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View Full Version : Building AR #4, need some help / advice from you guys


twinjetguy
04-29-2010, 9:17 AM
Hey guys,

I just went to Rifle Gear yesterday (that place is evil) and purchased a Mega matched billet upper and lower. I have built my previous 3 AR's myself, but have never built a complete uppper yet. Should be fun. Anyway, on to my questions.

I want to use a Noveske Fire Pig flash hider OR the Troy Industries Claymore Muzzle Brake. I also want to find the longest railed handguard (in flat dark earth) I can. My goal is to get the Flash Hider/Muzzle Brake as close to the handguard as possible. So far the longest railed handguard in FDE I can find is from Troy Industries http://store.troyind.com/13_TRX_Standard_BattleRails_p/strx-sta-f3bt-00.htm.

My question is, using one of the above mentioned FH/MB's, what is the shortest length barrel I can use and be legal? I am guessing my only choice is a 14.5 inch?

Any help?

pacrimguru
04-29-2010, 10:49 AM
w/ the KX3, it's 13.7".

twinjetguy
04-29-2010, 11:04 AM
w/ the KX3, it's 13.7".

Ok so a 14.5 barrel with the KX3 would come to a total length of 13.7? They said the length of the KX3 was a little over 3 inches so wouldn't that put it in the 17.5 inch area? Am I missing something?

Any suggestions on what length barrel I should go with? Want to stay with a carbine.

professorhard
04-29-2010, 11:10 AM
Ok so a 14.5 barrel with the KX3 would come to a total length of 13.7? They said the length of the KX3 was a little over 3 inches so wouldn't that put it in the 17.5 inch area? Am I missing something?

Any suggestions on what length barrel I should go with? Want to stay with a carbine.

The KX3 will bring a 13.7 inch barrel up to 16in overall when perm attached

pacrimguru
04-29-2010, 11:13 AM
The KX3 will bring a 13.7 inch barrel up to 16in overall when perm attached

yea sorry, i should have been more clear. ^ what he said.

twinjetguy
04-29-2010, 11:15 AM
Ahhhhhhhhhhhhh, ok got it! Thanks guys! Now for my next question, who makes barrels chambered in .556 with a 1/9 twist, 13.7 long?

pacrimguru
04-29-2010, 12:20 PM
oooh, that's a hard one. i think it will be easier to buy a barrel and then have randall (ar15barrels) cut it down and pin the muzzle device for you. 13.7" barrels aren't all that common.

shark92651
04-29-2010, 12:28 PM
Are you trying to build this upper yourself - or just design it and have it built for you? Building uppers yourself with barrels < 16" is a LOT harder than 16" barrels because of the welding requirement. I also don't know if you could even get to the area to weld if you put a 13" rail over a 13.7" barrel - unless the rail is one that will slip over the welded muzzle device and gas block and does not need to be installed first. Remember that the barrel is measured from the chamber (or closed bolt face) and extends into the receiver a bit. Just giving you some info to work with, I'd hate for you to end up with a collection of parts that won't work together.

twinjetguy
04-29-2010, 12:33 PM
oooh, that's a hard one. i think it will be easier to buy a barrel and then have randall (ar15barrels) cut it down and pin the muzzle device for you. 13.7" barrels aren't all that common.

Hey Pacri,

Thanks for the info! Been researching barrels all morning and you are right, 13.7 is not common, lol. Anyone know if JD Machine can cut down and thread a barrel? I know they can pin and weld on a flash hider. Tried calling them but Rob is out to lunch and I am impatient :p

twinjetguy
04-29-2010, 12:38 PM
Are you trying to build this upper yourself - or just design it and have it built for you? Building uppers yourself with barrels < 16" is a LOT harder than 16" barrels because of the welding requirement. I also don't know if you could even get to the area to weld if you put a 13" rail over a 13.7" barrel - unless the rail is one that will slip over the welded muzzle device and gas block and does not need to be installed first. Remember that the barrel is measured from the chamber (or closed bolt face) and extends into the receiver a bit. Just giving you some info to work with, I'd hate for you to end up with a collection of parts that won't work together.

