Bolt Action 30x173mm. - Page 3

[ARCHIVED THREAD] - Bolt Action 30x173mm. (Page 3 of 4)

Posted: 2/24/2010 3:24:53 PM EDT

[#1]

Quoted:

I don't think I got your e-mail.

Best way to contact me is through IM.

I have a lot on my plate at the moment, I should have time to work on a prototype break in 2-3 months.

If the original muzzle on your barrel is intact I should be able to use mine as a guide line.

No problem. Keep me in the loop if/when you start working on it and I'll do the same. We'll see who gets there first. My barrel is intact so once I get my gun running we can use it to test the effectiveness of break designs (if you want to try something out). In all honesty I'm just looking to increase blast for crowd appeal but recoil reduction will put less stress on the recoil system.

I don't think it will take too long to fabricate a break once one of us gets to it. The most effort will be spent on attaching it to the barrel. I'd like to use the ridge near the end of the barrel but haven't spent much time thinking about it yet.

Thanks,

Matt

I had the same idea as you with the rim in the end of the barrel.

I plan to use an externally threaded split ring behind that rim. The break would slip over the end of the barrel and thread to that ring locking it to the barrel.

I'll do something similar for the receiver but will include the locking threads that are already on the barrel.

A theme I'd sticking with is that no machining, welding, or other permanent alterations will be made to the barrel.

If it works out I might be able to build a few kits and anyone with a GAU-8 barrel, and basic hand tool could assemble it. Kit would include a wrench for the split rings for the muzzle break and receiver locking ring.

Receiver of the kit would be registered as a DD.

Posted: 3/20/2010 4:16:13 PM EDT

[#2]

What's next beyond 30mm?

Posted: 3/21/2010 5:50:12 AM EDT

[#3]

Quoted:
What's next beyond 30mm?

31mm

Posted: 3/22/2010 7:41:17 AM EDT

[#4]

Quoted:

Quoted:
What's next beyond 30mm?

31mm

35x228mm - http://www.quarry.nildram.co.uk/PICT0230.jpg

Or you could just skip all the baby steps and get right to something like Bofors 57mm - http://www.quarry.nildram.co.uk/PICT0247.jpg

Posted: 3/22/2010 9:13:15 AM EDT

[#5]

Quoted:

Quoted:
What's next beyond 30mm?

31mm

35x228mm - http://www.quarry.nildram.co.uk/PICT0230.jpg

Or you could just skip all the baby steps and get right to something like Bofors 57mm - http://www.quarry.nildram.co.uk/PICT0247.jpg

In all reality, if the muzzle break works as good as I hope, there is no reason larger guns couldn't be built other than overall weight.

As it is, the 30x173 will be right about 70-80 lbs. Your going to have to be in pretty good shape just to lug this gun from the truck to the range.

Posted: 4/5/2010 1:57:29 PM EDT

[#6]

I doubt it will be too accurate. One hole groups will already be > MOA. I also bet it wouldn't be any fun to shoot steel plates with, especially having to buy new plates after every shot.

Well excessive excessiveness is the American way. Don't forget the pics!!!

This thread warns the heart.

Posted: 4/5/2010 2:13:22 PM EDT

[#7]

a thread about a 30x173mm rifle eh.. seems like the apropriate place to drop this picture

call it inspiration to finish your build

Posted: 4/7/2010 11:57:06 AM EDT

[#8]

I'm falling a little behind schedule. The weather didn't cooperate for welding outside a couple weeks ago when I had time to work on the gun. Hopefully next week I'll start this project up full-bore again (so to speak). My gunsmith buddy 'might' be heading out of town though so we'll see.

We're ready to start welding/attaching main components together into the finished carriage: trailing arms and pintle to the axle, wheel segments, rims/tires, lower and upper armor, trunion, etc. I have the sprockets on order for the traverse mechanism and a plan in place to attach this via a Dodge steering gear. Elevation will most likely be a bottle style jack. Probably one off a Jeep Cherokee where a handle is turned to elevate the gun.

Next up on the 'backwoods engineering' plan will be integrating the Goldwing shocks into a 'backwoods engineered' recoil sled.

The anticipation of having this 5 year project finally complete is killing me. There have been many, many times that I've asked myself why I got into this 'mess'. Back then there were no 37mm guns for sale. Now it seems like they're popping up everywhere.

Matt

Posted: 4/18/2010 4:58:20 PM EDT

[#9]

I need a much bigger lath than what I have to machine the receiver for the 30x173mm

However. I have found a .223 barrel that is nearly identical to the GAU-8 barrel (but much smaller) and have snagged a deal on a JP rifles .223 "tank break".

