Building M4: 1:9 or 1:7 RHT?

[Erik2a4]

Gentlemen,

Working on a project and I'm trying to gather info. Should I use a 1:9 or 1:7 RHT barrel? Assume that it's a Bushmaster 14.5 (w/ Mini-Y compensator to bring to 16") with legal AR-15 bolt and Mil-spec lower-receiver, trigger assembly, buffer spring, etc.

I will be shooting primarily M855/62 grain with the option to go higher (to 77 grain).

I've been told 1:9 is the way to go.

Any thoughts would be much appreciated.

Oh, and any word on civilian versions of the HK 416?

Thanks,
Erik

[TacoDelRio]

1:7 is for the heavier bullets if I'm correct.

1:9 is for the lighter stuff. I used to work at a gun store, and looked through our suppliers thousands of pages of ammo, and could'nt find any 62gr M855-like rounds. Maybe it's just California?

If you want to use civie ammo, I'd go SAAMI .223 Remington spec'd chamber 1:9 twist for 55gr XM193's. They're more common.

Hope this helps. I get mixed up every now and then so I apologize if I'm not perfect.

[AlexNenadic]

You'll need a 1:7 barrel for 77gr bullets, period.

[ramy]

If you plan on shooting 77 gr rounds then get the 1/7.

For most people 1/9 is an adequate twist rate . I would prefer a 1/7 though...

I have a 1/9 twist barrel on my ar and it shooting 55,62 grain fine.... Never tried a 77 grain round.

[Creeper]

Ya going to a HBAR w/ a 1/9 twist?

[Limeyfellow]

I would also go with the 1/7 twist.

As for the HK416. No news on a civilian version. They are still doing tests on the military versions. They might have a civilian version out in a number of years.

[Frens]

www.ammo-oracle.com

[SMGLee]

Gentlemen,

Working on a project and I'm trying to gather info. Should I use a 1:9 or 1:7 RHT barrel? Assume that it's a Bushmaster 14.5 (w/ Mini-Y compensator to bring to 16") with legal AR-15 bolt and Mil-spec lower-receiver, trigger assembly, buffer spring, etc.

I will be shooting primarily M855/62 grain with the option to go higher (to 77 grain).

I've been told 1:9 is the way to go.

Any thoughts would be much appreciated.

Oh, and any word on civilian versions of the HK 416?

Thanks,
Erik

Erik,

A few things to clear up first...

Don't get a mini Y comp, it is useless. Buy a Bush with either a Vortx G6a2 or at least the Phantom hider.

Second, there is no law on the AR15 bolt carrier vs. M16 bolt carrier... Colt is even starting to ship civilian AR with M16 group. the heavier weigth will help with cycling.

1:9 is the best compromise between the 55 and the 62. I for one use the 1:7 which is good for the 77gr I shoot. but 1:9 is ok to use with the 77gr, just not the best choice... for 77gr, 1:8 is actually a better twist.

Fren is correct, go to ammo oracle, it is the BEST source for anything 556 related.

The latest word on the 416 is releasing to the individual LE officer shortly after the Shot show. I should be receiving a price list soon. since it is releasing to LEO, that means you might be able to get them as a civilain then. the price is suppose to be very competitive.

[Erik2a4]

Gentlemen,thanks for the comments and the wealth of info.

I doubt that I would be shooting any M193 or 55 grain, so I'll do some more research...but it seems that 1:7 is the way to go.

Thanks for the Ammo Oracle link.

I assume that the M-16/M-4 bolt carrier group is legal now? I'd prefer to use the heavier weight, plus it's an item I'm more familiar with. What about the option to chrome the entire bolt to avoid carbon build up? Yea, Nay?

I do have some friends in the LEO community. Will the HK 416 be offered as an upper receiver (with modified gas system)?

I have searched and I'm still doing my research...but hearing directly from shooters is greatly appreciated.

The weapon is primiary for training at the CQB/CQC level and out to 200m. I do not intend to go HBAR, nor use an ACOG or other magnified optic.

Thanks again fellas,

Erik

[SMGLee]

Gentlemen,thanks for the comments and the wealth of info.

I doubt that I would be shooting any M193 or 55 grain, so I'll do some more research...but it seems that 1:7 is the way to go.

Thanks for the Ammo Oracle link.

I assume that the M-16/M-4 bolt carrier group is legal now? I'd prefer to use the heavier weight, plus it's an item I'm more familiar with. What about the option to chrome the entire bolt to avoid carbon build up? Yea, Nay?

I do have some friends in the LEO community. Will the HK 416 be offered as an upper receiver (with modified gas system)?

I have searched and I'm still doing my research...but hearing directly from shooters is greatly appreciated.

The weapon is primiary for training at the CQB/CQC level and out to 200m. I do not intend to go HBAR, nor use an ACOG or other magnified optic.

Thanks again fellas,

Erik

Why don't you want to use 55gr? it is the best anti personal round around... much better then the crap 62grFMJ the military trying to shove down your throat. if you are looking to do CQB, the 55gr is the best solution...

