Home Forums Reloading Big Game Rifles 300 AAC Blackout

I'm going to start loading for 300 Blackout. Just starting to gather information on this round. I would like to get some feedback, first the dies you are using. I see that Lyman is offering a 3 die set small base sizing, seating and crimper plus a go-no-go gauge. I wouldn't think I'd have to crimp due to recoil although with the heavy sub-sonic loads I guess maybe there could be a need. Anyway any info you can provide on the reloading setup you are using (I like micrometer seating dies for instance), and any dos or don'ts would be welcome as well. It appears this cartridge can be tricky to load due to the huge difference in bullet weights and applications (supersonic vs subsonic) also the setup of the rifle can be tricky as well. So I'm all ears (or eyes in this case), any info you can offer will be greatly appreciated. BTW the rifle will have a 10.5" barrel so technically it's a pistol (it has a brace not a stock) until I get a SBR stamp.

you don't need a small base die set, standard is fine.
crimping is not needed.
you don't need a no go gage, that's for chamber cutting.

get a case gage, they are helpful.

you're pretty much restriced to OAL based on the mag. Unless you have a bolt gun, then it's different.

It's not very difficult to load for. Actually it's one of the easier ones.

your powder choices are limited, 1680, and shooters world 'blackout' powder are two good choices.

wt is from 110 to 220gr, just pick what you want to do with it and buy some and load up.

I have Rem 130gr PSP bullets that will kill deer and are good for plinking too.
standard 150 gr deer hunting bullets work well.

light bullets go fast, 2200 fps, heavy bullets go slow, 1100 (subsonic)

Blammer is right on with all of that - no small base dies needed, just learn to adjust your sizing die correctly. I just use the Lee 300 Blk dies and have always been happy with them, although I use them with other brand lock rings. I don't crimp my 300 Blackout loads, but I do use the crimp die (the Lee factory crimp die) to remove the case flare. You'll need to flare the case mouths if you're loading cast bullets, otherwise don't worry about that.

Only thing I'd say different from blammer is that with the lighter bullet choices max mag length will not be a limiting factor on OAL, it'll be the barrel's chamber, so learn a method to figure out max seating depth in your chamber, and go from there. I can suggest an easy method if you are interested.

Sounds like you're loading for an AR, so a couple specific comments on that:
- Your AR can be set up to run both super and subsonic loads with the same setup, and do a very good job with both. Both of mine (9" and 16") do this with standard carbine buffers and springs, and appropriately sized gas ports. If yours doesn't, let me know what it does wrong and I can probably suggest what to do about it.

- The 300 Blk Pmag is an excellent choice for subs (and supers too). Regular 5.56 Pmags work really well for pretty much all supersonic loads but can cause bullet stack-up issues with some long heavy subsonic loads.

- Powder selection for proper function with subsonics can be picky, but you get a few more options if you only need them to work with a suppressor. Honestly, subsonics without a suppressor in this setup are kind of pointless anyway. 1680 is the safe powder choice (I haven't tried Shooter's World powder) unsuppressed, but with a suppressor mine will run subsonics with Lil'Gun or H110. Lil'Gun is the quietest of these three, and the difference is noticeable.

- Subsonic loads should be in the 200-250gr range, although you can go out of that range on either end a little bit with the right loads.

- Supersonic loads should be 110-130gr for best results. Heavier bullets increase dwell time and pressure remains high at the gas port longer, so the gun will be overgassed with heavier supersonics if it's set up to work with subsonics.

- My top supersonic bullet choices for meat are the 125gr Nosler Ballistic Tip and the 110gr Barnes Black Tip. The 125 NBT is a lot more accurate in my rifles. Other good options to consider are the 110gr V-max (but be careful these rounds don't make it into a 5.56!!!) and the 130gr MK319 SOST bullet if you can find it. My powder preference for all of these is Lil'Gun first (less flash/blast) and H110 second.

Hope that helps.

