View Full Version : Cheap 300 BLK subs for plinking
I recently built a 300BLK SBR with 9" BCM barrel and a GA 30SD can. It's got a carbine buffer with yellow Sprinco spring. (This has since been changed out to an A5 RE with an A5H1 buffer. It also now had an SLR AGB) Since then, I've been on a mission to develop the cheapest subs that this gun can reliably cycle. Keep in mind, this gun will be used 100% suppressed with 100% of my reloads. I don't plan on shooting supers at all. If I do, they'll be my hand loads.
Anyway, I wanted to use 150gn FMJs as those appear to be the cheapest projos that I could find. I had read a lot of good things about Accurate 1680 for subs so that's what I started off with. Long story short, I couldn't get them reliably cycle &/or stay subsonic. Some rounds would & some wouldn't. They appeared to be very temp sensitive. They changed every few degrees, so I ultimately ditched that powder.
At that point I moved on to trying Accurate 5744. Bingo! First test loads cycled & stayed subsonic. Bummer, because it's significantly more expensive powder. I spent a little time chrono'ing them till I got to my target velocity of around 1050fps. This happened to be the sweet spot. I haven't tested these for groups, as that isn't my intent, but the accuracy was acceptable to me for the offhand load testing I was doing at the time.
These loads came out to $0.34 per round. Some components were purchased at full price from Wideners & Midway, and included hazmat fees. Purchasing locally and/or on sale will obviously lower the price per round.
These were 10.3gn 5744, 150FMJ Hornadys loaded to cannelure and CCI 41 primers.
http://uploads.tapatalk-cdn.com/20160519/d606333069ef03ba83233c76baf1e900.jpg
I also tested some 147gn FMJs but I had to bump up the charge to reach 1050fps. These are $0.32 loads & ultimately the ones I'll likely settle on, at least for now.
http://uploads.tapatalk-cdn.com/20160519/4e7755c77bcc22e77a6df0673222cf74.jpg
The downside to these loads is that they're filthy dirty & I get tons of unburnt powder. I've tried different primers (Tula, CCI400, Rem 7.5, CCI41), different seating depths, crimping, etc and can't correct it. I'm guessing it's the low charge weight & there's not much I can do with it. I'd like to try a faster burning powder like H110 yet but if there's any other suggestions, I'm all ears. I just don't want a bunch of powders laying around that don't work for my intended load.
Most people aren't running subs this light so it's hard to find decent info.
Both loads listed above cycle perfectly in my rifle so I'm ok if I'm stuck with them, but I'd really like to improve the burning if I can.
147 - 150 gr is really light for subs. Doesn't mean it's impossible, just a challenge. Nearly all of my loads are supers but I've tried most of the recommended powders plus a few that aren't and loaded some heavier bullets to subsonic levels.
Alliant's 300MP seems to be pretty versatile as does 4227. Trail Boss was a dismal failure (wouldn't cycle) but you might be able to make it work with the lighter bullets/suppressed combination.
I use 4227, no complaints.
I use 4227, no complaints.
4227 was on my list to try also. What bullet weight are you using with it?
Auto-X Fil
05-19-16, 06:31
These are cheaper, and way more forgiving to load for. Any hit much harder. I don't get any lead buildup in my cans with the coated bullets. They don't work in PMAGs when loaded long. They also stabilize easily for a 240gr, if your twist is a little slow.
http://missouribullet.com/details.php?prodId=204&category=20&secondary=36&keywords=
We load tons of them over various pistol powders. 2400 is my favorite. Lilgun also works well. My brother loves a fast rifle powder, AA1680, which is very popular for subs. It might be the best, but it's expensive and not stocked by my usual shops. 5744 might be better for the 240gr.
H110 is great for supers but kinda touchy. I don't like it for BLK. N110 is more forgiving, but 2400 is the best of those three magnum handgun powders, in 300 BLK.
My go to plinking round is 203gr palmetto projectiles over 10.2gr of 1680
I'm getting the 147's for about $0.15 each. I plan on sticking with the those & have no interest in using the typical heavies for subs. My SBR is "tuned" to them & that's all I plan to run for now.
I realize that these are very light as far as subs go but I enjoyed the challenge of getting them to work. I would; however, like to tweak them a bit more.
I'd be interested if anyone has any suggestions as to any powders or techniques that may improve the incomplete burn issue for the lighter projectiles specified.
The lightest I have gone is the 180 range for bullets. Currently using 220s.
I think that you may end up chasing your tail a bit using the lighter bullets.
That said, N110 would likely end up being the cleanest, but is also gonna be pricey, so probably out for the budget round you are after.
I think that you may end up chasing your tail a bit using the lighter bullets.
Actually, I have a loads that work very well now. They cycle reliably & are consistent. (see pics) I'm content with them as they are but if improvements can be made, I'm all for it.
Ryno, are you amember over at 300blktalk.com? I know there are a lot of guys over there working on lighter sub loads.
Ryno, are you amember over at 300blktalk.com? I know there are a lot of guys over there working on lighter sub loads.
No but I have done a fair amount of browsing over there. I did see some guys going down to the 150 range. Some were using 1680, as I recall, and having success with it. When I tried it, it burned cleanly but I just couldn't get them consistent enough.
I think some of those guys modified their gas port too & also have some funky buffer setups. I'm trying to not make any mods to mine beyond buffer & spring.
