andrew3081
CGN Ultra frequent flyer
- Location
- Vancouver, BC
Snopac beat me to it..I got mine from wolverine supplies.
XCR-L, can it be built better?
- Thread starter Zeroed-In
- Start date
I'm confused. In post 95 you stated "as I've learned from the actual completed modification using a Herron Arms SS barrel" but now you can't be bothered to search. Search for what? Did you do a Herron arms barrel conversion on your XCR or read it somewhere?
I think a match grade barrel would improve the accuracy slightly but the biggest flaw in the design of the XCR when it comes to repeatable consistent accuracy is the barrel retention system and until that is addressed the rifle will always be limited in accuracy potential no matter what barrel is installed. The rifle was designed to be a battle rifle so accuracy is not what it was designed around. It does do what it was designed to do and it for the most part does it well. If Rob Arms could tighten up it's QC the rifle would be a real winner, if it wasn't for the fantastic support Wolverine is providing all the guys that have problems the rifle would be in serious trouble here in Canada.
+1
I was happy this thread was going the way of the dodo, but he was referring to my post about barrel harmonics, so I did the research for him that I already knew:
"Second, part of the weight is a more secure (and often heavier) gizmo bolted on the barrel up front. That weight makes the barrel harmonics of firing a different thing than the DI system. You see, every time you fire, your barrel gets hit as if by hammer. It vibrates. Accuracy is the bullet leaving the muzzle at the same point in the barrel harmonics on each shot. If the barrel harmonics vary, so will accuracy"
And
"The stresses can be from the original steel bar, or be added in the machining or straightening process. As the barrel heats up, the stress lines “unkink” and the barrel points differently. It also changes the harmonics, and thus, potentially, accuracy. (A brief aside: hammer-forged barrels have the stress lines pounded out of them, and cryogenically-treated barrels have the stress lines relaxed.) If the AR-15 piston is a firmly-held object between block/barrel and receiver, it can lever the receiver as the barrel heats up and unkinks."
This is from:
http://www.gundigest.com/tactical-gear/tactical-guns/ar-15-pistons
Written by:
Patrick Sweeney:
Patrick Sweeney is Gun Digest‘s resident AR-15 expert. Read all four of his books in the Gun Digest Book of the AR-15 Series Set. The set contains volumes one through four of Sweeney’s Gun Digest Book of the AR-15 at a much better price than if purchased separately.
He's a master gunsmith.
It applies to all piston operated firearms.
As Cal9mm states in the next post after yours I was quoting him from earlier post he had made. Yes I've learned from another CGN'er who has completed the swap to a Herron Arms SS match barrel along with improvements to the retention system, that accuracy was greatly improved by the swap. So with some more funds laid out the XCR can be made into a more consistently accurate rifle.
Thanks to everyone for all the input, it was educational as well as entertaining.
Only problem with your theory on piston operated rifles not being able to shoot is that my PWS printed it's first sub moa group yesterday with factory ammo. I had never tried quality ammo in it before and decided to try some Black Hills 77gr match and I was very impressed with the results.
100yds with an Elcan Specter DR.
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I'm very curious to see what gains were had from it. I've never heard of Ian building a barrel for a black rifle other than an AR for less than $800.
I would expect to see it go from 3-4moa to 2-3moa with a better barrel.
Yay for your PWS, so based on one group from one rifle, my theory is wrong? OK, I'll grant you that, maybe your rifle is the standard to which all piston driven rifles aspire too, but...... Patrick Sweeney's theory and experience is wrong? Isn't he paid as a guns and ammo magazine editor to find these things out?
http://en.wikipedia.org/wiki/Patrick_Sweeney_(gunsmith):
Patrick Sweeney is an American gunsmith (retired), originally from Detroit, Michigan. According to an interview with Shotgun World magazine, he is a well-known author in the field of gunsmithing.[1] Retired from gunsmithing, his writes full-time. He teaches law enforcement classes on the patrol rifle, and gunsmithing the AR-15.
In addition to writing books, he is the Handguns Editor of Guns & Ammo magazine.
He has an impressive bibliography too:
Bibliography[edit]
Sweeney, Patrick (2009). Gunsmithing: Pistols and Revolvers. Gun Digest Books. ISBN#978-1-4402-0389-3.
Gunsmithing: Rifles
Gunsmithing: Shotguns
Gun Digest book of Smith & Wesson
Gun Digest Book of Ruger
Gun Digest Book of Glock, 1st & 2nd Editions
Gun Digest book of the AR-15, Vol 1, 2, 3 & 4
Gunsmithing: AR-15
1911: Vol 1&2
1911: the first 100 years
The Big Fat Book of the .45 ACP
Gun Digest book of the AK & SKS
Encyclopedia of Rifles & Machineguns (co-authored w/Will Fowler)
Gun Digest Book of the Tactical Rifle
Reloading for Handgunners
Please quote me where I said they can't shoot, I happen to know they can. I simply said they are at a mechanical disadvantage against DI in regards to accuracy.
