AR Newbie 300 blackout question

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brewer12345

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So I have a complete 556 Aero AR put together. While this is a nice toy, it is not a legal cartridge for me to hunt deer in my state. It looks like some of the offerings in commercial 300 blackout squeak over the required 1000 ft-lb at 100 yards requirement (a silly rule IMO, but there it is). Complete 300 BLK uppers are out there, but they are several hundred bucks. OTOH, it looks like I could just buy a barrel for around $200. Am I right in thinking that my 16" Aero AR would easily accept a 16" 300 BLK barrel without further modifications? If I needed to do further tinkering, what would be necessary? How much time and hassle is required to swap barrels (I am not terribly mechanically inclined)?
 
Swapping barrels requires clamping your upper in a vise, removing your gas tube and/or block, removing the barrel nut with an armorers wrench, and reversing these steps with a new barrel. Also, any optics will need to be re-zeroed every time you swap, due to the alignment between the barrel and the upper. Take a look at Radical Firearms uppers, at their website or at Primary Arms. +/- $200 will get you a free-float nitride upper. You can swap your BCG and charging handle to the one you are using, and the conversion will take about 15 seconds. I know it is frowned upon to swap BCG's, but, for hunting, it won't see much abuse, while you save up for a second BCG to dedicate to the new upper.
 
Wow, that is waaayyyy more than I would be willing to do. Sounds like a dedicated upper would be the way to go. Thanks.
 
The only parts that are 300 only are the barrel and flash suppressor, if you wish to permanently change to 300 the task takes about twenty minutes with the proper tools and a little knowledge. If your only AR I would recommend purchasing a second rifle or at least the upper in 300 Blackout outfitted with sights of your choice. Since I shoot only supersonic ammo I cannot report on the uses of subsonic fire, my rifles are acceptable in my state for hunting deer so an AR platform in 300 Blackout suits my needs just fine.
 
Wow, that is waaayyyy more than I would be willing to do. Sounds like a dedicated upper would be the way to go. Thanks.
That is how I started with the 6.8 SPC. I would swap uppers with the 5.56, but first chance on a deal later when my gun fund caught up, I built another lower. In your case, please be careful to not mix your BO and 5.56 ammo since the 30 cal bullet has trouble making it down the 22 bore.
 
I had not considered the possibility of mixing up the two. If/when I get a different upper I will be careful about marking things. Since I have other options on hand for deer, this is not a rush.
 
Yeah definitely a different upper since your also want to always have the 556 on hand for lower cost training and defense etc. Just get the 300 BLK upper and optic zeroed to it and your good to go.
 
I don't think its worth doing if you just plan on using 300 B-O for deer hunting. If that is the case, the rifle or top half of it or whatever will just sit most of the year. I'm a pretty serious AR guy, but I mostly hunt deer with my old 243 bolt gun- a couple months a year.
 
Definitely just get a second upper, it's way easier.

Also, I would strongly suggest setting up a separate range bags for your 300 and 5.56 uppers, and also consider marking magazines, either with paint or something like the rubber bands that denote caliber:

http://faxonfirearms.com/magazine-marker-bands/
Just curious, but I thought the 300 AAC Blackout could use the same magazine as the 5.56/.223 as the 300 is based on the 5.56 case. Why would you mark it?

Edited: Think I answered my own question -- if loaded ... Not to mix up between calibers.
 
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You are correct. The cool thing about 300 Blk is that you can use pretty much the same magazines, bolts, carriers, etc. as a .223 rifle.

The problem, though, is that (I am told) it's possible to chamber a 300 Blk round in a .223 rifle. As you can imagine, the results of touching off a 300 Blk round in a .223 rifle would be, well, not good.
 
If your intent is to hunt with the new upper I'd skip the 300BO entirely and step up to the 6.8/6.5. Either one will be a much more effective hunting round with better performance and longer range.
 
I second what Crazy said.
Unless you're running suppressed I don't understand the point of the 300BO.

I think the 6.8 SPC would be a much better choice for hunting. Of course this is only my opinion but I'm sticking to it. :)
 
I'll start by saying I dont hunt, but I was thinking 6.8 SPC would be a better choice, and you wouldn't have to worry about your ammo or mags getting mixed up.
 
6.8 or 6.5 are better on paper, but more expensive. If the OP isn't going to be taking shots beyond 150-200 yds it probably won't matter for practical purposes, might as well save the $ for specialized bolts and magazines and put it towards the optic.
 
Theory vs reality. The lighter 300 BO bullets do plenty well on deer sized critters. 110-125 grains at 2400-2500 fps are explosive on target out to 200 yards.
 
6.8 or 6.5 are better on paper, but more expensive. If the OP isn't going to be taking shots beyond 150-200 yds it probably won't matter for practical purposes, might as well save the $ for specialized bolts and magazines and put it towards the optic.


More than 5.56 but not BO. The VorTX load that is usually the yardstick for BO performance is extremely expensive.
 
Theory vs reality. The lighter 300 BO bullets do plenty well on deer sized critters. 110-125 grains at 2400-2500 fps are explosive on target out to 200 yards.



What theory is a 125 BO getting 2400-2500 fps? A 110 struggles to get to 2400.
 
What theory is a 125 BO getting 2400-2500 fps? A 110 struggles to get to 2400.
I get 2500 fps out of Nosler 110 Varmageddon 16" barrel Ruger bolt gun like clockwork. The brass flows like water out the neck and can't be reused without a resizing but its as reliable as the day is long. The brass flow comes more from the neck annealing Nossler does. I think Nossler claims 2400 fps but I double chrono everything and its more in the high 2400-low 2500 range. Even out of a 8 inch barrel its 2200 FPS. My handloads might be a little hotter at times with no pressure signs. Even Fiocchi 150 grain is a good 2000 FPS load I wouldnt have any problem shooting blacktail with at under 100 yards.
 
