Convert Any Full-Size Pistol into a Carbine

SigTac Adaptive Carbine Platform (ACP)

SigTac Adaptive Carbine Platform (ACP)

Sig Sauer has introduced a simple device to convert ANY full-sized railed pistol (up to a 5-inch barrel) into a carbine… easily, quickly, and inexpensively they say. It is called the SigTac Adaptive Carbine Platform (ACP). The information says it works with a Sig, Glock, Smith & Wesson M&P, Springfield XD/XDM, 1911 and other full-sized pistols. It certainly sounds inviting, but everything has pros and cons. I wonder if you have a non-Sig pistol with a standard rail will it really fit the ACP and perform well? If you own one of the flagship SIG pistols (e.g. P226, P229, P220) it probably will, but what if you have another Sig or different model pistol? Depending on the controls, safety and de-cocker for your particular pistol design, they might not be easily accessible. I wonder about malfunctions and stoppages with it and if they would be more difficult to clear. Perhaps SIG Sauer will publish a list of compatible models known to work reliably with the ACP or there will be independent, supportive studies.

The Sig ACP is simply a frame into which you lock a pistol to make it a shortened and lightweight version of a full-length rifle. It really is not a true carbine. It seems the intended benefit of this pistol-to-carbine conversion is to have a longer barrel to increase accuracy, stability, and muzzle velocity in a still relatively compact form with the pistol flexibility. Well, does it really enhance accuracy? Perhaps, the added weight of the ACP helps to manage recoil. This may help you bring your gun back on target more quickly than with a pistol alone. An advantage is that you can covert just about any caliber pistol that will fit the ACP, like .22s, 9mm, .40s, and .45s. The Sig adapter is not the first device to convert a pistol to a carbine, but others that exist generally adapt to only a very-limited range of pistols. To my knowledge, SIG is probably the first company that can claim their conversion device is multi-manufacturer friendly. An important consideration is that you must ensure that certain of your configurations and added accessories meet the Bureau of Alcohol, Tobacco, Firearms & Explosives (ATFE), Department of Justice regulations. For example, adding a vertical fore grip to a handgun-based platform MAY create a gun that is regulated under the Gun Control Act of 1968 as an “Any Other Weapon (AOW).” It would seem to this non-legal layman that it may be possible to legally add a fore grip IF it is done the proper way. Be careful and investigate this and other modifications for yourself before making any changes or additions.

Sig says that their ACP is the industry’s first universal, aircraft-grade aluminum pistol to carbine adapter designed to quickly and easily transform virtually any full-size railed pistol into an M1913 accessory customizable carbine platform. Simply slide your pistol into the accessory rail clamp adapter and lock it into place by tightening the rear pin of the clamp assembly they say. To place it into battery, just pull the ACP charging handle.

4-Tighten Rear Adapter on Pistol

 

2-Slide Pistol into Adaptive Clamp Assembly

 

The ACP provides the end user with a specific mission configurable carbine and is available in three configurations by Sig. It is my understanding that they must be purchased from a Sig Dealer, but some claim some third-party dealers sell them.

THREE ACP CONFIGURATIONS Offered By Sig

1.   ACP – STANDARD Comes with the ACP universal pistol rail adapter fitted with a QD sling mount- $279.

ACP-Standard ConfigurationTHE STANDARD ADAPTIVE CARBINE PLATFORM (ACP) allows any handgun with an accessory rail to be quickly modified into a personal defense weapon or carbine style firearm. Regardless of the brand, most pistols equipped with an accessory rail can be mounted to the ACP without the need for modification to the base gun.
ACP will accept most railed guns with barrels up to 5″ in length.

This standard model allows for fast, easy conversion and works with most railed pistols, equipped with a QD sling mount.

Fabricated from solid aircraft-grade aluminum, the ACP sports M1913 rails at the 3, 6 and 9 o’clock
positions with a full-length top rail at the 12 o’clock position. Compatible accessories such as lights, red
dot sights and lasers can be mounted for additional functionality. The ACP brings Personal Defense Weapon (PDW) features to almost any handgun.

