Ive seen some people bringing their m-4 knockoffs to the range with 20 round mags. Im wondering why, as 30-round mags hold 10 more rounds. Do the 20s feed better or something? I can see a 20-round if you go prone and stuff but half of these guns have vertical foregrips that are just as long
1 Box of ammo = 1 20rd. Mag
Other than bench or prone I see no reason to run 20s
For hunting I like the 20’s better. They hold more than enough yet don’t get in the way.
And the GI 20 rounders with alloy followers are very reliable. (I know so is Magpul, hey I even have some of those in 20 rounders…)
I wrote the following over a year ago in reference to 20 round mags:
I had heard some chatter on other boards about the usefulness of the Magpul’s new PMAG 20’s.
I shoot a local run and gun rifle match. It just so happens that two of match directors are a Police Captain and a Police Sergeant that work for the same agency as me.
In a recent match, Capt. Xxxxxx built a barrier that was the same height as the Ford Crown Victoria’s that we use at work.
On this stage you had to shoot under the barrier (same height as a Ford Crown Vic’s bumper). As you can see in the pic below I was using a USGI 30 round magazine.
Due to the lenght of the 30 round magazine, I was forced to cant my carbine in order to see the target.
A PMAG 20 would have been very useful in this situation:
Consider that the earth is not flat and conditions are not always perfect.
There may be times where you can see and engage the target from a standard prone position, but if you were to go into a lower position like a roll over prone, you may not be able to see or engage the target due to a curb, small hill, etc.
I have had situations come up at this match where I was shooting from the prone, using the magazine as a monopod, I could see the target through my optic, but my rounds were impacting a small dirt berm 20’ - 30" in front of me. Just by getting into a slightly higher prone position (getting the magazine just a couple inches off the deck) I was able to engage the target.
20 rounders have been popular in law enforcement circles for years.
Some agencies require 20 round magazines per policy.
On my agency per policy, it’s required that an Officer carry his Patrol Carbine / SWAT carbine in “Condition 3” (on an empty chamber press the trigger, after the trigger has released leave the fire selector on safe, and insert a fully loaded magazine), this is also known as “Cruizer ready”. Same condition most agencies carry their shotguns in. The Department doesn’t equip our Patrol units with carbine racks, because all carbines are personally owned. Thus per policy the rifle / carbine has to be carried in a case (soft or hard case in the trunk)
Because we have to carry in our carbines in “Condition 3” (and due to the fact that many Officers have optics on their carbines), many guys find that their carbines won’t fit in their rifle cases with a 30 round magazine inserted in the rifle, but the rifle / carbine will fit in the case with a 20 round mag. Part of our qualification course calls for the rifle / carbine to be in the case, in Condition 3, and the Officer has to retreive his rifle from his case, make ready and engage targets.
For some applications 20 rounders actually offer an advantage over 30 rounds.
Consider that a majority of law enforcement officers that carry an AR15, carry an AR15 with a carbine length gas system. Thus the AR15 has a carbine length handguard or carbine length rail system attached to it.
It’s not uncommon for a Patrol Officer to deploy his rifle / carbine and end up on a perimeter for several hours.
When sitting on a perimeter for several hours, most of the time you will try to find cover and use that cover to rest your AR on while still aimed in the direction of the threat. Sometimes that cover is a wall, a vehicle, the SWAT APC, etc.
With the shorter carbine handguard (ie. Colt M4 handguards / LaRue 7.0) and a curved 30 round magazine, this limits the pieces of cover an Officer can rest his gun on. Unless he wants to rest the barrel on the cover.
Here is a pic that can illistrate the situtuation better than I can explain it. In the pic below, the only reason the handguard of the rifle is on the barricade is because it’s a mid-length barrel with a LaRue 9.0 rail.
If I were running a carbine with a 7.0, my barrel would be on the barricade due to the curved 30 round magazine. With a 20 round magazine, I would be able to rest the forearm of a carbine on this barricade:
While I have never had to use a turned over 55 gallon drum in the field to rest my rifle on, this is just an example of how a 20 rounder has some utility for some of us.
