I want a 300 Blk pistol and an AR 9mm pistol. Budget's only going to let me build one in the near future. For serious cqb hd and hunting in thick woods the 300 Aac is a clear winner. Perhaps also the 300 with DI gas would be a little easier for wifey to handle. Of course the 9mm would be a lot more fun with cheap and common ammo as a range toy plus nothing to poo poo for home defense at least for wife or daughter to back me up with whilst I grab my 5.56 recce. Perhaps the AR9 could be a little more compact as a truck gun

It's killing me, I've just got to build something to hang my nice unused red dot on!   One day I get all excited about starting a 300, then I flop and want the 9mm. Which first?

In my mind the 300 should cost a little less to build, plus seems more of a legitimate "weapon" with longer range and accuracy. The 9 would be more of a fun at the range gun ( nothing wrong with that!)

Why are y'all voting one over the other?

Me personally, I'd build the 300BLK unless the cost of ammo is a factor for you. If ammo cost is a deciding factor then i'd go 9mm simply because I have TONS of it. YMMV.

Do you have a 9mm pistol?

I've had the same dilemma for a while now. I wanted for steel matches at the range. I decided to go the 9mm route and couldn't be happier. I bought a CMMG MK9 PDW and love it. Brownells has them on sale right now too. I paid $850 for mine from Primary Arms so look around for good prices.

Both pistols whenever I build will be custom. Probably in the $1300 range. Yeah the 9mm on short range steel would be a big fun attraction! If I build a 9, it will probably always be a pistol. The 300 just might be SBR maybe not.

How much do you want to shoot it? The 9mm will be much cheaper to shoot than the 300Blk.

I personally like the 300 but I think its not a great idea unless its suppressed.  Especially for HD.  

My next build is going to be a .300 but until then...


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I've built both 300 and 9mm

I wasn't impressed with the blackout, it worked great  but ammo harder to find and expensive compared to 9mm.

I like the 9mm better, I have a 9mm rifle 16" barrel and  AR pistol 7 1/2" barrel

I have both and prefer the 300AAC over the 9mm.

As you have said the 300 would be better at hunting and make a passable home defense gun, but the cost of ammo keeps you form shooting moor often.
The 9mm is a fun range toy but no way in hell would i use it for hunting anything bigger than a small pig. ammo is cheap so it ends up going on most range trips.

If you reload then no question about it go with the 300AAC.
Both will be great guns to suppress.

300aac at Walmart is around $16 a box of 20 i have found it for less at local shop for $14 a box but i reload it for around 30 cent a round so $6 to $7 a box of 20 if you reload.

It is a hard to pick between the 2 but for me i would go with the 300 blackout.

I would say go with the 300 blk and get a 9mm handgun. That's just my opinion

I think I've decided to build the 300 pistol first, then  build a separate 22LR pistol upper to go on it. That way the 300 will stay on it for HD/SD and then for just plinking and practice pop the 22 upper on it. That'll let me shoot some steel up close but won't be near as expensive building a whole dedicated AR9.

The subsonic 300blk ammo is considerably quieter than 5.56mm is. I would not shoot either one in a confined space if I can help it. I went 300blk, but now I am building 458 SOCOM and 6.5 Grendel so once you start the wildcat direction there seems to be no going back, I want them all.

IMO I would build the 300blk, it will be better all around for hunting, HD, range time etc.. The 9mm would probably be fine for HD and range toy buy not great for hunting. .