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.

AI aluminum Mag Adapter black 27268-BL 27268-BL - EuroOptic

AI aluminum Mag Adapter black 27268-BL 27268-BL

www.eurooptic.com

 

[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.

 

[RedJay5]

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

@PappyM3 Really appreciate you taking the time to convey this so that we can have an accurate and numerical assessment of how reliable these rounds are. Definitely surprised to hear how unreliable they seem to be when it’s the exact purpose that the product was designed for.

The short action rounds in the CIP length really seems to be the challenge… in you’re previous post you reference building up epoxy on some 30-06 magazines to hit the correct size, do you think this MPA product would help achieve success?

Long Action Chassis Magazine Insert - MasterPiece Arms, Inc.

These inserts are used on our BA Comp Long Action Remington 700 Chassis for setting the correct internal magwell length for the 3 different Long Action magazines used in these chassis. Choose between an insert for the 3.715 Length Magazine, 3.775 or 3.850 (CIP Length). Compatible with the BA...

masterpiecearms.com

Obviously this is pretty specific to my range chassis , but just curious. I haven’t seen a video of the product and how it works, but I’m pretty inexperienced on all of this

 

[RedJay5]

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.

To confirm, the AICS PMag you’re referencing is the non-CIP length magazine.. correct?

If the 300WM metal mags work effectively for .308 in the method you’re describing, I feel like that would be a clear answer. I’ve always thought “tweaking” metal mags just meant bending the feed lips… if you’re confident that this is a great solution, then I will follow suit. Also, are you saying that “tweaking” is expensive, or just that metal mags tend to be expensive? Thanks for your time.

 

[RedJay5]

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

Are you referencing the 3.850” Accurate Mag Long Action .308s ? Also what chassis are you running them out of?

 

[bohem]

To confirm, the AICS PMag you’re referencing is the non-CIP length magazine.. correct?

If the 300WM metal mags work effectively for .308 in the method you’re describing, I feel like that would be a clear answer. I’ve always thought “tweaking” metal mags just meant bending the feed lips… if you’re confident that this is a great solution, then I will follow suit. Also, are you saying that “tweaking” is expensive, or just that metal mags tend to be expensive? Thanks for your time.

Metal mags are expensive compared to the PMags from MagPul.

PMAG® 5 AC L, Standard – AICS Long Action

Long action GEN M3® technology

magpul.com

The metal mags with modified feed lips generally work fine but they're almost 3x the price of a PMag so that factors in for a lot of folks.

 

[PappyM3]

Metal mags are expensive compared to the PMags from MagPul.

PMAG® 5 AC L, Standard – AICS Long Action

Long action GEN M3® technology

magpul.com

The metal mags with modified feed lips generally work fine but they're almost 3x the price of a PMag so that factors in for a lot of folks.

PMAG doesn’t offer a CIP length mag.

@PappyM3 Really appreciate you taking the time to convey this so that we can have an accurate and numerical assessment of how reliable these rounds are. Definitely surprised to hear how unreliable they seem to be when it’s the exact purpose that the product was designed for.

The short action rounds in the CIP length really seems to be the challenge… in you’re previous post you reference building up epoxy on some 30-06 magazines to hit the correct size, do you think this MPA product would help achieve success?

Long Action Chassis Magazine Insert - MasterPiece Arms, Inc.

These inserts are used on our BA Comp Long Action Remington 700 Chassis for setting the correct internal magwell length for the 3 different Long Action magazines used in these chassis. Choose between an insert for the 3.715 Length Magazine, 3.775 or 3.850 (CIP Length). Compatible with the BA...

masterpiecearms.com

Obviously this is pretty specific to my range chassis , but just curious. I haven’t seen a video of the product and how it works, but I’m pretty inexperienced on all of this

That MPA product may work to use non-CIP mags. Not sure as I’ve never touched it.

My KRG chassis offers a shim to use non-CIP magazines, but it requires the chassis to be partially disassembled (removing ARCA and then removing the forward handguard from the chassis backbone). It’s a pain in the ass to switch, so I decided to try without using it.

 

[bohem]

PMAG doesn’t offer a CIP length mag.



That MPA product may work to use non-CIP mags. Not sure as I’ve never touched it.

My KRG chassis offers a shim to use non-CIP magazines, but it requires the chassis to be partially disassembled (removing ARCA and then removing the forward handguard from the chassis backbone). It’s a pain in the ass to switch, so I decided to try without using it.

If you must use a CIP mag then you need to spend the money on metal mags and modify the feed lips. When we've done these for customers they're not using CIP specific bottom metal, nor is my personal rifle, so it's not an issue.

 

[PappyM3]

If you must use a CIP mag then you need to spend the money on metal mags and modify the feed lips. When we've done these for customers they're not using CIP specific bottom metal, nor is my personal rifle, so it's not an issue.

But the question is which metal mag? Accurate mag offers one already set for 308 feed lips. But their follower sucks and wobbles all over because the follower isn’t CIP length. Perhaps a magnum magazine with feed lip adjustments from a place like MDT might be better.

As it stands, the market offerings (including follower/spring/spacer kits) for multi-caliber setups with long actions and CIP chassis/bottom metal is virtually non-existent and there is tons of room for improvement with magazine reliability. That said, I realize the market itself is rather small because half the small group of people interested are probably going with Barrett, AI, or Cadex anyway.

