300blackout or 5.56

[Glock22]

I'm building a sbr using a Noveske gen3 upper and lower and I'm looking at using a 10.5 barrel and eventually getting a suppressor for it. Not having bought the barrel yet which is the better caliber for this application?

 

[jagee]

https://www.indianagunowners.com/forums/long-guns/428588-talk-me-into-300-black.html

 

[DanVoils]

https://www.indianagunowners.com/forums/long-guns/428588-talk-me-into-300-black.html

I agree this is a great place to start. I have both in an SBR that is suppressed. Both serve different applications.
Dan

 

[ljk]

The SBR stamp only applies to your lower. So you can have multiple uppers with different calibers and barrel length.

Go short on the 300, 8.5" is ok. 10.5" or 11.5" for 5.56.

Adjustable gas block is STRONGLY recommended, so you don't have to mess with buffer and spring on the lower.

 

[jstwrit]

If you search on this there are LOTS of different answers. I'd suggest calling your local branch to clarify. Some posts indicate that you can have multiple uppers/calibers but must have them on file with the BATF and that you must be able to restore it to the way it was originally listed. I don't know what information is correct but these are the questions you want to have answered ahead of time. Sounds like you're going to have a lot of fun!

 

[jd4320t]

What do you want to do with the rifle? Ammo cost and performance aren't going to be the same. I wanted a short and fun 300blk SBR that suppressed well so I went with 8.2"

 

[Amishman44]

The SBR stamp only applies to your lower. So you can have multiple uppers with different calibers and barrel length.

Go short on the 300, 8.5" is ok. 10.5" or 11.5" for 5.56.

Adjustable gas block is STRONGLY recommended, so you don't have to mess with buffer and spring on the lower.

In the 10.5" barrel...I went with the 5.56 caliber. Using an Anderson upper and lower, I built it for my wife and she absolutely loves it. I shoot it (occasionally) and am very happy with it. And in the end, and since mine is set-up for use around the home, I have been very happy with the lighter caliber in the slightly (2") longer barrel.

 

[grahamsy2k]

Get the 11.5 bravo company barrel in 556. I wouldn't go any shorter than that for 556.

If your wanting something shorter, go for a 300 blk 8.2 in barrel.

I would get the 11.5, simply because its cheaper to shoot.

But a 8.2 in 300blk with subs and a suppressor is extremely quite. 11.5 with silencer is quite, but still kinda loud, wouldn't want to shoot it all day without ear pro.

 

[sgreen3]

You are literally going to get a ton of answers on this issue, boils down to a few simple questions. 1. how much do you plan to shoot it. If its a bunch may want to go with 5.56 since ammo cost will be lower. Unless you reload then price comes down quite a bit, but you have to factor your time in to reload them. 2. What kind of shooting do you plan to do, if its stuff inside of 150yrds either will do fine, any further the 5.56 may be a bit better for you. 3. Biggest piece of advice I can give speaking as someone that had 300blk suppressed as an SBR, Try it out it was fun and super quite but other than a talking piece for when people came over to shoot I never shot it and always gravitated toward my 5.56 rifles, so i ended up selling the upper and focusing on my 5.56 SBR. So if you end up not liking it just sell it and move on...

 

[ljk]

BCM chose 11.5 with their reasons: https://www.ar15.com/forums/t_2_138/174764__Q__Why_BCM_chose_the_11_5_SBR_over_the_10_5_.html

Everybody else went with 10.5 without problems, i.e. CQBR, MK18 of various manufactures.

If I'm building an SBR, I want it short, that's the whole point.

All 4 of mine are 10.5", 2 later ones are built with adjustable gas blocks, 2 earlier ones without. They are suppressed 99% of the time, I shoot them naked only when I wanna **** off the guy in the next lane with a musket.

 

[Psode27]

I say both. I'd get 5.56 first due to it being easy, then a 300 when you are ready to tinker.
I'm with ljk, if I get an SBR, I like it to be short! While there are hypothetical "issues" with 10.5's, mine has been fine. My 7.5 runs 100% too. This isn't a call out saying BCM is wrong on their choosing 11.5, only saying for my purposes I'm good with going shorter.
I would only personally get a 300 if you reload. Making 300 casings out of 5.56 doesn't seem that bad. It's on my to do list for next winter probably.

 

[Sling10mm]

If you are thinking of getting a 5.56mm suppressor, I would decide on the brand and model and then check with them on the shortest barrel they will warrant it for. If you go with a 30 cal suppressor, then you could eventually have both uppers and use the same suppressor. My guess is that the 30 cal can with a shorter (10.5") 5.56mm barrel would be fine, but again, I would verify with the manufacturer.

 

[ljk]

Or, get the BCM 11.5" and pin a Griffin Spartan 3, make it a 1 stamp AR.

Griffin Armament Spartan 3 - 5.56mm Rifle - Silencers