Specifications:

  • Length – 14.0 in
  • Width – 2.75 in
  • Height – 5.0 in
  • Weight – 17.0 oz
  • Features – Machined Aircraft Aluminum Housing with M1913 Top Rail and 3 Additional Rails

Not for sale in the State of California. Also available in a LE version with folding stock NFA rules (registered serial numbers, etc.) apply.

2.   ACP – ENHANCED Comes with the ACP universal pistol rail adapter, QD sling mount, MIL-GRADE Mini Red Dot Sight and a single point bungee sling- $399.

ACP-Enhanced-Red Dot Sight and Sling ConfigurationTHE ENHANCED VERSION ADAPTIVE CARBINE PLATFORM (ACP) allows any handgun with an accessory rail to be quickly modified into a personal defense weapon or carbine style firearm. Regardless of the brand, most pistols equipped with an accessory rail can be mounted to the ACP without the need for modification to the base gun. ACP will accept most railed guns with barrels up to 5″ in length.

This enhanced model includes the new SIG SAUER Mini Red Dot Sight, a quick detachable sling swivel and a Single Point Bungee Sling.

Fabricated from solid aircraft-grade aluminum, the ACP sports M1913 rails at the 3, 6 and 9 o’clock positions with a full-length top rail at the 12 o’clock position. Compatible accessories such as lights, red dot sights and lasers can be mounted for additional functionality. The ACP brings Personal Defense Weapon (PDW) features to almost any handgun.

Specifications:

  • Item Number – ACP-L
  • Length – 14.0 in
  • Width – 2.75 in
  • Height – 7.0 in (w/Mini Red Dot Attached)
  • Weight – 17.3 oz
  • Features – Basic Plus – Red Dot Sight, Quick Detachable Bungee Sling

Not for sale in the State of California. Also available in a LE version with folding stock NFA rules (registered serial numbers, etc.) apply. 

3.   ACP – LE A tactical and law enforcement variant that comes with the ACP universal pistol rail adapter and a folding stock- $399. All NFA rules (NFA registered serial numbers, etc.) apply.

ACP-LE- with Folding Stock ConfigurationThis law enforcement version with the folding shoulder stock may be viewed by the ATFE as being a short barreled rifle (SBR) which means it would have to be registered, you would pay a $200 or so tax stamp fee, and wait six or so months for permission to use it. I would guess that the Standard or Enhanced ACP versions would NOT have to be registered with the ATFE as an SBR, only the LE version as an NFA device. You need to investigate this for your jurisdiction and situation. I wonder if you decide later to use a different pistol with your ACP (given the ATFE definitions of firearm, SBR, pistol, etc.) would you need to register and pay another transfer tax for the second “pistol?”  Probably, since the pistol itself would be registered as the SBR. This would mean that you cannot use any other pistol in the ACP unless you register it also and pay the $200 stamp tax for that other gun. If you decide to sell your pistol, you would then probably have to have it de-listed as an SBR or else it would be transferred to the buyer with a special form and pay the tax, etc. So, is there a valid reason for the time and money expenditures just to get the folding stock version? Not for me, but your call!

THE SIG SAUER® LE ADAPTIVE CARBINE PLATFORM (ACP) allows any handgun with an accessory rail to be quickly modified into a personal defense weapon or carbine style firearm. Regardless of the brand, most pistols equipped with an accessory rail can be mounted to the ACP without the need for modification to the base gun. ACP will accept most railed guns with barrels up to 5″ in length.

NOTE: This National Firearms Act-regulated military/law enforcement model features a top folding shoulder stock. Civilian purchasers must comply with the requirements for registering a short-barreled rifle.

Fabricated from solid aircraft-grade aluminum, the ACP sports M1913 rails at the 3, 6 and 9 o’clock positions with a full-length top rail at the 12 o’clock position. Compatible accessories such as lights, red dot sights and lasers can be mounted for additional functionality. The ACP brings Personal Defense Weapon (PDW) features to almost any handgun.

