300 Blackout Magazines

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alamo5000
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Re: 300 Blackout Magazines

Post by alamo5000 »

Does anyone have a list of bullets that they have tried or that require the use of 300BLK mags or altering a standard PMag?

I am considering buying a stack of 300BLK Magpul mags to have just in case, but before I fork over the money I am wondering how widespread the problem is.
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John A.
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Re: 300 Blackout Magazines

Post by John A. »

I primarily use Colts mags.

I also have a few Lancer magazines that have worked flawlessly.

Though I prefer metal magazines over plastic. That's why Colts are my first choice.
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Baltimoreed11754
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Re: 300 Blackout Magazines

Post by Baltimoreed11754 »

I’ve altered 4 old 5.56 pmags and had a couple that occasionally allow the bolt to slide over the bullet and not strip it out of the mag. Seems that the base of the case is tilted down slightly. I’m loading 110 gr RN bullets which feed fine from another pmag. I’ve ordered some anti tilt followers. Do I need to file on my ribs some more?
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BobinNC
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Re: 300 Blackout Magazines

Post by BobinNC »

Time to reawaken this topic.

Given the availability of good, affordable dedicated 300 Blackout magazines I see no clear rational for buying 5.56 magazines for any 300 BO application. And it doesn't matter if you shoot nothing but supers, dedicated 300 BO magazines are the way to go. The risk of confusion with a 300 BO round entering a 5.56 chamber is too great to be complacent. IMHO

Currently I'm running 2 Lancer 300 BO 10 Rounders
18 Lancer 300 BO 20 Rounders
and 5 Magpul 300 Blackout 30 rounders

All work and feed great. The only failure to feed I had with any of my reloads was with my one FDE Lancer 5.56mm Mag with 110 grain supers. Coincidence maybe??

Later this fall Magpul will start releasing dedicated 300 BO 20 round magazines.

As far as D&H 300 BO metal mags, the price on these is still way too high for what you get. They should sell for $3 to $4 cheaper than Lancers or Magpul 300's, but instead they are the same price or cost more on some sites. Metal mag tech and stampings are 60 years old technology, and metal Okay Ind. 5.56 mags can routinely be found in the sub $12 range, as can 5.56 D&H mags. The price they want for the D&H 300 BO mags is ridiculous.

IMHO and YMMV
ReadyAimDuck
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Re: 300 Blackout Magazines

Post by ReadyAimDuck »

What is it about the dedicated blackout mags that prevents them from being confused with 5.56?
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BobinNC
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Re: 300 Blackout Magazines

Post by BobinNC »

ReadyAimDuck wrote: Mon Oct 04, 2021 6:59 am What is it about the dedicated blackout mags that prevents them from being confused with 5.56?
Aside from them being marked prominently with 300 Blackout (Magpul, D&H, Lnacer) written on the side, Lancer Mags also use a different color floor plate.
ReadyAimDuck
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Re: 300 Blackout Magazines

Post by ReadyAimDuck »

I guess I just don’t see that helping keep 300blk rounds out of a 5.56 chamber enough to buy all new mags. Sure if you’re starting from scratch then why not? But if it comes down to looking at a marking on the side of the magazine, I can also just look at the rounds in the magazine and see clearly which ones they are. Which is exactly what I do, besides storing them completely separately. For my purposes, the marking on the side doesn’t add anything helpful. But to each their own. Maybe that really helps yourself and others.

If it did something mechanical to prevent the mixup I would be all for it. But the mark doesn’t help me any more then the visible rounds that are in the magazine.
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BobinNC
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Re: 300 Blackout Magazines

Post by BobinNC »

ReadyAimDuck wrote: Mon Oct 04, 2021 9:32 am I guess I just don’t see that helping keep 300blk rounds out of a 5.56 chamber enough to buy all new mags. Sure if you’re starting from scratch then why not? But if it comes down to looking at a marking on the side of the magazine, I can also just look at the rounds in the magazine and see clearly which ones they are. Which is exactly what I do, besides storing them completely separately. For my purposes, the marking on the side doesn’t add anything helpful. But to each their own. Maybe that really helps yourself and others.

If it did something mechanical to prevent the mixup I would be all for it. But the mark doesn’t help me any more then the visible rounds that are in the magazine.

The whole point of this particular thread is about which magazines to BUY, 5.56mm or dedicated 300 Blackout magazines for your 300 Blackout. Nobody is saying for you to buy all new magazines if you don't want to.

If your happy with the performance of your 5.56 mags in your 300 Blackout rifle, and don't want to spend more money on magazine that fits your 300 blackout rounds, for all bullets weights, then rock on with what you have....
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Re: 300 Blackout Magazines

Post by BJK »

Short lesson, pardon me. Ignore if you wish.

The mag' pushes the stack of rounds up so that they can be picked up by the bolt. That needs to happen in a nanosecond. A 5.56 cartridge can weigh significantly less than a 300BLK round so the springs need to be stouter for 300BLK. If one thinks that one doesn't need 300BLK mags, then excellent. Let us know how you make out in the long term.

So far no matter what I put in my Lancer 300BLK mags has worked fine. So far up to 225 grain bulleted loads. I admit that I have not used 5.56 mags so the test data is lacking. But with a new 300BLK firearm I required more mags so I have no problem with specific mags for the new firearm. If 300BLK had been around when I bought my 5.56 mags they'd all be 300BLK mags. That would take care of the new spec'. But using the old spec' for the new cartridge might be a problem.
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dellet
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Re: 300 Blackout Magazines

Post by dellet »

BJK wrote: Wed Oct 06, 2021 11:26 pm Short lesson, pardon me. Ignore if you wish.

The mag' pushes the stack of rounds up so that they can be picked up by the bolt. That needs to happen in a nanosecond. A 5.56 cartridge can weigh significantly less than a 300BLK round so the springs need to be stouter for 300BLK. If one thinks that one doesn't need 300BLK mags, then excellent. Let us know how you make out in the long term.

So far no matter what I put in my Lancer 300BLK mags has worked fine. So far up to 225 grain bulleted loads. I admit that I have not used 5.56 mags so the test data is lacking. But with a new 300BLK firearm I required more mags so I have no problem with specific mags for the new firearm. If 300BLK had been around when I bought my 5.56 mags they'd all be 300BLK mags. That would take care of the new spec'. But using the old spec' for the new cartridge might be a problem.
Probably approaching 30,000 rounds fired.

Never seen a 300 Blackout magazine except in online ads.

Never modified a magazine to make one work.

Have shot bullets from 85-265 grains super sonic. 110-265 grains subsonic AR’s

Velocity from from 750-3000 fps.

Shot boat tails and flat base bullets loaded backwards to prove it’s how you load, not what you load them in.

This cartridge has been around in some form or another for probably 25 years or more before someone decided a dedicated magazine was needed.

I’ll be sure to check back in when I can match the long term of shooting this cartridge like some of the rest of you guys for my lesson.
300 Blackout, not just for sub-sonics.
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