Rechamber, rebore an AR-15 barrel

Dezynco · February 14, 2009, 07:52 PM

Is it possible to rechamber and rebore an AR15 barrel to a 7mm TCU? I know that there is a company that makes an upper assembly in 7mmTCU, but they will not sell only a barrel. The 7mmTCU is based on the 223 Rem case, but I don't know if there is enough meat in the chamber for the change. Has anyone done this?

The 7mmTCU is one of my favorite handgun rounds in my Contender, just wondering if I could change an AR-15 barrel.

zoomie · February 14, 2009, 07:57 PM

Sorry I can't answer your question for you, but you might consider buying the complete upper, and then selling the parts you don't want (receiver, gas block, etc). In this environment, they wouldn't last 2 hours on any firearms forum, and you might even end up with your barrel for a pretty good deal. Just a thought...

musher · February 14, 2009, 08:03 PM

I second zoomie. The thing that makes the most sense is to buy the 7mm upper and sell your 223

Dezynco · February 14, 2009, 08:06 PM

Hadn't thought of that, but the "company" that makes what I want charges nearly $1500.00 just for the upper! I'm not saying that it wouldn't be a high quality upper, but I just don't have that sort of ransom money right now. I figure that if I could get a standard .223 barrel and make it into what I want, I could probably do it for around $400.00 or so.

sadsack · February 14, 2009, 08:23 PM

Dezynco: It would be no problem to fit a 7 TCU barrel to your upper, but you would be limited to light weight bullets because of the cartridge overall lenth. Even the light weights would have to be seated very deep in the case to fit in the magazine.

Dezynco · February 14, 2009, 08:36 PM

Yep, I already figger'd that out, but that's OK. It would still make a fine short-range deer rifle. I think the 139-140 grainer's would fit in there nicely, I might have to sacrifice some powder capacity. Should still get 2000 - 2200 fps out of a 16 - 18" barrel.

Dezynco · February 14, 2009, 08:40 PM

So do you think I could start with a .223 barrel? I'm just not sure if the reposition of the case shoulder would work OK or not. I'm sure there would be no problem reboring the barrel, just whether the chamber will would out or not.

sadsack · February 14, 2009, 09:38 PM

Dezynco: No, it won't work with 139's at all (except as a single shot). The 100 -120's are about the heaviest you'll be able to work through the magazine, and they will have to be seated very deep into the case.
If you do insist on a 7 TCU it would be cheaper to rebarrel with a new barrel blank.

Dezynco · February 14, 2009, 10:05 PM

OK, if it's just not practical, then I'll consider some other cartridge. I'm just not a fan of the little .223 (nothing wrong with it, I've just got no real use for it), and I want a larger bore that will work in the AR15 platform. Maybe the 6.8, 300 Whisper (I love to wildcat, btw).

zoomie · February 14, 2009, 11:28 PM

If you like the 7mm TCU, then, based on these specs (http://www.reloadbench.com/cartridges/w7mmtcu.html), you oughta like the 6.8SPC or 6.5G.

As for the 6.8.... With the right twist and chamber (you want a 1:11 or 1:12 twist and SPCII or DMR chamber; the original barrels were too fast and too tight), the 6.8 now has 85gr bullets leaving the barrel at 3000+ fps, 110gr bullets at 2600+ fps, and 130gr bullets at ~2300fps, all out of a 16" barrel. The 6.8 is better suited to short barrels than the .223 due to the faster burning powders being used. The 6.5G is better in the longer barrels. You really don't gain much MV at all in the 6.8 past 16" - MAYBE 18" if you're picky. I think 19.5" was the ideal for the 6.5G.

http://www.yuntaa.com/FileManager/Do...40A8C0030270ED

longrifles, Inc · February 16, 2009, 05:48 AM

All you have to do is have a barrel manufacturer whip you up a barrel in 7mm in the desired twist rate set up for an AR-15, M-4 (what ever)

Then take it to a GS that understands black guns and have him/her chamber it.

Done. Easy. And you get a premium barrel out of it so it'll shoot better.

Mark Chanlynn
Kreiger
Lilja

All are top shelf barrel makers.

Good luck,

Chad

hoekster · February 23, 2009, 11:17 AM

ER Shaw makes AR-15 barrels for Model One Sales. Maybe you can talk them into making the one you want for your personal application.

Harris

Fclass · September 29, 2009, 06:27 PM

Actually am working on this project myself,,, had a base reamer cut for use in an AR15 and will be assembling the beast over the next couple of months, determining gas port size, fine tuning freebore length,,, all the fun stuff.

It shows real promise shooting 100-120 grain bullets magazine length using a 5.56 Bolt and magazines - the only non standard part is the barrel so will be great for do it yourself builders.

Best of all readily available loading dies, 30 years of loading data and use 223 Remington brass. My calculations indicate I can use the Speer 110 TNT and achieve velocity to match the 5.56 M262 load to 600 yards with more on target energy.

February 14, 2009, 07:52 PM	#1
Dezynco Senior Member Join Date: May 7, 2008 Posts: 401	Rechamber, rebore an AR-15 barrel Is it possible to rechamber and rebore an AR15 barrel to a 7mm TCU? I know that there is a company that makes an upper assembly in 7mmTCU, but they will not sell only a barrel. The 7mmTCU is based on the 223 Rem case, but I don't know if there is enough meat in the chamber for the change. Has anyone done this? The 7mmTCU is one of my favorite handgun rounds in my Contender, just wondering if I could change an AR-15 barrel.

