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Modifying the Kel-Tec SU-16

The question of modifying the Kel-Tec SU-16 comes up mostly in California, where it was (until the advent of Off-List Lowers) the closest thing to a true detachable-magazine AR-15 that a post-2000 rifle buyer could get. Due to its budget-priced construction, a number of areas have been identified where the base model's performance can be improved.

A number of SU-16 owners have come up with their own solutions to reliability issues encountered with Kel-Tec's SU-16 rifle. This article attempts to create a list of the more common ones. Further submissions are welcome.

Incorrect SU-16 Myths

• The SU-16 uses mil-spec M-16 / AR-15 firing pins: This is absolutely not the case. AR-15 firing pins will not even fit into the SU-16. It may be possible to turn one in a lathe to cut it down to fit the SU-16, but the SU-16CA I have absolutely will not accomodate a stock AR-15 firing pin.
• The SU-16 uses an AR-15 bolt: This is partially correct. Were an AR-15 bolt to be cut at a certain spot, I am confident that it would function in an SU-16. However, an unmodified AR-15 bolt absolutely will not fit into it.

AR-15 Parts Compatibility

• Furniture: Kel-Tec now sells a replacement rear end which allows the SU-16 to accommodate any pistol grip and stock designed for an AR-15. This opens up a whole new world of furniture options for the SU-16.
• Muzzle devices: The muzzle threads on the C/CA/D models, are the same pitch as used on the AR-15. Thus, it's possible to install an AR-15 muzzle brake or flash hider on the SU-16. In California, it's worth noting that the installation of a flash hider would make the SU-16 an illegal assault weapon unless other exotic/silly/pointless modifications were made.
• Extractor: The SU-16 extractor can be replaced with an AR-15 extractor. It is reported that this greatly decreases jamming.
• Front sight: The front sight on the SU-16CA is a standard AR-15 front sight. This means that, if desired, one could install a Tritium or other fancy front sight on the SU-16.
• Replacement stock pin: While the original pin has been known to fall out on its own, the diameter is actually the same as an AR-15 takedown pin. While a standard AR-15 pivot pin won't exactly work (the detent slots would carve up your SU-16's polymer eventually), there are a number of vendors which supply different takedown pins. .25" cotter pins from a hardware storewill also work, however it's advisable to add grooves in them at the same location as the original pin. This will allow the retention mechanism to grip the pin and reduce the risk of it falling out.

Other Modifications

• Railed handguards: Kel-Tec sells a 'compact foreend', which replaces the existing front end. It's also possible to use an AK accessory tri-rail handguard and clamp it onto the barrel, which does adversely affect accuracy. The one point to make on this is that if your goal with the Kel-Tec is an in-home short-range rifle, the change in accuracy won't be noticeable at those distances. Handguard information courtesy of Lectrikhed, from Calguns
• Replacement charging handle: The slanted polymer charging handle on the SU-16CA is said to create jams, by kicking ejected shell casings back into the action of the weapon. Replacing the newer-style polymer charging handle with the old, round charging handle is said to correct this issue.
• Replacement Magazines: Kel-Tec's original polymer magazines were absolutely horrible, and tended to vomit their contents into the magazine well with the slightest tap, if the action is open. They have since improved their designs, and offer a trade-in program for owners of the original magazines. All SU-16 rifles will also accept STANAG-spec AR-15 magazines.

-- SeanNewton - 07 Dec 2007