Carbine SBR Planning

[mursalot]

The hkparts 18mm trilug is tapered on the inside just past the threads. That's what gives it that conical appearance. If you have you barrel cut down to the existing 18mm threads and don't use the barrel nut as a jam nut, then the only contact between the trilug and your barrel will be the edge of the outer diameter of the barrel and the threading. This will not give you a solid and reliable setup. You should either use a trilug that has a flat face on the inside (like the manticore) or use a jam nut, or even both. Or your can get the new trilug barrel someone on here is making and forget about all of this.

What I'm trying to say is; if you have your barrel cut down to the 18mm threads and torque down an hkparts trilug without a jam nut, the tapered shape on the interior may do damage to either our barrel through compression or to the adapter since there is less supporting material compared to the barrel. All of this while not guaranteeing a center bore alignment since the adapter was designed to be torqued against the barrel nut and not merely the edge of the muzzle

[Valk]

Are there any other options then for having a "QD" (or close to it) flash hider/compensator that can go on over a 3-lug? The suppressor I'm buying is going to pull double duty on handguns, so I do want something to go over the 3-lug when not in use. If it can suppress flash or, better yet, provide recoil compensation to make the gun shoot even flatter, all the better.

[mursalot]

Are there any other options then for having a "QD" (or close to it) flash hider/compensator that can go on over a 3-lug? The suppressor I'm buying is going to pull double duty on handguns, so I do want something to go over the 3-lug when not in use. If it can suppress flash or, better yet, provide recoil compensation to make the gun shoot even flatter, all the better.

Yes
https://www.hkparts.net/shop/pc/viewcategories.asp?idcategory=82

If you look at the bottom of the first page, there is a whole slew of attachments for the trilug

[Valk]

re: compensators, it's not that I think this gun recoils hard or is difficult to control, but rather that I'm looking at this from a "when I don't have a suppressor on this, can I turn a soft-shooting gun into one that barely recoils at all?" perspective.

Back on barrels, I noticed CZ Shop has OEM pistol barrels with dual threading for $150, though they're out of stock at the moment. Having never disassembled the front end of my carbine, would it hypothetically be less expensive to just have a gunsmith swap out the barrels rather than cut and recrown the existing carbine barrel? If so, is the barrel nut necessary, optional, or incompatible with the HBI pistol handguards?

[Batt 57]

re: compensators, it's not that I think this gun recoils hard or is difficult to control, but rather that I'm looking at this from a "when I don't have a suppressor on this, can I turn a soft-shooting gun into one that barely recoils at all?" perspective.

Back on barrels, I noticed CZ Shop has OEM pistol barrels with dual threading for $150, though they're out of stock at the moment. Having never disassembled the front end of my carbine, would it hypothetically be less expensive to just have a gunsmith swap out the barrels rather than cut and recrown the existing carbine barrel? If so, is the barrel nut necessary, optional, or incompatible with the HBI pistol handguards?

+1. Inquiring minds want to know... I'm thinking of getting the faux can carbine, sending in the paperwork, and using the gun as-is in PCC matches until I get my Form 1 back.

The option to put on an effect brake would be great for matches.


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[Valk]

Still trying to figure out how to do the barrel thing - surely someone has just had a gunsmith put in a pistol barrel instead of chopping their carbine barrel...right?

[omnidj]

What's wrong with just a simple direct thread silencer these days?

Seems like everyone and their brother wants to add extra unnecessary pieces, weight and expensive proprietary parts to the end of their muzzles.

Direct thread muzzles/silencer gives the most universal and easy attachment method there is.  I mainly don't like proprietary silencer mounts because they force you on to have to buy their mounts to use the silencer on other host....

Nothing wrong with direct threads.

Most universal? Probably...

Most easy to attach? Hell no! 3lug for the win!


I'm a 3lug guy. I can pop my can on and off in 2secs. I don't have to check if my can is still tight after every mag either!!! Adds maybe a couple ounces in weight and doesn't add much length either(granted, my barrel is cut and threaded 1/2x28 so I'm using a small 3lug adapter). I also don't have threads to accidentally bang up, a thread protector to lose, or threads I have to keep clean....those are all wins over direct thread in my book.

LH threaded barrels(not using an adapter to go from RH to LH) are the way to go if going direct thread. They do not loosen up nearly as much as a RH thread. This is because RH threads loosen in the direction the bullet spins whereas LH threads tighten in the direction the bullet spins.

