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There has been a lot of back and forth in this article regarding the operating system of the XCR. Specifically, some argue that it is of the short-stroke type, and some that it is of the long-stroke type. In my last edit, I reverted a change so that the article (which now reads short-stroke) would be in agreement with the article on gas operation (http://en.wikipedia.org/wiki/Gas_operated). Apparently, to some this is unsatisfactory.

I propose that the references to stroke, either short or long be removed from this article until a source can be provided to show that one or the other view is correct. Once everyone is satisfied with the reference, then we may edit this and other related articles to reflect what we've learned.

The discussion seems to be one of semantics. The Gas Operated article refers to a long stroke as one where the piston moves under pressure for a distance greater than it's diameter. Short-stroke is where the piston moves under pressure for a distance less than it's diameter. The key words are under pressure. The distinction is made between a long and slow gas impulse that moves the parts the length of the weapon's operation and a sharp and fast gas impulse that imparts momentum to the piston and operating group of the weapon and is afterward vented. This definition, if true, means that the XCR (and pretty much every other modern gas-op firearm) uses the short-stroke operation. It can be summed up by saying that the stroke refers to the length of time that gas pressure impinges on the piston. The gas is what's doing the stroking, not the piston.

The other view is that the term stroke is entirely independent of how long gas impinges on the piston, and refers only to how far the piston moves: either longer or shorter than it's diameter. This definition would have the AK-47, the XCR, and any other weapon where the piston moves the same distance as the rest of the operating group as a long-stroke operation. I believe this is the common usage of the term as applies to engines. The difference is that in engines the diameter of a piston contributes an effect on the operation of the engine, but in firearms the diameter of a piston contributes nothing to the operation (and probably only affects the rigidity and weight of the piston itself, and the effect that that has on felt recoil). In this definition, it's the piston doing the stroking, not the gas.

I'll see if this generates any discussion and make the change to stroke free in a couple of days if we haven't got it resolved by then. CrunchRiff (talk) 06:26, 6 July 2008 (UTC)[reply]

It's a long-stroke system. The op-rod is attached to the bolt I believe. If you look at the disassembled weapon picture (here: http://www.robarm.com/XCR_Fieldstripped.gif), you can see that it attaches to the bolt-carrier. It isn't captive, but assembled, it attaches directly to the bolt and stays that way. Short-stroke piston systems instead strike against it once and only once, and the bolt would go back and cycle. This isn't semantics. Long-stroke systems and short-stroke systems differ mainly in that either the piston is or isn't attached to the bolt carrier. The AK is a long-stroke, the FAL is short-stroke, so is the SVT-40 and whatnot.

So it's long-stroke gas system.--76.200.150.0 (talk) 03:43, 18 May 2009 (UTC)[reply]

Made a change to the wiki, to change the clause that states the 3.5 lb 2 stage trigger is in development to be released and for sale. —Preceding unsigned comment added by 76.200.158.37 (talk) 22:43, 18 May 2009 (UTC)[reply]

Updates & Improvements

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In researching the XCR I had to scour the forums and other sites to find information on what updates and improvments Robinson Arms has made since the rifle's introduction. Today I figured I'd contribute what I learned here, but went back into the history of the page first. I found a recent (May 2009) addition that had subsequently been removed (July) with the comment of "removed marketing". I can sorta see how this content, as written appears as "marketing", but I do know it was PRECISELY the kind of factual information I would have expected to find in this article.

In fact, articles for other rifles in this genre, for example the AR-15 or M16, include this sort of information in "History" section. I'd like to suggest the following updates be made to this article which I copied/paraphrased from the update that was removed in July.

It would be great if there were authorative sources for each of these, other than xcrforum.com. cek 05:31, 9 September 2009 (UTC)[reply]

History and variants

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The XCR was designed in 2004 by Alex J. Robinson fo Robinson Armament Co. Production of the XCR-L variant of the rifle began in mid-2006.

