View Full Version : Mid-length upper on a rifle lower?
I just recently bought a Spikes 14.5 Mid-length upper and have been using it on my Colt 6940 lower.
I am looking to pick up a lower and, since I live in the People's Republik of New Jersey (where adjustable stocks magic transform rifles into assault weapons), have been considering putting an A1 stock on the gun. They are nice and light, about the right length for me (maybe a little long), and the improved cheek weld over M4 type stocks makes it worth it.
The one question I have is what to run in the rifle tube. The lesser dwell on a 14.5 means that there will be less gas pushing back (http://www.03designgroup.com/technotes/carbine-vs-mid-length-gas-system).
I have seen that some folks run an H1 buffer. Some have even put a spacer in the end of the tube to make it carbine length, then run a carbine spring and buffer.
Any recommendations? Thanks.
Run a rifle buffer and spring. The rifle length system is much more accommodating of different gas systems than the carbine length system.
I was worried about the mid length 14.5 being undergassed for the rifle length tube and buffer. I will try it out and see how it goes.
One of my rifles is a PSA middie using an A2 buttstock. It's a very soft shooter, works perfectly.
Cowtown556
08-04-12, 07:26
Both my mid lengths have rifle buffers and stocks,no problems.
Awesome. I am glad to hear it. Thanks for the replies!
I did some measuring recently and realized that I was running my stocks out at lengths that in some cases exceeded the length of even the A2. So I ordered an A1 Cavarms stock from Brownells and I'm going to do some playing around with the A1 and A2 stocks and various uppers to see what I get. I have a BC 14.5" with pinned PWS brake and that was one of the first things I was planning on attaching to the new lower(s).
I did some measuring recently and realized that I was running my stocks out at lengths that in some cases exceeded the length of even the A2. So I ordered an A1 Cavarms stock from Brownells and I'm going to do some playing around with the A1 and A2 stocks and various uppers to see what I get. I have a BC 14.5" with pinned PWS brake and that was one of the first things I was planning on attaching to the new lower(s).
Rob,
I have had excellent results with the later A1 take offs from Numrich at:
http://www.gunpartscorp.com/catalog/Detail.aspx?pid=564730A&catid=13510
These are usually in VG-Exc condition (unlike the cheap non-storage compartment models). If you don't like the few minor scratches, you can shoe polish or paint. I have ordered at least six and have never seen rust. They appear to be at least as tough as Colt A2 stocks from the late 80s to early 90s, and, weigh about 2.5 oz (16.25 compared to 13.75 oz.) more. (Making me think they are very well constructed indeed.) They cost about 1/2 a new Cav stock, and, as I stated, are probably more durable. Don't forget the A1 screw. (Not meant as an insult, but I have forgotten to do that before, and I knew better.)
My only concern with running a 14.5" midlength on a rifle lower comes from a note at the bottom of the AlphaOps website concerning the Vltor A5 system, reading:
'Special Note
The A5 Buffer system has been known to cause short-stroking in 14.5 inch Mid-length DI uppers. Just an FYI!'
Yeah, I know they are different systems, but the A5 is closer to the rifle system than other carbine systems, so ... I have a few concerns until I can test it, and I don't have a 14.5" midlength.
Please let us know how it turns out.
jonconsiglio
08-04-12, 11:06
I've been running a BCM 14.5" on a Vltor A5 for about 10 months now. It was sluggish with the standard A5 buffer, so I lightened it by replacing one tungsten with a steel weight, per Vltor's instructions and it's been fine ever since. I usually only shoot 5.56 ammo, but 223 has run fine as well.
I can't see there being much difference between a rifle RE and an A5 when it comes to the 14.5" mid length, but I haven't tried it, so I can't say for sure. Of all my rifles, the only one that feels more solid with a carbine RE is the 14.5" BCM mid length.
I finally put together my rifle, a Noveske Chainsaw Gen 2 lower, Fulton Armory A1 stock with rifle tube, rifle buffer and spring, and the Spikes 14.5 mid-length upper. I took it to the range on Sunday to sight it in and test function, and shot 60 rounds of PMC 223 through it slow-fire with only one feeding/extraction incident. But what an incident it was. The fired case did not extract. The new round was halfway forced in the chamber. The charging handle would not budge. I ended up having to use an aluminum rod and mallet to force back the bolt and clear the jam. At this point I am going to just keep shooting 223 and 5.56 though it and see how things go. I don't think there is anything you could do with a rifle buffer (7 steel weights) short of removing one of the steel weights. I suspect I am going to have to make a wood dowel spacer to put in the tube, and go with a carbine spring and buffer. We shall see. As always, any suggestions would be appreciated.
lifebreath
08-27-12, 10:04
I run a 16" Noveske mid-length upper on an A2 with no problems.
