300 blackout cast bullet loads for ar-15

[nouseforaname1246]

Ok so im going to be finishing my latest ar-15 build chambered in 300 blackout in the next week or so. 16" 1-8 twist stainless barrel with a carbine length gas system. I got the dies last week and have formed up a few hunded pieces of brass.
I have spent the last 2 days looking for cast bullet load data and havn't come up with much, mostly jacketed data and subsonic cast data.

I dont want subsonic data, I dont plan on buying a supressor in the forseable future. I dont plan on hunting with it, so I dont care about terminal ballistics (which is what every thread ive come across ends up being about.) Im looking for accurate and reliable target loads. I plan to work up my own loads over a chrony, I just want some good starting points and I will post my results for others who are having a hard time finding load data for this cartridge.

Ok so I have 3 bullets at the moment that I want to try; lee 309-170f. Lee 312- 155r. And the lyman 311359. I will probably buy a mould specifically for the blackout, but I would like to try making one of those 3 work. Any suggestions on which mould to buy for my intended purpose would be appreciated.
I have read of people using rx7 and 5744 for subsonic loads, but can they be used for supersonic loads? I ask because I have them on hand and powder is hard to come by right now.

So what are you guys using for your 300 blackout supersonic cast bullet loads?

[Jailer]

Lee 312-155-2R and 15.3gr H110. Runs about 1800 FPS is very accurate and has reliable cycling.

[300blk]

One of my favorites is lee tl 230 5r. sitting atop 11.8 grains of h110. Cycles 8.5 barrel no leading straight lee liquid alox. Fired hundreds. Jailers is very near where i run that boolit. Good luck.

[300blk]

Also due to case capacity the blackout is a hoot to shoot cast in. Fun and much like finding an accurate 9mm load and a lot less like finding an accurate -06 load... If that makes any sense.

[Jupiter7]

Agreed, the 312-155 is the ticket. I run mine sized to .309 seated to crimp with lee FCD over 15.7gr h110.

[nhrifle]

Reloader 7, AA5744 and Lilgun work well with that boolit as well.

[lksmith]

With that setup, using supers, gas checks are a must in my opinion due to the gas system. My best supersonic accuracy has been 17-20gr H110 under a 120-130gr bullet at 23-2400fps, but that was using jacketed since my only mold i have that is suitable for that caliber for using subs

[jarrodl]

One of my favorites is lee tl 230 5r. sitting atop 11.8 grains of h110. Cycles 8.5 barrel no leading straight lee liquid alox. Fired hundreds. Jailers is very near where i run that boolit. Good luck.

Do you crimp? What kind of accuracy do you get? Is it subsonic? if not what velocity?
Thanks

[Moonie]

My favorite load atm is also the .312 Lee 155gr with 15.3gr H110/W296, getting around 1,850 out of my 16" carbine gas.

[nouseforaname1246]

Ok I finally finished my build so im going to go test some loads tomorrow. I loaded up some 170 gr lee fp (I had a bunch already lubed up) over some rx7. Ill let you know how it goes

[Jupiter7]

I'll add my favorite new load for 300bLK. It's a little odd but had to try it out.

Noe clone of ranch dog 311165 standard lube grooves sized .309
Tumble lubed LLA
Aluminum gas check, total weight 169.5grs
COL 1.91
13.5grs lil gun

Isn't the lee 170rf the same design?

This loads feeds from standard GI mags with anti-tilt followers and functions in 10" AR pistol. Also the first rifle boolit I've been pleasantly surprised with accuracy, cloverleafed at 50yds 1st time out. I believe there's room to work up and make this a decent hunting load. If I was OP, I'd use the 5744.

[Moonie]

Ok I finally finished my build so im going to go test some loads tomorrow. I loaded up some 170 gr lee fp (I had a bunch already lubed up) over some rx7. Ill let you know how it goes

I had some trouble with the Lee 170 FP in mine, magazine length issue, they would nose dive in the GI mags I had. Seemed to work better in the magpul mags, but still had issues, they were just too darned short.