6.8 or 6.5 are better on paper, but more expensive. If the OP isn't going to be taking shots beyond 150-200 yds it probably won't matter for practical purposes, might as well save the $ for specialized bolts and magazines and put it towards the optic.

The cost for a complete upper, including BCG, is the same for a quality 300BO or a 6.5/6.8. Magazines are also priced in the same range and not a concern for a hunter needing a single 5-15rd magazine. The cost for hunting ammo is pretty much the same for 5.56, 300BO, 6.5/6.8 as well. In fact, the 6.8 frequently has the cheapest when the 90gr Gold Dot goes on sale for $10/20rd box every two months or so.
 
Thanks for the interesting discussion, folks. Looking at the ballistics of different calibers that might work, it seems like 6.8 is likely the most capable. My quarry would be chunky mule deer within 200 yards (but most likely 100 yards or less), so a bit more oomph would be helpful compared with hunting smaller whitetails. I have some research to do.
 
My handloads might be a little hotter at times with no pressure signs.

there is the key..... Using 300BO to hunt with is a reloaders game.. The commercially loaded mouse farts are not the best tool for the job.
 
Brewer, I have taken numerous Texas hogs with the 300 BO and my handload (125 gr TNT 16 gr H 110) has put down many without difficulties (also use .223 but that is another story). Many of the hogs are in the 200# category and my biggest was over 350#, one shot will put them down which is nice since i often have my AAC Handi rifle which is a one shot wonder. In Washington my yard is always full of mule deer which are famous for eating everything except my neighbors yellow Volkswagen. I would not hesitate to use the 300 on Mule deer at ranges out to 150 yards or so with a well placed shot.
 
The real issue is choosing a cartridge before the game. It's doing it backwards.

Choose the game, then what ballistic envelope you need to hunt it. What range, what target. It's obvious when we discuss deer out to 200m vs prairie dogs out to 500m - there may be an overlap in performance but few would say the same gun would be optimal for both. Even the optics won't cross over well.

Deer can be seen and hit out to 400m, if you choose a cartridge that only goes half as far are you knowledgeable before hand that it's lacking? Goes to understanding what range and target. Deer DO need 1,000 foot pounds of force to ETHICALLY drop them close to where they are shot. A lesser cartridge won't do that and mortally wounded deer could get away. It happens all the time and is frequently posted in hunting subforums. People sometimes spend DAYS tracking them out only to discover them too late for a food source.

It's why game departments do make arbitrary decisions on what cartridges are legal.

MO had a minimum caliber requirement at one time but as the average hunter matures they understand that the smaller bullets tend to have a shorter effective range and hunt accordingly. I did the same - .308 at first, buddies were using up to 8mm Remington Magnum. As time wore on I kept seeing that the effective range on Ozark broken woodlands was actually only as far as I could see IN the woods where deer would move in daylight hours late fall. That was 200m max. Even then, plotting all the known kills in the area I hunted for the last 40 years, I found most of the shots were under 100m, usually less. I didn't even need 6.8, which I had moved to.

Taking advantage of the MO seasons I found I could hunt twice as much with an AR PISTOL in 5.56, which has 1,000 foot pounds out to 80m hunting exclusively on wooded ridgetops where most of the daylight traffic occurs. I built one and used it last seasons - plural - knowing it was "enough gun" for any deer I could see between the trunks of the trees.

You could use .300BO just as effectively, but you can't shoot any cheap surplus in it, or 6.8, or 6.5, regardless. They are commercial loads, not military surplus, and there is no cheap ammo. Period. 5.56, yes.

Choose whatever tickles your fancy, but if it doesn't fit the requirements for your hunting game for range and target it's not going to do the job. Don't choose the cartridge first, examine the hunting requirement and then choose a cartridge that FITS. I was never a great fan of 5.56 back in the day, and the AR wasn't my first choice of rifle. Using one for 22 years in the service and then building one I began to understand it. Using the cartridge in the service for 22 years and then building an AR pistol I fit it to the job that I needed done.

Is .300BO a good choice? Maybe - but if you work thru the range/target question it's a more sure choice than simply going with the Bullet of the Month and then hoping it works. Will it deliver 1,000 foot pounds out as far as 85% of your potential shots hunting? is the real question. We are all presented with game shots hunting but not all of them are actually high percentage situations - go for a choice that gets most of them and you will know which ones would have taken a crew served weapon and forward observer.

Range and target first, then the short list of what conforms to that ballistic envelope. That's the correct choice.
 
I hear you, Tirod. Frankly, my usual choice for deer and other large game is not small bullets going fast. I tend to prefer bigger bullets. I don't own a 45/70, but it is what I would buy next in a hunting caliber. My usual choices for large game are either 35 Rem or 44 Mag (carbine). These put a big wallop on deer et al. inside 150 yards and if a particular load does not quite make it to 1000 ft. lb. it does not matter given the size of the holes in the critter and the fact that These bullets almost always make a large exit wound. I also enjoy rabbit hunting with a carbine using 38 special with a 158 grain bullet (we don't need no stinking expansion...). This sort of thing is why I regard the AR in 556 as mostly a toy, teensy bullet going fast. If I can find an alternative that would work with just a new upper, well, it is nice to have options. If not, no biggie. I already own short to medium range thumpers.
 
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