Specifications:

  • Item Number – ACP-LE
  • Length with stock folded – 15.0 in
  • Lenght with stock open – 22.0 in
  • Width – 2.75 in
  • Height – 5.0 in
  • Weight – 24.0 oz
  • Features – Basic Plus – Top Folding Stock (NFA Regulated, Civilian purchasers must comply with registering a short-barrel rifle)

Not for sale in the State of California. Sig states that all configurations must be purchased from a Sig Dealer.

SUMMARY 

An interesting new Sig product for you to consider the pros and cons for YOUR use. Undeniably, Sig pistols are quality, well-made pistols and I own several. However, for this adapter product you must ask yourself: What is the optimal utility for me? What will this ACP do for me and my shooting experience? Will the ACP fit and perform well with my particular model pistol? Do you want the advantages and benefits of a carbine with your pistol? If so, are there other options or self-contained small carbines that meet my needs. Am I willing to pay for any added benefits? Have fun exploring this and be safe!

Continued success!

* This personal opinion article is meant for general information & educational purposes only and the author strongly recommends that you seek counsel from an attorney for legal advice and your own personal certified weapons trainer for proper guidance about shooting & using YOUR firearms, self-defense and concealed carry. It should not be relied upon as accurate for all shooters & the author assumes no responsibility for anyone’s use of the information and shall not be liable for any improper or incorrect use of the information or any damages or injuries incurred whatsoever. 
© 2014 Col Benjamin Findley. All Rights Reserved. This article may not be reprinted or reproduced in whole or in part by mechanical means, photocopying, electronic reproduction, scanning, or any other means without prior written permission. For copyright information, contact Col Ben Findley at [email protected]

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  • Cobrawing

    If it ain’t broke . . . don’t fix it.

  • Cobrawing

    If it ain’t broke . . . don’t fix it.

  • PeaverBogart

    Nice, but none of my handguns have an accessory rail.

  • Randy

    Interesting. You mention that the intended benefit is to have a longer barrel, but I didn’t see anything about provisons in the device that would extend the barrel. Actually, I can’t quite see how one would extend a barrel without alignment problems, unless the barrel is threaded. If the package could extend the pistol’s barrel, then it would be an attractive accessory. Thanks for the article, Colonel.

  • rca_cajun

    I bought one of these Christmas 2012, and I have mixed feelings about it. It is a fun piece of equipment to play around with on a short range pistol course where you are trying to get bullets to hit an 8″ plate at 15 yards, but you can’t get accurate with it because of the interface of the pistol to the ACP. I have a SIG P229 and a P226 and everyone who tired to shoot accurately with the ACP couldn’t match their accuracy they achieved by using the pistol alone. The plastic interface with the rail doesn’t hold zero either after about 30 rounds of .357 SIG, 9mm or .40 S&W. If you change guns, or remove the gun you have to zero it again. If you change the amount of pressure you are holding the ACP in relation to the pistol, your zero changes. If you brace up on a barrier, your zero changes. Initially I dropped my .22lr kit in on my P229, and it took about 100 rounds to zero because I didn’t figure out that if you don’t hold the ACP and pistol the exact way with the exact pressure, it will change the zero.

    It was fun to shoot at 10 yards with a burris fast fire II, but I can’t imagine using this thing in a real situation.

    If anyone wants to buy mine, l’ll sell it for $100. You would have more fun and get more utility buying an 8 round mag tube for a shotgun.

  • PodBoy

    I love Sig, and I think they make great and beautiful products. That said, this thing is BUTT ugly, and I think they lost a LOT in trying to make it work with anything. The Mako for the Sig 226 is MUCH nicer, but still pointless with out the stock and foregrip.

  • Gary M.

    Indeed. This is trying to fill a niche that does not actually exist. Pistol caliber carbines already occupy this spot and they are far more accurate than this contraption, use the same mags as the primary pistol (usually) and are low cost..

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