It's been a fun project so far.
http://uploads.tapatalk-cdn.com/20160519/125e5ebe795e9f943166cc611dd1a811.jpg
http://uploads.tapatalk-cdn.com/20160519/88b6723a6504a7d61242eefacbed3602.jpg
sasquatchoslav
06-01-16, 13:47
Great info thanks. Regarding your cost per round if you wouldn't mind sharing and the breakdowns on used/new brass etc please? I'm really torn I love the 300 sub/suppressed for hog control. Not that 5.56 can't and doesn't work, but the noise factor of the aforementioned is so sweet. Not had a chance to shoot one, but have heard it and me likey. I have access to kabillions of used .223/5.56 brass so that can really get the cost down after cutting them down and if I can do that feasibly then 300 is maybe all I'd use up to and including plinking. *Seems* on cursory google searches I could get Hornaday lead, my own brass and the rest down to under .30/round and that is what I pay for my PMC 55g .223 new.
Thanks for any knowledge you can lend on my 300 'stick my toe in the pool' experiment.
Glad you mentioned it. I just realized that I fat-fingered my earlier calculations.
I've bought both processed 300 brass & processed some of my own 5.56 brass. The cost per round calculations are based on using OFB 5.56 brass. Below are screenshots of my calcs.
(Note: some prices are sale prices)
http://uploads.tapatalk-cdn.com/20160601/dbcf385da3d0decc63d63c0a341fbb01.jpg
http://uploads.tapatalk-cdn.com/20160601/afe1a8954ca8027833aa38bacaa42bba.jpg
I should add that these are just plinking loads & I'm not sure they'd be good for hunting. I was going to test some 150 HPBT projos to see how they expand at this velocity but I haven't got around to it yet.
sasquatchoslav
06-01-16, 17:43
Awesome thanks. Any idea what kind of velocity you are getting? The one guy I know who has put down a couple of hogs with subs was right at 1050-1060 he tested it so I'm wondering how far below 1100 you can get and still punch hard. Thanks again.
Awesome thanks. Any idea what kind of velocity you are getting? The one guy I know who has put down a couple of hogs with subs was right at 1050-1060 he tested it so I'm wondering how far below 1100 you can get and still punch hard. Thanks again.
The chrono data for both loads is in the OP.
sasquatchoslav
06-01-16, 17:56
Face palm. My brain is soggy from hotel room sleeping this week. Thanks again great info.
;) No problem, glad you liked it.
I'm having a blast testing these oddball loads. I've got some other ones I'm anxious to try when I get some time.
A little bit of an update...
I decided to change direction with my 9" BCM Blackout SBR. With my original configuration, I was severely limiting my ammo choices that I could shoot. That was fine initially as I had no desire to run anything else. As my BLK load experimenting has progressed, I wanted more room to grow.
I decided to install an SLR AGB for fine tuning the gas. In addition, I swapped out the carbine RE for an A5. I really didn't think it would reliably cycle such light subs but to my surprise, it did. In fact, it did it better than my old setup (yellow Sprinco reduced power spring w/ carbine buffer). I would've bet it'd never work but it did. (The A5 is amazing!). With the SLR opened all the way, I could cycle 147FMJ subs with an A5H2 buffer. It did feel a bit sluggish, but it worked. Ultimately, I've settled on using an A5H1.
I can now essentially run any factory supers/subs or my reloads of any weight or velocity without any significant changes. At best, a couple of clicks on the SLR.
I also decided to give some other powders a try to lower my cost per round. The 147gn with 5744, that I currently use, works great but I'd like trying new things.
I decided to try some 1680 again. Initially, I had issues with inconsistent velocities & problems cycling it with the 147s. I've since shortened the OAL to 2.04" & tried Rem 7.5 primers. This seems to have a more consistent burn which also appears to help with more consistent velocities. They now cycle well too.
Another powder I tried was CFE BLK. The powder's burn rate is right there with 5744 & 1680 so I figured it'd be doable with 147gn subs. This powder has more first round pop than the others I've tried. Not sure what causes that... Anyway, the shorter 2.04 OAL & Rem 7.5 primers seem to tone it down. It's still there but not as bad as when I used CCI41 & a longer OAL. The 7.5 primers seem to work better with ball powder at low charges.
I still need to tweak both these loads a bit more. There's still some incomplete burn, which I doubt I'll ever eliminate but being ball powder, it's not quite as dirty as the 5744 stick. The CFE leaves more of a gritty residue than the 1680 but neither are as dirty as the 5744. I think this is just the nature of the beast when running suppressed subs. To the ear, however, the 5744 sounds quieter than the ball powders.
I'd also like to tighten up the velocities on the 1680 & CFE BLK loads. They both cycle perfectly in my setup (detailed above).
These loads are as follows:
11.8gn 1680, 147gn FMJ, Rem 7.5 primers, 2.04" OAL
11.6" CFE BLK, 147gn FMJ, Rem 7.5 primers, 2.04" OAL
Both loads are around roughly 950-1050fps and cost me $0.23/round. I no longer factor in brass as the cases I'm using have been reloaded numerous times.
hotrodder636
02-19-17, 11:08
Nice project. I enjoy following these.
What are you using to crimp after you seat the bullet?
I use Lee FC dies. I haven't been crimping any yet but I may try that.
If ya like cheap but effective and accurate look at King Shooters Supply's 215gr purple coated bullets. Those things are powder thrifty, smooth to run, and obscenely quiet. All ya gotta know to run them is they run faster than jacketed so lower the powder charges and flare open the case mouth with a flare die or a Dillon 30 Carbine powder funnel so you don't shave off the coating when seating the bullet.
If ya like cheap but effective and accurate look at King Shooters Supply's 215gr purple coated bullets. Those things are powder thrifty, smooth to run, and obscenely quiet. All ya gotta know to run them is they run faster than jacketed so lower the powder charges and flare open the case mouth with a flare die or a Dillon 30 Carbine powder funnel so you don't shave off the coating when seating the bullet.
Do you have a starting recipe for those?
Do you have a starting recipe for those?Out of a 10.5" barrel I load them at 7.2 grains of W296 at 2.095 OAL.
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