Frequently Asked Questions

This post will help you understand the different XCR Options click here.

XCR stands for eXchangeable Caliber Rifle, eXtremely Cool Rifle, or eXtreme Combat Rifle.  You decide.

Robinson Armament’s mission was to create the perfect autoloading rifle for collectors, hunters, police, and military.  It is NOT an AR15 – It is better.   It is NOT an FN SCAR, SIG MCX, ACR, CZ, B&T, or H&K – It is better.

The XCR borrowed ideas from the best rifles and improved upon them.  The XCR’s action is similar to that of the AK47 which has great feeding, extraction, and ejection for reliability.  From the AR15 was borrowed the excellent straight in and out magazine change, exchangeable pistol grips, and aluminum upper and lower receivers for light weight.   To these we added a quick-change barrel system allowing caliber and length changes; and the best ergonomics meaning the operator can keep his eyes on the target while manipulating all controls with either the right or left hand.

The XCR-L has been in production since 2006.  The XCR-M has been in production since 2012.

The XCR-L is chambered for 5.56 (.223), .300 Blackout, 7.62×39, 6.8 SPC II, and 6.5 Grendel, 5.45×39, .224 Valkyrie, 6mm ARC, and .223 ARC, and .338 ARC

The XCR-M is chambered for 7.62 NATO (.308), .243 WIN, .260 REM, and 6.5 Creedmoor, and 8.6 Blackout.

All our barrels whether marked .223 or 5.56 can shoot either .223 or 5.56 ammunition.  They have .223 Wylde chambers.  Our chambers are designed to handle either cartridge.

No, the XCR-M is designed to shoot cartridges based on the .308 cartridge which is longer and wider than the 5.56 cartridge.  It does not make sense to make the XCR-M shoot .556 because it has a larger frame to shoot the larger .308 ammunition.  It would be a large and heavy 5.56.

Yes, it will due to the excellent design of its operating system.

All the calibers the XCR-M is chambered for are based on the .308 cartridge and are roughly the same width and length.  Therefore, to convert from one caliber to another usually only a barrel changed is needed.  However, when going to or from a subsonic caliber, such as 8.6 Blackout, a different, shorter Oprod and Gas Tube may also be needed.

Most of the cartridges the XCR-L is chambered for have different sizes and shapes.  Therefore, more than just the barrel needs to be changed to convert from one caliber to another.   Please refer to the chart below to see what parts are needed.  We offer the parts needed in the form of Caliber Conversion Kits.   Some of these kits require more parts that other.  In any case, the conversion process is simple and takes less than 5 minutes.

Legend for Caliber Conversion Chart.  Parts Needed to Convert

A = Nothing
B = Barrel, Operating Rod, Gas Tube
C = Barrel, Bolt, Magazine
D = Barrel, Bolt, Firing Pin, Magazine
E = Barrel, Firing Pin, Magazine
F = Barrel
G = Barrel, Bolt, Operating Rod, Gas Tube, Magazine
H = Barrel, Bolt, Operating Rod, Gas Tube, Magazine, Firing Pin
I = Barrel, Magazine

For 5.56(.223), we use a 1/2×28 thread.   For all other calibers we use a 5/8×24 thread.

The hole in the magazine well of the XCR-L is the same size as an AR15.  The following calibers use the following mags.

.223, 5.56, .300 BLK:    Standard AR-15 Magazines
7.62×39:  We prefer the DuraMags made by CProducts Defense, but most other AR-15 mags will work including PMAGs.

6.5 Grendel, 6mm ARC, 22 ARC, and 338 ARC:  6.5 Grendel DuraMags made by CProducts Defense.

6.8 SPC, .224 Valkyrie: 6.8 SPC DuraMags made by CProducts Defenss.

The hole in the  XCR-M’s magazine well is made for SR-25 pattern mags.   These mags will work with .308, 6.5 Creedmoor, .243, .260, and 8.6 Blackout.  There are many manufacturers of these mags.  We prefer the .308 DuraMags made by CProducts Defense.  However, most brands will work including PMAGs.

We use 7.62×39 magazines made by CProducts Defense.   Unlike some AR-15s, the XCR works perfectly with these mags.  We do not use AK47 mags because they have no bolt hold open feature.   

The XCR uses a gas operated piston to cycle the weapon.  This is only part of what makes it more reliable than the AR15.  Other features such as the design of the bolt, extractor, and ejector also make the XCR more reliable.

Both the XCR-L and XCR-M use a piston driven, heavy-duty, three-lug bolt with an extractor and ejector which are very similar to that of the AK47 which results in better feeding, extraction, and ejection than systems used by our competitors.