I'll be building a .223 scale version to include the shell holder, interrupted thread breach, firing mechanism etc. An exact copy of my concept just scaled down.

I even came up with a sort of gas seal/forcing cone that seals the aria between the bolt and barrel gas tight. I plan to test it buy literally drilling a hole in the case head of a .223 round and firing it. The same test will be done to test the gas seal on the 30x173mm.

The other thing delaying me is that I'm moving my shop to Montana and re-licensing everything. I should be moved in and have the shop fired up by June. I hope.

Posted: 4/20/2010 9:48:38 AM EDT

[#10]

Quoted:
I need a much bigger lath than what I have to machine the receiver for the 30x173mm

However. I have found a .223 barrel that is nearly identical to the GAU-8 barrel (but much smaller) and have snagged a deal on a JP rifles .223 "tank break".

I'll be building a .223 scale version to include the shell holder, interrupted thread breach, firing mechanism etc. An exact copy of my concept just scaled down.

I even came up with a sort of gas seal/forcing cone that seals the aria between the bolt and barrel gas tight. I plan to test it buy literally drilling a hole in the case head of a .223 round and firing it. The same test will be done to test the gas seal on the 30x173mm.

The other thing delaying me is that I'm moving my shop to Montana and re-licensing everything. I should be moved in and have the shop fired up by June. I hope.

Sweet! We definitely need a play-by-play on the scale design and testing process. That's amazingly interesting.

I just finished up 6 more days of work on the project. The wheeled carriage and trunion are done. Now to start the recoil sled....... Pics to follow.

Matt

Posted: 4/28/2010 8:22:23 AM EDT

[#11]

subscribe

Posted: 5/3/2010 7:54:54 PM EDT

[#12]

ditto

Posted: 5/4/2010 11:53:01 AM EDT

[#13]

Quoted:

I don't think I got your e-mail.

Best way to contact me is through IM.

I have a lot on my plate at the moment, I should have time to work on a prototype break in 2-3 months.

If the original muzzle on your barrel is intact I should be able to use mine as a guide line.

No problem. Keep me in the loop if/when you start working on it and I'll do the same. We'll see who gets there first. My barrel is intact so once I get my gun running we can use it to test the effectiveness of break designs (if you want to try something out). In all honesty I'm just looking to increase blast for crowd appeal but recoil reduction will put less stress on the recoil system.

I don't think it will take too long to fabricate a break once one of us gets to it. The most effort will be spent on attaching it to the barrel. I'd like to use the ridge near the end of the barrel but haven't spent much time thinking about it yet.

Thanks,

Matt

I had the same idea as you with the rim in the end of the barrel.

I plan to use an externally threaded split ring behind that rim. The break would slip over the end of the barrel and thread to that ring locking it to the barrel.

I'll do something similar for the receiver but will include the locking threads that are already on the barrel.

A theme I'd sticking with is that no machining, welding, or other permanent alterations will be made to the barrel.

If it works out I might be able to build a few kits and anyone with a GAU-8 barrel, and basic hand tool could assemble it. Kit would include a wrench for the split rings for the muzzle break and receiver locking ring.

Receiver of the kit would be registered as a DD.

I have a 20mm m61 barrel that I want to build into a DD as well.. Same F1 the receiver, do as little mods to the barrel as possible. I'm going to copy Matt's design for rcver/bolt, aka the whole thing is one big thread.

My idea for a muzzle brake is to copy the Cobb/Bushmaster design where it's two pieces of plate bolted together, drilled and milled, and they clamp around that ring on the end of the barrel. No cutting/threading etc necessary.

J

Posted: 5/4/2010 2:15:52 PM EDT

[#14]

Quoted:
Using a JP style tank break.

s n i p

The rub... To make the break work I need to use FULL POWER loads. O.O

s n i p

Not only do I have to build a rifle action that can handle 30x173 I have a very narrow window between enough pressure to make the break work and enough pressure to blow up the gun.

Oh yeah............I like where this thread is going

Posted: 5/4/2010 2:18:12 PM EDT

[#15]

Quoted:
What's next beyond 30mm?

Re-constructive shoulder surgery.....re-attaching retinas

Posted: 5/4/2010 6:17:16 PM EDT

[#16]

The recoil sled design is done. The front part of the sled will travel on the Goldwing shocks and the rear part of the sled will use dual rods through pipe sections.. Now to put together the materials list.

