300 BLK Questions?

[kcofohio]

After resisting the 300 BLK, I ended up building an AR pistol, unsuppressed, with a 8 1/2" barrel.

I liked the idea of everything, besides the barrel, are shared with the 223.
That is, except for the cost of factory ammo and reloading components. I just spent about $80 for 60 rounds at Bass Pro.

Yesterday I shot sub and super sonic rounds to check for function. All went well with both. I think I like the subs (220 gr.) better. This will be a 25-50 yd. gun.

If I go with say, Berry's 220 gr. BLK bullets, my cost aill be into the 40 cent range. But I would really like to try MBC 215 gr. coated bullets.

One forum listed AA 1680, along with AA#9 as good powders in the subsonic range. There was mention that IMR 4198 doesn't do well in sub.

Most data that list pressure data for the subs, seem to be in the 20k psi realm. I'm thinking that folowing closely the data provided for jacketed bullets should be safe for leads at that pressure.

Any flaws in my thinking? I would greatly appreciate any experiences you have. Thanks!

 

[jmorris]

I resisted for awhile too then playing with different concepts of converting cases for a local manufacturer I wound up with a lot of brass that wasn't useful for anything except 300 blk or .380 shot shells.

This was the last "concept" machine before I built the machine they are using today.



Anyhow a $60 barrel sale happened somewhere and I have one. H110/296, is the powder I use most, supers with some of the many 150 gn JSP's I have. Other magnum pistol powders too, with HS-6 being the fastest I have used with heavy subs.

Cast bullets will make it cheaper to shoot if they will feed, I had mixed results with my cast .308 bullets but didn't spend much time figuring it out. I just get out a 9mm AR most of the time if I want to chunk a bullet subsonic down range.

 

[kcofohio]

jmorris, interesting on the HS-6. I do have almost 2 lbs. of 300MP. But so far very limited info for BLK. and 300.

Good point about the feeding of cast. MBC 215 gr. is titled for the Blackout. But I will probably just order 1 box to start.

 

[kcofohio]

jmorris, just watched your video. Simple, but innovative. Well done again, Sir!

Edit: Please don't take "simple" wrong. I know what it can take for the making of tools and such. It's my trade. I envy your talent for the ideas you come up with.

 

[bangswitch]

After resisting the 300 BLK, I ended up building an AR pistol, unsuppressed, with a 8 1/2" barrel.

Are you planning to suppress? IMO, no point in shooting subs unless you do. From that short a barrel, an unsuppressed sub is just as loud as a super from a carbine barrel. 50 yards or 250, you'll get better accuracy with supers, and do more damage.

If you do suppress later, you may find your SBR/pistol's performance will change, relative to cycling, and you may need to revise your load workup.

 

[kcofohio]

Are you planning to suppress? IMO, no point in shooting subs unless you do. From that short a barrel, an unsuppressed sub is just as loud as a super from a carbine barrel. 50 yards or 250, you'll get better accuracy with supers, and do more damage.

If you do suppress later, you may find your SBR/pistol's performance will change, relative to cycling, and you may need to revise your load workup.

At this point I'm just barely getting my feet wet in the 300 BLK pool.

My 1st priority is to see what loads work. From some of what I had read online, I was concerned about whether subs would cycle in the AR.

At this point I can't say what I will be doing (supressed/unsuppressed). Nor can I agree or disagree with you. But I will keep what you are saying in mind.

 

[jmorris]

Edit: Please don't take "simple" wrong.

No problem, I have spent my life turning things that seem complicated into simple solutions. Most problems have simple solutions, it's people that make them complex.

 

[Walkalong]

Most problems have simple solutions, it's people that make them complex.

You speak the truth here.

 

[Walkalong]

I shoot supersonic with mostly 125 and 130 gr bullets, but when pulled 147s are available cheap enough (Been some time now), they work great for cheap plinkers. AA #9 and 2400 work great for 147 FMJ plinkers. Enforcer, H-110, 1680, etc work well for more FPS with 125/130 Gr stuff.