No.  We find no evidence that piston driven guns are less accurate than direct impingement ones.

The XCR does not use AR15 trigger parts.  If it did, the lower receiver would have to be .5 inches taller.  We designed the XCR to be sleeker with a superior fire control (trigger) system.  The XCR comes stock with a reliable two-stage trigger.  We can provide a straight rather than curved trigger upon request.

The trigger pull is about 3.5 lbs.

No, we do not.  Gunsmiths can make one using our parts.  Two-stage triggers are safer and are more durable.

Our lower receivers are made from 7075  T6 Aluminum.  The uppers are made from a proprietary aircraft aluminum.  It is not 6061; it is harder and stronger.

They are made 4150 steel and chrome plated.  We also make some barrels in 416 R stainless.

They are not.  There is no advantage to hammer forging.  Our barrels are all button rifled and chrome lined or stainless steel.

The choice of twist rate chosen often depends on the caliber, barrel length, and weight of projectile to be used.   The twist rates available for any caliber and barrel length are displayed on our XCR-L and XCR-M Builders.

We use 1/2×28 tpi for 5.56, 5.45.   We use 5/8×24 tpi for almost everything else. 

First of all, we recommend using Muzzle Brakes instead of Flash Hiders.  If you think you’re going to get into a fight at night, then go with the flash hider, otherwise, we suggest you choose a muzzle brake. 

For many of the calibers we offer, a muzzle brake with the gas on the right setting will eliminate most or all of the recoil. 

If you choose a muzzle break other than ours, it should have ports only on the right and left sides, or all the way around.  A muzzle device without even porting may affect accuracy.

Always remove the barrel from the upper receiver before removing or installing a new muzzle device.  You will need a vise.   Inexpensive aluminum barrel vise jaws can be purchased on Ebay. 

 If you are installing a muzzle device for a suppressor, do not use a crush washer.  Use the flat shim(s) that came with the muzzle device for the suppressor.

We can pin and weld on a muzzle device such as a flash hider or muzzle brake (either ours our yours) for $100.00.   If you send your brake to us, it must have the proper thread to match your barrel and you must put your order number on the package.

The answer to this question is personal.   Heavy contour barrels are noticeably heavier.  The best way to answer this question for most customers depends on what the firearm is to be used for.  If you mostly go to the range and shoot targets from the bench, we would suggest a heavy contour barrel.  If you are going to carry the rifle around to plink and hunt, we would suggest the light barrel.  One of the great things about the XCR is that you can own both light and heavy barrels and swap them back and forth in minutes.

The adjustable gas system meters how much gas goes from the barrel to the piston which cycles the action.   A higher number allows more gas to cycle the action.   You should use the lowest setting that reliably cycles your action.  Here’s how to find the right setting.  After you’ve broken in the weapon by firing 40 to 60 rounds, put one round in the magazine and find the lowest setting that ejects the round and holds the bolt open.  Some like to set it one setting higher just to be sure.  Each brand and type of ammo is different so you may need to change the gas setting when you change ammo.   As your XCR wears in, it needs less gas to cycle.  You may want to check again to see which is the lowest setting that holds the bolt open.

What kind of ammo are you going to use?   How good a shot are you?  With the proper ammo, we’re finding sub MOA accuracy with many of the calibers.   It’s typical to find .75 to 1.5 MOA depending on ammo.

For the XCR-L models  there are five different length upper receivers from shortest to longest – Micro, Mini, Standard, Mid and Competition.  For the XCR-M models, there are four different length upper receivers from shortest to longest Micro, Mini, Standard, and Competition.  These receivers have a 1913 Standard Picatinny Rail running down the entire length of the top.   We can machine the other three sides of the receiver with Keymod or M-LOK Rails.    

We offer two different gas systems for the XCR-L and XCR-M.  One is a Type 2 Gas System which uses a Type 2 Gas Block which is labeled GB 2 in the XCR-L and XCR-M Builders.   The other is a Type 3 Gas System which uses a Type 3 Gas Block which is labeled GB 3 in the Builders.

The Type 2 Gas System has a short piston contained in the Gas Block.  (It is similar to the gas system as found on the M14 Rifle which is a White Gas Cut off System.  Some call this a Short Stroke Piston.)   As the piston in the gas block moves, it cuts off additional gas.   Our Type 2 Gas System has the gas adjustment dial on the side where it’s easy to see and adjust.  There are six positions including off.  The Type 2 Gas System is arguably cleaner, but weighs more and has more parts.  It may also have some advantages when used with a suppressor.  The Type 2 Gas System is not available on our upper receivers that used buried gas systems.