Hey Shark,

Thanks for the reply! Funny you should post because I just bought the Mega lower and upper from you yesterday. I am planning on building this myself. I was going to go with a barrel that has a A2 sight on it then cut it down to fit underneathe the rail. I was planning on going with the Troy Industries floating 13 inch rail that mounts to the barrel nut. Will I run into a problem using the Noveske KX3 flash hider?

Really appreciate the info and advice! Hate spending money on parts I can't use.

professorhard
04-29-2010, 12:39 PM
Are u going to try and put something like the DD14.0 rails over a 13.7 barrel and then try to perm attach the KX3? Sounds like that might be pretty difficult to acces the bottom of the muzzle device to pin/weld it.

twinjetguy
04-29-2010, 12:42 PM
Are u going to try and put something like the DD14.0 rails over a 13.7 barrel and then try to perm attach the KX3? Sounds like that might be pretty difficult to acces the bottom of the muzzle device to pin/weld it.

So glad I posted this thread! Please help me with any info you can provide. I don't HAVE to go 13.7. My goal was to get the muzzle device as close to the rails as possible.

shark92651
04-29-2010, 2:10 PM
Hey Shark,

Thanks for the reply! Funny you should post because I just bought the Mega lower and upper from you yesterday. I am planning on building this myself. I was going to go with a barrel that has a A2 sight on it then cut it down to fit underneathe the rail. I was planning on going with the Troy Industries floating 13 inch rail that mounts to the barrel nut. Will I run into a problem using the Noveske KX3 flash hider?

Really appreciate the info and advice! Hate spending money on parts I can't use.

Talk to Matt at the shop. I'm pretty sure he had a 16" DD M4 upper with 12" rail that he had cut down and a Noveske pig permanently attached. If you contact him he can probably arrange for you to come by and check it out to get ideas. In general though, a two piece free float rail will be more flexible for this type of build as long as the flash-hider is outside the rail, or small enough to fit inside the rail.

rchman
04-29-2010, 2:23 PM
OC Armory had a Noveske Pig by itself that I got a chance to hold...all I can say is that thing IS HEAVY. Just keep that in mind.

djleisure
04-29-2010, 2:25 PM
Also, keep in mind that if you are ordering barrels under 16" and have them in your possession WITHOUT possessing an AR pistol lower you are subject to "constructive possession" laws for SBR's. Just throwing that out there, so you know!

twinjetguy
04-29-2010, 2:28 PM
Talk to Matt at the shop. I'm pretty sure he had a 16" DD M4 upper with 12" rail that he had cut down and a Noveske pig permanently attached. If you contact him he can probably arrange for you to come by and check it out to get ideas. In general though, a two piece free float rail will be more flexible for this type of build as long as the flash-hider is outside the rail, or small enough to fit inside the rail.

Hey Shark,

Thanks for the info again. Will definetly talk to him and see if I can take a look at it. Will look into the 2 piece floating style as well. Love your shop, you guys sure know how to help a guy in need when it comes to spending money LOL.

OC Armory had a Noveske Pig by itself that I got a chance to hold...all I can say is that thing IS HEAVY. Just keep that in mind.

As of now, it's a toss up between the Noveske Pig and the Troy Industries version. Leaning towards the pig because I like the smooth finish. Weight shouldn't be too much of an issue for me. Thanks for the tip.

pacrimguru
04-29-2010, 2:30 PM
how about going with a tube? this is what my KX3 looks like under a JP/VTAC handguard. the tube fits right over the KX3, so there would be no problems if it were perm. attached. (i do have to agree though, they are heavy and pointless on anything longer than 12.5")

http://i277.photobucket.com/albums/kk62/pacrimguru/AR-15%20Pistol/406122cc.jpg

L4D
04-29-2010, 2:40 PM
how about going with a tube? this is what my KX3 looks like under a JP/VTAC handguard. the tube fits right over the KX3, so there would be no problems if it were perm. attached. (i do have to agree though, they are heavy and pointless on anything longer than 12.5")

http://i277.photobucket.com/albums/kk62/pacrimguru/AR-15%20Pistol/406122cc.jpg

curious, Is it because of the weight placed up front that makes it useless on anything longer than 12.5"?
does it still effectively hide flash with a barrel longer than 12.5"?

