Longest internal length AR mags

[Stag556]

What would be the magazine with the longest allowable case length for the AR15 platform?

Bought a couple ASC mags that advertise 2.316” of internal length but all I could get in them was 2.270” with a 77gr Berger.

Any insight would be helpful. Thanks.

 

[TonyTheTiger]

Did you get the stainless ASC's? They all take 2.31 for me.

 

[Sniper266]

If you need longer mags you might aswell mill out the face of the magazine and then the front of the upper receiver into the barrel extension to allow the tips of bullets to be longer than “mag length”.

Then you can load 80gr eldm’s to “mag length”

I feel like anything short of this you're just chasing 1 or 2 thousands of an inch for a 77gr bullet.

 

[Stag556]

Did you get the stainless ASC's? They all take 2.31 for me.

Yes, I did get the stainless. Myself and another friend went together on the order and we both got the same results with different mags from the order.

It’s not something that’s make or break, just figured I’d try to find the longest available. The details of the ASC mags made them attractive but my results aren’t as expected.

 

[lennyo3034]

Can you take a picture of the top of the mag facing down?

About half my ASC mags are capable of handling 2.310". The other half have a little tab from an improper weld that takes up mag space.

 

[XLR308]

I only have one 10 round ASC I use for hunting with a 68spc and it allows 2.3" load length I wasn't aware that they had any other type for that size of cartridge.
I assume you are using them for the Valkyrie ?

 

[Stag556]

Can you take a picture of the top of the mag facing down?

About half my ASC mags are capable of handling 2.310". The other half have a little tab from an improper weld that takes up mag space.

Sure. That sounds identical to what I have here.

 

[lennyo3034]

Yep. That's your problem. Unfortunately a number of the mags they put out are like this.

 

[Stag556]

Yep. That's your problem. Unfortunately a number of the mags they put out are like this.

Grabbed them from gun mag warehouse online. I’ll reach out but do you know whether they admit and rectify the issue if you own one of these? Seems the whole order (4 mags) are like this.

 

[Conaso]

Backcavitybullets sells .223 and 6.8 mags that have cutouts, professionally done, 2.36". One shooter on 6.8 forum also cutout his magwell and modified his feed ramps to get 2.425" COAL.

 

[TonyTheTiger]

One shooter on 6.8 forum also cutout his magwell and modified his feed ramps to get 2.425" COAL.

I've been shooting a 223 like this for a while now. Loading 75 ELD's at 2.41" near 2900fps really puts it in different league than lower BC 77's at regular mag length.

 

[Stag556]

I've been shooting a 223 like this for a while now. Loading 75 ELD's at 2.41" near 2900fps really puts it in different league than lower BC 77's at regular mag length.

I’ll have to do some research but what’s involved in creating a setup like this?

 

[TonyTheTiger]

Just cutting out the front of the mag and filing out a notch in the magwell for more bullet tip clearance then a matching notch in the barrel extension. It's like half an hours work, triple that if you blend it all and polish it to look professional.

 

[Raffica762]

Just cutting out the front of the mag and filing out a notch in the magwell for more bullet tip clearance then a matching notch in the barrel extension. It's like half an hours work, triple that if you blend it all and polish it to look professional.

Love to see pictures

 

[TonyTheTiger]

 

[Raffica762]

Thank you Tony ..hmm that totally changes things on the plus side

 

[Blazin]

Damn, now that's dedication!

 

[XLR308]

Another option for a 2.3" COAL magazine are PRI, they are a bit spendy but really are the Cadillac of magazines for cartridges of 68spc size and it's variants.
I only have two one 10 round bought for hunting and the original gen 1 non waffle design, both have been flawless in function.

 

[Raffica762]

Another option for a 2.3" COAL magazine are PRI, they are a bit spendy but really are the Cadillac of magazines for cartridges of 68spc size and it's variants.
I only have two one 10 round bought for hunting and the original gen 1 non waffle design, both have been flawless in function.

Thank you..I’ll try them

 

[Longshot85]

View attachment 6954205View attachment 6954206

Would you mind providing some load data for this ? Obviously start low and work up and be safe.

I've thought about this myself and I am currently working up a load with XBR 8208 and 77 TMK ...... 23.5 and 23.8 were a little too hot (even though SD was 5 and ED was 14) and I'm trying 23.2 next.

If I can do these mods and run the 75's THAT fast.......now I'M INTERESTED!!

 

[Longshot85]

Also, if you could post pics of the modded mags that would be fantastic

 

[TonyTheTiger]

@Longshot85 My load is 24.3gr 8208XBR with CCI450's in prepped LC brass at 2.41" OAL. Obviously the long OAL is a crucial part of getting that much powder in the case without pressure issues, I also have a heavier buffer and the gas turned down to minimum on a rifle length gas system. I suspect if I changed any one of those parameters things could get sporty on me. Brass looks great and I haven't had any primer pocket failures over several firings and the primers only occasionally are slightly flatter on the edges, but all that said go slow if you want to try this yourself. Oh and I wouldn't bother cutting any mags that aren't stainless. Aluminum or polymer won't do.

 

[Longshot85]

Thanks for posting this, now I need to find a stainless mag lol

What brand do you use?

 

[TonyTheTiger]

ASC mags, and some AR Stoner branded mags made by ASC.

 

[ChadL]

Just cutting out the front of the mag and filing out a notch in the magwell for more bullet tip clearance then a matching notch in the barrel extension. It's like half an hours work, triple that if you blend it all and polish it to look professional.

Very interesting! I have a 6x6.8 that I've cut the front of the mag out. I can run 2.350" long and get reliable feeding. I like what you've done. 2.41" would let me try the 105 grain Berger VLD bullets again.

Thanks for the pics......I'm now inspired