[Sur-shot]

I too am interested in the 300 with cast as the supply of jacketed is at least short. I finished my work with the 160gr 6.5 Grendel with a can and now turn my attention to the 300. But in the 300 I have several moulds that I have used for years including the RCBS silhouette bullets and the Lyman .308s and .311 - .312 bullets. I use the .311s in my M-99 Arisaka that I have not shot now for decades. Might have to break that old mould out.

I thought the RCBS 150 FPGC would be a natural for the 300 with H-110, but have yet to try them. I was not aware of the diving problems with the 300, however, I loaded some 125gr Sierra HPs which have a large open mouth and had to shorten them up a good bit so they would feed the last round on the follower, over the mag front. I determined years ago that the AR will function, with some rounds, if you shorten the OAL rather than extend it.
Ed

[Jupiter7]

I had some trouble with the Lee 170 FP in mine, magazine length issue, they would nose dive in the GI mags I had. Seemed to work better in the magpul mags, but still had issues, they were just too darned short.

What was cartridge length?

The trick is making the magazine think it's feeding .223. Otherwise mimicking the neck of .223 with nose of bullet. I'm loading this bullet with top drive band out of case neck. Rib of magazine is hitting bullet about 1/3 from top of nose.

[nouseforaname1246]

Ok so I had some intersting results. I worked it up from 13 gr up to 16 gr. Everything under 14.5 gr wouldnt cycle the bolt. At 15 and it would cycle but wouldnt lock back on the last round. 16gr was cycling perfectly and I had groups around 1.5 inches at 100. (2 five shot groups)
I had no leading at all so far, so im going to work up a few more grains to see if I can shrink that group down some.
I did have problems with the mags feeding properly. They kept nose diving in the mags. I was using gi mags and the bullets were seated so the last lube groove was just barely covered by the neck. I think im going to try my pmags and try seating them longer as well.

[nouseforaname1246]

Ok so I tried several more loads with the 170 fp using different oals and even tried using lil gun. Couldnt quite get them to feed reliably enough. Im pretty sure its the magazines causing the problem so I ordered some anti tilt followers. So in the mean time I finally had time to cast up the 155 gr 312 lees. Loaded those up with 16 gr of rx7 and all 15 of the test rounds fired and fed beautifully. And they held a fairly tight group. So I loaded up a half dozen or so different loads using rx7 and lilgun. Going to fire those off today during my lunchbreak hopefully.

[fredj338]

Are you using gas checks w/ the Lee 155? I am wanting to do a 300 upper & want it just for shooting lead bullets but would rather not gc for say 1500-1600fps.

[Overton-AR]

Well I am just now getting into casting. It is about 90% due
to the new fun 300BLK SBR that I am playing with. I went
with the Accurate mold Bullet design #31-240E. It was designed
specifically to keep the lube rings ABOVE the powder.

I am going to try it with straight linotype and a 50/50 mix
of wheel weight and linotype.

[338RemUltraMag]

Are you using gas checks w/ the Lee 155? I am wanting to do a 300 upper & want it just for shooting lead bullets but would rather not gc for say 1500-1600fps.

At 15-1600 you will need gas checks for a 30 cal.

[fredj338]

At 15-1600 you will need gas checks for a 30 cal.
Thanks 338, I was hoping I could run it like my 45-70, I just hate fussing w/ gc.

[gatorshooter]

My plain water quinch GC WW lee 170fp work fine at 14.5 gr of h110. Lock back bolt too. Tried 1 coat of dry tumble HF red powder coat. Bullets look great. Gc and lubed anyway with lbt blue lube. In lyman lubrisizer. Now they will not allow bolt to fully close. Very hard to extract loaded round. Good thing i crimped bullet. Tried seating coated bullet deeper still not functioning 100%. Obtw sota arms 16" full float upper carb. Length gas. No high pressure signs. Running stock m4 buffer and lower. Will test for accuracy after get function correctly. So far accuracy looks promising.

