What are the best AR mags for 300 blackout

[Calvino]

Iam having feeding issues with 556 mags in my 300 blkout I tried several different makes of mags, magpul, Cproducts, hexmag and they all have the same issue , the bolt is not picking the round out of the mag going in to battery all the time.
Are magpul 300 blackout specific mags different than 556 magpul mags ?
Maybe if I try a different BCG!
ANY FEEDBACK IS WELCOME

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[arrowshooter]

I only use Lancer mags for 300 BLK which are specific for the round.

https://lancer-systems.com/product/l5awm-300blk-10-magazine/

A big issue when using 5.56 mags for 300 BLK is the side rib near the front of the mag which was designed for the thinner 5.56 bullet/neck. The rib will force the 300 BLK round too far inward which can cause the feeding issues like you are having. See below 5.56 on left, 300 BLK on right, arrow at this rib.

 

[Twodogs]

I have been using Lanser mags out of my 8" 300 BLK with no problems.
Try shooting one round at a time if the bolt doesn't lock back its your ammo not the mag.

 

[arrowshooter]

Try shooting one round at a time if the bolt doesn't lock back its your ammo not the mag.

Sorry, I missed the part about not picking up the next round. I agree with Twodogs in that you could need different ammo if lock back is not 100%.

I ended up going up two sizes on the gas port of my 16" which solved any under gassed situations with any ammo.

 

[NobullSKS]

Lancer hybrid…..
Polymer body steel lips…

 

[Eustace28]

I have both magpul and the lancer 300 blk specific mags. Both work but I like the lancer's better. Midway had them on sale the other day for $12 bucks a mag which is a great price.

 

[Eustace28]

Still on sale at $12.99 a mag.

Lancer Systems L5 AWM Advanced Warfighter Mag AR-15 300 Blackout

The Lancer Systems L5 AWM Advanced Warfighter 300BLK magazine has been specifically engineered for use with heavy subsonic .300 Blackout ammunition,...

www.midwayusa.com

 

[Calvino]

Still on sale at $12.99 a mag.

Lancer Systems L5 AWM Advanced Warfighter Mag AR-15 300 Blackout

The Lancer Systems L5 AWM Advanced Warfighter 300BLK magazine has been specifically engineered for use with heavy subsonic .300 Blackout ammunition,...

www.midwayusa.com

Ty, going to get a few of these, for suppressed shooting

 

[edzz]

I agree on the Lancer maggazines for 300 BLK, they are the only I use for 300 BLK . For safety sake they look and feel different from the Magpul magazines I use for 5.56, as already mentioned they function well.

On to the issue at hand, sounds like the rifle is under gassed and or under lubed. My first .300 BLK had the same issues you describe, lubed the crap out of it and ran 40 - 50 rounds thru it wiped it down and it's run well ever since. So... what I'm saying is before increasing gas try lubing it first.

 

[arrowshooter]

Ditto the lube.

I have also gutted a buffer and the lighter weight (about 1.0 oz) worked too.

 

[saxon]

i use lancer and p mags 300 specific, will never use hex ever, after i bought some for 300 AAC and they failed to feed after the first two rounds,
messaged hex and was told that for 300 aac you only load 8 rounds and if you don't like it take it back to where you bought it and ask for a refund as it was not their problem....

 

[Calvino]

I agree on the Lancer maggazines for 300 BLK, they are the only I use for 300 BLK . For safety sake they look and feel different from the Magpul magazines I use for 5.56, as already mentioned they function well.

On to the issue at hand, sounds like the rifle is under gassed and or under lubed. My first .300 BLK had the same issues you describe, lubed the crap out of it and ran 40 - 50 rounds thru it wiped it down and it's run well ever since. So... what I'm saying is before increasing gas try lubing it first.

This that you descibe could be true, it is a new gun that is not broke in thanks

 

[ferret427]

Can you clarify a bit on the malfunction? Is the bolt stripping the round out, but not closing completely, partially stripping, but hanging up, or ejecting the previous round but closing on an empty chamber, not grabbing a fresh round at all? Also, how frequent? Every time? 1 in 10? Do you get lockback of the bolt on an empty mag? Does an empty mag drop free when hitting the release?

If you have pics, might be helpful. In my blackout, I have always used standard AR mags (metal, polymer, polymer with metal feed lips) without issue. There might be something else going on...

Is this a factory build, or did you build it yourself? If self, what parts (BCG, buffer tube assembly, barrel, etc).

 

[Loc]

Iam having feeding issues with 556 mags in my 300 blkout I tried several different makes of mags, magpul, Cproducts, hexmag and they all have the same issue , the bolt is not picking the round out of the mag going in to battery all the time.
Are magpul 300 blackout specific mags different than 556 magpul mags ?
Maybe if I try a different BCG!
ANY FEEDBACK IS WELCOME

I had the same problem, went through all the same machinations that you are currently doing, and discovered...it was the ammo. Just a bad batch of Freedom Munitions; switched to Winchester whitebox (of all things) and the feed issues disappeared. In defense of FM, they do make a good product and are standup folks; they refunded me the price of the remaining ammo. I have yet to try anything other than Winchester whitebox 150gr.

Can you provide more info on your weapon build?

 

[Calvino]

Can you clarify a bit on the malfunction? Is the bolt stripping the round out, but not closing completely, partially stripping, but hanging up, or ejecting the previous round but closing on an empty chamber, not grabbing a fresh round at all? Also, how frequent? Every time? 1 in 10? Do you get lockback of the bolt on an empty mag? Does an empty mag drop free when hitting the release?

If you have pics, might be helpful. In my blackout, I have always used standard AR mags (metal, polymer, polymer with metal feed lips) without issue. There might be something else going on...

Is this a factory build, or did you build it yourself? If self, what parts (BCG, buffer tube assembly, barrel, etc).

I built this rifle 16 " barrel aero precision upper and lower and lpk , ballistic advantage barrel ,the only issue really is that it will not strip a round out of the mag 1 out of 3 shots
Bolt holds open on last shot , feeds well into battery, extracts empty casings well, mag stays locked in place, basically when it shoots every thing performs well except pulling a fresh cartridge from magazine

 

[Loc]

I built this rifle 16 " barrel aero precision upper and lower and lpk , ballistic advantage barrel ,the only issue really is that it will not strip a round out of the mag 1 out of 3 shots
Bolt holds open on last shot , feeds well into battery, extracts empty casings well, mag stays locked in place, basically when it shoots every thing performs well except pulling a fresh cartridge from magazine

Yep, same exact build as me with exact same problem. What ammo are you using?

 

[Kruel J]

Good info here. I've been using PMags for years but I might give the .300AAC-specific Lancer mags a try.

 

[Calvino]

Good info here. I've been using PMags for years but I might give the .300AAC-specific Lancer mags a try.

AAC 220 OTM AND AAC 150 GRAIN

 

[leatherjunkie]

Interesting. I use the cheap 5 round 556 mags from midwayusa with my 300 blackout. never an issue feeding the ar.
might be because its only 5 round mag, not sure.

 

[Calvino]

Yep, same exact build as me with exact same problem. What ammo are you using?

So far 125 and 150 grain ran very nice I started having the issue with the 220 grain
All ammo is AAC so far