Long Action feeding Short Cartridges (AICS)

[RedJay5]

My intent is to use my Terminus Zeus Long Action (QC) with various barrels in order to shoot both short action and long action cartridges (.308, 6.5CM, and .300PRC). This would enable me to save money by using only 1x action and 1x scope, and having the ability to freely change the chassis/barrel combination between a heavy range configuration (MPA chassis + steel .308 barrel) and a lightweight hunting configuration (MDT26 chassis + carbon fiber .300PRC barrel). I know that we have precedent in the military for LA systems running short cartridges (M24), and ideally it would be similar to our Mk 22/MRAD running .300Norma or .308 just by making use of the proper magazines to ensure reliable feeding… I just need help understanding how to best do this on my personal gun making use of AICS compatible folding chassis systems (I prefer these over stocks).

I’m looking for feedback from everyone on:
(1) descriptive feedback from any shooters who have tried the “ Accurate Mag AICS .308 LA Magazine “ with short action rounds (ie whether I will encounter reliable feeding without issue).

(2) any recommendations for which AICS magazines or mag kits I should acquire in order to reliably feed short action cartridges like .308 into a Long Action (Zues) within a modern chassis system (MDT HNT26 + MPA ESR) if the aforementioned Accurate Mags are not ideal.

Amplifying Information:
**I have seen the Barbour Creek videos with James running Hawkins Precision 30-06 magazines to reliably feed short-action 6.5CM into a long action Terminus Zues… but the employees at both Barbour and Hawkins have communicated on the phone that this is only compatible via a stock with bottom metal using the m5 inlet, and my intent is to use chassis rather than stocks (specifically, MPA ESR and MDT HUNT26). MDT said that I would need AICS compatible 3.850 CIP magazines.

**I have read through the forums for months and encountered conflicting information and mixed word on whether or not the Accurate Mag listed above are a reliable, malfunction-free solution… “Islas82” seemingly communicated Initial Success with these accurate mags beginning 29NOV2024, but then Likely Failure due to feeding issues on 02FEB2025.. supposedly even “ rlsmith1 “ had used these accurate mags for short actions into a Long Action as well… if anyone can provide additional updates or new information, I would appreciate it. I would like to hear if anyone has experience with running .308 thru the LA Accurate Mags into the LA Terminus Zues.

*** I saw the thread on magazines being made with a spacer linked by Tyler Kemp, but it seemed unresolved to me and currently unviable for my use case (.308 capability in my Zues LA which has a lightweight .300PRC MDT26 configuration and heavy MPA .308 set up). Please advise if there is another currently viable, well known magazine option for short calibers in long actions… specific to AICS compatibility.

**** Some additional consulted resources so that others know I’ve done extensive research before posting this thread: Thread 1 / Thread 2

Couldn’t find a way to DM/PM some of those individuals, so hope that posting this casts a larger net for potential sources of information with applicable insight/experience. Thank you for your time.

 

[PappyM3]

Similarly, I built a Zermatt TL3 long action with the intent to do caliber swaps (6.5CM, 300 PRC etc)..

It is in a KRG Whiskey 3 chassis.

Yes, you will need CIP length magazines for the 300 PRC.

Which is problematic for the short actions. Accurate Mag does make a CIP length 5 round 308 magazine. I have two that I’ve tried with 6.5 CM and they have been fairly reliable, but sometimes nose dive. One major flaw is that they appear to use non-CIP length followers so the follower can easily tilt/shift.

I have also tried Magpul 30-06 mags that I built up the front with polymer epoxy and sanded flat so that the mags are 3.850” long. However, these all nose-dive for the 3rd-5th shots. I did test this prior to doing the mod and saw the same issue, I just hoped fitting it to size would help.

I may be able to adjust my mag latch to solve some of the issues. But the sloppy follower in the accurate mags has me thinking of some solutions with 3D printed spacers with their own ramps to help feeding, but haven’t made them yet.

Reliability is only one problem. The second is that you’ll only have 5 shot magazines, or 7 if you can get a long action extension to work properly. There are rare 10 round 300 wm magazines that you could adjust the feed lips for, but they are not CIP length.

It’s frustrating because the mags could easily be made reliable but there is no market support for running short action cartridges in long actions, especially with CIP length. Most people just build two rifles.

For me, I’m going to keep going with it because the 6.5CM is just a caliber to train with and the rifle isn’t intended to be a competition gun. But the path you’re looking to go for is not easy or simple.

 

[7mmShooter]

The only legitimately reliable ways I’ve seen to do it with AICS mags are magazine well “sleeves” like AI/Cadex do, or complete magwell/lower swaps like the Eliseo RTM. It really is a shame but someone will flesh it all out I’m sure

 

[Maurygold]

I’d really like to see someone make a good solution for long action/ cip mags to shoot 308 bolt face stuff.

I haven’t tried these but seem like the best solution out: https://accurate-mag.com/shop/magazines/longactionaics/308-win-long-action-sssf-magazine/

 

[7mmShooter]

Same, and also 223 in my case

 

[PappyM3]

I’d really like to see someone make a good solution for long action/ cip mags to shoot 308 bolt face stuff.

