Magazines matter (LR/SR)

Information

When I first got my 16.5″ 6.5 Creedmoor DPMS LR pattern rifle built I purchased three inexpensive metal magazines. I went with 10 round magazines because I planned on shooting prone while accuracy testing different ammunition. I also went with metal magazines because I assumed that was the better route. The magazines ended up working very poorly, or not at all. I thought it was strange that I had such bad luck and ended up double checking that my rifle contained the proper components, which it did.

I’ve been told the AR Stoner magazines I purchased are manufactured by Bear Creek Arsenal for Midway USA. The magazines use an ASC follower and are very economically priced. I was only able to use these magazines in two Aero Precision lowers, they had issues in both. One magazine wouldn’t engage, the second would fall out every time you fired a round and the third was useable but only with 9 or less rounds. I tinkered with it to fit 10 rounds but was unsuccessful. After feeling frustrated I begin gathering a small sampling of quality magazines to find which type functioned best in my rifle.

Current selection of magazines we’re using in our large frame semi-auto rifles.

Image showing the available length in each type of magazine. Cartridge length is 2.81″

I started with the Magpul 10 round. They are the most affordable magazine I’m using at roughly ~$20.00 each. I have a preference for 10 round magazines in my large frame AR. I think they look better and are easier to manage. Magpul magazines have a reputation for working very well. They also make a 20 round magazine & 25 round M118 version. The M118 version allows for ammunition with a cartridge overall length of up to 2.83″ to accommodate M118 LR special ball. The standard 10 & 20 round magazines have been working very well. The only issue I ran into was not being able to insert a fully loaded magazine into the rifle with the bolt closed. This was the case with all three 10 round magazines. The issue can be resolved by modifying the follower. During a Sin City Precision monthly long range match they functioned very well, I finished 13th/30. During the match you started each stage with the bolt open. The only issue I had was when pressure on the magazine caused a failure to feed while shooting from a spool prop. The downside with the Magpul 10 round magazines is the SAAMI cartridge overall length which can hinder your options when reloading and having to modify the followers for my rifle. I think they are an excellent option and the best inexpensive magazine.

Next is Lancer Systems 10 & 20 round L7 AWM, or Advanced Warfighter Magazine. They run about ~$50.00 and are available in 5, 10, 20 & 25 round magazines. These magazines stood out to us because of their polymer and metal construction. The Lancer magazine is middle of the pack cost wise. We like that they are translucent and have unique aesthetics. Initially I loaded both magazines to capacity and inserted them into my rifle with the bolt closed. The 20 round magazine went in with a pronounced “click” but the 10 round magazine didn’t want to engage. I went ahead and took it apart and trimmed the follower with a file. The L7 AWM allows for a slightly longer than SAMMI cartridge overall length and have been functioning extremely well (we also like their AR-15 magazines). The downside is we needed to modify the follower on both 10 round magazines but that is not a big deal. I will be utilizing the Lancer magazines during a rifle competition soon and will update this post.

The Knight’s Armament Company magazine are the most expensive we’re using at roughly ~$100.00 each. The KAC is comparable in size, or slightly smaller than other 10 round magazines but with a capacity of 12 rounds. They also offer a 20 round and allow for a cartridge overall length of 2.88″. This gives hand loaders more options when dialing in a recipe and greater flexibility with heavier projectiles. The magazine is constructed from heat treated steel and the seem located at the front of the magazine is stitch welded. We didn’t have any issues inserting a full magazines into the rifle with a closed bolt. I completed the March 2021 Max Ordinate Academy Desert Duel match using the KAC 12 round magazines and didn’t have a single issue. The match contained a couple stages where you were required to single feed your rifle putting an emphasis on the bolt locking back. I was able to manage 7th out of 20 shooters and Top Gas Gun. The downside regarding these magazines are the cost but they have so far functioned exceptionally in our rifles.

The most recent magazines I purchased were the LaRue 7.62. They are only available in 20 round and cost ~$80.00 each. You save a little money by purchasing two or more at a time. They came highly recommended and were originally made for the LaRue OBR rifle. The magazines feature steel construction and a laser welded hidden seem at the rear of the magazine. They allow for a cartridge overall length of 2.88″ which is good news for hand loaders. I had zero issues inserting a fully loaded magazine into the rifle with the bolt closed. Durning the April 2021 Max Ordinate Desert Duel match I ran LaRue magazines (finished Top Gas Gun/Tac). The larger size of the 20 round magazine made it more likely to suffer a failure to feed caused by pressure on the magazine. During two stages I had the magazine pressed against something while on the clock. Clearing a malfunction during a stage burns up a lot of your par-time. I became very deliberate on how I would position the rifle to avoid any contact with the magazine. During stage 6 “Biggie Smalls” I did suffer one failure to feed not induced by pressure or contact. On stage 4 “Let’s get some distance” I experienced one failure to lock back, during this stage you were required to to single feed the rifle. The LaRue magazines are very well made and I would love to see them come out with a 10-12 round magazine. The downside is cost and availability.

Overall the different types of magazines we tested are a significant improvement compared to the ones we started with. Some needed to be refined by trimming the follower but all have been reliable magazines. I think the final decision for a lot of people will come down to cost and which features are important to them; for example someone who doesn’t hand load may be indifferent to the longer cartridge overall length allowed by the LaRue and KAC magazines. The Magpul magazines will be most appealing to those on a strict budget and the Lancer System magazines represent the entry to the high end with unique aesthetics. The LaRue and KAC are the most expensive but also overall the most refined. My favorite is the KAC 12 round magazine. They have functioned best in my rifle so far. I like the size, capacity and features but admit the price hurts my feelings. While gathering information for this blog post I did a lot of accuracy testing with the rifle using all 4 brands. I was not able to identify a point of impact change due to the magazines. Below is a 9 Hole Review inspired test where we shot 3, 9 round 100 yard groups and averaged them to set an accuracy baseline for the rifle.

9 Hole Review inspired test with DMR 16.5″ 6.5 CM LR-308 pattern rifle
DPMS-LR pattern large frame AR build with DMR LLC 16.5″ 6.5 CM barrel.

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