I hate to say this but it's too bad that summer in Alaska is here. It's going to be awhile until I get time to work on this again. The next window is in mid-June or late-July....

Any thoughts on turning projectiles? Once I run out of the experimental 30mm projectiles I'll need to look into turning my own. I'm hoping to not have to press on driving bands and just machine the projectile and driving band as one piece.

What's the least expensive metal that will work for this? Copper would be nice but the price is way too high.

Thanks,

Matt

Posted: 5/4/2010 6:47:05 PM EDT

[#17]

Quoted:
The recoil sled design is done. The front part of the sled will travel on the Goldwing shocks and the rear part of the sled will use dual rods through pipe sections.. Now to put together the materials list.

I hate to say this but it's too bad that summer in Alaska is here. It's going to be awhile until I get time to work on this again. The next window is in mid-June or late-July....

Any thoughts on turning projectiles? Once I run out of the experimental 30mm projectiles I'll need to look into turning my own. I'm hoping to not have to press on driving bands and just machine the projectile and driving band as one piece.

What's the least expensive metal that will work for this? Copper would be nice but the price is way too high.

Thanks,

Matt

Mild steel and a pressed on plastic driving band is pretty much your best bet.

The other option would be to sabot cups out of plastic and drop in more readily available 20mm and 25mm projos.

You could probably push a 20mm projo over 4000fps that way.

Posted: 5/5/2010 9:54:26 AM EDT

[#18]

Mild steel and a pressed on plastic driving band is pretty much your best bet.

The other option would be to sabot cups out of plastic and drop in more readily available 20mm and 25mm projos.

You could probably push a 20mm projo over 4000fps that way.

Thanks for the info. Any thoughts on the tools needed to cut and press on plastic driving bands, the type of pastic to use, etc? If I could get set up with the tools to press the band on, then using mild steel and plastic driving bands should help drive down the cost per round.

Matt

Posted: 5/5/2010 10:28:24 AM EDT

[#19]

Quoted:

If I recall correctly, the 25mm bushmaster on the Bradley fighting vehicle exerts a massive amount of recoil. I know that the muzzle brake alone cuts down on something like 5-10k of recoil and the dampening system far more. I can't remember off the top of my head, I haven't been to school for it yet. Anyway I wish you luck in your project but I don't see how you're going to make a 30mm weapon that is somewhat portable with one man and will be able to not break your shoulder at the same time. That's going to be interesting.

The Bushmaster generated 10,000 foot pounds of recoil. The muzzel break attenuated 7,000 pounds of the force and the remaining 3K is absorbed by a hydrolic shock absorber mounted on top of the weapon. While I haven't seen it happed, I've takled to the old school Chief, and he said it would crack the welds on the pedistal if it was fired without the muzzel break.

Posted: 5/5/2010 10:40:46 AM EDT

[#20]

Hey, you would not happen to know a guy named Shannon would you??

Slug-O

Posted: 5/5/2010 1:38:47 PM EDT

[#21]

Quoted:

Mild steel and a pressed on plastic driving band is pretty much your best bet.

The other option would be to sabot cups out of plastic and drop in more readily available 20mm and 25mm projos.

You could probably push a 20mm projo over 4000fps that way.

Thanks for the info. Any thoughts on the tools needed to cut and press on plastic driving bands, the type of pastic to use, etc? If I could get set up with the tools to press the band on, then using mild steel and plastic driving bands should help drive down the cost per round.

Matt

Delrin is a good plastic.

Delrin pipe in the right size could be turned using just a drill press and a cutting head. You can find several distributors by doing a google search for "delrin".

You heat the delrin with a hot air gun and use a bit of pipe to push it over the projo.

Posted: 5/5/2010 1:39:13 PM EDT

[#22]

Quoted:
Hey, you would not happen to know a guy named Shannon would you??

Slug-O

Posted: 5/5/2010 5:37:48 PM EDT

[#23]

Thanks SOC!

Posted: 5/5/2010 5:39:16 PM EDT

[#24]

Quoted:

Quoted:
Hey, you would not happen to know a guy named Shannon would you??

Slug-O

..... You have no idea how small this world is......

Slug-O

Posted: 5/9/2010 7:11:32 AM EDT

[#25]

Carriage pics as promised!

Posted: 5/9/2010 3:20:49 PM EDT

[#26]

DAMN!!
That's a fine bit-o-fabricatin' ya done there !!

