Barrel length/cycling problems

hicaliber

hicaliber

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I have read about people having reliability problems with short barrel uppers.
At what length do these usually occur?
I am thinking of having a barrel shortened to 11.5" but want to avoid these problems.
 
To be legal and avoid this issue you'll want to buy a new barrel (if you can find one) or have a new barrel made.

I've spoken to two smiths who are knowledgable and they will not shorten any barrels to lengths less than 18.5" (yes, even though it is already restricted).

The problem you are referring to though is a gas port problem; the gas port on longer barrels is smaller than on the short barrels. If you "chopped" a 20" barrel to 11.5" (and gas port size didn't change) you could have a reliability problem.
 
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Typically the 14.5" smaller gas ports ( last time I stuck a pin gauge in one I seem to recall .062" - don't have one handy to measure now.

Obviously we are talking carbine length gas port . If you start with a rifle length barrel and rifle gas port and buck the barrel down the gas port would not be in the ideal location

I just measured the port size on a Noveske and WOA 10.5" and they are both about .080"

My LMT 10.5 has a relatively smaller port of about .071" . The reason for this is LMT would never expect a user to run anything other than NATO pressure ammo. They also have the port on the small side to run with a can ( go luck with that in Canuckland ) This was the way it was explained to me by LMT when I called them and asked why my 10.5 sometimes short strokes with SAMI pressure .223 ammo.

They suggested to try a Noveske KX-3 since it helps build some back pressure to help cycle . It seems to work

I don't see a need for a KX-3 on other 10.5s however. LAst 2 10.5s I cobbled together ran like a top without the KX-3 and now wear Vortexes

Keep in mind that buffer weight ( H2 , H3 , 9mm , Enidine etc ) also has somthing to do with this as well

Keeping in mind I'm just a hobby guy that and far from being a professional but in my opinion, you should have no problems with reliability if you buck the 14.5 to 10.5 assuming you have a proper sized gas port. BTW you need to ream out the port a bit at at time so there is no burr in the bore side of the gas port. Don't even think about using a drill bit

Bottom line, if you have a 10.5 and its not 100% reliable its not set up right
 
TRG-42 said:
Typically the 14.5" smaller gas ports ( last time I stuck a pin gauge in one I seem to recall .062" - don't have one handy to measure now.

Obviously we are talking carbine length gas port . If you start with a rifle length barrel and rifle gas port and buck the barrel down the gas port would not be in the ideal location

I just measured the port size on a Noveske and WOA 10.5" and they are both about .080"

My LMT 10.5 has a relatively smaller port of about .071" . The reason for this is LMT would never expect a user to run anything other than NATO pressure ammo. They also have the port on the small side to run with a can ( go luck with that in Canuckland ) This was the way it was explained to me by LMT when I called them and asked why my 10.5 sometimes short strokes with SAMI pressure .223 ammo.

They suggested to try a Noveske KX-3 since it helps build some back pressure to help cycle . It seems to work

I don't see a need for a KX-3 on other 10.5s however. LAst 2 10.5s I cobbled together ran like a top without the KX-3 and now wear Vortexes

Keep in mind that buffer weight ( H2 , H3 , 9mm , Enidine etc ) also has somthing to do with this as well

Keeping in mind I'm just a hobby guy that and far from being a professional but in my opinion, you should have no problems with reliability if you buck the 14.5 to 10.5 assuming you have a proper sized gas port. BTW you need to ream out the port a bit at at time so there is no burr in the bore side of the gas port. Don't even think about using a drill bit

Bottom line, if you have a 10.5 and its not 100% reliable its not set up right
Click to expand...

I wonder why LMT wouldn't just make and adjustable gas block? Or do they? It seems that for reliability and to use a suppressor it would be what they SHOULD do to make it as reliable as possible. Or is an sdjustable gas block a no no on a direct gas AR?
 
Clobbersauras said:
I wonder why LMT wouldn't just make and adjustable gas block? Or do they? It seems that for reliability and to use a suppressor it would be what they SHOULD do to make it as reliable as possible. Or is an sdjustable gas block a no no on a direct gas AR?
Click to expand...

Most adjustable AR gas blocks ( PRI etc ) are not practicle to adjust on the fly ( set screw adjustment ). The new Noveske Switchblock is designed to address those concerns ( can flip from supressed to non easily )

Having said its not an issue at all with LMT because they don't expect any of their customers to be running only NATO pressure ( like the SAAMI pressure 223 or the Wolf ) . It would be analogous to an owner of a Corvette not running premium gas

LMT does know a thing or two regarding ARs. My 10.5 LMT runs like a top with 5.56 . It only short strokes slightly ( ocassionally doesn't lock back on empty mag ) with underpowered loads AND an Enidine buffer. I only run full power handloads and M193 ( Federal )
 
You'll find a similar thread started by me on this very same subject of shortening a barrel, it is not against the law to do so, I called the CFC to ask and they said you are not changing the class of firearm so it does not matter, you can already buy a 7.5 inch barrel, and 20 inch barrels, it does not make the rifle anymore RESTRICTED, you can do whatever you like to your barrel.
 
ajayofcanada said:
You'll find a similar thread started by me on this very same subject of shortening a barrel, it is not against the law to do so, I called the CFC to ask and they said you are not changing the class of firearm so it does not matter, you can already buy a 7.5 inch barrel, and 20 inch barrels, it does not make the rifle anymore RESTRICTED, you can do whatever you like to your barrel.
Click to expand...

Things got a little off track I am more concerned with the gas system problems and building a reliable shorty.
 
ajayofcanada said:
You'll find a similar thread started by me on this very same subject of shortening a barrel, it is not against the law to do so, I called the CFC to ask and they said you are not changing the class of firearm so it does not matter, you can already buy a 7.5 inch barrel, and 20 inch barrels, it does not make the rifle anymore RESTRICTED, you can do whatever you like to your barrel.
Click to expand...

And who exactly did you speak to when you "called CFC"? Some lady who basically is a data entry clerk for inputing transfer requests? These people do NOT know all of the regulations and should not be relied upon for this kind of info.

Call CFC again and this time ask to speak to a knowledgeable person in Ottawa at the Registry Section or better yet at the Classifications Section. Quote them the section in the Firearms Act (that releates to this issue) and then ask them if they can please send you a WRITTEN ruling on whether you can do what you are asking.

If it isn't in writing then it's meaningless... and the minute you ask for it in writing you'll see if the person you're talking to actually has the knowledge and authority to answer your questions :)

Mark
 
The only problem I had with my 10.5" was remedied by installing a stonger extractor spring and proper (black) plunger. Before then, I was getting double-feed stoppages when a casing would only partially extract and new round picked up by the bolt would become jammed into the base of partially extracted case. This is a very typical problem with shorties, but a cheap fix.
 
TRG-42 said:
Most adjustable AR gas blocks ( PRI etc ) are not practicle to adjust on the fly ( set screw adjustment ). The new Noveske Switchblock is designed to address those concerns ( can flip from supressed to non easily )

Having said its not an issue at all with LMT because they don't expect any of their customers to be running only NATO pressure ( like the SAAMI pressure 223 or the Wolf ) . It would be analogous to an owner of a Corvette not running premium gas

LMT does know a thing or two regarding ARs. My 10.5 LMT runs like a top with 5.56 . It only short strokes slightly ( ocassionally doesn't lock back on empty mag ) with underpowered loads AND an Enidine buffer. I only run full power handloads and M193 ( Federal )
Click to expand...

Thanks for this, good info.
 
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