300 Black Out Magazines

johnkn · Apr 26, 2020

EDIT Looking for info on 300BO mags

SWO Daddy · Apr 26, 2020

I've never had any issues with USGI mags and 300BO.

That said, Big Dog Outfitters has 300BO mags, both magpul and Lancer. I'd call first if it's a long drive though.

Squaregrouper · Apr 26, 2020

The D&H standard AR magazines work fine with my .300AAC
(I use only aluminum mags for .300AAC and only Magpul for .223/5.56)

johnkn · Apr 26, 2020

Thanks guys, I went to cancel the post but saw there were already responses. I'll try original NOS Colt mags and see what happens with this new 300 HAM'R. thanks!

John from MD · Apr 26, 2020

Magpul and Lancer both have 300 BO mags. I like Lancer better after testing them one against the other. Lancer has metal feed lips and it feeds with less drag. Best prices are gunmagwarehouse.com

Melnic · Apr 26, 2020

Isn't there a mod for magpul to make them more friendly to 300blk or was that a certain gen of magpul mags?

sleepingdino · Apr 26, 2020

I use Lancer mags for 300 BLK esp for subsonic rounds. If it is just for range applications, then use whatever you want.

Fox123 · Apr 26, 2020

Melnic said:
Isn't there a mod for magpul to make them more friendly to 300blk or was that a certain gen of magpul mags?

Early gen has nubs down inside that usually ran on the shoulder of a 556, depending on the bullet profile of the 300bo that nub may or may not rub against the ogive and not allow the cartridge to sit properly.

John from MD · Apr 26, 2020

Melnic said:
Isn't there a mod for magpul to make them more friendly to 300blk or was that a certain gen of magpul mags?

You can file down the front guide rails of .5.56 mags to .125. It just takes some elbow grease but is hardly worth it now that they have .300 BO mags at the same price.

This needs to be done for certain profile bullets. The Lee 160gn cast for instance. I don't think it is needed if you shoot something like Horn 150 FMJ-BT or lesser weight bullets with the same profile.

teratos · Apr 26, 2020

I haven't ever had problems with Magpul running .300 BLK.....other than that time I put it in my 5.56.

John from MD · Apr 26, 2020

teratos said:
I haven't ever had problems with Magpul running .300 BLK.....other than that time I put it in my 5.56.

What kind of bullet do you use?

teratos · Apr 26, 2020

John from MD said:
What kind of bullet do you use?

I use the Gallant 220 grain coated and have also run 208 grain Hornady A-Max. Don't recall OAL offhand.

johnkn · Apr 26, 2020

What about NOS 30-round Colt mags. I’ll be running mostly 130 Hot Bonded SP ammo in this HAM’R. Am I overthinking this? Not opposed at all to picking up some dedicated mags for this build though. Thanks

outrider58 · Apr 26, 2020

Fox123 said:
Early gen has nubs down inside that usually ran on the shoulder of a 556, depending on the bullet profile of the 300bo that nub may or may not rub against the ogive and not allow the cartridge to sit properly.

Wasn't that more of a problem with gen1-2? I have gen 3s and have never experienced a problem.

outrider58 · Apr 26, 2020

teratos said:
I use the Gallant 220 grain coated and have also run 208 grain Hornady A-Max. Don't recall OAL offhand.

Do you size them before loading? I have to, even though they don't recommend it. All the Leatherhead/Gallant PC s I've loaded needed resizing. They shoot great, BTW. My go to plinking subs. :thumbsup:

I load mine(Gallant PC) with 10.5gr of A 1680 at 2.060 COAL

John from MD · Apr 26, 2020

johnkn said:
What about NOS 30-round Colt mags. I’ll be running mostly 130 Hot Bonded SP ammo in this HAM’R. Am I overthinking this? Not opposed at all to picking up some dedicated mags for this build though. Thanks

For 130gn bullets, you shouldn't have a problem. I only had problems with the 150 grain cast bullets that were PC'd . The reason was that the bullet nose section would grow to .305-.306. from PCing. This caused problems with the nose guides on the 5.56 magazines.

John from MD · Apr 26, 2020

teratos said:
I use the Gallant 220 grain coated and have also run 208 grain Hornady A-Max. Don't recall OAL offhand.

I know nothing about bullets made for subs. Are they jacketed?

teratos · Apr 26, 2020

outrider58 said:
Do you size them before loading? I have to, even though they don't recommend it. All the Leatherhead/Gallant PC s I've loaded needed resizing. They shoot great, BTW. My go to plinking subs.

I load mine(Gallant PC) with 10.5gr of A 1680 at 2.060 COAL

I haven’t had to resize. The cycle fine. Cheap as hell to shoot once you have brass.

John from MD said:
I know nothing about bullets made for subs. Are they jacketed?

Yeah, made for subs. Gallant bullets are coated with something, they don’t foul the barrel. The Hornsby A-MAX is coated with a polymer tip.

outrider58 · Apr 26, 2020

John from MD said:
I know nothing about bullets made for subs. Are they jacketed?

The Gallants are poly coated and the A-max are polymer tipped jacketed. I.use the 110gr A-max on deer(supersonic). My preference for jacketed subs is the Hornady ELD-X or ELD-M in 220g and 208g, respectively. I also play around with the Lehigh Defense 194g Max Expansion sub. Things open up like a mechanical broadhead.

teratos · Apr 26, 2020

outrider58 said:
The Gallants are poly coated and the A-max are polymer tipped jacketed. I.use the 110gr A-max on deer(supersonic). My preference for jacketed subs is the Hornady ELD-X or ELD-M in 220g and 208g, respectively. I also play around with the Lehigh Defense 194g Max Expansion sub. Things open up like a mechanical broadhead.

The Lehigh sounds awesome. I assume you’ve taken deer with them?

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