But once I have some spare time I’m planning to draw up a 3D model for a spacer for the 308 CIP accurate mag. It will just require trimming the follower back towards the spring and some test and analysis for the angle/height of a slight ramp built into the spacer.

I’m also going to look into an external front spacer for the Magpul 30-06 mag with a built in very very slight ramp that overlaps with the top of the front of the mag. I’m much less confident about that one, but will likely try it still.

 

[Maurygold]

@MDT_OFFICIAL @MDT_Josh seems like a big market gap for those that run long action or cip long action that would really like to run short caliber out of a magazine…

 

[bohem]

But the question is which metal mag? Accurate mag offers one already set for 308 feed lips. But their follower sucks and wobbles all over because the follower isn’t CIP length. Perhaps a magnum magazine with feed lip adjustments from a place like MDT might be better.

As it stands, the market offerings (including follower/spring/spacer kits) for multi-caliber setups with long actions and CIP chassis/bottom metal is virtually non-existent and there is tons of room for improvement with magazine reliability. That said, I realize the market itself is rather small because half the small group of people interested are probably going with Barrett, AI, or Cadex anyway.

But once I have some spare time I’m planning to draw up a 3D model for a spacer for the 308 CIP accurate mag. It will just require trimming the follower back towards the spring and some test and analysis for the angle/height of a slight ramp built into the spacer.

I’m also going to look into an external front spacer for the Magpul 30-06 mag with a built in very very slight ramp that overlaps with the top of the front of the mag. I’m much less confident about that one, but will likely try it still.

What purpose would the spacer serve? Just a little food for thought:

I made a spacer kit for AW and AICS for a number of years and offered it for sale. The AICS kit was a spring, follower, and spacer and it had enough clever engineering in it that we got 2 utility patents issued on it. There was a cheap knockoff that pervaded the market because it was cheap and they were sold as a 3D printed product for a while before MDT basically copied that one and brought it to market in a turn key setup. We still sold several thousand kits based on the number of springs that I have ordered over the years.

The AW kit was resoundingly simple, it was just a spacer that used the factory flat spring and a trimmed follower to run Dasher and BR cartridges in the body. Anyone with a dremel, razor, or hacksaw could modify it. However, since it required modification of the factory follower and that modification was not reversible virtually nobody bought them even at $10 for the spacer due to not being able to turn the mag back into a standard setup.

On a long action there was no necessity in any of my personal rifles or rifles built for customers to require a spacer to properly feed 308's in a long action. It also works fine for Mausers and Tikkas as well as internal boxes. It was just needed for the super short Dashers and Grendel case bodies.

I think it was Cadex and AI that both offered a setup to change the bolt stop position and swap in a spacer for LA chassis to be able to run SA mags in a LA for swap barrel setups. Maybe Sako did as well, I don't recall for sure now. Perhaps you see a niche product slot that we didn't identify back in 2015 and 2016 when the development and patent work was being done.

 

[PappyM3]

What purpose would the spacer serve? Just a little food for thought:

I made a spacer kit for AW and AICS for a number of years and offered it for sale. The AICS kit was a spring, follower, and spacer and it had enough clever engineering in it that we got 2 utility patents issued on it. There was a cheap knockoff that pervaded the market because it was cheap and they were sold as a 3D printed product for a while before MDT basically copied that one and brought it to market in a turn key setup. We still sold several thousand kits based on the number of springs that I have ordered over the years.

The AW kit was resoundingly simple, it was just a spacer that used the factory flat spring and a trimmed follower to run Dasher and BR cartridges in the body. Anyone with a dremel, razor, or hacksaw could modify it. However, since it required modification of the factory follower and that modification was not reversible virtually nobody bought them even at $10 for the spacer due to not being able to turn the mag back into a standard setup.

On a long action there was no necessity in any of my personal rifles or rifles built for customers to require a spacer to properly feed 308's in a long action. It also works fine for Mausers and Tikkas as well as internal boxes. It was just needed for the super short Dashers and Grendel case bodies.

I think it was Cadex and AI that both offered a setup to change the bolt stop position and swap in a spacer for LA chassis to be able to run SA mags in a LA for swap barrel setups. Maybe Sako did as well, I don't recall for sure now. Perhaps you see a niche product slot that we didn't identify back in 2015 and 2016 when the development and patent work was being done.

The intent for the spacer would be twofold.
1. Prevent follower tilt
2. Prevent nose-diving rounds by providing a short sled at the front of the magazine

Though it sounds like maybe I’m just unlucky. The feed lips seem properly tuned in the accurate mag and the height of my mag catch seems appropriate. But maybe I could mess around a bit.

 

[bohem]

The intent for the spacer would be twofold.
1. Prevent follower tilt
2. Prevent nose-diving rounds by providing a short sled at the front of the magazine

Though it sounds like maybe I’m just unlucky.

Just be careful not to tread on toes with your design features, that patent space is very well populated by several companies. Magpul is one of them and they have the internal budget to go 50 Shades of Grey on you legally.

 

[PappyM3]

Just be careful not to tread on toes with your design features, that patent space is very well populated by several companies. Magpul is one of them and they have the internal budget to go 50 Shades of Grey on you legally.

It’s all personal use for me.

 

[MDT_OFFICIAL]

@MDT_OFFICIAL @MDT_Josh seems like a big market gap for those that run long action or cip long action that would really like to run short caliber out of a magazine…

The market for this one is very small, and putting time and resources behind a project like this would not be in our best interest. However, if it becomes more and more common on the market, it may be something we consider.

-Paige