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Miscellaneous Questions #22

How good are the polymer magazines for the M16?
How can I start roll pins (split spring pins) straight without damaging them?
What are the dimensions of large and small primers?

Q. How good are the polymer magazines for the M16?

A. While early polymer magazines left something to be desired as far as ruggedness and durability many current polymer magazines are very good.  However, the premier polymer magazines in use today are the Magpul brand "PMags" that are US Military approved and that are very popular among the troops and civilian shooters.  I have been using their Gen 2 magazine for several years and have not had a single problem or malfunction and I highly recommend them over other brands.  They are currently available in 10, 20, 30, and 40 round capacities.

There have been several generation of PMags and the data below explains the major differences in them

The GEN 1 PMag  was Magpul's first AR15/M4 compatible magazine.  It featured a polymer construction, easy to disassemble design with a flared floor plate, stainless steel spring, and an anti-tilt follower.  It came with a dust cover that could not be stored on the base of the magazine. It was available with or without a round count "window."

The GEN 2 PMag was Magpul's second design polymer AR15/M4 compatible magazine. It features an improved impact resistant polymer construction, easy to disassemble design with a flared floor plate, stainless steel spring, and an anti-tilt, self-lubricating follower for increased reliability.  The dust cover will snap onto the base of the magazine for storage.  It is available with or without a round count "window."

The GEN 2 MOE PMag is identical in form and function to the original Gen 2 PMAG except that the dust cover is now sold separately.  It is available with or without a round count "window."

The GEN 3 PMag is Magpul's latest polymer magazine for AR15/M4 compatible weapons. It incorporates new material technology and manufacturing processes for enhanced strength, durability, and reliability, especially in cold weather. Modified internal and external geometry also permits operation with a wide range of non Colt-spec platforms such as the HK 416 and MR556A1, M27 IAR, British SA-80, FN SCAR MK 16/16S, and others. A redesigned bolt catch notch in the rear of the magazine provides increased bolt catch clearance, while an over-travel stop on the spine helps ensure the magazine will not over-insert on compatible weapons.    It has constant-curve internal geometry for reliable feeding, and includes a dust cover.  The dust cover will not snap onto the base of the magazine. Low profile ribs and new aggressive front and rear texture provide better handling control, and a paint pen dot matrix has been added to the bottom side panel of the body to allow easy marking by the end user for identification. A new floor plate aids extraction and handling of the magazine while providing improved drop protection, and is slightly slimmer than before for better compatibility with tight double and triple magazine pouches.

PMags are also available in 7.62 NATO for the SR25/M110, MK 11 rifles, in 6.8SPC for the AR platform, and in a 5.56 x 45 design specifically for the HK 36.  See Magpul's website at www.magpul.com for more information.

Magpul also offers a magazine called the EMag (Export MAGazine). It is a lightweight 30-round 5.56x45 NATO polymer magazine that features a number of aesthetic and functional changes from the PMAG. While the EMAG remains 100% compatible with the AR15/M16 platform, its unique geometry is optimized for foreign-made weapons such as the British SA-80 (L85A1/A2, L86A1/A2, L22A1, L98A1/A2), HK 416, M27 IAR, and others.

EMAG features the same dust cover as the PMAG GEN M2 Dust Cover and can be stored on the magazine's floorplate to prevent possible loss.  It has large dual-sided windows with numerical indicators added to the body to identify 5, 15, and 25 loaded rounds.

Magpul also makes 20 rd AR magazines.  The Gen 1/2 were of the straight design and the current Gen 3 is a curved design which is also available in a 10 round configuration.

Note that the dust covers for the Gen 3 and the earlier magazines are different.  If you order replacement mag covers be sure to specify what generation magazine they are for.

And a plug for Magpul.  Magpul makes a wide variety of not only magazines, but stocks, grips, slings, and other accessories that are top notch in all respects.  Check out their website at www.magpul.com.

Thanks to the folks at Magpul for the magazine samples for the photographs..

Q. How can I start and drive in roll pins (split spring pins) straight without damaging them

A. To start the pins you can use what is called a roll pin holder which is steel punch with an appropriate sized hole in the end to support the pin.  Unfortunately, they are not cheap and if you don't normally need to insert split pins they may not be cost effective.  Brownells carries them.  However, you can easily make your own from a short section of 1/4 inch steel rod or even a small bolt by drilling an appropriate size hole.  The table below gives the proper hole size for several common roll pins.  Drill the hole about 1/8 to 1/4 inch deep depending on the length of the pin being used.

To finish seating the pins or to drive them out you should not use flat punches but rather a tipped roll pin punch that has a small dimple that sits in the hole of the roll pin to guide the punch.  These punches are also carried by Brownells.  Picture below.

Q. What are the dimensions of large and small primers?

A. The chart below gives the nominal dimensions.  Note that these dimensions seem to vary a little bit depending on the source.