The Type 3 Gas system has only one long piston attached to the operating rod.  It goes directly into the Gas Block (Type 3).  It has eight positions including off.   There is no separate piston in the gas block.  It has fewer parts and is smaller and lighter.   It can also fit inside our upper receivers where a buried gas system is needed such as in the Mini Buried, Standard Buried, and Competition upper receivers.  You can see these different upper receiver selections in our Builders.

If you are unsure which gas block to choose for the XCR-L, choose the Type 3 (GB 3).

The only difference between the exposed and buried gas blocks is that the exposed gas block is outside the upper receiver and the buried is inside.  The gas block is always buried when the upper receiver is longer than the gas system.  For more information, watch this video

Yes.  There is a dial on the gas block that is accessible through the oval ports on each side of the upper receiver. 

 WARNING!!! MAKE ABSOLUTLEY CERTAIN THE MAGAZINE HAS BEEN REMOVED AND THE CHAMBER IS EMPTY BEFORE ADJUSTING THE GAS DIAL.  

When the firearm is cold, you can  use two fingernails one on each side of the gad dial.   If hot, use the tip of two rounds one on each side of the dial.   

If the gas dial is too hard to turn, remove the barrel and use an allen wrench inserted into the set screw in the gas dial to use as a lever to turn the gas dial.

n ATF Form 4 is used when you are buying a Short Barrel Rifle (SBR) from a local FFL Dealer or individual.   In addition to personal information, the ATF Form 4 requires you to supply passport sized photos and fingerprints so the government can do a background check on you.   You will also have to pay a $200 one-time tax.  It can take several months to a year for your ATF Form 4 to be approved before you can take possession of you SBR.

An ATF Form 1 is used when you want to put together or manufacture a Short Barrel Rifle yourself.  It requires the same personal information, photos, fingerprints, and one-time $200 tax as the ATF Form 4.   It also takes several months to a year for the ATF Form 1 to be approved before you can take possession of the SBR.  Some prefer the ATF Form 1 because they can buy and take immediate possession of a rifle after a standard firearm background check and use the rifle while they wait for their ATF Form 1 to be approved.  Once it’s approved, they can install a barrel under 16” in length and possess their SBR.   Alternatively, they could buy a pistol and take immediate possession of a pistol after a standard background check and use the pistol while they wait for the ATF Form 1 to be approved.   Once it’s approved, they could install a stock on their pistol and possess their SBR.

Note:  Once you have an SBR, you cannot take it to another State without approval of the NFA Branch of the BATFE.

Ordering

Our products are built to order so you may not find what you want at a local dealer.  It’s best to order firearms directly from us using the Builders on our website https://robinsonarmament.com/products.  However, firearms and firearm receivers must be sent to a local Federal Firearms Licensed (FFL) dealer who can perform the required background check and transfer.   You will have to send us a copy of your FFL dealer’s license.  

Your satisfaction is guaranteed.  Should you not like your XCR, you may return it to us.  You will be reimbursed for all but the shipping fees. 

Payment Options

You an pay all up front, or we have two payment plans.  Learn More here.

Yes, we do.  Read more about it here.

The XCRs can be shot thousands of rounds reliably without in cleaning.  However, it is good practice to clean a firearm each time it is shot if only to examine the firearm to make sure it’s all in working order for the next time it is to be used.

The answer to this question is Yes.  One can hold the XCR by either hand and and manipulate all controls while keeping his eyes on the sights and target.   If one supports the XCR with the left hand, he can reach under the firearm with his right hand and easily cycle it.  (This is exactly how experienced right-handed operators cycle AK47s.)   Those who are left handed often ask whey we don’t have a charging handle on both sides of the XCR?   The answer is that the only place to put it would be near the top rail which makes it difficult to operate with optics and other accessories on the top rail.   We placed it well below the top rail in accordance with the wishes of seasoned SF operators who also wanted it non-reciprocating which it is.  Left handed shooters love the XCR because it’s easy to operate and it ejects the spent cases forward.

Under the National Firearms Act (NFA), a Short barrel rifle (SBR) is defined as,

“a rifle having a barrel or barrels of less than 16 inches in length; or a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length.”

It is illegal to possess an SBR that is not first legally registered to you with the NFA Branch of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).

For more information go https://robinsonarmament.com/xcr-rifle-sbr-or-pistol/

Robinson Armament Co. does.  We make many them in many different lengths, configurations, and calibers.   They all work extremely well.  We sell components so that you can build your own.   You must follow all NFA Rules

Update 12-29-23

Because of a decision by the 5th Circuit Court of Appeals, we can now sell Pistols with Arm Braces. That may change. If it does and you have one of our Pistols with an Arm Brace, you will have to remove the Arm Brace, make your pistol into a rifle with a 16″ barrel, or register you firearm as an SBR.

