Convert to 300 BLK or Not...

[Jeff H]

Well, it's done.

I ordered an AR-Stoner stainless barrel from Midway, a barrel wrench, .300 BLK dies, a case holder/length gauge, and I picked up some 110gr FMJ .308 projectiles today.

I just need to grab some powder, looking at H110, but it more or less depends on what I can get locally.

I may go ahead and make another complete upper out of the .223 barrel, I haven't decided yet.

Make sure you check the gas system. I've read that some (most?) 300BO barrels use a pistol length gas system since it works better for that round. If that is the case for your barrel, you'll need a new gas tube and a low profile gas tube block...

My 300BO upper is still on back order so I have no first hand knowledge yet. YMMV

 

[jmorris]

For your deer hunting there are bullets for the .223 that would out perform your 110g .30 cal FMJ's

 

[MrGiggles]

For your deer hunting there are bullets for the .223 that would out perform your 110g .30 cal FMJ's

The bullets I got yesterday actually won't work. They're a round nose carbine shape and supposedly won't feed well in an AR. I will swap them out with something more pointy tomorrow.

I don't plan on hunting with FMJ. Those are just for plinking/setting my zero. I will use a Hornady SST Interlock or similar for hunting, and I'm open to suggestions in that department.

The MP15 is supposed to have a carbine-length gas tube, along with the barrel I ordered. They should be compatible.

 

[CraigC]

IMHO, if you're not going to suppress it, the 6.8SPC is a better choice.

 

[ThePenguinKnight]

I went with 277 WLV myself, but I considered 300BO heavily before doing so.

Also, don't discount the round nose bullets out of hand. They may fail to feed, or they may not. A friend loaded and fired 100 of the 110 RN throigh his 300BO pistol with no issues.

If you can straight trade them for pointy bullets then great, but I'd try to shoot a couple before taking a loss on them.

 

[CraigC]

Anybody try the Speer plinker in the .300BO?

 

[<*(((><]

I think the 300 Blackout is a really efficient round, and has a lot of things that are positive about it, same magazines as 5.56 (blessing and a risk), and same bolt, so ease of finding parts and maintaining the rifle are a definite plus. And if your end goal is to suppress it, then for sure go the 300 AAC/B.O. route, as there are much better bullets to select from at the higher weights. I just wanted to be a voice of reason as to another option for you on lobbing a .30 cal bullet downrange.

And I'll echo CraigC above that if you are only looking for a good shooter and are willing to pay a little bit more for ammo (comparable to the 300 AAC ammo costs) I would recommend the 6.8SPC, that is one of the best hunting rounds for the AR15 in my opinion. And based on you wanting to deer and coyote hunt with it the 6.8SPC makes all the sense in the world.




I had previously assembled an 8" noveske barreled 300 AAC/B.O. pistol, and while it was a nice firearm, doing research into the differences between 300 AAC/B.O. compared to 7.62x39mm that at close ranges (both firing the same weight bullet) the 7.62x39mm bests the 300 AAC/B.O., it's only at distance when the better BC's of the .308 bullets come into play that the 300 AAC bests the 7.62x39mm. I realized that FOR ME it made more sense to sell it and build a 7.62x39mm upper, I can still reload for accurate hunting/target rounds, but have the added benefit of being able to practice and have fun with cheap russian steel case (i have to admit I put a lot of emphasis on cheap ammo availability on the calibers in my stable). I don't have any regrets, and I hope to get a .308 can (need to check if someone makes the baffles holes that will allow for a .311 bullet) down the road for my bolt gun, and see if I load up some suppressed loads for the 7.62x39mm.

And don't let any one tell you the 7.62x39mm AR's have issues nowadays from my experience and have read, that is gone and past. The only credible problem that I foresee with the 7.62x39mm in and AR is the need for a spare bolt or bolt replacement down the road due to having to mill out more of the AR bolt face. I've ran about 300-350 rounds (4 different type of steel cased ammo) through mine so far and have not had one hiccup.

 

[Sistema1927]

If you don't find H110 locally see if they have some W296 on the shelf. Same exact stuff (barring the normal deviation that occurs with all powders from lot to lot).

H110/W296 is what you want for 300 AAC, especially for the 110 bullet.

 

[Llama Bob]

"Ammo manufacturers will not make this caliber widely available because it is not widely used."

I'm guessing you don't get out much.

