going to add some sort of "handles" for the crew to be able to move it around quickly, the whole trailer wieghs less then 250lbs. I'm not going to be adding a whole lot, and I'm going to be taking some off. The gun should be fully mobile. And the nice thing is, it's a road worthy trailer so I can tow it where I want it. I don't have to pack it up or anything, just hitch it up and go.
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Adler69
Master sergeant
Legio Patria Nostra
Posts: 2,859
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Post by Adler69 on Oct 24, 2009 14:31:51 GMT -5
Forget the trailer , make the M3 , then get yourself a Willie's , a water cooled .30 cal MG and turn it into one of this to take out that "tank" ;D ;D ;D ;D ;D
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Post by hairy apple on Oct 24, 2009 16:15:29 GMT -5
Ha ha, I almost got a willys at one point. I ended up with a land cruiser instead. Which is much better for what I wanted it for. I saw that photo a few times while reading about the M3. That poor little jeep... I bet it pulls some sweet wheelies while going up hill though.
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