300 Blackout - curious. [Archive] - Glock Talk

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Uncle Don
06-03-2014, 20:23
Been thinking about the 300 Blackout - anyone loaded it? Granted, I have some research to do, but any input on steps beyond standard loading, I'd appreciate it.

PCJim
06-03-2014, 21:29
Don, I picked up a 10.5" upper in 300BLK a couple of months ago for use with a suppressor. I have prepped roughly 200 brass of varying LC headstamps, but have yet to begin reloading them. Waiting on the SBR stamp as I can't see getting any accurate load developed using a pistol lower.

H110, AA1680 and Lil Gun are supposedly the preferred powders. I'm stocked with 4# A1680 that I will be working with. It apparently will produce enough gas pressure with subsonic rounds to reliably operate the AR.

The most interesting aspect I've come across of reloading this cartridge relates to determining the COL when loading to run on the AR platform. Measure the intended bullet to determine where the bullet diameter is .25" and mark it with a Sharpie. You will want to seat the bullet such that this mark rides on the guide bump inside the AR magazine - this keeps the cartridge properly aligned in the magazine for pick up by the bolt.

Uncle Don
06-03-2014, 21:39
Thank you - that is excellent information, most of which I was unaware. Sounds like it's an investment in additional knowledge and some basic equipment to create the brass, but it seems it may be worth it.

rg1
06-03-2014, 21:45
Easy to load and fun to shoot 30 caliber bullets from 110-220 grains. You only need a way to cut the necks off of .223 brass and a lot use the cheap Harbor Freight mini-chop saw. Best brass and most recommended is to use Lake City LC brass. Some brands have too thick walls and the necks of converted brass may be over diameter. Loaded neck diameters should be .334 or less. I load 110 V-Max, 125 gr. Nosler Ballistic Tips, and pulled or new 147 grain M80 FMJ loads. I use Hodgdon data and H110 for loading 110-150 grain bullets. Lil-Gun is another popular powder. There are others that work better for heavier bullets and for sub-sonic loads. Steps to convert brass are simply to cut off the necks of .223 brass. The brass will grow about .005-.008" when sized so don't cut too long or there will be more trimming to do. Use the chamfer tool to remove saw burrs. Lube and run the cut cases into the 300 BLK. die, trim to length and load. I do highly recommend a headspace gauge and Hornady's Headspace gauge set with the B350 insert works great. Factory rounds sized minimally can have as much as 7-8 thousandths headspace depending on your chamber where you actually only want 3-4. All rounds fit AR15 .223 magazines and the only warning is I have read that a .223 Rem. round will not chamber in the short Blackout chamber BUT it is possible to accidently load a .308 dia. Blackout round into a .223 AR15 and it could chamber and fire. A bad thing as a .308 bullet won't fit a .224" bore. It's a fun round to load and fun to shoot.

willie_pete
06-04-2014, 13:13
300 Blackout fired in 5.56 upper = bad juju. I've colored my BO magazines after I read about three or four guns destroyed. This is one:

WP

Atomic Punk
06-04-2014, 14:22
Some good info here, also seems a good place for a question I have been wondering.

With subsonic rounds, and a suppressor, how does the 300 blk differ from a heavy and slower pistol round? I want to build an sbr setup and reload for it, but it almost seems like it would be cheaper to put a suppressor on a G21, and get similar results.

PCJim
06-04-2014, 15:47
.... With subsonic rounds, and a suppressor, how does the 300 blk differ from a heavy and slower pistol round? I want to build an sbr setup and reload for it, but it almost seems like it would be cheaper to put a suppressor on a G21, and get similar results.
AP, I've heard that same argument numerous times. For hunting purposes at close quarters, you could well do that with a pistol and appropriate SD bullets that will expand at pistol velocities, and maybe have better success.

The 300BLK gives its owner the option of using a rifle, shoulder rested, which "should" result in more accurate shots at further ranges. The biggest problem with its use in hunting is that there currently are no bullets available in 30 cal that will reliably expand at the subsonic velocities. Hunters I speak with regularly tell me that hogs that have been downed with the 300BLK look like someone took a .30" ice pick and drove it thru the hog. (these hunters only take head shots - these are 75-125lb meat hogs they are after).

I just like the idea of carrying two uppers and one lower out to the range and being able to shoot whichever I want. I haven't a place to hunt hogs yet (unless I want to just go shoot one in one of those multi acre pens, which I do not consider hunting). The 300BLK for me is for the most part a curiosity thing and being able to shoot it suppressed just adds icing to the cake.

Atomic Punk
06-04-2014, 16:37
AP, I've heard that same argument numerous times. For hunting purposes at close quarters, you could well do that with a pistol and appropriate SD bullets that will expand at pistol velocities, and maybe have better success.

The 300BLK gives its owner the option of using a rifle, shoulder rested, which "should" result in more accurate shots at further ranges. The biggest problem with its use in hunting is that there currently are no bullets available in 30 cal that will reliably expand at the subsonic velocities. Hunters I speak with regularly tell me that hogs that have been downed with the 300BLK look like someone took a .30" ice pick and drove it thru the hog. (these hunters only take head shots - these are 75-125lb meat hogs they are after).

I just like the idea of carrying two uppers and one lower out to the range and being able to shoot whichever I want. I haven't a place to hunt hogs yet (unless I want to just go shoot one in one of those multi acre pens, which I do not consider hunting). The 300BLK for me is for the most part a curiosity thing and being able to shoot it suppressed just adds icing to the cake.


thank you. thats all pretty much what i thought, i thought i may have been missing something. still want one.

batman4706
06-05-2014, 07:55
I use a band saw and a wooden block I drilled to the right depth to cut cases, I can do 10 at a time this way.