The round [usually 110g-240g loads] is incredibly popular these days for a variety of reasons. Major mfrs. have recognized that .300BLK has a substantial future.

This is a versatile round with broad applications, and it is usually quite affordable. If you save your spent 5.56 brass, chop it and reload with a .30 caliber bullet, you will be able to shoot at a truly inexpensive rate.

Yup - 300BLK has by far the best ammo support of any secondary AR15 cartridge. It's not my personal choice - I'd MUCH rather be shooting 6x45 in ARs for pretty much all applications - the trajectory of .308 with match bullets, and the option to shoot a wide range of .243 varmint and medium game bullets is pretty much ideal. But so far the rest of the world hasn't figured out 6x45 is what they should be shooting, so we get .300BLK and 6.8SPC and 6.5BadDesign. Of those, .300BLK is the one the ammo makers have decided to jump on.

 

[Llama Bob]

And don't let any one tell you the 7.62x39mm AR's have issues nowadays from my experience and have read, that is gone and past. The only credible problem that I foresee with the 7.62x39mm in and AR is the need for a spare bolt or bolt replacement down the road due to having to mill out more of the AR bolt face. I've ran about 300-350 rounds (4 different type of steel cased ammo) through mine so far and have not had one hiccup.

Breaking bolts isn't an "issue"?

I tend to classify guns that have a habit of breaking the parts keeping hot gas from my hands and face as unmitigated disasters. But that's just me...

 

[MrGiggles]

I went with 277 WLV myself, but I considered 300BO heavily before doing so.

Also, don't discount the round nose bullets out of hand. They may fail to feed, or they may not. A friend loaded and fired 100 of the 110 RN throigh his 300BO pistol with no issues.

If you can straight trade them for pointy bullets then great, but I'd try to shoot a couple before taking a loss on them.

I'm on good terms with the LGS, it shouldn't be any big deal to swap them out. They probably won't have light 30 cal bullets though, might have to go with a 150 grain.

 

[mavracer]

If you have to go that heavy get a lightly constructed one like Hornady A Max if you're going to hunt with em. One of the nice thing about long range hunters the bullet companys are making some bullets that work well at 400+ yards where a 308s velocity is down to where a 300 BO is at the muzzle.

 

[Ibmikey]

Giggles, As i load only supersonic rounds for my rifles and with hunting Hogs or deer i prefer the 125 grain bullet loaded with W296 / H110 powder. A nice field rifle (when you get the AR done) is a Ruger American Ranch, 16" barrel and 300 blackout chambering....add a 1x4 scope and you are GTG.

 

[MrGiggles]

The barrel came in today.

I drove out the taper pins and slipped off the gas block. The new barrel is only dimpled for a set screw, so I can't use the S&W gas block.

Is there a gas block available that uses a set screw but will still hold the retainer for my stock hand grip? Doesn't need to have a sight post. All I can find are low profile grips for a quad rail setup, and I wasn't wanting to change that yet.

You can see the difference here.

 

[MrGiggles]

I took a closer look at my gas block, and it does already have a hole right where the dimple is, but it's not threaded.

Could I just tap that hole, install set screw, and be good to go?

 

[wally]

I'm a bit puzzled by the dimple in your barrel. All I've seen are plain and there are two common types of gas blocks -- clamp on and set screw, both usually have at least two screws.

For maximum economy I don't see why you couldn't drill and tap your FSB for a setscrew, assuming you've got a way to locate the hole properly. I'd suggest doing it twice to use two set screws as is commonly done with low profile gas blocks. I wouldn't worry about dimpling the barrel for the second screw.

 

[MrGiggles]

I'm a bit puzzled by the dimple in your barrel. All I've seen are plain and there are two common types of gas blocks -- clamp on and set screw, both usually have at least two screws.

For maximum economy I don't see why you couldn't drill and tap your FSB for a setscrew, assuming you've got a way to locate the hole properly. I'd suggest doing it twice to use two set screws as is commonly done with low profile gas blocks. I wouldn't worry about dimpling the barrel for the second screw.

Unfortunately the bayonet lug prevents me from drilling a hole there. The first hole is already there and in the right spot, just needs to be threaded.

Even a low profile gas block will hold my hand guard retainer, correct? I may see what I can find locally. There isn't much meat on the factory gas block, and I don't want the screw to strip.

 

[grampajack]

I have wanted an AR for years now, and had a like new Smith and Wesson MP15 Sport 2 fall into my lap as a partial trade for a truck that I was selling.