Posted: 5/10/2010 5:21:27 AM EDT

[#27]

Thanks! I think we have about 5 days into that to include T&E work that's not attached yet. I can't take much credit though. My machinist/gunsmith/jack of all trades buddy gets the credit. I'm more of the helper that writes the checks when we need supplies and otherwise follow orders.

Matt

Posted: 5/11/2010 1:13:50 AM EDT

[#28]

So, will it be ready for Anderson?

Posted: 5/11/2010 8:11:33 AM EDT

[#29]

Anderson 2011? Yep.

I really wanted to finish it by Memorial Day this year but it's just not going to make it. It's the little stuff like work, relatives visiting, my son's high school graduation, etc that keep getting in the way.

You're more than welcome to come play with it though the next time you're in town.

I'm talking with a guy in Fairbanks on a projectile run. I'll post info to the group if we get it going. They'll most likely be brass projectiles following the T328 projectile profile. It's just in the initial stages now. Any thoughts from the group on this?

Matt

Posted: 5/16/2010 10:56:13 AM EDT

[#30]

This is too awesome for words. When I saw the title, I thought this guy can't be serious. Then I saw the GAU-8 barrel for sale leaning against the truck and I was:

Posted: 6/1/2010 9:01:33 PM EDT

[#31]

Took delivery of my barrel last weekend. It looks good. Now i just need Form 1, projectiles, powder, primers, cases, muzzle break, receiver, action, sights, mount, carrage or turret, tow vehicle, etc., etc.

Posted: 7/30/2010 12:32:41 PM EDT

[#32]

Updates?

Posted: 7/30/2010 12:49:22 PM EDT

[#33]

Thanks for the interest. It helps keep me motivated when I realize how many years into this build I am.

"I missed ANOTHER of my self imposed milestones. The sled and channel are fitted. Now I'm working on the attachment of the shocks. I always think I'm about 4 days worth of work away. I'm not sure when I'll get another block of time to work on it. It may be a few months.

The recoil sled sure looked sweet when we mocked up the fit with the barrel, receiver and shocks and then mocked up the fit into the carriage. (and yep - I neglected to take pics so it probably never happened ) "

Matt

Posted: 7/30/2010 4:22:15 PM EDT

[#34]

PGU-15A/B TP specifics taken from page 32 of this file.

Projectile weight: 378g or 5033gr
Muzzle velocity: 1021m/s or 3350fps
Propellant weight: 145g or 2238gr

JBM Ballistics, figures 125,395fpe at the muzzle!

Handloads recoil calculator figures a 100lb rifle will free recoil at 37fps with 2111fpe.

A 200lb rifle reduces that to 18fps and 1056fpe. That, of course does not take into account the effect of the muzzle brake or the shooters mass behind the rifle.

I would make sure any mounted optics have good eye relief, say a 20' cord to a video monitor.

Posted: 8/2/2010 7:22:35 AM EDT

[#35]

Thanks for the recoil numbers! This is very interesting as I'm curious to see if the Goldwing shocks can handle the energy over multiple shots. The scope will be linked like the real 37mm AT gun and won't be part of the recoil mechanism.

Thanks again for the numbers,

Matt

Posted: 8/15/2010 10:46:34 AM EDT

[#36]

Awesome project. Make sure you post lots of finished pics. And target pics too.

Posted: 8/16/2010 6:44:51 AM EDT

[#37]

I managed to get a few hours in the shop with my buddy over the weekend. We cut slots in the bottom of the channel to allow the shocks to connect to the recoil sled and started preparing the front and rear blocks which will attach the barrel to the recoil sled. The sled will attach via those blocks and also via bolts under the receiver.

The Goldwing shocks have 6 inches of travel. It'll be interesting to see how they do on the test fire. We have room under the recoil sled to add a third shock or springs as needed. The weight of all the recoiling parts to include the barrel, receiver, recoil sled, mounting blocks, etc has to be pushing the high 250-275 pound range. That should help dampen the recoil. I'll get actual weights once it's finished.

I really need to remember my camera.....

Matt

Posted: 8/16/2010 10:20:21 AM EDT

[#38]

Goldwing weighs around 800 + 2 adults. You gotta figure hitting a pothole with 1300lbs would be comparable to your gun firing :)

Posted: 8/16/2010 10:42:28 AM EDT

[#39]

Quoted:
Goldwing weighs around 800 + 2 adults. You gotta figure hitting a pothole with 1300lbs would be comparable to your gun firing :)

That's a really similar 'calculation' to what we used!