[TreeKiller]

Check the nose diameter did you bump them up in the sizer?. Had that trouble with Lee 160gr and the 65gr NATO in the 223. Baking the PC made the boolits soft.

[gatorshooter]

May have to get the lee push through sizer...ill keep playing with it for now.

[gatorshooter]

Sized the bullet deeper in sizer without lube and seated gc. Then seated it deeper in case to top groove. Inserts and extracts easily now in chamber. Test fired no high pressure signs. tried 15 gr h110. All ok so far. Pulled bolt after about 30 rds fired of plain hard cast and found leading behind gas rings on tapered part of bolt this had to be scraped off to remove. Will load up a few more and see what they yield off the bench.

[popper]

I use the 31-165C in 308 & 300BO. PC'd, no GC, 1750 (308 1.5 MOA), 1680 (BO) no problem. Haven't tried faster in 308 but BO was a full load of Re7. No crimp or lube grooves to get in the way, nose is .297 PC makes it .300 so it fits seated long. Sand ~ 0.005 off the ribs in the 10 rnd Pmag so the mag doesn't bulge. COAL 1.95 fits mag fine, sized 0.310. BO pretty much vertical stringing @ 50, got ~ 100 jacketed through it so time to try 100. Unsized it fills the throat and I don't see any land markings yet. Using PPU, Hornady, LC, Rem brass - no problems in a diamondback bbl.

[fredj338]

At 15-1600 you will need gas checks for a 30 cal.

How about cast hard, epoxy paint coating, no gc @ 1500-1600fps?

[HMC710]

I'm running the Lee 230 5R and love it. It's actually designed to fit the BO chamber and it works as designed. No fuss, no muss, & 7.5gr of Lil Gun.

[Mark-II]

I'm running the Lee 230 5R and love it. It's actually designed to fit the BO chamber and it works as designed. No fuss, no muss, & 7.5gr of Lil Gun.


Could you give some details as to bullet prep and OAL? I've got a blackout upper on its way, along with that very mould. I'm curious as to whether it needs sizing, since its a TL design. I was just going to cast it from range scrap, which seems a touch softer than WW, since that's the only lead I've got at the moment.

I've got to track down some lil gun. In the meantime I'm wondering if the likes of RL7 or 2400 are worth playing with in the AR15 with that bullet

I also have some RCBS 165-sil that I use in my m1a clone available to try.

[Moonie]

RL7 is a great powder to use, 2400 might be a little fast to cycle the action.

[Jailer]

RL7 is a great powder to use, 2400 is too fast to cycle the action.

There, fixed it for ya. ;)

[popper]

So how low can you safely go with Rx7 or 4227? Any problems at 10 gr or so? Not much load data in that range.

[BearBear]

This is a long thread with many discussing how they've used lead bullets for the 300 Blackout. I am about to get a 300 blackout but have been advised that one can't use lead bullets because the lead fouls the gas operating system. Is this advice wrong?

[Moonie]

I've run nothing but cast in our 2 300BO uppers, no issues with fouling. I also use cast in 5.56 and 6.8SPC uppers, no fouling issues at all between them.

People make assumptions based on ignorance and hearsay, we shine the light on this and have done it quite well.

[HMC710]

Built two more 10" uppers to go along with the 16" for some comparisons. My goto boolit has been the Lee 230 5R so I cast up about 100 of the gems, tumble lubed, and seated 10 of them to crimp groove over 8gr of Lil Gun. Much to my surprise, I was getting keyholing at 50 yards with about an 8" spread. Brought back to 25 yards and still got some key holing. One thing I did notice was a very large amount of smoke when firing these loads and clean up afterwards revealed a lot of leading. I didn't chrono these loads but the J220's were 1010fps. My lead is a bit soft, but didn't have the issue before. I tumble lubed the batch again, will clean the barrels up and try again....

