AR 300BLK won’t chamber the first round from full clip

Moderators: gds, bakerjw, renegade

Shushh
Member
Posts: 45
Joined: Fri Nov 23, 2018 10:42 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by Shushh » Fri Jul 03, 2020 3:52 am

What 20X11 said...

You'll never get factory 30rd 5.56 Pmags to work properly with 30 rounds of 300blk. There's ribs that with 5.56 rounds ride on the side of the neck, when loaded with 300blk, in particular heavy 300blk those ribs press in on the bullet making them load pigeon toed. This makes the stack taller and nose high. So it'll be too full with 30, and will sometimes be nose high enough that the bolt over-rides the rim.

There's some answers
1) Load lower capacity, though not a true solution it helps.
2) Different mags, some mags don't have that ridge or it's smaller. Mag-pul and others make 300blk specific magazines as well.
3) A file, file/sand down those ribs, I've done this on 40 round Pmags, time consuming but a true solution.

For max capacity if that's important to you I've found a few solutions that work for me so far.
1) Again 40 round P-mags and a file.
2) Strike Industries EMP+5, A reasonably priced 5 round extension. Filed 40s plus 5 makes for a reliable 45 if the base plate is left out.
3) Surefire 60 round quad stacks. So far mine work OK with 300blk, they're kinda delicate and finicky, but handled right so far so good. Really, just don't drop them loaded and they're fine. The 100 round versions, much more finicky.

BulletFlight for Android
Rockingj
Member
Posts: 12
Joined: Mon Jun 15, 2020 1:43 pm
Location: Tucson, AZ.
Contact:

Re: AR 300BLK won’t chamber the first round from full clip

Post by Rockingj » Sat Jul 04, 2020 4:15 pm

Gyrkin wrote:
Wed Jul 01, 2020 11:05 am
Get some of these mags https://www.midwayusa.com/product/1022346310
I ordered 3 of those magazines the other day and a 10 round aluminum. I need to be prepared for when the Commiefornia gun nazis spill over to Arizona! You know it will happen sometime in the not too distant future!
John Brock
Rocking J Metalworks

golfindia
Silent But Deadly
Posts: 1368
Joined: Thu Jun 20, 2013 1:16 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by golfindia » Sun Jul 05, 2020 9:18 am

Too many shells in your clip .....

Rockingj
Member
Posts: 12
Joined: Mon Jun 15, 2020 1:43 pm
Location: Tucson, AZ.
Contact:

Re: AR 300BLK won’t chamber the first round from full clip

Post by Rockingj » Sun Jul 05, 2020 1:16 pm

golfindia wrote:
Sun Jul 05, 2020 9:18 am
Too many shells in your clip .....
30 rounds in a 30 round magazine is too many?
I did get a response from Palmetto around a month after sending the request for a return authorization. They wanted to see pictures of the original packaging and the individual packaging, these magazines were bought over 2 month as ago now. Who keeps the shipping boxes and plastic bags the magazines came in for 2 months, I gave them my order number so they should be able to look up my original purchase. We’ll see if it takes them another month to respond to me again.
John Brock
Rocking J Metalworks

20X11
Silent But Deadly
Posts: 1515
Joined: Fri Aug 03, 2012 11:43 pm
Location: Aurora, CO

Re: AR 300BLK won’t chamber the first round from full clip

Post by 20X11 » Sun Jul 05, 2020 2:13 pm

Rockingj wrote:
Sun Jul 05, 2020 1:16 pm
golfindia wrote:
Sun Jul 05, 2020 9:18 am
Too many shells in your clip .....
30 rounds in a 30 round magazine is too many?
...
Yes, 30 rounds of 300BLK in a Magpul 30 rnd magazine designed for the 5.56 round IS TOO MANY.

User avatar
dellet
Silent But Deadly
Posts: 6436
Joined: Fri Nov 30, 2012 1:25 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by dellet » Sun Jul 05, 2020 2:18 pm

Rockingj wrote:
Sun Jul 05, 2020 1:16 pm
golfindia wrote:
Sun Jul 05, 2020 9:18 am
Too many shells in your clip .....
30 rounds in a 30 round magazine is too many?
I did get a response from Palmetto around a month after sending the request for a return authorization. They wanted to see pictures of the original packaging and the individual packaging, these magazines were bought over 2 month as ago now. Who keeps the shipping boxes and plastic bags the magazines came in for 2 months, I gave them my order number so they should be able to look up my original purchase. We’ll see if it takes them another month to respond to me again.
I’m guessing the reason they want pics and proof might have something to do with you saying they are Gen 1 Pmags. Pretty sure those have not been made for 5+ years. If that’s true, I can understand their thinking.