OP how about a 14.5" with a pinned/welded KX3 and a Midwest industries 15" (http://www.parallaxtactical.com/store/midwest-industries-super-single-rail-ss-forearm-15-black-800.html) Single rail free float?

pacrimguru
04-29-2010, 2:57 PM
the kx3 isn't used to hide flash. it's used to blast everything forward away from the shooter and his "teammates". powder, concussion, smoke, fire, etc. therefore on a SBR (pistol) style build it makes sense since that's the kind of thing you'd be shooting up close and personal right up next to your guys in small confines. well, in theory at least. the extra weight on a 7" barrel is negligible. but when added to the end of a 14.5", it can throw the balance off significantly.

twinjetguy
04-29-2010, 5:28 PM
how about going with a tube? this is what my KX3 looks like under a JP/VTAC handguard. the tube fits right over the KX3, so there would be no problems if it were perm. attached. (i do have to agree though, they are heavy and pointless on anything longer than 12.5")

http://i277.photobucket.com/albums/kk62/pacrimguru/AR-15%20Pistol/406122cc.jpg

Pacri,

That AR pistol is SWEET!!! I have been wanting to get one, but the Draco was much more affordable. I still want what you have though, lol. Thanks for all the help today.


curious, Is it because of the weight placed up front that makes it useless on anything longer than 12.5"?
does it still effectively hide flash with a barrel longer than 12.5"?

OP how about a 14.5" with a pinned/welded KX3 and a Midwest industries 15" (http://www.parallaxtactical.com/store/midwest-industries-super-single-rail-ss-forearm-15-black-800.html) Single rail free float?

L4D,

I checked out the M.I. 15 Single today and it just isn't what I want. I saw 15 inches and thought "that could be the route" but I really want the quad rail on the build that I am doing.


To everyone else, thanks for all the input! This is exactly what I was looking for. Thanks to this site it saved me from making a mistake which could have cost me a bit of money. Rest assured I will be posting pics of the finished product.

jbooker9
04-29-2010, 6:01 PM
Hey twin I just wanted to let you know that it is hard to find ff rails that fit on Mega Billet uppers, another member on here mentioned that he tried to use three different troy rails on his build and they were a no go. I had a fun time getting my larue rail on my billet set (got in some good dremel time), just thought you should know

twinjetguy
04-29-2010, 8:08 PM
Hey twin I just wanted to let you know that it is hard to find ff rails that fit on Mega Billet uppers, another member on here mentioned that he tried to use three different troy rails on his build and they were a no go. I had a fun time getting my larue rail on my billet set (got in some good dremel time), just thought you should know

That is definetly good to know! Any info on specific rails that will fit without mods? Not that I mind modifying, I have a dremel, and my dad was a tv repairman, he has a *****en set of tools (joke, I have my own tools).

jbooker9
04-29-2010, 8:46 PM
I've only installed the larue but i'm sure other members have tried others

killshot44
04-29-2010, 8:48 PM
my dad was a tv repairman, he has a *****en set of tools (joke, I have my own tools).

Fast Times....great movie!

tommyid1
05-11-2010, 12:06 PM
bravocompany sells a Midwest industries 15 inch tube...

FMJBT
05-11-2010, 12:26 PM
the kx3 isn't used to hide flash. it's used to blast everything forward away from the shooter and his "teammates". powder, concussion, smoke, fire, etc. therefore on a SBR (pistol) style build it makes sense since that's the kind of thing you'd be shooting up close and personal right up next to your guys in small confines. well, in theory at least. the extra weight on a 7" barrel is negligible. but when added to the end of a 14.5", it can throw the balance off significantly.

If the components on the front of the rifle are light weight enough, the KX3 won't have a negative effect on the balance of the rifle. The rifle I built for my wife has a Sabre 14.5" barrel with pinned/welded KX3 using a Midwest SS-12 forend, and is not front heavy at all. The balance point with the stock at it's shortest length is about 1" back from the front of the receiver.

FMJBT
05-11-2010, 12:38 PM
Permanently attaching a KX3 will involve some creative construction techniques, as the diameter of the unit is too large for any barrel nuts or gas blocks to fit over. The barrel nut and gas block will have to be in place on the barrel before the KX3 gets attached. If possible, I'd try to get a barrel cut down to 13.7" rather than going with a 14.5". I went with a 14.5" barrel on my build, and the overall length now with KX3 is pretty much the same as a standard 16" barrel with A-2 flash hider.