300-221 in an AR help me with mags

[mak91]

The two 20 round PMags I have have major feeding issues. The rounds don't sit level and I get bolt over failure to feed almost every round. If I had not removed the front ribs on them I would have sent them back there is something out of wack with them. The thirty rounders with the front rib removed work fine. The mags that seem to work the best for me are DH Teflon coated G.I. 30 rounders, the only mods I made to them was to take the sharp edge off the front of the mag that would catch on the case mouth.

[rsilvers]

AR mags feed ammo for which the 0.250 ogive of the bullet contacts the rib on the magazine. Ammo makers design their ammo with this in mind.

[mavrick]

Originally Posted by mak91

The two 20 round PMags I have have major feeding issues. The rounds don't sit level and I get bolt over failure to feed almost every round. If I had not removed the front ribs on them I would have sent them back there is something out of wack with them. The thirty rounders with the front rib removed work fine. The mags that seem to work the best for me are DH Teflon coated G.I. 30 rounders, the only mods I made to them was to take the sharp edge off the front of the mag that would catch on the case mouth.

Any one have pics of this mod. The OAL does fit in the ar mag but the 220s might need to be set back just a little more to help with the feeding and stacking issues.

Dustin

[mavrick]

Oh and thanks guys

[N310toN170]

Previously from http://300aacblackout.com/ ;now I don't see it listed on their page anymore:

Existing AR magazines have a rib which normally contacts the 5.56mm case-neck. With 300 BLK ammo, the contact is on the bullet. Because the bullet is a larger diameter, the rib will push the cartridges out of alignment, and can lead to binding potentially resulting in Failures to Feed. For this reason, it is important to load ammunition so that the contact point with the magazine rib is on the bullet ogive in an area of about 0.250 inch diameter. Here are some suggested OAL for popular bullets:

• Hornady 110 V-Max, OAL: 2.000
• Barnes 110 TSX, 2.015 OAL
• Sierra 155 Palma, 2.150 OAL
• Sierra 220, 2.089 OAL
• Lapua B416 200 grain, 1.960 OAL
• Hornady 150 FMJ-BT 3037, 2.065 OAL
• Nosler Ballistic Tip 125 grain, OAL: 2.085
• Remington AccuTip 125 grain, OAL: 2.085
• Hornady 130 SP #3020, OAL: 2.010
• Sierra H2120 125 ProHunter, OAL: 1.950
• Speer TNT 125 1986, OAL: 2.010

[rsilvers]

Originally Posted by N310toN170

Previously from http://300aacblackout.com/ ;now I don't see it listed on their page anymore:

Because I took it down. It is not so cut and tried that there is one length everyone should use.

[1911man]

Here's what's working for me............

Lancer 20rd, you can load full with short OAL and 15 or so with long loaded ammo

Pmag 20rd with the guts from a 30rd Pmag, works perfect for short loaded and perfect for long loaded or 7.62x40 with the front rib removed. You loose 2-3 rounds capacity but this eliminates the bolt over malfunction completely.

[mavrick]

When you say guts you mean just the follower right? or the spring to?

Dustin

[pud-knocker]

Originally Posted by 1911man

Here's what's working for me............

Lancer 20rd, you can load full with short OAL and 15 or so with long loaded ammo

Pmag 20rd with the guts from a 30rd Pmag, works perfect for short loaded and perfect for long loaded or 7.62x40 with the front rib removed. You loose 2-3 rounds capacity but this eliminates the bolt over malfunction completely.

even with .223 I had some experiences with the bolt over malfunction you described. the followers tilt way more than the 30. I found if I reshaped the top part of the spring to put more pressure on the rear of the follower it helped.

I use the 30 round follower in my 20 round mags with my 300 whisper and 7.62x40 also. no problems with tilt now.

just wish there was a easier way to de-rib the mags.

[pud-knocker]

Originally Posted by mak91

The two 20 round PMags I have have major feeding issues. The rounds don't sit level and I get bolt over failure to feed almost every round. If I had not removed the front ribs on them I would have sent them back there is something out of wack with them. The thirty rounders with the front rib removed work fine. The mags that seem to work the best for me are DH Teflon coated G.I. 30 rounders, the only mods I made to them was to take the sharp edge off the front of the mag that would catch on the case mouth.

To use my 20 round de-ribbed PMAGs for prone or from the bench, I put 30 round PMAG followers in them to stop the tilting. Lost a couple rounds capacity but they worked 100%.