I run a 16" Noveske mid-length upper on an A2 with no problems.
Thanks. It makes me think that extra 1.5" of dwell time you have is significant.
Thanks. It makes me think that extra 1.5" of dwell time you have is significant.
The extra 1.5 is ALL THE DIFFERENCE in the world.
not even comparible to the 14.5. You need to have every part just right to run a rifle buffer reliablely.
I just got through changing the gas tube on my 14.5 middy. The part the tube that the gas key slides over was .010" too narrow and it was giving my carbine lock back fits. I could see a lot of carbon fouling on the tube forward of the upper receiver.
No misfeeds, but almost constant failures to lock back. My 14.5 BCM middy will run a rifle buffer system as long as I'm not losing gas ANYWHERE in the system. It's borderline... and H buffer is optimal.
Do you mean an H buffer with the rifle spring? Thanks.
Sent from my ADR6410LVW using Tapatalk 2
Do you mean an H buffer with the rifle spring? Thanks.
Sent from my ADR6410LVW using Tapatalk 2
No. An H buffer should not be used with a rifle spring.
They do make a spacer for the rifle buffer tube.... and the 14.5 middy is the only acceptable reason to deploy it. In all other cases, the rifle buffer is the more reliable system.
No. An H buffer should not be used with a rifle spring.
They do make a spacer for the rifle buffer tube.... and the 14.5 middy is the only acceptable reason to deploy it. In all other cases, the rifle buffer is the more reliable system.
Thanks. I wanted to be sure.
Thanks. It makes me think that extra 1.5" of dwell time you have is significant.
It depends on how the gas port was designed. If it's designed for minimal cyclic rate with a carbine buffer the rifle system may cause issues.
The 14.5" mid length can be reliable with any set up, if it's designed for it.
It depends on how the gas port was designed. If it's designed for minimal cyclic rate with a carbine buffer the rifle system may cause issues.
The 14.5" mid length can be reliable with any set up, if it's designed for it.
This is true. I've even seen a 16" upper with a rifle gas system that worked using a .090" port.
lifebreath
08-27-12, 11:59
If you can't cycle reliably with the standard rifle buffer, you could use the JP Enterprises low-mass buffer, which is 3 oz (equivalent to carbine buffer). If you still can't cycle, you could try the JP low-mass bolt carrier, which would knock off another 2.5 oz. However, the forward assist will not be operative with their bolt carrier.
It depends on how the gas port was designed. If it's designed for minimal cyclic rate with a carbine buffer the rifle system may cause issues.
The 14.5" mid length can be reliable with any set up, if it's designed for it.
I spoke with the folks at Spikes. The upper was designed to be run in a carbine gas tube with an H buffer. They hadn't had any experience with running it on a rifle tube/buffer setup (since most states don't have NJ's retarded gun laws). I think my best bet will be, assuming my current setup has more hiccups than the one yesterday, to get the buffer spacer and run a carbine spring/buffer setup.
The extra 1.5 is ALL THE DIFFERENCE in the world.
not even comparible to the 14.5. You need to have every part just right to run a rifle buffer reliablely.
I just got through changing the gas tube on my 14.5 middy. The part the tube that the gas key slides over was .010" too narrow and it was giving my carbine lock back fits. I could see a lot of carbon fouling on the tube forward of the upper receiver.
No misfeeds, but almost constant failures to lock back. My 14.5 BCM middy will run a rifle buffer system as long as I'm not losing gas ANYWHERE in the system. It's borderline... and H buffer is optimal.
So i have had a few more stoppages.
I just went and ordered a carbine spring and an H buffer. Tonight I will pick up a Spikes buffer spacer from a friend that has a spare. Hopefull this is the magic combination. Thanks for the help.
So i have had a few more stoppages.
I just went and ordered a carbine spring and an H buffer. Tonight I will pick up a Spikes buffer spacer from a friend that has a spare. Hopefull this is the magic combination. Thanks for the help.
It should. Look at your gas tube too. I had a bad one that was leaking gas at the key because it was .010" too thin on the outer diameter...
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.