I haven't tried any subsonic. A short barreled suppressed 300 BLK would be nice.

 

[dgod]

I have loaded and shot 220gr ELD-X with 9.4gr IMR-4227 that Chrony'd at 994 fps Un-Suppressed, and 984 Suppressed.

 

[LoonWulf]

When i was playing with the blackout i shot 220 round nose sierras, and 245mbcs, as my subs. I mostly shot them from my side charging upper or my RAR so cycling the action didnt matter. I used 231/hp38 and managed to get report from my 16" rar down around the level of a 22mag, or perhaps a hyper .22.

Accurate to 100yds, but i never did chrono the loads. I think the mbcs were doing about 800fps considering the drop.

One thing i did noice is loading them as long as possible usually improved feeding.

 

[kcofohio]

I have loaded and shot 220gr ELD-X with 9.4gr IMR-4227 that Chrony'd at 994 fps Un-Suppressed, and 984 Suppressed.

I watched a video with a Gunner Sergeant produced to show that there is very little difference suppressed/unsuppressed velocities.

 

[jmorris]

watched a video with a Gunner Sergeant produced to show that there is very little difference suppressed/unsuppressed velocities.

They can (no pun intended) make a load run that won't run unsuppressed, if the rifle is gas operated.

 

[kcofohio]

They can (no pun intended) make a load run that won't run unsuppressed, if the rifle is gas operated.

That makes sense. Slowing down the zero pressure of the barrel.

 

[dgod]

I have heard of individuals having to change recoil springs due to the difference in pressures for Suppressed vs Unsuppressed. I have been fortunate that the loads I have developed function as desired without parts exchange. It is Bullet load information, Barrel Length, Twist Rate, Suppressed vs Unsuppressed. If my memory serves, there is a difference where Subsonic ammo, thru a unsuppressed rifle may not fully eject the spent cartridge. Not enough pressure on the bolt to cycle the action. IMO, work your Subs up with caution to prevent FTE's

Good Luck

 

[SCC]

My 300BLK experience if it helps…

Two guns, 8 1/2" SBRed AR with adjustable gas block and a RARR. Both are almost always shot suppressed. The RARR has a dedicated Form-1 can and the SBR shares a short Surefire with the .223's. I run several different loads tailored to each gun.

SBR:
Sub: 175gr SMK equiv, A1680.
Super: 147gr military bullet, H110.

RARR:
Sub: 175gr SMK equiv, HP-38.
Sub: 225gr Hornady, H110.
Sub: 200gr Maker, H110.
Super: Same 147gr as above.
Super: 110gr Varmageddon, H110.
Super: 110gr Barnes Tac-TX, H110.

The 147gr load in the RARR is a plinker only. Just can't seem to make it accurate enough for my liking.

Both 175gr loads are my favorites, although the 225gr is more accurate (and more expensive) in the RARR. The 175 in the RARR is amazingly quiet, just a short metallic hiss then the thwack and thump 100yrds downrange. When shooting the RARR with this load I only wear ear pro if someone else is on the range shooting. Most of my 300BLK shooting is done with the 175gr loads, AR or RARR. These are also inexpensive, since I got a deal on the bullets and bought a bunch.

The 110gr Varmageddon load in the RARR is the most accurate, but I prefer shooting subsonic.

I haven't shot enough of the Tac-TX and Maker loads to form an opinion, they're too expensive.

Note that I must change the gas block setting on the AR between super/sub for proper function and that A1680 makes H110 look clean. Unfortunately, I have a lot of A1680 (and H110) to burn through before trying some of the better powders.

---Scott.

 

[Mr.Revolverguy]

Now I am biased but I think it is the largest information gathering on the net including loads. http://www.dayattherange.com/?page_id=3460 It is my journey from late 2013 with 300 black, using friends rifles along with mine to test with. Many loads tested across chronograph in 6 different rifles.