[rongaudier]

Quick progress report on my custom boolit load for .300 BO. Quick rundown, I have am running a Hardened Arms 8.25" upper that worked fine with several brands of factory ammo. My boolit is a 160gr spire point and is PC with red HF paint and aluminum gas checks. I first ran it in my 30-06 bolt action at around 2200 fps and had pretty decent results. I finally got some powder for the .300 BO and loaded up a few rounds to try out. My powder for now is 4227 and ran 14.8 grains of it today. Well there are some issues in my AR. First off, I was having trouble getting it to feed. Next was the problem of it not wanting to go into battery. I attribute that to having the boolit set too far out. Unfortunately, the radius of the ogive requires that I set the boolit back pretty far and have now settled on a COAL of 1.89". I also had pretty inconsistent bolt lock back. I'm thinking setting the boolit back will take care of the not going into battery issues, and I'm going to try upping the powder charge to 15.8 gr. Hopefully that will give me more consistent bolt lock back. Not too sure about the feeding issue though. Is the short COAL the culprit? Here's a video of my first session.

http://youtu.be/seUPeOjwIgk

[Sticky]

Are you sizing those and if so, to what diameter?

The bolt lock back in the one that was shown on video didn't occur since you didn't have an empty mag in the rifle to engage the bolt lock, I assume you tried it with only a single round in the mag to check for lockback, otherwise you won't get it, regardless of your ammo.

FWIW, my testing with the 300 using subs is to load a single round in the mag first, fire and check for bolt lockback, then load 3 rounds, fire all three, checking feed, cycling and bolt lockback on the final round... Then I load the mag up and continue to test the loads.

I primarily load for subsonics, just started casting, so I have a lot to learn there, but have cast some lee 3092305R's to test for sub loads in the blackout. I have had awesome success loading subs with AA1680, it is my go to powder for subsonics in the 300. Almost every load I have tested with jboolits have cycled my 10.5" pistol, down to about 800fps with several boolits, but as you said, those jboolits are pricey for loading subs, thus my quest to cast for it..

Good luck with your testing! Anxious to see how you make out with it!

[rongaudier]

Are you sizing those and if so, to what diameter?

The bolt lock back in the one that was shown on video didn't occur since you didn't have an empty mag in the rifle to engage the bolt lock, I assume you tried it with only a single round in the mag to check for lockback, otherwise you won't get it, regardless of your ammo.

FWIW, my testing with the 300 using subs is to load a single round in the mag first, fire and check for bolt lockback, then load 3 rounds, fire all three, checking feed, cycling and bolt lockback on the final round... Then I load the mag up and continue to test the loads.

I primarily load for subsonics, just started casting, so I have a lot to learn there, but have cast some lee 3092305R's to test for sub loads in the blackout. I have had awesome success loading subs with AA1680, it is my go to powder for subsonics in the 300. Almost every load I have tested with jboolits have cycled my 10.5" pistol, down to about 800fps with several boolits, but as you said, those jboolits are pricey for loading subs, thus my quest to cast for it..

Good luck with your testing! Anxious to see how you make out with it!

Yes the boolits are sized to .309. I figured that thing out about the bolt lock back after watching the video again. I've loaded up another batch with 15.8 gr 4227 and the bullet seated a little deeper. I think I have hit the max powder load without compressing. I'll take it out and try it again.

[Sticky]

You may also want to try sizing larger, if you can. Many are shooting 300's at .311, or thereabouts. I have a .311 die coming today for the 309230's, hope to be trying them out here shortly. My mold drops them at about .311, but after coating, they are a tad larger, may even try some with Hi-Tek and no sizing, since it's a pretty thin coating after curing.

I ran some through the .309 sizer to try out in my AR308, anxious to try that out too!

[Greg Skinner]

Ron,I am running the same Hardened Arms 8 1/2" upper and have experimented with 4 different cast boolit designs. I have the Lee 150 fp, the Lee 170 fp, the Accurate 31-150B and the Accurate 31-235A. I power coat everything and I don't use gas checks. I size .309 and have used Lil Gun,IMR4227 and IMR4198. The super loads using Lil Gun and 4227 have all functioned fine, fed OK and locked back. OAL is 1.89 for the Lee bullets and 2.01 for the 31-150B. I've used only a 10 round Magpul mag and don't usually load more than 6 or 7 at a time. The mag will not seat with the bolt closed, but if I insert it with the bolt open, it functions fine with no problem either picking up the round or ejecting it. These boolits, especially the Lee are just too fat to allow the mag to seat when the bolt is closed, even if I seat them deeper. I suspect that filing the ridges in the mag might help, but so far it has not been enough of a problem to warrant that action.