The XCR-L is currently available in 5.56mm, 6.8 Remington SPC and 7.62x39mm cailbers.[1] Each of these calibers is available in kit form for converting an existing rifle to one of the other cailbers.

The 6.8 Remingon SPC variant began shipping in November of 2007.[2]

The 7.62x39mm rifles and conversion kits began shipping in July 2008.[3]

In August 2009 Robinson Arms began shipping 3 different sized upper receivers enabling PDW and pistol style variants:[4]

  • Standard Upper Reciever - The original length and designed to support barrel lengths from 11" to 18.6".
  • Mini Upper Recievers - 15.25" long and designed to support barrel lengths from 9" to 18.6". Primarily intended for barrel lengths from 9" to 10".
  • Micro Upper Recievers - 13.25" long and designed to support barrel lengths from 7.5" to 18.6". Primarily intended for barrel lenghts from 7.5" to 8".

Variants are also available in "California" versions which are limited to meet the more restrictive State of California firearms laws.

Since its introduction in 2006, components of the XCR have been updated. Most of these enhancements are available to existing XCR owners.

  • In November 2006 the firing pin was redesigned and made more durable and robust. [5]
  • The first few hundred XCR's shipped with Yankee Hill Machine (YHM) back up iron sights (BUIS). The most recent iteration ships either without BUIS or with BUIS designed by Midwest Industries.
  • A 2nd generation adjustable gas system started shipping with XCR rifles in July 2007. The 1st generation gas system required tools (a 5/8" wrench) to adjust. The 2nd generation system can be adjusted by hand.[6]
  • The XCR's hammer was updated in July 2008 concurrent with the release of the 7.62x39 rifles/kits. The new heavier design allows the XCR to ignite some newer Wolf 7.62x39 ammunition made with extra-hard primers.[7]
  • In early 2009 Robinson began shipping rifles with an integral winter style trigger guard and new paddle style safety. A provision for a quick detachable sling loop was added to the stock mount.
  • A two stage match trigger is available which will break at approximately 3.5lbs. This trigger can be ordered with a new rifle or retrofitted to an older one. The older one was a two stage trigger that was about twice as heavy, and some complaints included trigger slap. As of May 2009, the trigger has been shipping with all new rifles.

References

  1. ^ http://www.robarm.com/XCR_Cal_Conversion_Specs.asp
  2. ^ http://www.robarm.com/News_Archive.htm
  3. ^ http://www.robarm.com/News_Archive.htm
  4. ^ http://www.robarm.com/Forthcoming_Products.htm
  5. ^ http://www.robarm.com/XCR_Upgrades.htm
  6. ^ http://www.robarm.com/XCR_Technical_Updates.htm
  7. ^ "XCR Forums".

Changes by Serial number

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I've had about 15 xcrs come through my shop ranging from 1100-8500 on the sn. If noticed the updates and tried to see where the updates happened. Some of this is on the wiki too.

1114 had the newest gas system but was a retro by RA, old style bolt. Terra said no 6.8s were made with the old style bolts. Assume that applys to the 7.62x39 also 1253 new style bolt, larger barrel bolt 2421 still had larger barrel bolt. 3855 integral trigger guard back 1/4 barrel bolt 4390 new trigger and ambi safety, new bho 5129 new oprod 5437 still had lite cuts in the upper 8202 new style break open, one piece oprod, ambi everything, mil spec rails, fast, noticed the gas tube doesn't rattle and appears to be slightly different than the original design.

Not meant to be the go to. Just what I have noticed. Not to say some upgrades were added to older rifles before I saw the rifle. — Preceding unsigned comment added by 173.181.79.37 (talk) 10:13, 25 April 2013 (UTC)[reply]


Sources?

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I tried to track down some of the facts in this article, but most of it is unsourced. Further, the links are mostly inoperative. I see that at least one section has been tagged for six years. Maybe it's time to clean up this article and remove unverifiable material. Any other suggestions? Rezin (talk) 22:12, 16 October 2014 (UTC)[reply]

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