I have used the above listed powders with success and also 5744, 4227, Lil Gun & H4198. The 5744 loads are very quiet with a suppressor using Nosler 190's.

With the 125 TNT (cheap for fun shooting) I've had good luck with 4227 & Lil Gun.

I've even used Unique in it and got good accuracy, but doesn't work action.

Scott30
06-05-2014, 10:07
Uncle Don.. Reloading for 300 Blk is the same as any other after you cut/reform the case. If you plan on running subsonic get a pistol length gas system. It will run both subs and supers. Many have problems with carbine gas and subs and end up drilling gas ports, etc. You cannot overgas a 300.

For your reading enjoyment. http://www.300blktalk.com/forum/

I built my 300 and love it. Mainly shooting 125g bullets as I use it for hunting whitetails. PM me if you have questions.

Andrew Tacquard
06-06-2014, 15:00
Loaded some in my pro1000 and also in my LM. Good results. I've done 125s super, and 220s sub. I ended up loading the 220s to long, the bullet is in the lands/groves. I've since looked up how to determine max OAL for rifles (was the 1st rifle I loaded for). Also, outlaw state bullets makes a reliable 225 grain for subsonic in the AR. I haven't tried any myself, but I am on the waiting list. I converted both of my ARs to 300 BLK, so I don't have to worry about a 300 in a 5.56. Someday when I get to move home I plan on using both for pigs and whitetail. I did buy a couple thousand converted LC from a guy on the 300blk forum. Several folks sale it there, I didn't want to go through the trouble of converting.

Uncle Don
06-06-2014, 16:00
Getting some good info here so I think I'm going to pull the trigger so to speak, and buy an upper. Since I know nothing about gas systems, I'll have to buy a complete one, but regardless, it should work.

Andrew: I can only tell you my elementary manner of determining OAL in a particular gun, your way may be better.

I place the bullet alone in to touch the lands and grooves and hold it there - then put in a dowel that is a fairly close fit for the bbl, and put in the front of the bbl until it stops which is the front of the bullet. Make a fine mark at the end of the bbl and then knock the bullet out and do it again with the bolt forward. Make another mark - the distance between the two is the max OAL. I subtract about .010 and so far, it's never let me down but still allows clambering without a problem.

Andrew Tacquard
06-06-2014, 19:55
I found my method online, I was a Nosler article. Use a fired shell, make a small dent in the neck for tension. Make a bullet with a sharpie, put the bullet into the neck at more than max OAL, chamber, send the bolt home, extract. The bullet will have a mark at the point it pushed into max OAL (it was seated in the grove/lands), line the mark up with the case neck, measure max OAL, subtract .01 to .03. I think I measured something like 2.26 which was what I was loading to, so I needed to subtract a little. The still work well enough for plinking.

cohutt
06-07-2014, 06:47
If you are looking for something that you can endlessly tinker with, this is the round for you.

AA 1680 is probably the most used heavy subsonic powder (but rots-o-ruck finding any....)

h110/w296 is the consensus for lighter supersonic projectiles

My latest and ongoing experiment involves subsonic 300 bo -
cast from noe 311-247 mold with 1680 powder through daniel defense 16" 1x8 upper w/ Liberty Infiniti suppressor.

It has taken a while but the combo above is finally tuning to a decent grouping at approximately 1030 fps. last weekend I was hitting a railroad plate consistently at around 130 yards from a sitting position, which is a longer a shot than I'd ever take with this setup (hogs my mountain property). it is ridiculously quiet; i swear I could hear the hiss of the large projectile leaving the area....

http://i107.photobucket.com/albums/m284/cohutt/GUN/DSC_1727.jpg

I've tried both dry and wet powder coating a little and the early results are encouraging despite ugly lipstick colored bullets

http://i107.photobucket.com/albums/m284/cohutt/GUN/20140526_110532.jpg

PCJim
06-07-2014, 08:29
Off thread, but....
For determining rifle COL (on other than this 300BLK cartridge), I take a resized case and cut two slits, 180 degrees apart, lengthwise in the neck with a Dremel cutoff wheel. Insert the bullet of choice just barely enough so that the neck will hold it in place. It will be long.
Carefully, chamber this modified round, close bolt. The bullet will be pushed back into the case as it engages the rifling. Open bolt and very carefully extract the round. Measure the COL. Pull the bullet back out of the neck and repeat this several times, five would be good, each time measuring COL.

When reviewing the results, remember that the shortest COL you measured should be your max COL for this particular bullet.

Atomic Punk
06-07-2014, 12:50
Off thread, but....
For determining rifle COL (on other than this 300BLK cartridge), I take a resized case and cut two slits, 180 degrees apart, lengthwise in the neck with a Dremel cutoff wheel. Insert the bullet of choice just barely enough so that the neck will hold it in place. It will be long.
Carefully, chamber this modified round, close bolt. The bullet will be pushed back into the case as it engages the rifling. Open bolt and very carefully extract the round. Measure the COL. Pull the bullet back out of the neck and repeat this several times, five would be good, each time measuring COL.

When reviewing the results, remember that the shortest COL you measured should be your max COL for this particular bullet.

I have heard of doing something similar. Using special cases with a thinner neck. Same result. I think I like your way better.