Regardless there is a date code stamp on the body of the magazine, a photo of that might be helpful to them.

Back in the day I used the Gen 1’s without issue loaded full with 220 SMK’s. I know there were a lot of problems with some billet lowers that were not actual military dimensions. Having problems with an 80% would not surprise me. As I said before care was needed in how the last round was loaded.

I have not used anything but Lancer for a long time, so can’t comment too much for current Magpul quality.
300 Blackout, not just for sub-sonics.

User avatar
dellet
Silent But Deadly
Posts: 6436
Joined: Fri Nov 30, 2012 1:25 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by dellet » Sun Jul 05, 2020 2:23 pm

20X11 wrote:
Sun Jul 05, 2020 2:13 pm
Rockingj wrote:
Sun Jul 05, 2020 1:16 pm
golfindia wrote:
Sun Jul 05, 2020 9:18 am
Too many shells in your clip .....
30 rounds in a 30 round magazine is too many?
...
Yes, 30 rounds of 300BLK in a Magpul 30 rnd magazine designed for the 5.56 round IS TOO MANY.
I don’t know if Wilson Combat still has the warning on their website. They used to explicitly state that any magazine other than their proprietary ones could not be loaded more than 28 rounds for 300 Blackout.

It’s also why there very distinct COAl lengths for most bullets, to keep the .240” diameter of the bullet tip on the rib. That being about the neck diameter of a loaded .223 round.
300 Blackout, not just for sub-sonics.

golfindia
Silent But Deadly
Posts: 1368
Joined: Thu Jun 20, 2013 1:16 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by golfindia » Sun Jul 05, 2020 4:40 pm

I was also making fun of the use of the word "clip" in this thread title.....

But yeah, unless you load taking the 0.25" mag rib width into account you'll never fit 30 in regular mags. In the old days, AAC put this tip in their upper instruction manual. Seems like everyone now sees 2.26" in their loading book and they go with it......

Rockingj
Member
Posts: 12
Joined: Mon Jun 15, 2020 1:43 pm
Location: Tucson, AZ.
Contact:

Re: AR 300BLK won’t chamber the first round from full clip

Post by Rockingj » Mon Jul 06, 2020 12:29 am

I never claimed these Magazines were Gen.1, they are Gen. 2. I have done a lot more research on the inter web and now I know better, all I was asking palmetto to do was exchange these three magazines for some 300 BLK specific Magizines and I would pay the difference.

Yes I did Screww up calling the magazine a clip.... that goes back about 50+ yrs and old habits are hard to break! I don’t always catch my mistakes, or I could alsways blame it on auto correct changing it...LOL
John Brock
Rocking J Metalworks

User avatar
dellet
Silent But Deadly
Posts: 6436
Joined: Fri Nov 30, 2012 1:25 pm

Re: AR 300BLK won’t chamber the first round from full clip

Post by dellet » Mon Jul 06, 2020 4:34 am

Rockingj wrote:
Mon Jul 06, 2020 12:29 am
I never claimed these Magazines were Gen.1, they are Gen. 2. I have done a lot more research on the inter web and now I know better, all I was asking palmetto to do was exchange these three magazines for some 300 BLK specific Magizines and I would pay the difference.

Yes I did Screww up calling the magazine a clip.... that goes back about 50+ yrs and old habits are hard to break! I don’t always catch my mistakes, or I could alsways blame it on auto correct changing it...LOL
Rockingj wrote:
Sun Jun 21, 2020 3:50 am
I am new to this forum and new to AR 15’s. Not new to shooting. I recently completed my first AR 15 build from a Daytona Tactical 80% complete kit chambered in 300 BLK. The problem I’m having is with Magpul 1st gen 5.56 30 round magizines. When trying to chamber the first round the bolt seems to be dragging the top cartridge when retracting the charging handle, and the first round doesn’t chamber fully. But after I clear that round, everything works as it should. This happens with factory ammunition 125 grain bullets and 150 grain bullets from a different manufacture. Is this typical for the 300 Black out? Or do I need different magazines?
It’s not typical as long as whoever puts the ammo together is aware of the issue. Not all .308 bullets are compatible with all magazines or the cartridge in general.

I had less problems with generation 2 than 1. Less problems with steel GI magazines than anything Magpul. And less problems than GI with Lancer. I have never used a magazine specific to 300 Blackout nor have I ever had to modify one to work.

You can modify the ones you have to make them just like Magpul did by changing their mold in the time it took to read this post. All they did was change the height of the rib.
300 Blackout, not just for sub-sonics.

Post Reply