I tried the 235 gr as subs with both 4227 and 4198. They functioned OK with the 4227 but would not lock back on the last shot. Function with 4198 was perfect. I think I seated them 2.15. The problem with them is that the bore ride portion of the nose is not great enough diameter, even when powder coated, and they appear to be tipping before getting out of the barrel. They are obviously not entering the target totally straight on, although they aren't grouping terribly at 50 yds - about 2", m-o-m for sure.

Accuracy with the 150 grain supers is not great - best groups are about 1" - 1 1/4" at 50yds, 1600-1700 fps, so it is still a work in progress, but Jacketed accuracy is not a great deal better, averaging at best 1" at 50 yds.

The Blk seems to be fairly sensitive to variations of any sort so part of the challenge is figuring out how to be totally consistent in re-loading technique. I haven't tried annealing the brass but I do trim between each firing and use a Lyman "M" die for the cast boolit reloads. The seating depth seems to be fairly critical, also - lots of room for experimenting. Maybe I need to try sizing .311 next to see if that would tighten groups any. Or maybe get a gauge to check for run-out.

[rongaudier]

Greg,
Great info. Hey if I could get 1" groups at 50 yards with this gun I'd be tickled pink. If you watched the video you could see I was having problems getting the mag to seat. Glad to see I'm not the only one. In the future I'll keep the bolt locked back for mag insertion. I'm going for round two tomorrow with the bullets seated a little deeper (should cure my not going into battery problem). I've also upped the powder charge slightly. I think I'm pretty close to the max powder charge (about 15.8 gr) without starting to compress.
I'm also gonna take a closer look at that pmag and see about trimming it a bit as you suggest. Quick edit: I went ahead and filed those ribs on the pmags a little. Let's keep our fingers crossed for tomorrow.

[rongaudier]

Back from range today, two problems fixed, one new one. First off, trimming the rails in the mags took care of the feeding issue and setting the bullet back a little further took care of the not going into battery thing. New problem..in my infinite wisdom I decided to run the cartridges though my factory crimp die and put a nice solid crimp on them. Guess what? It was ripping a ring of lead off the bullet as it exited that cause the following bullet to NOT GO INTO BATTERY and jam hard into the throat. Here's a pic of the last cartridge to jam and sure enough, there was this ring of lead around the case mouth causing enough interference to prevent going into battery and jamming it up solid enough that it took a wack with a tool on the charging handle to get it out.
130131

[Greg Skinner]

Keep us posted on your testing. The optimum seating depth varies depending on the ogive of the bullet. Usually for cast it is good to have the boolit seated just short of the lands, which can be determined a couple of different ways. If you determine that beforehand then you shouldn't have a problem with the bullet jamming and not going into battery.
I think my load for IMR4227 and my 150 gr cast is 16.6 grains, seated at 2.015", so with a little heavier boolit you may be close to max. However, my experience with 4227 is that it compresses fine, so I wouldn't worry about that if you are not getting any other pressure signs. I'm using 18.8 grains with a 110 grain jacketed and it is definitely a compressed load.
I've also had some fun results working up subsonic loads with the 150 gr. cast and Green Dot powder. They don't cycle the action, but they are pretty quiet and fun to shoot, single shot mode. At 50 yds they shoot to the same poi as the supers and at 20 yds with the same sight setting they drill one hole in the target dead center - great for close range pest control.

[Greg Skinner]

I guess I was writing my post while you posted. I use the LFC die, also, but my seating depth allows me to crimp at the bottom edge of a lube groove, so I don't have a problem with a lead ring. I can see where you may have to do some further adjustment.