Yes, we asked this question of the ATF.  In short, they stated that you can possess a pistol and a kit containing a rifle stock and barrel 16” or longer.  However, you cannot put the stock on the pistol unless the 16” barrel has been installed first.   If you install the stock with the pistol barrel (which is shorter than 16”) on the firearm, you have made and Short Barrel Rifle that is not registered which is federal offense with severe penalties.

With such a kit, you can still File an ATF Form 1 and register your firearm as a Short Barrel Rifle.  After receiving your approved ATF Form 1, you could then use the barrel less than 16” with the rifle stock.  All NFA Rules Apply

Visit www.atf.gov

In addition to the Black, Flat Dark Earth (FDE), and Olive Drab  Green (ODG) shown on our builders, we offer almost all H-Series Cerakote, GunKote, and Gun Candy colors.   Additional Cerakote colors are $100 extra.  Two Tone and Gun Candy Colors are $300 extra. 

We offer M-LOK rails systems on the XCR.   We have discontinued making uppers with Keymod or  1913 Standard (Picatinny) Rails on the sides and bottom of our uppers.

Whether you have an Keymod or M-LOK rail system on your XCR, you can remove your barrel without removing the accessories, but you must use screws of the proper length.   Many of the screws that come with your Keymod or M-LOK accessories have screws that are longer than needed.  By simply using shorter screws, you can solve the problem.  If you cannot find shorter screws, send your accessories to us and we’ll shorten the screws for you.

When ordering online, if you don’t see the option or color you want, you can put what you want in the comments.   We will get back to you with availability and pricing.

We have a complete satisfaction guarantee.   If you order from us, and you are dissatisfied with our rifle for any reason, you may return it within 15 days of purchase for a full refund of the purchase price excluding shipping.  We will deduct for any damage that is done to the product.  So go a head and order with confidence.  We are sure you will find it to be the best product of its kind.

No.  We’ve tried to do our best to explain things in as simply and accurately as possible.  However, laws changed from time to time and differ from state to state and from city to city. You should consult the ATF, your local firearms dealer, and a lawyer for legal advice.

If you live in the US, you can return a firearm to us for repair or upgrades without going through an FFL Dealer.   You’ll want to make sure you package it so it won’t be damaged.  Make sure to get a tracking number.  You are responsible for loss during shipment so you may want to insure it.  It’s best not to have anything on the package that would indicate it’s a firearm.   For more information contact [email protected]  Our shipping address is:

ZDF Import/Export, LLC
925 W 100 N Ste A
North Salt Lake, UT 84054
801-355-0401

We can upgrade any XCR to the current specs.   If you want to see the changes that have been made to the XCR over the years, go here.   We have stopped making replacement parts for some earlier versions so it’s wise to upgrade.  The upgrades make the XCR smoother, more reliable, and more accurate.  They also make your old XCR compatible with the newer caliber conversion kits.  You can upgrade you rifle by emailing [email protected] for pricing and instructions on returning your XCR to us.  

The XCR’s adjustable gas system is a key feature that makes it exceptionally compatible with suppressors. A common issue with suppressors on autoloading firearms is the significant backpressure they generate. Excessive backpressure can lead to harsh cycling, potentially damaging or shortening the lifespan of firearm components, and can direct unpleasant and dangerous gases back towards the shooter. These problems are often made worse when using supersonic rifle ammunition in conjunction with very short barrels and suppressors.

For this reason, we do not recommend using suppressors with supersonic ammunition on XCRs with barrels shorter than 12 inches, unless the suppressor itself is designed for very low backpressure. However, if you already own a suppressor that generates significant backpressure, it will likely perform very well on XCRs with barrels 12 inches or longer, thanks to our highly effective gas adjustment system. We even offer a service where you can send us your suppressor, and we will custom-tune your XCR rifle to optimize its performance with your specific suppressor.

The length and weight of any XCR depend on the configuration you choose.  We offer thousands of different configurations.    If you want to know the the weight or length of a specific build, please use the builders on our website to configure your XCR, take a screen shot of it and email it to [email protected].   

If a round is stuck in the chamber, always treat it like the round is live.   KEEP THE MUZZLE POINTED IN A SAFE DIRECTION AT ALL TIMES AND FOLLOW THESE INSTRUCTIONS.