If you go 3lug and want to share the can on multiple host that have diff thread pitches, then you still only need one setup for the suppressor to jump hosts since you can get 3lug adapters in many thread pitches.

3lug is superior to direct thread in my book....I also always opt for LH threading when I have to direct thread as well. LH threads are superior to RH.

COCOWHEATS has it right, in my opinion. 3-Lug is the best way to go. Won't back off. Easy to mount/dismount. Easy to swap silencers from one weapon to another

[mursalot]

re: compensators, it's not that I think this gun recoils hard or is difficult to control, but rather that I'm looking at this from a "when I don't have a suppressor on this, can I turn a soft-shooting gun into one that barely recoils at all?" perspective.

Back on barrels, I noticed CZ Shop has OEM pistol barrels with dual threading for $150, though they're out of stock at the moment. Having never disassembled the front end of my carbine, would it hypothetically be less expensive to just have a gunsmith swap out the barrels rather than cut and recrown the existing carbine barrel? If so, is the barrel nut necessary, optional, or incompatible with the HBI pistol handguards?

The only issue I see here is removing the barrel nut on the carbine. A couple of companies sell the super duper deep socket to remove the barrel nut for $80 -100. If you or someone you know that can weld, well then you could probably make it yourself with $8 worth of materials. It's possible that some of these online barrel threading companies have a tool and can take care of it for you

It will cost you about $100-150 to mail your upper off, have it chopped/crowned and have it sent back to you. Since you won't be using your carbine handguard anymore, you could just disassemble the two upper halves of the receiver and take out the whole barrel assembly. Then replace that with a new barrel and handguard. You can even sell your assembled barrel/handguard for $200 - $300 to help offset the cost of your new barrel and handguard.

Once you have your barrel cut down (or new barrel), you can slap on your hbi handguard and enjoy. The barrel nut for your original handguard is optional since the hbi handguard attaches to the trunnion with the included hardware and not halfway down the barrel.

Hope this helps

[Valk]

Sounds like the smart thing to do at this point would be to just have the carbine cut down to 7.7" with a 1/2x28 thread, then attach a Griffin or similar tri-lug adapter to it. The more I think about it, the more I'm realizing I keep wanting the standard CZ-spec threads kept so I can revert to a carbine handguard, attach a CZ OEM pistol handguard (or the Pakse Development handguard, should it use the CZ barrel nut), or attach the OEM brake. All of these things with the exception of using the CZ/Pakse pistol handguards more or less defeat the purpose of me buying a suppressor and Form 1-ing the Evo in the first place.

I still have plenty of time to change my mind, but it's looking more and more like I should just stick to what's simple.

[Valk]

Back with more questions.

I was having a look at the SP89 on display at the local gun store and noticed that they have an MP5N-style 3-lug and threaded endcap, similar to the drop in barrels that have been getting discussed lately. Since I'm still planning to just keep my factory barrel, I'm looking at possible ways to get a similar setup on my Evo once it's cut.

I found IGF sold an MP5N-style 3-lug, but it's not one piece, as the MP5N is threaded all the way down and then the 3-lug is threaded onto it, followed by the thread protector, so I'd need more than the normal amount of threading added to the muzzle (I *think* you need 1.5" of threading to put both on). Would I need to leave more of my barrel compared to the "stock" 7.7" I planned to cut it down to in order to provide clearance for my Rugged Obsidian in 3-lug config?

If I can't do that, I can always go with the Griffin adapter instead, but as should be obvious by now, I like keeping my options open.

[Kenneth]

The scorpion is easy to change barrels on.

I'm pretty sure there is a member here that's doing threading and cutting for the EVO.



That's is a pistol barrel with a carbine handguard from HBi. That's a Octane45 HD as well.

If I was going to look for a really short compact gun I would get the pistol length hand guard from HBi and cut the barrel back a few inches into that.

I run my pistol cans as direct thread.


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[omnidj]

While we're looking at a photo of a carbine handguard with a suppressor, it's good to note that you can only mount MLOK attachments BEHIND the suppressor, where there is enough room for the MLOK nut. You can mount anywhere along the bottom of the handguard, because space has been provided, but for those of us who like to mount lights or other items on the side and forward, be aware of this limitation. Anyone else observe this on their carbine?

[Kenneth]

I have not messed with it yet but if I was going to run a light I would go with a surefire M300 or clone and a IWC Thor tail mount. That would push the light forward along wide the suppressor and allow you to grab the rail up towards the front.


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[mursalot]

The suppressor looks like it's almost touching the lower set of mlok rails, but the top line of rails look good to go