Frequently Asked Questions

Q:  What does XCR stand for?

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

Q:  What is the XCR?

A:  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, or an H&K 416 or 417 – 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.

Q: How long has the XCR been in production?

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

Q:  What calibers is the XCR Chambered for?

A:  The XCR-L is chambered for 5.56 (.223), .300 Blackout, 7.62x39, 6.8 SPC II, and 6.5 Grendel.  We’re still working on 5.45x39 but it’s not available at the moment.

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

Q: Can I shoot 5.56 in barrels marked .223 and vice versa?

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

Q:  Can the XCR-M model shoot the smaller calibers such as 5.56 (.223)?

A:  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.

Q:  Will the XCR cycle steel cased ammo reliably?

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

Q:  How do you change calibers on the XCR-M?

A:  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, only a barrel change is necessary which takes two minutes.

Q:  What magazines does the XCR-M use?

A:  It uses the most popular .308 magazine for autoloaders which is the SR25 pattern .308 magazine made by several companies including DPMS, CProducts Defense, ASC, and Knight’s Armament.  Magpull plastic magazines will work in the XCR-M but are not recommended.

Q:  How do you change calibers on the XCR-L?

A:  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.


Conversion Caliber
Existing Caliber 5.56 .300   6.8 7.62x39 6.5
5.56 A B C D C
.300 B A C D C
6.8 C C A D C
7.62x39 D D D A E
6.5 C C C E A


Legend for Caliber Conversion Chart.  Parts Needed to Convert

A = Nothing
B = Barrel, Gas Tube, Operating Rod; or just the Barrel if your 5.56 barrel has a blackout length gas system.
C = Barrel, Bolt, Magazine

D = Barrel, Bolt, Firing Pin, Magazine

E = Barrel, Firing Pin, Magazine

Q:  What is the torque setting for the bolt that holds in the barrel?

A:  Only a 1/4” Allen Wrench is used to remove and replace the barrel.   It is recommended that you tighten the bolt with a torque wrench set to 240 inch pounds each time you remove the barrel.  You can achieve something close to this without a torque wrench by getting the bolt hand tight using the wrench and the trying to turn the bolt another 60 degrees.

Q:  What magazines are used to shoot the different calibers in the XCR-L?

A:  The hole in the magazine well of the XCR-L is the same size as an AR15.   For 5.56 (.223) and .300 Blackout, a standard AR15/M16 magazine is used.   For calibers 7.62x39, 6.8 and 6.5 Grendel, special magazines in many capacities are made by companies such as CProducts Defense in Florida.

Q:  I’ve read on the web that 7.62x39 doesn’t work reliably in the XCR because of the magazines?  Why don’t you make an XCR with an AK47 magazine well?

A:  We had a lot of problems with the quality of AR15 magazines made in 7.62x39 for a few years.  Once we switched to the CProducts Defense magazine in 7.62x39, we have not had problems.  We guaranty that the XCR will function reliably with the correct magazine in all calibers we offer.

We have thought seriously about making an XCR-L version with a 7.62x39 magazine well, but in doing so the bolt would not be held back when the magazine is empty (an important feature) and the CProducts Defense magazines are working very well so it really is not necessary.

Q:  Does the XCR use a piston to cycle the action or is it direct impingement?

A:  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.

Q:  Aren’t piston driven guns less accurate than direct impingement?

A:  Wrong Buckwheat.  We find no evidence that piston driven guns are less accurate than direct impingement ones.

Q:  Describe the XCR’s action?  What kind of bolt does it use?

A:  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.

Q:  Does the XCR use AR15 trigger parts?

A:  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.  More trigger options will be available in the future.

Q:  What is the weight of the trigger pull?

A:  The trigger pull is about 4 lbs.

Q:  Do you offer a single-stage trigger?

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

Q:  What are you lower and upper receivers made from?

A:  The lower receiver is made from a 7075 forging.  The uppers are made from a proprietary aircraft aluminum.  It is not 6061; it is harder and stronger.

Q:  What are your barrels made from?

A:  They are made from either 4140 or 4150 steel and chrome plated.  We also make some barrels in 416 stainless.

Q:  Are your barrels hammer forged?

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

Q:  What barrel twist rates are available?

A:  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.

Q:  Should you purchase a light or heavy contour barrel?

A:  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.

Q:  What kind of accuracy can I expect?

A:  What kind of ammo are you going to use?   How good a shot are you?  You can expect 1 to 1.5 MOA or better using good ammo for our 2017 model year rifles.  Some of our customers are reporting groups well under 1 MOA.   Older XCRs can be accurized for a fee.

 Q:  What upper receivers are available?  Please explain them.

A:  For both the L & 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 upper receiver and Keymod rail system holes on the sides and bottom.    We can also make upper receivers with 1913 Standard rails on all four sides, but they are heavier.   You can always add 1913 Standard Rail segments to the Keymod upper.  They are available from many sources such as Bravo Company and Brownells.

Q:  What’s the difference between the Gas Block (GB 2) and Gas Block (GB 3) in your Builder?

A:  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.

Q:  Can you adjust the gas system when the gas block is buried inside the upper receiver?

A:  Yes.  There is a dial on the gas block that is visible through the oval ports on the upper receiver.  It is very simple to adjust the gas dial with the tip of a cartridge.

Q:  Do you make Uppers with the M-Lock Rail System.

A:  No Buckwheat.  You’ve been reading too much propaganda (fake news) on the web.  The Keymod system is highly superior to M-Lock because it precisely and firmly fixtures accessories.   If you must have the poorly engineered M-Lock system because you buddy has it and says it’s cool, we can probably make it for you but it will make your upper heavier and uglier.

 Q:   Do you make models for states with special legal requirements such as California, New Jersey, Massachusetts, etc?

A:  Yes, we do.  We currently make compliant models or these states and for other countries.  Let us know your state’s requirements.  Chances are we can build a rifle or pistol to conform you those requirements.

Q: How often should the XCR be cleaned?

A:  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.