[popper]

Too much crimp. Adjust to remove flare only. Neck thickness will change the amount of 'crimp'. I adjust so I 'feel' the flare go away then stop. Set to just close on a thick neck, pull the handle till you feel a good resistance then stop. My Lee press is ~ 0.050 off the stop, allows for thin necks.

[rongaudier]

Too much crimp. Adjust to remove flare only. Neck thickness will change the amount of 'crimp'. I adjust so I 'feel' the flare go away then stop. Set to just close on a thick neck, pull the handle till you feel a good resistance then stop. My Lee press is ~ 0.050 off the stop, allows for thin necks.
Just got back with my first mass produced (on the loadmaster) loads. Like you described, crimp just enough to remove flare. Now works perfect no malfunctions.

[rnt300]

The one i am interested in is the Lyman #311359. 115 grain with a nice stream lined profile. http://www.midwayusa.com/product/661909/lyman-2-cavity-bullet-mold-311359-30-carbine-762x39mm-309-312-diameter-115-grain-pointed-tip-gas-check

[Jeff Maney]

Just got back with my first mass produced (on the loadmaster) loads. Like you described, crimp just enough to remove flare. Now works perfect no malfunctions.
Yes, use only a very light crimp just to remove the flare. Also, flare the mouth ONLY enough to get the boolit started squarely. This really saves over working the brass.

Jeff

[Maximumbob54]

Found this thread and wanted to join in since I just ordered a new upper that's going to need feeding. I have a MP 311-410 and would love to find a good load with it. Optimally I'd like to mimic a decent 7.62x39 loading. They weigh in at 132gr when powder coated. Given the option I would like to use Win 296 as it's available locally.

I should add that I did see Hodgdon's listing for a Sierra 135gr HPBT and was thinking of working up a load from that as it lists 17.3 to 18.4 but it would be nice if anyone knew a confirmed loading.

[ShooterAZ]

I had some trouble with the Lee 170 FP in mine, magazine length issue, they would nose dive in the GI mags I had. Seemed to work better in the magpul mags, but still had issues, they were just too darned short.

Same here, it was accurate as all get out...but wouldn't feed worth a hoot.

[dudel]

I use the LEE TL309-230-5R and they work well (I find them a bit tedious to cast; but a good way to clean out 20# pot!); but I really prefer the Hornady 150 gr FMJ-BT. The Hornady's shoot great for me. Midway has them on sale.

[PewProfessional89]

I have been experimenting with IMR 7383 to work in my AR-15 chambered in 300 blackout with a pistol length gas system. It doesn't run the gun on it's own... not even at 106% case fill with a lee 230 gr. boolit. So I did some reading and found that people were "duplexing" this powder and wc860 in 45-70 govt. with some good results. So I called Jeff Bartlett and placed an order for a couple jugs of BR-5 (Unique equivalent) and IMR 7383. I started off by trying a case full of 7383, which didn't work, then I added 1 gr of BR-5 to the bottom of the case and reduced the 7383 by 1 gr. and put it on top of the pistol powder before seating the 230 gr boolit. I kept the case fill at around 103%. After some trial and error and shooting several rounds with my butthole puckered really tight, I managed to get 3.2 gr. BR-5 below 9.3 gr of IMR 7383 to run my gun and push the pill out at an average velocity of 1248 fps. with a standard deviation of around 12 fps. More experimenting is needed, but I made a rather rough looking video of my trials and results. The video includes chronograph data.

https://www.youtube.com/watch?v=EdxzWY3_o0g&t=845s

[248dm]

I have reloaded 300 Black extensively. Couple points: For a 16" barrel, I needed the H2 buffer to cycle subs (220 gr) reliably. My SBR prefers pistol length gas system.

I do shoot subs suppressed, 220 gr at 1,025 fps mostly with Reloder 7 and sometimes with Littlegun. For supers Littlegun seems to work the best for 110 to 125 gr bullets loaded to 2,300 or so fps.

The subs are PC coated, the supers are jacketed.