Just food for thought
Take care and be safe,
S/F,
Jeff
And for those of us in Cali, post-ban magazines are limited to 10 round capacity. Since there isn’t a huge supply of 10-rd bodied mags, it is pretty popular (and legal) to purchase 20 or 30-round magazine “rebuild kits”, and rivet/epoxy a follower block to limit the capacity to 10. In this case, it would be a waste to choose a larger/heavier 30-rd mag instead of a 20-rd, since it would only be holding 10 anyways.
20-rounders are also quite handy when storing a “go to” carbine in a safe or safety cabinet. If need be, you can stow a spare short mag in a coat or back pocket if in a rush.
We use 20 rounders for two of our patrol rifles…as the rifles won’t fit in the gun vaults with a 30 round magazine.
they also fit better in some patrol car racks
I like a 20 in the well for jumping in and out of a vehicle. Less dangling magazine to catch a seat belt, door, or other part of the platform.
Another great use is a different type of ammunition, typically specialty. I have known Forward Observers that would carry one 20 rounder of straight tracer to direct aircraft towards a target.
Finally, I like a 20 rounder to drop in the back pocket of my jeans when I am walking around low profile. Nobody even imagines that you have a reload on your person.
+1
A 30 can also interfere with the steering wheel.
There are plenty of good examples of why the 20 can be an advantage. I like them for prone, bench, field shooting.
Dont forget the reduced drag.
It does save a surprisingly noticable ammount of weight.My latest build was done with my wife and young son in mind(that’s my story and i’m sticking to it).I tried to keep it as light as possible and going to 20 rnd mags made as much difference as anything.
It will also scare the fudds slightly less when hunting…maybe.
Heard this at a recent training (paraphrased): (apologies to Mr Taylor if he did not really say this)
“Chuck Taylor said: The AR system was designed around 20R magazines so 20R magazines are the best to use with the system.”
I like them for less weight, prone shooting behind berms, etc.
Frankly, I don’t much bother with them anymore. Shooting prone on a clean manicured range without obstruction I use the 30 rounder as a monopod. Shooting any other time where I may be under low cover or whatnot I use non-traditional firing positions, which is a training issue not a gear issue. I’m not bailing out of a vehicle with a carbine, and if I am I am probably good and screwed already.
The 20s I have at this point either came with the gun, are leftovers from the ban days when I’d take what I could get, or came for free with something else. I have them in an ammo can with a variety of ammo and a sandbag that I use for beginning the zero process off of a bench but even then it’s really just so that I’m not taking good 30 rounders out of rotation.
+2
A 20 round mag made a significant difference when trying to keep the weapon handy and quick to deploy while riding in an M1114 up-armored HMMWV or M1A2 SEP tank.
With the 20 rounder in place, it fit just right in the space between my left leg and the transmission in the HMMWV and was easy to take in and out.
It is surprising how much difference that little bit of clearance can make when space is at a premium.
Also, what others have said regarding keeping one full of tracers for when you would like to mark something. It is easy and quick to figure out which one has the tracers when it is different from all of the other mags, even in the dark under stress.
HTH
The original USGI 20 round mags are about the best mags ever for the AR. People like to credit the excellence to the alloy follower. But I think the mag design itself is superb, and the follwer is just the only difference the apes can see.
I dont plan to throw the ar on my passenger seat and get ambushed on the way to the grocery store…I see the prone shooting idea though, and for range time all i’d do is target shoot. Im looking at a model that comes with a 20, and you can get a second 20 reduced price. After that, its all 30s
is that supposed to read leave the fire selector on “fire”?
I agree with this. Before PMAGs (and improved followers) came along, the 20 round Colt mags were the only safe bet for a durable and reliable mag in the AR system. I still have a couple in the mix and use them quite often.
Also, as stated before, if mounted in a verticle vehicle mount, the 20’s are easier going on the elbows…less obtrusive. Deploy out with the 20, 30 rounders for spares.