EDIT: look dude, I generally agree with you on various topics, We might differ in minor details but generally I agree with you, including this one. And this one:
"This is something we agree on. The internal piston system of the DI rifle is a great design and is one of the reasons the AR is one of the most accurate semi auto rifles out there.
I own both piston and DI rifles and both are great. Each has positives and negatives but the only negative to the DI system is the gas venting in your face. The claims of cleaner and cooler only make a difference when running high volume full auto. 5 round mags semi auto at a range would require someone to run a couple thousand rounds through each rifle to see any difference.
I don't like my PWS rifles because they are external piston design, I like them because they are built extremely well and have so far been 100% reliable after thousands of rounds.
You're right, there is nothing wrong with a DI rifle. The external piston is just another way to do the same job."
And
"In this case only because owners in past posts were blaming their 8 pound trigger for why the rifle couldn't shoot tight groups and raving about how a better trigger would drastically tighten up groups.
I don't expect much change in the accuracy department but the rifle will be nicer to shoot.
I've stated many times that these and rifles like the XCR and ACR are battle rifles and that 4 moa is exactly what they were designed to deliver. If they can shoot better than that then that's great but I don't expect much more. If you can hit a 12 inch plate at 300yds your rifle is working perfectly.
I actually think it's funny when guys spout off about how a $2000+ rifle should be sub moa for that price." ect.
I assumed, and may have incorrectly, you were being facetious in regards to the "my" theory comment. Thus my cynicism and sarcasm. If you were being facetious then:
"I actually think it's funny when guys spout off about (insert name) guns can shoot sub MOA based on one photo with 5 holes (isn't 10 the base line standard?) from one gun (that's not even pictured too) and think that's the standard for all guns of the same family/manufacture/caliber/action ect."
If you weren't being facetious, then I apologize.
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Cal9mm,
I agree that the external piston rifle is at a slight disadvantage to a DI rifle but that isn't why most XCR's don't shoot well. The method Rob Arms used to attach the barrel is the problem with the XCR.
Sweeney is right but it isn't the huge difference most think it is.
Honestly none of this really matters as it mostly comes down to the finger pulling the trigger. I've witnessed on many occasions someone I'm shooting with makes groups (shooting off a rest) that they aren't happy with and ask me to try their rifle with the same ammo, groups usually shrink.
You're 100% right, I need to go make more groups with the expensive ammo.
This kinda sucks though, now I'm going to have to develop some handloads for that rifle as well. I wasn't expecting it to be able to shoot that well and I can't afford to feed it Black Hills match every time I shoot it.
I agree that the external piston rifle is at a slight disadvantage to a DI rifle but that isn't why most XCR's don't shoot well. The method Rob Arms used to attach the barrel is the problem with the XCR.
Sweeney is right but it isn't the huge difference most think it is.
Honestly none of this really matters as it mostly comes down to the finger pulling the trigger. I've witnessed on many occasions someone I'm shooting with makes groups (shooting off a rest) that they aren't happy with and ask me to try their rifle with the same ammo, groups usually shrink.
You're 100% right, I need to go make more groups with the expensive ammo.
This kinda sucks though, now I'm going to have to develop some handloads for that rifle as well. I wasn't expecting it to be able to shoot that well and I can't afford to feed it Black Hills match every time I shoot it.
Word.
And see this is one of those minor differences I was talking about. I don't see the retention method as negative. Bolt locks inside the barrel extension anyway. And as long as battle standard accuracy is maintained then whats the issue? Ease of maintenance and modularity is also highly desirable too in a battle rifle. Could it be better? Sure it could. But why fix something that's not broke in the first place?
With my reloads, same twist, out of DI (16" bbl) I'm getting 1" and with piston (18.5" bbl) i'm getting 1.25.
I was of the opinion that piston rifles were not as accurate, by a large margin.
The acr has changed my tune though. With a quality barrel, it's shooting almost as well as a high end, direct impingement ar15.
You obviously care, or you would not have taken the time to make that reply. Not sure how that could send you into a tailspin, it was a simple statement.
?........
Okay guys this is going to sound lame, but I cannot find the post to corroborate the info. of exactly what was done and for what gains (I went back more then eight pages in the black guns forum, perhaps I read it in another forum?).
I can only tell you from memory that it was another CGN'er from Alberta that had posted up regarding an improvement to their XCR-L by swapping to a S.S. Herron Arms match grade barrel with a cost of around $1,000 or just over (this included labour to modify and/or secure the barrel better as well, however no info. was given as to what was done to improve the barrel retention system). There was no mention of the exact gains in accuracy achieved, only that accuracy was significantly improved and it was money well spent.
I'm sorry for not being able to substantiate my words better and will keep looking for this members particular post. (2 out of 3 ain't bad)
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Hello Zeroed-In:
Was this the post you were looking for?
http://www.canadiangunnutz.com/foru...-Grendel-XCR?p=8381652&viewfull=1#post8381652
Have a nice day.
Regards,
Chizzy
