Ask Josh: What Is The Deal With AICS and SR-25 Mags?

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Have a question for Josh? Email it to [email protected]

Today’s Ask Josh is about the wide world of rifle magazines. Reader and range addict Matt K. asks . . .

What is the deal with all the different magazine sizes out there? I’ve been trying to find a Rem 700 that works with AR-10 magazines, but they only have AICS ones out there. Then, with the AR-10, there are different sizes as well, like SR-25. There should be one type of .308 size magazine to make it easier for everyone out there.

There’s a pretty straightforward answer here: the market tends to decide what’s best. Just like M-LOK vs KeyMod, the stronger commercial option usually (but not always) takes the prize. KeyMod is relatively unpopular now, and MLOK has become a virtual standard.

The same principal applies to magazines.

The AICS mags are the most common in bolt action rifles because their design works with more of them. They are narrow and single-stack.

AICS mags were originally designed for the first commercially successful chassis, the Accuracy International Chassis System (AICS). This type of magazine eventually grew in popularity to the point that a large majority of modern bolt action rifles feed from it. All of my modern 700-class rifles feed from detachable AICS style magazines.

An older AICS patter ten round mag from Alpha Mags

The AR-10 magazine is also a bit of a misnomer, as there are several classes of them, with the most widely supported being the SR-25 type. These magazine types were typically the product of one company to start, and then were adapted as other designs flourished.

The most popular eventually became the standard, and the SR-25 magazines are now dominant. This is a double-stack mag that is rarely found in bolt actions, although guns like the Q Fix were designed to use them.

The Mag Well Is What Matters

The design separation between these magazines is based on their exterior dimensions, not necessarily the caliber. The AICS pattern short action magazine is essentially now the standard magazine for most bolt action rifles. This base .308 Win design can feed most .308-based rounds, such as 6.5 Creedmoor, .338 Federal, 22-250, 7mm-08, .243 Win, 450 Bushmaster, and so on.

There are, of course, some small tweaks that may need to be made for specialized rounds, such as in the case with 450 Bushmaster, which has an easy time from metal box magazines, but a harder time with the all-polymer versions due to case geometry. Basically, if you can make it fit in a .308 AICS magazine, it should feed in a .308 size action.

The AICS short action magazine well also accepts special .22LR and rimfire adapted mags, which share the same footprint and can thus use full-size accessories and chassis. The increasingly popular NRL22 sport is seeing constant innovation here.

It should also be noted that specialized magazines exist to allow the .308-size action to feed .223/5.56 rounds, including 300 Blackout. These are fewer available, but I hope to see that change soon.

The Q FIX is a very compact bolt action 6.5 or 308. It is only 6.4 lbs and is a great alternative to a semiauto for compact hunting- and brass retention.

A big plus of these bolt action mags is that they have the ability to allow for handloaded ammo with longer-than-normal overall length and can easily feed wildcat cartridges and neck-sized brass.

The SR-25 Blues

The AR-10 magazine family isn’t as forgiving as the bolt action AICS and its variants. This is largely due to the fact that a semi-automatic rifle is far more particular than a bolt gun and requires many moving parts to work together to get the gun to cycle reliably.

The end result is a bit more restrictive in terms of the overall length of the cartridge and the type of sizing it has. These semi-auto magazines will, depending on brand, have a hard time feeding with neck-sized brass and won’t feed longer-than-standard length cartridges.

That means if you have almost any semi-auto magazine for the AR-10, the ammo needs to be at (or very close to) factory spec and it shouldn’t vary much.

Why Not One Magazine Type?

I get asked this from time to time as to why someone doesn’t make an AR-10 that takes single stack magazines. I’m sure there is someone out there who does, but there isn’t really much of a need for that at this time. There may come a day when some company sees a need in a “high capacity” ban state, but I don’t see it as applicable right now.

The 6.5 CM owes a great deal of its success to the fact that the groundwork was already in place thanks to 308 Win. The 6.5 CM works in all 308 mags and actions.

The same goes for bolt actions with AICS mags. Since the AICS is meant as a bolt action mag, it functions great as what it is. The SR-25 mag is wonderful in the Q Fix, but that rifle was designed to use it and isn’t an adaptation of any other design out there. It’s that adaptation where things tend to fall apart, and for other bolt actions to use the SR-25 mag they would need what amounts to a different bolt setup entirely.

Even in the ever-flexible AR-15 platform there are wild magazine variations. The 450 BM functions in an AR as well as the AICS mag and it uses a special mag in the AR, where it uses the standard version in the AICS. The 300 BLK round functions from a 5.56 magazine, but there are improved versions out there that feed it better. Likewise the family of rounds like the 224 Valkyrie need a 6.8 SPC mag to feed correctly.

450 Bushmaster feeds from 308 AICS mags… and modified 5.56 AR mags depending on the rifle platform.

In the end, the only way you will get to have one shared magazine to rule them all is to set yourself up to do it that way. But if you did that, you’d really be limiting yourself to gun types.

I like what the AICS offers in a bolt action and I like what the SR-25 type offers for a semi-auto and dedicated bolt actions like the Fix. It’s best to play to your strengths and in this case, it’s better to leave well enough alone and accept that there just won’t be just one mag type out there.