February 14, 2009, 11:28 PM	#10
zoomie Senior Member Join Date: January 23, 2006 Location: GA Posts: 1,862	If you like the 7mm TCU, then, based on these specs (http://www.reloadbench.com/cartridges/w7mmtcu.html), you oughta like the 6.8SPC or 6.5G. As for the 6.8.... With the right twist and chamber (you want a 1:11 or 1:12 twist and SPCII or DMR chamber; the original barrels were too fast and too tight), the 6.8 now has 85gr bullets leaving the barrel at 3000+ fps, 110gr bullets at 2600+ fps, and 130gr bullets at ~2300fps, all out of a 16" barrel. The 6.8 is better suited to short barrels than the .223 due to the faster burning powders being used. The 6.5G is better in the longer barrels. You really don't gain much MV at all in the 6.8 past 16" - MAYBE 18" if you're picky. I think 19.5" was the ideal for the 6.5G. http://www.yuntaa.com/FileManager/Do...40A8C0030270ED Last edited by zoomie; February 14, 2009 at 11:35 PM.

February 23, 2009, 11:17 AM	#12
hoekster Junior Member Join Date: February 23, 2009 Posts: 6	Try E.R.Shaw ER Shaw makes AR-15 barrels for Model One Sales. Maybe you can talk them into making the one you want for your personal application. Harris

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February 14, 2009, 07:57 PM	#2
zoomie Senior Member Join Date: January 23, 2006 Location: GA Posts: 1,862	Sorry I can't answer your question for you, but you might consider buying the complete upper, and then selling the parts you don't want (receiver, gas block, etc). In this environment, they wouldn't last 2 hours on any firearms forum, and you might even end up with your barrel for a pretty good deal. Just a thought...

February 14, 2009, 08:03 PM	#3
musher Senior Member Join Date: April 23, 2005 Posts: 462	I second zoomie. The thing that makes the most sense is to buy the 7mm upper and sell your 223

February 14, 2009, 08:06 PM	#4
Dezynco Senior Member Join Date: May 7, 2008 Posts: 401	Hadn't thought of that, but the "company" that makes what I want charges nearly $1500.00 just for the upper! I'm not saying that it wouldn't be a high quality upper, but I just don't have that sort of ransom money right now. I figure that if I could get a standard .223 barrel and make it into what I want, I could probably do it for around $400.00 or so.

February 14, 2009, 08:23 PM	#5
sadsack Senior Member Join Date: February 4, 2006 Posts: 206	Dezynco: It would be no problem to fit a 7 TCU barrel to your upper, but you would be limited to light weight bullets because of the cartridge overall lenth. Even the light weights would have to be seated very deep in the case to fit in the magazine.

February 14, 2009, 08:36 PM	#6
Dezynco Senior Member Join Date: May 7, 2008 Posts: 401	Yep, I already figger'd that out, but that's OK. It would still make a fine short-range deer rifle. I think the 139-140 grainer's would fit in there nicely, I might have to sacrifice some powder capacity. Should still get 2000 - 2200 fps out of a 16 - 18" barrel.

February 14, 2009, 08:40 PM	#7
Dezynco Senior Member Join Date: May 7, 2008 Posts: 401	So do you think I could start with a .223 barrel? I'm just not sure if the reposition of the case shoulder would work OK or not. I'm sure there would be no problem reboring the barrel, just whether the chamber will would out or not.

February 14, 2009, 09:38 PM	#8
sadsack Senior Member Join Date: February 4, 2006 Posts: 206	Dezynco: No, it won't work with 139's at all (except as a single shot). The 100 -120's are about the heaviest you'll be able to work through the magazine, and they will have to be seated very deep into the case. If you do insist on a 7 TCU it would be cheaper to rebarrel with a new barrel blank.

February 14, 2009, 10:05 PM	#9
Dezynco Senior Member Join Date: May 7, 2008 Posts: 401	OK, if it's just not practical, then I'll consider some other cartridge. I'm just not a fan of the little .223 (nothing wrong with it, I've just got no real use for it), and I want a larger bore that will work in the AR15 platform. Maybe the 6.8, 300 Whisper (I love to wildcat, btw).

February 16, 2009, 05:48 AM	#11
longrifles, Inc Senior Member Join Date: February 16, 2009 Location: Sturgis, South Dakota Posts: 152	All you have to do is have a barrel manufacturer whip you up a barrel in 7mm in the desired twist rate set up for an AR-15, M-4 (what ever) Then take it to a GS that understands black guns and have him/her chamber it. Done. Easy. And you get a premium barrel out of it so it'll shoot better. Mark Chanlynn Kreiger Lilja All are top shelf barrel makers. Good luck, Chad

September 29, 2009, 06:27 PM	#13
Fclass Junior Member Join Date: September 29, 2009 Location: Houston, Texas Posts: 1	Actually am working on this project myself,,, had a base reamer cut for use in an AR15 and will be assembling the beast over the next couple of months, determining gas port size, fine tuning freebore length,,, all the fun stuff. It shows real promise shooting 100-120 grain bullets magazine length using a 5.56 Bolt and magazines - the only non standard part is the barrel so will be great for do it yourself builders. Best of all readily available loading dies, 30 years of loading data and use 223 Remington brass. My calculations indicate I can use the Speer 110 TNT and achieve velocity to match the 5.56 M262 load to 600 yards with more on target energy.