Thanks to you both. Good info. I bought Redding dies, (not small base) have always had good luck with them. Ran into some brass issues but have them sorted out. I looked at SAAMI specs, some of the brass I received (various head stamps) once the bullet was seated were .010 over max neck diameter. IVI head stamp. Yondering your help was great on that issue. This AAC Blackout is an interesting round. Going to be fun to play with. Very diverse, heck of a lot of fun to shoot.
I did have a couple of issues with some ATOMIC sub-sonic rounds, 220 grain SMKs, maybe not enough gas, maybe just a new rifle having teething pains. Failure to cycle with a full mag, after two rounds were fired from mag, no failure to feed, super sonic so far not an issue other than thick case necks. I've got some 1680 and 296 on hand and I think I'll pick up some Lil Gun as well. I'll have to look but I think I have a box of the 110 gr V-Max, and other various .308 bullets that didn't work out in my 308s.
My barrel cleaning regimen for rifles is three part, Hoppes #9 two patches then scrub with nylon bore brush, patch that out, then run a patch of JB bore cleaner back and forth 10-12 times, patch that out with dry patches followed by ISO alcohol, let that dry then Wipe out foam cleaner for the copper. My question is do I risk plugging up the gas port with the JB? Squirt some brake cleaner down the gas tube to make sure I get it out?

You could skip those first two and just use Wipe-Out. Not much need for Hoppes or JB Bore Cleaner when you're using that stuff, and the whole point is to eliminate unnecessary cleaning rod passes in the bore.

I don't do anything to plug the gas port for Wipe-Out, just blow it clean when I'm done.

Have two 300 BLK's...this bolt Ruger & an Aero Precision 16" AR

My dies are Forster FL & standard BR seater....don't forget the Lee collet die

If you're gonna run a bolt gun.....I run 110 Nozlers....125 Speer TNT's kick azz too

Custom assembled Aero Precision w/16" tube......

Yondering, what can you tell me about resizing Rem 223 to 300 AAC?

I use a cutoff wheel on a 4.5" angle grinder (mounted in a bench vise) to cut the 223 cases off at the shoulder/body junction. Then deburr, size in the 300 Blk FL die, trim to length, and deburr/chamfer. That's a bunch of steps, but I haven't really bothered to streamline my process for it yet.
I don't normally anneal, but some people do.

There are easier methods if you want to invest a little in equipment. There are some good jigs available to work with a small Harbor Freight chop saw; those are supposed to work pretty well and I've heard you can skip the initial deburr step. My abrasive cutoff blade leaves too much burr, so if I don't deburr before sizing that stuff scrapes up the case necks.

Another method that looks good (but a lot more expensive) is a Dillon or aftermarket trimmer mounted in a Dillon trim die; that setup can size then trim (while the case is up in the die) in one step. Even the cheaper aftermarket trimmers for this are ~$200 though and the Dillon trim dies are pricey as well.

10.5" Blackout shooting results using Hornady brass, Fed Match Small Rifle Primers, Nosler 125 grain Accubond bullet, Win 296 powder. 2.060 OAL, charge range 15.5 - 17.5. I started at 16.0 shot 4 - 5 round groups 16.0,16,5, 17.0 and 17.5 grains. Hot day 92 degrees, 2300 feet elevation, low humidity. Book Max velocity from 16" Pac Nor barrel: 2128
Velocities as follows:
16.0 : 1928, 1800, 1920, 1913, 1909. AVE 1913, ES 29, SD 10
16.5 : 1965, 1948, 1993, 1927, 1949 AVE 1949 ES 66, SD 22
17.0: 1990, 2019, 1993, 1996, 1998 AVE 1998, ES 29, SD 10
17.5: 2061, 2058, 2060, 2060, 2054 AVE 2054 ES 7, SD 2 BEST GROUP

Old lot of H110 ..cci 400 18.8 gr 125HRH HP got me 2057fps with very similar set up
#9 14.1gr = 1783fps. Similar accuracy