Have a question for Josh? Email it to [email protected]


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  1. Kind of like the whole “glock mag” crap. Just because it’s popular doesn’t make it the best fit for a gun.

  2. This is a very long winded way of saying:

    Different guns have different magazines from a variety of manufacturers with different production process. It all seems quite clear to me. Or do we need 10/22 rifle magazines to work with S&W revolvers?

    AR10’s don’t quite have universal standards like AR15’s do.

  3. I can’t imagine why anyone (except maybe a ban-happy politician) would wonder / want a single-stack mag for a semiauto rifle.

    The fact that many bolt guns have standardized on a single-stack a century and a quarter after Mauser started using double-stacks, OTOH?

        • I used to own a Lee-Enfield and I’m a bit of a WWI history buff. By far the best infantry rifle prior to the Garand. They were, however, fed with 8 round stripper clips rather than mag swaps. Still, the (for 16 months) all volunteer BEF soldiers were expected to hit a 12″ target at 300 yards 15 times per minute. Imagine crossing no man’s land with those soldiers on the other side. In Gallipoli where no man’s land was as short as 25 yards, the ANZACs developed a method using their pinky fingers on the triggers to get off 70+ rounds per minute.

        • Gov,
          I agree with your assessment, and your admiration for the ANZACs. I always thought the Lee chargers held five, though.

        • I’m thinking in WWI it was one 8 round and maybe two 5 rounds in WWII. Been a while though and you’d probably have to dig a bit to find out.

    • And Lee-Enfield as well.

      My No4 .223 conversion magazine is a modified No4 magazine with a different insert. It can hold 12 in less than half the space of my Ruger Scout’s 10 round single stack magazine (in 5.56).

      • Correct. The Lee-Metford was the predicessor to the Lee-Enfield. I was thinking Enfield myself but I double checked before posting. The Lee-Enfield was adopted in 1895.

        The only reason I don’t own a Ruger Scout in .308 is the single stack magazine. Perhaps the standard Hawkeye stock is too narrow to adopt a detachable double stack magazine, but there’s no excuse for not adapting it for a the scout.

        • dark eagle customs will supply ten round double stack mags for the savage scout… some 10rd savage mags may work as well.

      • Southern Cross,
        I’ve never seen that conversion, but it sounds cool. I had an AICS mag once and found it a huge, clums disappointment compared to the same-capacity factory Mauser mag.

        • They were made by local gunsmiths. Not cheap but very pleasant to shoot. And cheap to run ammunition wise. My main one is in its 3rd barrel. Externally it looks like a No4 with a target back sight.

          The main bits to convert are to solder a collar to the bolt head and a modified extractor for the .223 cartridge. The firing pin is turned down and a plug in the bolt face for the smaller firing pin. A plunger ejector in the bolt face, but some use a blade ejector.

          And an insert in the magazine for the .223 cartridge but modified Mini-14 magazines can be used. Not perfect but if the bolt is operated hard and fast like you’re in a rapid fire match, it works well enough.

          I did an article on the conversion many years ago which the surplus rifle forum site hosted.

        • That sounds very cool. I love practical modifications like that, and hate it when everyone bitches at someone for optimizing his own property for his own use – like one of ten million lowest-bidder government clunkers was some sort of irreplaceable art treasure.

        • No historical artifacts were ruined for my conversations. The first had a completely rusted out barrel and stock timber that was dented and gouged. The barrel was replaced during the conversion and the stock restored. The second was built by the former owner from a pile of parts.

  4. I thought the .260 Remington was based on the .308 and the 6.5 Creedmoor on the .30TC…

  5. Mossberg makes/made a 308 bolt action that took Mossberg mags, M14/M1A mags and DPMS pattern AR10 type mags. I had one and sold it because I wanted a Savage Scout style rifle more. Never got to shoot the Mossberg but it did mount all three type mags fine. I’m still on board with the Enfield detachable 303 box mags.

  6. I have 2 No. 4 MKII rifles that came out of Canada some years back. Both were converted by Canadian gun smiths to fire 7.62 NATO as target rifles. Both have hammer forged Enfield 7.62 barrels. Magazines were replaced with a skid plate type affair since they were only used for single load competition. Both are actually quite accurate.

  7. If the Q-Fix caught your eye, but you’re not made of money:
    Mossberg makes the MVP 7.62 (and 6.5 CM) in various configs from ~16″ barrel ‘scout’ to 18-20″ varieties. They run well sub-$1k in most configurations. The 7.62 (and 6.5 CM) version(s) takes ‘AR-10′(LR308/SR-25)and M1A/M14 mags. Most of the models have ‘ar-10 standard’ 5/8″ x 24 muzzle threads too.
    The ‘Long Range’ model w/ ‘Scout’ furniture, PMAG LR/SR mag, and ‘AR-Stoner’ AR-10 Linear Compensator from MidwayUSA make for a nice, fairly affordable hunting / long-range rifle. (couldn’t recall the scope off the top of my head; the scope was a gift)

    (I swear Ruger made a variant of the American that also took AR-10/SR-25 mags for sub-$2k but I cannot find any record of it on their site.)


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