Posted: 9/25/2010 5:17:38 AM EDT

[#40]

what type powder ? an amount are you using to load the 30mm gau 8 round ?? also what projectiles are you using ? an does the cases hold up ok ?

Posted: 10/1/2010 5:29:54 AM EDT

[#41]

whos got the bbl for sale will they trade ????????

Posted: 11/2/2010 10:20:43 AM EDT

[#42]

Quoted:
what type powder ? an amount are you using to load the 30mm gau 8 round ?? also what projectiles are you using ? an does the cases hold up ok ?

this, and who makes reloading dies and presses that will fit a 30MM ? much less a manual...

Posted: 11/2/2010 11:30:30 AM EDT

[#43]

Quoted:

Quoted:
what type powder ? an amount are you using to load the 30mm gau 8 round ?? also what projectiles are you using ? an does the cases hold up ok ?

this, and who makes reloading dies and presses that will fit a 30MM ? much less a manual...

870 and 876 should work. He's using a stash of projos he got, but is looking into custom lathe turned last I heard.. or maybe cast.

You don't need to do much resizing if it's going to be fired in same chamber. Just press the primer out/in, powder, put new bullet in, crimp with a dull pipe cutter.

Posted: 11/3/2010 4:36:32 AM EDT

[#44]

wc860 0r even wc 872 is to fast for this case an for priming it will take more than a 50 bmg primer to prime this case for sizing you will need a sizer die because all cases shot out of any machine the base swells i have some 30mm items for sale cases primers powder

Posted: 11/8/2010 8:56:36 AM EDT

[#45]

Email sent to shadygrady. Thanks for the offer!

Powder is an issue since new cannon powder is now supposedly regulated as an explosive and not a propellant. I have a stash of SuperSlow powder (under the old propellant regulations) and T321 projectiles that I'm using and we're researching new powder sources and projos as mentioned previously. One of the reasons I went with the screw breech and not a sliding block was specifically because of the resizing operation. With the screw breech I'm able to chamber the unsized cases. With a sliding block I would have had to come up with a sizing die.

Once we figure out more on CNC lathing our own projectiles I'll let folks know in case there is any interest in a group buy to help lower per item costs.

Thanks for the continued discussion. Keep it coming.

Matt

Posted: 11/8/2010 9:02:57 AM EDT

[#46]

I was planning on using 50BMG primers at some point in the future along with an adapter to fit them into the 30mm primer pocket. This would still use the black powder 'booster' charge in the case to initiate the smokeless powder. Any reasons this wouldn't work or other issues?

Along the lines of powder, what does the group think about TrailBoss powder? Since it can be scaled up to rifle cases, does the same logic apply to scaling to the 30mm case? If it would work, is there any value on using TrailBoss over using non-corrosive black powder substitutes since I'm assuming the velocity would be low with TrailBoss powder (just like with BP subsitutes).

Thanks,

Matt

Posted: 11/9/2010 4:07:16 AM EDT

[#47]

50bmg bushing collectly primers on top of the flash tube with bp will work as long as you can keep the ammo stored with no water in the air they seem to draw water into that bp if not reloaded an shot soon yes any parts cases bbls projs let us all know about any supplys thats for sale or your projs being made i have vihtauori oy cannon powder but its high an the import cost so if you run out let me know i have powder the 872 is to fast an the bp an trail boss is just to fast you need very slow powder to be safe sg

Posted: 11/10/2010 8:21:10 AM EDT

[#48]

Quoted:
50bmg bushing collectly primers on top of the flash tube with bp will work as long as you can keep the ammo stored with no water in the air they seem to draw water into that bp if not reloaded an shot soon yes any parts cases bbls projs let us all know about any supplys thats for sale or your projs being made i have vihtauori oy cannon powder but its high an the import cost so if you run out let me know i have powder the 872 is to fast an the bp an trail boss is just to fast you need very slow powder to be safe sg

Is there no smokeless powder suitable for use in the flash tube in place of black powder?

Posted: 11/10/2010 6:17:06 PM EDT

[#49]

i believe bullseye would do it

Posted: 11/18/2010 7:08:47 AM EDT

[#50]

Here are some updated pictures. We spent three days getting the recoil system laid out, assembled, and fitted. The gun could now be mounted and fired!

Next up is the T&E. The 'T" is ready to attach once we fabricate the mounting brackets. The 'E' is back in redesign mode. The car jack we considered using previously is too long to use. It would hang too far under the axle.......

[ARCHIVED THREAD] - Bolt Action 30x173mm. (Page 3 of 4)

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