1/2 scale AR-15

[barnbwt]

Why is it every time I visit this thread, I get Amazon adds for carbide inserts?



Also, a thought occurs; how do you plan to pull the trigger? The guard looks way too small for adult finger tips

TCB

 

[SolubleSpork]

Been floating around the forums for a while and finally registered. I have to say this is absolutely amazing. I went through all the old posts and it truly is a neat project. I'm a firearms design engineer at the company I work for now and just finished designing a new rifle by myself. I had to recently design and model a lower receiver to basically match the DPMS platform 308 ARs and I completely agree with your comment about the AR being a difficult design from a machining standpoint. I didn't realize how complex it really was until handling all the tweaking that had to be done in order to make it more machinable. And I also feel the pain of trying to reverse engineer some of its complexity. Keep up the good work and for the record, I'm all about the mini FAL in 5.7x28 idea you had.

 

[Bobson]

Also, a thought occurs; how do you plan to pull the trigger? The guard looks way too small for adult finger tips

Loop a piece of string around the trigger, and loop the other end around one of the user's teeth. He then jerks his head back and forth to operate the trigger. Voila!

Jokes aside, I think you make a good point. Judging from the pic below (and I realize his thumb is blocking it, so this is a guess), it looks like the only way the OP could get his finger into the trigger guard is if the trigger is held fully to the rear. Sort of like trying to shove both hands into one glove.

 

[MachIVshooter]

Jokes aside, I think you make a good point. Judging from the pic below (and I realize his thumb is blocking it, so this is a guess), it looks like the only way the OP could get his finger into the trigger guard is if the trigger is held fully to the rear. Sort of like trying to shove both hands into one glove.

I can't get my finger in the trigger guard at all, regardless of trigger position. What I can do, though, is get just enough traction on the edge of the trigger with the very tip of my finger to pull it.

 

[Trent]

I imagine when it comes time to shoot it, you'll be using the string-pull method with a single round in the chamber at least once.

 

[WestKentucky]

Trigger guard extension and a thin, flatter trigger should open up enough room to do some work.

 

[shotgunjoel]

I imagine when it comes time to shoot it, you'll be using the string-pull method with a single round in the chamber at least once.

Don't know why you would, he's using a commercial barrel and logic would dictate starting with a heavy recoil spring/ buffer and working your way down until it cycles.

 

[MachIVshooter]

Well, had another no-show appointment today, so got after the front handguard retainer and the flash hider.

Initial thought was to use a heavy washer for the HG retainer, as it would be a lot less machining. Low and behold, I could not find one thick enough that had 3/8" or smaller ID with a .900" or larger OD, so I ended up cutting it from 1" bar stock.

FH was made from 1/2" round stock. About 3 hours for both pieces. Standard A2 FH for comparison:

 

[anothernewb]

damn. just. damn...

patent it as the ar7.5?

 

[Zach S]

So, when you patent this, and start production, with the rails be 1/2 scale 1913, or 3/8 dovetail?

 

[jerkface11]

Am I the only one who noticed the grenade launcher cut on the barrel?

 

[Stacer]

^ Nope, and I can't wait to see if it's abused

 

[mainecoon]

Now I want to see the 20mm grenade launcher.

 

[MachIVshooter]

Now I want to see the 20mm grenade launcher.

I have been toying with the idea. If I do it, it'll be 12 ga., and we'll cut the hulls off of high brass shells, then just use the primer to expel a plastic or rubber projectile.

That's gonna be another ATF letter, though: I don't know if that would be qualified as an SBS. It wouldn't be able to chamber 12 gauge shells and wouldn't even use a powder charge, so I'm thinking they might let it classify the same as the non-firearm 37mm lauchers.

 

[barnbwt]

Just do a sub-caliber insert for a 50cal cream puff round (recoil concerns). A true 1/2 scale bore would have a painfully thin barrel, would it not?

Heck, designing the launcher for brad-blanks and nothing else would be pretty fun in itself. 1/2 scale rifle grenades would be super awesome, though (grown up lawn darts )

TCB

 

[Yellow Box]

could this be considered a AOW?

 

[armoredman]

Make the "grenade" launcher a rifled 410 barrel, and use cut down .410 shells. It's then made as a "pistol" like the Governor, and the final few mm of "barrel" can be widened out for dramatic effect, to match the relative dimensions. Heck, just use 45 Colt shells, primer powered with parrafin loads, for that matter.
This has been a lot of fun to watch - your skills are incredible, sir.

 

[USAF_Vet]

Am I the only one who noticed the grenade launcher cut on the barrel?

I was thinking a .410 rifled barrel, so it wouldn't be either an AOW smoothbore pistol, nor a SBS if done in 28 gauge or larger.

It wouldn't exactly be half scale, but whose counting? If it were beefy enough, it might even be able to handle a full 3" .410 shotshell.

 

[maxxhavoc]

If you are just going to use the primer charge, just drill it to use 209 primers without shells. Then it is simply a "muzzleloader". Primers are cheaper than shells, too.

 

[Trent]

Is black powder shotshell a non-firearm?

If so you could have a fire breathing, smoke-belching M203 1/2 scale..

 

[WestKentucky]

I would make the 203 a smoke pole in 24 or 28 gage. It can be loaded as light as you want and have no issues with the federales

 

[MachIVshooter]

Perhaps this is the best way to go:

http://www.sportsmansguide.com/product/index/12-gauge-flare-conversion-insert?a=1506846

They're meant to convert a 26.5mm flare pistol to use more economical 12 ga flares

 

[ArchAngelCD]

With how small your project is will a 12ga size shell be too big for the launcher? If it does fit that looks like a GREAT option for the launcher...

Keep up the good work and thanks for taking us along for the build trip.

 

[MachIVshooter]

With how small your project is will a 12ga size shell be too big for the launcher? If it does fit that looks like a GREAT option for the launcher...

A 12 ga shell would be almost exact for scale at 19.7mm, although the bore of the flare tube would be somewhat smaller, about 18.5mm.

I did get the bolt catch/extractor done as well. That was a really challenging piece to machine, lots and lots of operations on all sides, which meant detaching it from the stock early on. There was also the slot to cut in the bolt carrier, as well as relieving the upper for the extractor portion of it. Came out OK, though I did lose two more 1/16 cutter making the slot.











Plan is to cut a slot in the back of the mag and run a 0-80 or 1-72 socket head into the follower to engage the BHO.

 

[CLP]

A 12 ga shell would be almost exact for scale at 19.7mm, although the bore of the flare tube would be somewhat smaller, about 18.5mm.

I did get the bolt catch/extractor done as well. That was a really challenging piece to machine, lots and lots of operations on all sides, which meant detaching it from the stock early on. There was also the slot to cut in the bolt carrier, as well as relieving the upper for the extractor portion of it. Came out OK, though I did lose two more 1/16 cutter making the slot.











Plan is to cut a slot in the back of the mag and run a 0-80 or 1-72 socket head into the follower to engage the BHO.

Outstanding work. Just noticed you used a drill bit for the port cover rod. One of the most intriguing threads I've ever read on this site.