SBR Build

[jjl103]

I've decided I want to build an SBR, however, I am pretty on the fence about whether or not I want to do a 5.56 or a 300blk caliber. What have you guys seen as far as performance goes from a 10.5" 5.56 barrel? I am looking at a Noveske or Rainier match barrel for this.

I'm still undecided about a suppressor. I know I still intend to get one for my 14.5, and since I can just swap out muzzle devices on the 10.5 build, I can pop it on if I wish.

I am mainly looking to build something short and lightweight that is able to perform well between 20 and 75 yards (obviously 75 yards becomes a bit of a stretch, but I might need to shoot that far) and possibly something I'd keep in my truck.

Anyone have any input that isn't purposed to completely tear down my ambition of building an SBR (I don't want to do a sigtac pistol build, and I don't want to hear about how I don't "need" to build an SBR...)

[KevinBLC]

Slightly off topic. Do you live in an area you can feel safe leaving your gun in your truck?

[MoxyDave]

Probably not a good idea to keep an NFA item in your truck. I can only imagine the legal hassles if that were to be stolen ...

Otherwise, build away. I have 2 SBRs and I enjoy the heck out of them. Even with the Sig brace available now, I'd still do it again.

[Pyzik]

A 5.56 AR with a 10.5" barrel is capable out to 200 and up if you are. Though, will be "harder" to suppress than .300.
That being said, .300 is really designed for this roll and can do everything 5.56 can, better. Even if you don't plan on running a suppressor.

Do you want another caliber?


Probably not a good idea to keep an NFA item in your truck. I can only imagine the legal hassles if that were to be stolen ...
I think he was going to tell him to just go pistol route.

[tappedandtagged]

No person experience, but from the data I've seen online it seems a 11.5" is MUCH better velocity wise. Do a Google search for 10.5 vs 11.5 velocity and you'll see what I'm talking about.

As far as 300 Blk goes, at this time, I just don't see it being practical to shoot and train with unless you reload due to the cost and scarcity of the ammo.

Even when reloading, the edge goes to 5.56/.223. I can reload .223 for less than 0.25 a shot (with my supy of free brass). With 300 Blk, the bullet itself almosts costs that much. You're talking .35-40 cent plinking loads IF you already own the brass. If you don't have the brass, you'll have to buy it at a slightly higher cost than 5.56 brass, or buy 5.56 brass and spend your time converting it to 300 Blk brass.

If I were to do a SBR build, it would be a 5.56 with a 11.5" barrel. Now that's my opinion TODAY. It may change tomorrow. And it varies with your wanted use. If you want to hunt with it, 300 Blk. For protection from 2 legged predators, 5.56 gets my vote.

[GaSwamper]

I'd say the .300 but I tend to like the bigger calibers more. The .300 was made to shine at this role especially suppressed. Not trying to change your mind but I'm doing a .277 Wolverine 10.5" in a few months, pretty much same as the blk but with .277 projectiles and don't have to bandsaw the brass just size and trim.

[Computalotapus]

You know the wife and I have been tossing the idea of a SBR around as well. The big thing is I don't want to have to stock a lot of different calibers. I build my AR's in 5.56 so I can run either 5.56 or 223 and personally the 9mm fits what I want to do in a hand gun. Never shot a 300Blk but from what I have heard it shines in the SBR division. When we talk about an SBR we look at what it will cost to use it. I don't have time for something that is going to sit in the safe and only come out to Oooo and AAaaah over. If I own it I want to shoot it a lot, and shooting 300Blk limits how much I get to shoot it.

So we are either going to build the SBR in 5.56 or 9mm haven't decided yet. Either way we will be building a AR pistol that will be identical in caliber as the SBR.

[GaSwamper]

You know the wife and I have been tossing the idea of a SBR around as well. The big thing is I don't want to have to stock a lot of different calibers. I build my AR's in 5.56 so I can run either 5.56 or 223 and personally the 9mm fits what I want to do in a hand gun. Never shot a 300Blk but from what I have heard it shines in the SBR division. When we talk about an SBR we look at what it will cost to use it. I don't have time for something that is going to sit in the safe and only come out to Oooo and AAaaah over. If I own it I want to shoot it a lot, and shooting 300Blk limits how much I get to shoot it.

So we are either going to build the SBR in 5.56 or 9mm haven't decided yet. Either way we will be building a AR pistol that will be identical in caliber as the SBR.

Yep I like to try to cross as many calibers and guns as I can. Me and my dad hunt and shoot together a lot and have always mirror each others calibers and sometimes even guns and gear to swap back and forth. Doing a .277 WLV for me was a no brainer since I reload a lot for 6.8 and already have hundreds of projectiles I 've scraped together from pulls, over runs, and blems plus it uses 5.56 brass that I can recycle to it.