It's a nice shooter and all, but it has limited usefulness as a .223. There is very little varmint hunting in this area. I have aspirations to hunt Coyotes, but have yet to actually realize them. That is just about the only practical use I can think of.

I deer hunt quite a bit, but .223 is marginal at best for that. I've seen a lot of posts that show 300 BLK as being a pretty decent whitetail cartridge at <150 yards with a ~125 grain bullet. My AR is a lot shorter and lighter than my .270 deer rifle. This area is very hilly, and the longest shot I have ever taken was 200 yards. Most are less than 100. I can always use the .270 for open country.

I reload, and have almost 300 rounds of 223, some loaded and some not, and primers/powder. Bullets are only slightly more expensive.

From what I understand, the only thing I need to change is the barrel to accommodate .300. Midway has an AR-Stoner barrel on sale for around 100 bucks.

So for any that have done the conversion, was it worth it?

.300 BLK isn't a good deer cartridge. It's good as a subsonic load in a suppressed 7'' barrel, and that's about it. Basically you're getting .44 mag power from a package not much bigger, or louder, than the MP5SD. For any other use, there are better, and cheaper, options.

If you want to turn that into a deer gun, then my suggestion would be 6.5 Grendel. If it were me, I would just build a new upper for it. Considering that you can get a slick upper receiver from Anderson for 50 bucks (I've used them before and they're okay), you wouldn't save much by retrofitting that one. Just my 2 cents.

ETA: Ah, there's a second page. Okay, what's done is done. With supersonic ammunition, the ballistics aren't too far removed from 6.8 or 7.62x39, so it will do close in. Just remember that in terms of power, it's not much better than .223, so make your shots short and humane.

 

[Ibmikey]

Giggles, The retainer plate will slip on to it's normal place and the gas block will butt up against it.....no issues there. The dimple should line up with the screw hole closest to the receiver, take the set screw out and visually line up gas block and dimple, set forward screw to hold everything in place. Lock tite is recommended but I modify my rifles often necessitating removal of the block so I do not locktite. I have never had a block come loose under firing, quite the contrary, occasionally,
they tend to lock the screws permanently.

 

[FL-NC]

The 300 b-o is an interesting cartridge, but until its available at competitive prices to 5.56 (like wolf or PMC) I would have no interest in a rifle designed for a high round count with such an expensive round. If I just wanted it for hunting I would buy the Ruger American ranch to hunt with.

 

[CraigC]

.300 BLK isn't a good deer cartridge.

JD Jones would probably disagree with that assessment.

 

[MrGiggles]

Well, my barrel nut wrench finally came in and I was able to get the barrel swapped.

My set screw fix on the gas block seems to be holding fine, but I've only got a few rounds through it. It shoots and cycles great. Just a bit more recoil. I'm running factory Remington UMC 120 grain right now.

I have a jug of H110 and some 110gr FMJ projectors on order, will be here next week.

I can't believe how much more tolerable it is to shoot without a muzzle brake. I wear plugs while target shooting, but not while hunting. It would really ring your bell before if you weren't wearing hearing protection.

 

[Ibmikey]

Take it from the ringing ear and "what did you say" crowd......,,wear protection whenever at the firing range, hunting or just clearing the home invaders in the living room. You will do yourself a great service with ear protection.

 

[MrGiggles]

Ran through the last of my ammo this morning sighting it in.

I'm not really thrilled with the elevation adjustment on the scope, but it's too late to return it now. This is the first out of 6 Barska scopes I've owned that has given me any trouble, but in that price range it was inevitable. It seems to be holding though.

80 yards, leaning on a tree. Includes shots before scope adjustment. Would hold 2 MOA with a good rest.





I have a thread protector ordered, I wonder if a linear compensator would make it even quieter to the shooter?

 

[george burns]

If I were to build or buy a 2nd rifle to go with my AR-223/556. I have been thinking of a 300 Blackout pistol, "one reason is the shorter range and larger round". This is strictly for recreational shooting and HD. Does anyone think that this has merit, or should I just go with an AR pistol.
I just wanted something small, Like a Carbine" with more knockdown power", for an emergency or even a truck gun. With a eotch or primary arms red dot.
I thought I should get it now before the election takes place, just to have another weapon that may not be available later on.
Other choices could include an AK pistol, but they seem kind of similar, and I like the AR platform more.