416 will be offered as a upper package with carrier group, rail system and buffer. sight is still undetermined.. around 1400.00. you don't need LEO friends, just have to find a dealer that is willing to sell it to you.

M16 BCG has always been legal, as long as you don't have any other M16 prats in your gun...

Chrome bolt is a myth.....try Slip2000, it will remove anything.

[Erik2a4]

Why don't you want to use 55gr? it is the best anti personal round around... much better then the crap 62grFMJ the military trying to shove down your throat. if you are looking to do CQB, the 55gr is the best solution...

416 will be offered as a upper package with carrier group, rail system and buffer. sight is still undetermined.. around 1400.00. you don't need LEO friends, just have to find a dealer that is willing to sell it to you.

M16 BCG has always been legal, as long as you don't have any other M16 prats in your gun...

Chrome bolt is a myth.....try Slip2000, it will remove anything.

I'm not happy with M855's terminal ballistics. I do know that M193 has better terminal velocity under 200m. It simply comes down to logistics...I can get more 62 grain to practice with than I can any other. Since the wave of the future seems to point towards the heavier grain and composite bullets, though, I'd like to have the option to transition to that ammo...especially if I find I need to go beyond 200m later on.

I'd like to have my cake and eat it to with an adaptable weapon :)

Would the 416 be a better investment long term over an M4 style? The whole point of this is to be able to train and work on my OODA loop and muscle memory, 3-gun skills, etc.

Thanks Lee, appreciate the info

[SMGLee]

M4 and the M416 isn't that much different in handling. I don't think it will mess with your cycle. as far as your OODA, it will be pretty much the same.

investment? not sure... it will be easier to clean... I ran my MRP to about 1500 rounds between cleaning. the piston will last much longer then that and it is much better with suppressed and or CQB-R.

416 is heavy.

if 62 is all you got then that is what you need to train with....

get a 1:7 twist and your frag ratio is about 50 yard...once it drops below 2700fps then you are SOL....

[dangerdan]

Screw Bushmasters 14.5" bbl w/ permanant comp/izzy/ phantom flash suppressor....

Get the CMMG 14.7" w/ permanant A2 flash suppressor upper. It has a chrome lined 1/7 twist bbl.

And the military uses 1/7 twist to stabalize the M856 tracer (wich is really long)

Make sure your barrel is chrome lined. It doesnt really matter id you choose 1/9 or 1/7, that both work equally well. 1/7 is slighty better on bullets heaier than 55-60 grains, but it does good with 55gr. 1/9 is pretty much and all-around good twist rate for .223.

And also screw SAMMI (or is is SAAMI?) and Wylde chambers, get a 5.56 chamber.

[James]

Restricted, but...

http://www.diamondbacktactical.com/Gas-Piston-System-Uppers-Upper-Receivers-Only-P1161C0.aspx

[Seraphim]

James, you should get money from DBT for all the advertising you do for them.

[Geezah]

Tagged....

[combat jack]

Good info from all. I like this site because there is a wealth of knowledge here.
No one barrel twist is the best, no one type of ammunition is the best, it all depends on what your planned use is, right? Murphy's law always applies. You said Close Quarters, right? First, if its close enough to not need optics, use a pistol. I now that ARs are short, but still a pain in the ass to move around a door frame in a three foot hallway. That is close quarters. Try a red dot. Russains had nothing but good reports when they first got their's in Chechneya.

[TacoDelRio]

Good info from all. I like this site because there is a wealth of knowledge here.
No one barrel twist is the best, no one type of ammunition is the best, it all depends on what your planned use is, right? Murphy's law always applies. You said Close Quarters, right? First, if its close enough to not need optics, use a pistol. I now that ARs are short, but still a pain in the ass to move around a door frame in a three foot hallway. That is close quarters. Try a red dot. Russains had nothing but good reports when they first got their's in Chechneya.

Atop that, I back up the chorus of EoTech. Can't love that thing enough over an Aimpoint. Now if they'd only make a tritium-illuminated one.... ;)

[Seraphim]

Atop that, I back up the chorus of EoTech. Can't love that thing enough over an Aimpoint. Now if they'd only make a tritium-illuminated one.... ;)

But then they will start charging us 1000+ p-)

[BlackRain]

Gentlemen,

Working on a project and I'm trying to gather info. Should I use a 1:9 or 1:7 RHT barrel? Assume that it's a Bushmaster 14.5 (w/ Mini-Y compensator to bring to 16") with legal AR-15 bolt and Mil-spec lower-receiver, trigger assembly, buffer spring, etc.

I will be shooting primarily M855/62 grain with the option to go higher (to 77 grain).

I've been told 1:9 is the way to go.

Any thoughts would be much appreciated.

Oh, and any word on civilian versions of the HK 416?

Thanks,
Erik

If you are trying to build an authentic M4 Colt configuration, you will need the 1:7 twist. That is how the Colt M4 upper is configured and is capable of eating NATO M855/SS109 and U.S. M193 with no trouble.

HK will not be releasing the HK416 to civilians nor will the yrelease the HK416 upper to civies either. Even though they offer semi-auto receivers, HK will only sell to LEO and military.