[GOST]

I was considering both calibers also and decided on a 10.2" Noveske 300. The numbers I looked at showed that 12.5" was about the prime for 5.56. Different people's chronographs showed the a Noveske crusader 12.5" to a little over 100 fps slower than a 16". If your really wanting 5.56 I would suggest considering a 12.5", it is still pretty short. I'm in the process of building a 10.2" 300 myself.

[GOST]

The biggest plus to 300 BO is how well it handles compared to 6.8. The 300 really shines in the 10.5" to 8.2" range.

[GaSwamper]

The biggest plus to 300 BO is how well it handles compared to 6.8. The 300 really shines in the 10.5" to 8.2" range.

Your not trying to poke the 6.8 guy are you?? Besides I mentioned the Wolverine not a 6.8.

[BC98]

To the OP:

If you're looking to do a really short SBR (i.e. 8" to 9"), I would go with 300 BLK. BUT, understand that you will be paying more for ammo and there isn't a ton of cheap mainstream 300 ammo available at the moment. If 10.5" is the minimum barrel length you're looking at, I would go 5.56. I would say you'd be fine with a 10.5" barrel (Noveske or DD would be my recommendations) but I would also consider a 12.5" barrel. I run a Centurion arms barrel and it has been super reliable, accurate, and has a documented 130 fps (minimum) increase in velocity over my DD 11.5" barrel.

[GOST]

Your not trying to poke the 6.8 guy are you?? Besides I mentioned the Wolverine not a 6.8.

Nope, 6.8 spc II is a great hunting round but is not as easily manageable as 300 BO in my opinion.

[jjl103]

I have definitely taken into consideration the "different caliber" mindset. Honestly, I cannot see having a completely different load out for another caliber. Maybe use the same mags, but I have those filled with 5.56. I'm really leaning towards 5.56 for that matter.

I also want to address the "truck gun" issue. I like going on nice drives, etc. I'd like something smaller to keep in the truck on these trips. Not necessarily at all times, and only appropriately, of course. I don't think I'd bother myself with taking an AR if I were going to just keep my car parked at the airport or something while going somewhere.

Suppressability (if that is a word) is not a concern of mine. I intend to eventually try it out, but the performance of it with a suppressor is not something that is a deal breaker.

300blk ammo is rare and expensive. I don't know that I have the time to reload 300blk. Of course, its a really neat concept and I'd like to own a gun in that caliber to be unique, but I don't think its feasible right now.

12.5 vs 10.5. Is the performance of the 12.5 worth the 2 extra inches? If that is the case, why not just stick with my 14.5? If my 14.5 is good for a long distance, and the 10.5 is good to 200 yards at least, I think the 10.5 is the route I want to go considering I want to be as short as possible (within reason) while maintaining some kind of functionality. I'd ideally like to pop this in a backpack or something while I am going to the range or wherever so I don't draw attention from others while I am travelling.

With all that said, the Tax Stamp will be for the lower, correct? So would I legally be able to build 2 different uppers (or however many uppers) and swap them out as long as I don't swap them with my non-SBR rifle? Where exactly to the lines get drawn there?

[GOST]

Don't know if this will be any help to you but using M855 here's the data I've seen from others on average. Don't know if your concerned about the 2700 fps threshold for fragmentation.

10.5" 2627 fps
12.5" 2836 fps (Noveske Crusader)
14.5" 2907 fps
16" 2989 fps

[MoxyDave]

Keep in mind that a shorter barrel might be less reliable. Anything less than 12" and you might have an issue with weaker ammo. Also the blast and concussion will be greater the shorter you go. I did all this research years ago and found that for me, 12.5" was just right. No need for weird muzzle devices like the KX3, functions fine even with low-powered Wolf .223, and it's short enough to be useful in tight quarters.

The lower is the serialized part, so yes you can have 1 SBR lower and as many uppers as you'd like. The ATF would like you to notify them when you change it out, but that is merely a recommendation not a requirement.

[tlw613sp]

As long as you have a legal combination for every upper you have, you will be fine.

You can have 100 short uppers w/ 1 SBR lower, and 1 regular lower w/ >16" upper and be fine.
All the short uppers have a lower they can fit on, and the regular lower has an upper that it can go with.

Just don't have a regular lower with only short uppers, or a short upper with no SBR lower.

[jjl103]

I've all but decided on an 11.5" barrel for this build. Definitely going to invest in a suppressor before I finish this whole build (will be able to use this for my 14.5 right now, as well as this one eventually). I am probably going to get the process started with a Rainier arms lower and get a tax stamp for it.

[tlw613sp]

SBR the lower you have and get it started now. Plus you could SBR the billet lower and get the nice billet upper for your 11.5"

[jjl103]

SBR the lower you have and get it started now. Plus you could SBR the billet lower and get the nice billet upper for your 11.5"

Not sure I like the billet to be honest. My NTD/Spikes combo is nice, but having that NTD upper would be nice as well. I could SBR this lower, get that upper and find a nice spike's lower to match my spikes upper... that'd be nice. But weight and all... I'll have to research it.