• Do not pound on the charging handle.
• Remove the magazine.
• Collapse the stock.
• Hold the firearm by the handguard with one hand while holding the charging handle with the other.
• Slam the butt of the firearm on the ground while simultaneously pulling down hard on charging handle.
• Note:  it may take several tries.  If you still cannot get it out, contact us.

The primary cause of the problem is that the gas is set too low causing an expanded empty case to be shoved back in the chambers.   Try a higher gas setting next time.

If a live round is stuck in the chamber, this is unusual.   Contact us. 

Feeding issues with the XCR are extremely rare.  Usually, what looks like a feeding issue is actually caused by the bolt not travelling far enough to get behind the base of the cartridge.  You can tell this is the case when the tip of the round to be fed is stuck above the chamber and the bolt smashed into the side of the case usually leaving a dent in the case.

The solution is to set the gas higher so that the bolt can get behind the base of the cartridge.

Here are some things that can help improve the accuracy of the XCR

Make sure the barrel retention bolt has been tightened correctly to 240 inch pounds.   You can usually achieve this by turning getting the retention bolt hand tight and then turning about 60 to 70 degrees.   Buy a torque wrench in inch pounds if you are not sure.

After you have tightened the barrel retention bolt, loosen the set screw on the bottom of the gas block.  If the barrel does not look centered in the upper, you can use a rubber mallet to pound the barrel right or left to center it.   Then retighten the set screw hand tight and turn the wrench another 45 to 60 degrees.  Use a new, unworn Allen wrench to avoid stripping out the set screw.   No Loctite is needed as leaking gases will help lock it in place.  

Take the wobble of the FAST2 or FAST 3 stocks.   If there is any wobble in the stock’s hinge, you can fold the stock and slightly unscrew the set screw until there’s no more wobble when the stock is deployed.  The sliding butt of the stock can be tightened with the thumb screw on its underside.  See the Operator’s Manual for more details.

Make sure you optics are mounted correctly and to the correct torque settings of the manufacturers of your optics and mounts. 

Make sure you’re using good match ammo that has the right projectile weight to match the twist of your barrel. 

We have found better accuracy with a good muzzle brake than with flash hiders.  A good break should have venting on both sides only, or equal vents all the way around to balance the barrel when fired.

Sometimes when rounds are loaded in the chamber, the projectiles can be marred.  Polishing the bottom and sides of the barrel extension can improve this.

Check the crown of your barrel.  If it looks uneven or has some burrs, recrowning my help. 

If you have an older XCR-L with the Type 0 or 1 Gas block, upgrading to the Type 3 Gas block and Type 3 Gas Tube can help.

If you have an older XCR-M with the Type 2 gas system that wasn’t fit to the gas tube, having us upgrade that will help.  Many of those rifles were also shipped with 7.62 NATO chambers which didn’t help accuracy.

The trigger pull can be improved by shortening the second stage and polishing the parts.  This should only be done by a competent gunsmith.  You become responsible for any liablity.  

The best way to contact us is by email to [email protected] for sales questions, or to  [email protected] for technical assistance.   

We are trying to implement our Chat system to answer most of your questions instantly.  Just click on the little speech bubble on the lower right corner of the screen to start the chat session. 

We don’t answer the phone often, but if you leave a message, we will call you back as soon as we can.  You can also text or fax us on 801-355-0401.  

We do not take orders over the phone.  

We do!  It’s 10% off almost everything.   Here’s how to get the discount.  Before placing the order, send proof to [email protected].   You will be given a discount code valid for a few days.  Use it when ordering on our website.

Yes, the bolt of the XCR is must stronger than AR15 bolts and is designed to handle higher loads.  It will not break when using properly manufactured 6mm ARC or 6.5 Grendel ammo. 

At the rear of an XCR lower receiver, there is usually a folding hinge, non-folding stock adapter, picatinny rail adapter or AR15 adapter with a QD sling swivel mounting hole on the bottom.   The FAST3 Stock and Tail Hook Arm Brace have QD sling swivel mounting holes on both sides.  The FAST2 stock has a small hole through which cord can be attached or you can mount an aftermarket QD Sling  swivel attachment like this.

For forward sling mounting positions, we suggest you use something like this attached to the top rail so that  your sling doesn’t interfered with the charging handle.

You can also find QD mounting accessories for M-LOK and Keymod that attached to those rail system. Like this.

To become a dealer, please send your FFL to [email protected].   There is a minimum order of 2 firearms. 

Yes, we can export to other countries.  Contact your local importer of firearms and have them contact us [email protected]  They will need to fill out a form BIS 7-11 and provide a copy of their import license.  If their country doesn’t require and import license, we need a letter saying so.