I haven’t tried these but seem like the best solution out: https://accurate-mag.com/shop/magazines/longactionaics/308-win-long-action-sssf-magazine/

I have a couple of those. They work pretty well, but not as good as I expect a magazine to function. Accurate mag cut corners to reuse a non-CIP follower in the CIP magazine and it shifts back and forth and tilts easily.

 

[bene-201]

I’m working through the same question for a LA 6.5 PRC. The polymer MDT 3 round mags did not work great. The spring did not seem to have enough force to feed the last round. Going to try Hawkins at the next range trip

 

[RedJay5]

The only legitimately reliable ways I’ve seen to do it with AICS mags are magazine well “sleeves” like AI/Cadex do, or complete magwell/lower swaps like the Eliseo RTM. It really is a shame but someone will flesh it all out I’m sure

@7mmShooter Interesting, I haven’t heard of the sleeves… any chance you have a link to this so that I could dive deeper into what you’re describing?

I have a couple of those. They work pretty well, but not as good as I expect a magazine to function. Accurate mag cut corners to reuse a non-CIP follower in the CIP magazine and it shifts back and forth and tilts easily.

@PappyM3 , thanks for taking the time to write up that first response in this thread. Unless I’m misunderstanding, my initial expectation from your response is that I will likely be satisfied with those Accurate-Mag LA 308 magazines… you stated they were “fairly reliable, but sometimes nose-dive”… is this like an every other magazine type occurrence? I’m curious if you have any more specifics on how reliable you found them vs how often they nose-dived/caused issues.

 

[RedJay5]

I’d really like to see someone make a good solution for long action/ cip mags to shoot 308 bolt face stuff.

I haven’t tried these but seem like the best solution out: https://accurate-mag.com/shop/magazines/longactionaics/308-win-long-action-sssf-magazine/

Yeah, that’s the exact magazine that I’ve linked in the original post, and am looking to see if anyone who has used it is willing to share any feedback on their experiences. I’m looking forward to seeing what sort of more descriptive feedback Pappy comes back with regarding specific feeding error probabilities he encountered with them, but am also hoping to hear back from anyone else that has experience with them as well…

I’m also curious to find out if this is the exact magazine that was used by @rlsmith1 in his LA/short-cartridge set up.

Thanks for everyone for their continued time and support to this line of questions.

 

[VSP968]

I’ve got a hot rodded 308 R700 LA with .170 free bore that I’m running 200.20X Berger Hybrids that have a COAL of 3.12.

I tried an Accurate mags that @PappyM3 mentioned and I didn’t like the way the follower would tip.

I ended up using the plastic MagPul AICS LA standard (30-06) magazines and they worked without any problems.

 

[7mmShooter]

@7mmShooter Interesting, I haven’t heard of the sleeves… any chance you have a link to this so that I could dive deeper into what you’re describing?


@PappyM3 , thanks for taking the time to write up that first response in this thread. Unless I’m misunderstanding, my initial expectation from your response is that I will likely be satisfied with those Accurate-Mag LA 308 magazines… you stated they were “fairly reliable, but sometimes nose-dive”… is this like an every other magazine type occurrence? I’m curious if you have any more specifics on how reliable you found them vs how often they nose-dived/caused issues.

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AI aluminum Mag Adapter black 27268-BL 27268-BL

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[PappyM3]

Yeah, that’s the exact magazine that I’ve linked in the original post, and am looking to see if anyone who has used it is willing to share any feedback on their experiences. I’m looking forward to seeing what sort of more descriptive feedback Pappy comes back with regarding specific feeding error probabilities he encountered with them, but am also hoping to hear back from anyone else that has experience with them as well…

I’m also curious to find out if this is the exact magazine that was used by @rlsmith1 in his LA/short-cartridge set up.

Thanks for everyone for their continued time and support to this line of questions.

So I just took the rifle to a two day class. I haven’t checked the exact amount fired yet, but ~250 rounds fired. Of those, about ~140 fired with the two Accurate Mags.

Of those ~140, I only recall one instance of a nose dive. However, there were a handful of instances where a round wasn’t picked up. One instance was on a timed stage and I couldn’t pop it up, so I had ti drop the mag slightly and hand load a spare cartridge.

At home yesterday I tested one of them feeding a whole mag, 6 times. Of those, only one instance of not picking up the cartridge and a slap of the mag helped it grab it. Then I switched to the other mag and had 3 failures to pick up within the first 5 rounds. I ran out of time, but will do more testing next week probably.

Edit: in my KRG W3, the mags aren’t jammed up to the action, but there might be a mm of vertical wiggle room? I’ll have to confirm with calipers. Also, the feed lips seem to position the cartridges high enough without letting them pop out, but I can get measurements later.

 

[bohem]

The easy solution to this, and I've done this a number of times, is the AICS PMag for 30-06.
Sometimes we get 300 WM metal mags and close the feed lips a little bit to make it feed the 473 case bodies properly. Most customers find it more palatable to buy plastic mags than to pay us to tweak (more expensive) metal mags for them.

 

[wvfarrier]

I have a 300prc that I rebarreled to 308 and swapped bolt heads on.. Still using the 3.8" mags with no issue.