What as a minimum would I need to convert....

[jimb16]

I already have a quality AR15 in .223. What is the absolute minimum in parts that I would need to convert it to 300 blackout? I'm talking about keeping the .223 upper intact so I can easily switch back and forth. I obviously need a new upper with a barrel, but what else do I need?

[lefty o]

upper,ejection port,forward assist, barrel nut, handguard, barrel, gas block, and gas tube. a complete bolt carrier group is a good idea, but not an absolute. or you can just buy a complete upper.

[country gent]

If you build the complete upper then its a simple 2 pin change over. Upper reciever, barrel, barrel nut, handgaurd, gas block. Sights or scope. Also stamp the barrels as to caaliber outside the hand gaurd tube where its visible so you know what is what. If you throw in bolt carrier, bolt, extractor and ejector you can simply lift one off and the other on.

[Scharfschuetze]

I was just looking at AR 15 upper receivers and barrels yesterday. A complete upper already assembled in 300 Blackout was in the neighborhood of $600 to $700 USD depending on the features and the store.

[Hamish]

http://www.jsesurplus.com/300blackout-3.aspx

I have three of their uppers, happy as a pig in slop with them.

[BigMagShooter]

a barrel wrench, and vice for an ar 15 and a 300 bo barrel, that's all you'd need.

[Multigunner]

I think he is asking for the absolute minimum parts. If any of the parts other than the upper with barrel and gas tube can be easily switched over from one upper to the other he won't really have to have those parts just yet and could buy those parts later on when money is not as tight.

Are any of the parts like forward assist, ejection port cover, etc specific to the .300 conversion?

[nicholst55]

Are any of the parts like forward assist, ejection port cover, etc specific to the .300 conversion?

The barrel and the muzzle device (if any) are the only caliber-specific parts.

Having just seen pictures of a .223 AR that was destroyed by firing a .300 BO round in it, I would personally want to make the .300 upper/rifle very distinctive in appearance to preclude having such a catastrophe occur. I think I'd spray my .300 with purple Gun-Kote or something!

[mcdaniel.mac]

I already have a quality AR15 in .223. What is the absolute minimum in parts that I would need to convert it to 300 blackout? I'm talking about keeping the .223 upper intact so I can easily switch back and forth. I obviously need a new upper with a barrel, but what else do I need?
Just the built upper. Bolts and everything in the lower and interchangeable. You may need to tune or swap out the buffer and spring your lower depending on what the upper was tuned for.


NB: several people have blowed up their rifles becase .300 blackout will chamber in a 5.56 rifle, just pushes the bullet back into the case. To avoid a run-in with Comrade Kaboom, consider spray-painting (or having a custom coating) on the blackout upper, and consider using a specific style and color or magazine for .300 Blackout, something that both feels and looks different.

Personally I switched my .300 to only use Magpul 20rd or 'slant' pattern 20rd AR mags. They feed .300 whisper better, and if i grab one by mistake there's ko mistaking one for the other

[Earlwb]

Just buy a complete upper unit either completed or as a kit. You poke out the two takedown pins and swap the uppers and viola a new caliber to shoot and have fun with.

[jimb16]

Thanks guys. I think I'll start by researching prices on complete uppers. If I can't find a good quality affordable one, then I'll look at building one. BTW, I really wouldn't care if it was purple! But realistically, painting it in a camo pattern makes more sense! *LOL*

[Texas by God]

The barrel and the muzzle device (if any) are the only caliber-specific parts.

Having just seen pictures of a .223 AR that was destroyed by firing a .300 BO round in it, I would personally want to make the .300 upper/rifle very distinctive in appearance to preclude having such a catastrophe occur. I think I'd spray my .300 with purple Gun-Kote or something!
I did exactly that except no purple. Camo'd my .300 use metal mags painted to match with .300 Sharpied on all. My 5.56 is all black with Magpul mags. No kabooms please. Best, Thomas.

[DCM]

I Might look here
http://daytonatactical.com/products/300-aac-blackout-stainless-steel-upper-16-inch-with-12-slim-keymod-no-bcg-or-charging-handle or
http://daytonatactical.com/collections/300-blackout-rifle-uppers-300-aac-upper/products/16-300-blackout-aac-upper-10-quadrail-no-bcg-or-charging-handle


I paid more than that for my barrel but you do get what you pay for.

[DerekP Houston]

if it were me....I'd just buy the complete upper so I could easily swap between the two. Probably not the minimalist answer though.

[jimb16]

Right now, I'm trying to figure out the best twist rate for a dedicated cast bullet shooter.

[Scharfschuetze]

Right now, I'm trying to figure out the best twist rate for a dedicated cast bullet shooter.

For the 223?

If so, get a 1 in 12 twist and you'll be good to go and it'll still handle the most commercially available ball round: the M196 with the 56 grain FMJ bullet. Until the M16A2 came on the scene, that was the standard twist rate for the M16A1, CAR 15 and the XM177 in 5.56mm. If you have a sub-cal device for 22LR for your AR, then the 1 in 12 works the best for that application also.

The very first iterations of the M16 had a 1 in 14" twist, and that worked fine in warmer climates, but bullets would start to tumble during the Winter months in very cold areas.

From what I've seen lately, the 1 in 9" twist is the most common, but 1 in 8" and 1 in 7" are available. While they'll work, these are all too fast for a dedicated cast boolit rifle.

[Multigunner]

"Right now, I'm trying to figure out the best twist rate for a dedicated cast bullet shooter. "

I'm certainly no expert on the subject but I get the impression that slow twists were used in the old days to prevent stripping of soft lead bullets in the rifling.
Since most now use fairly hard alloys for cast boolits a faster twist is unlikely to strip the boolit surface or cause excessive leading, in the nominal .300 caliber at least.
If you are going for long heavy boolits at subsonic velocities it seems to me that a fairly fast twist of 1:10 would be a good compromise to stabilize a fairly long bullet.
As I say I'm no expert so I'd ask for more members to express their opinions.

PS
It may be apples and oranges but I've read that Military marksmen when using autoloading .32 S&W wadcutter target pistols found that making their own replacement barrels with tighter bore and faster twist than the standard factory barrels greatly improved accuracy. They used cut off sections of M14 or Garand barrels to make these target barrels. Not sure if the improvement was more due to the tighter bore or the tighter twist.

[jimb16]

I've been asking this question of a lot of people. 1:8 seems to be the most popular. As a long time shooter of cast, I thought that 1:10 would be best. But I can see the 1:8 for longer bullets. It should stabilize them better particularly at lower velocities. My .222 Rem is 1:10 and shoots 45-55 gr pills very accurately. I haven't tried heavier in it yet. I have 8 rifles that I use for cast; (2) .30-06, (2) M1 carbines, a .30-30, 8mm Mauser, 7.62X54R and a 7TCU. I haven't played with cast in my single shot .223 yet. Since the .300 BLK would be new to me, I wanted to know the most common twist rate and how well it worked with a wide variety of weights.