barrel profile on MP15 sport 1?????

bamaranger · August 8, 2022, 09:50 PM

Can anyone advise on the barrel profile on a S&W MP15 gen 1?

I am considering purchase of same, used, as the basis for a lightweight build AR. The semi slick side upper is a plus for me, but the owner cannot advise on barrel profile. At present, neither of us are in proximity of the rifle, which is stored in a different location. Ideally, I would like the rifle to have a factory barrel of pencil like dimension, or at least lighter than the GI/A4 style. I would prefer not to invest in a new barrel.

The carbine in question is all factory, sporter carbine, with front sight tower and carbine handguards, picatinny receiver, semi-slick side, and what appears to be a MagPul rear sight.

If the barrel profile is lightweight, I would remove carbine handguard , front sight tower and rear sight, add new low gas block and mod-lok free float lightweight handguard.

TunnelRat · August 8, 2022, 10:21 PM

I had a Sport Gen 1. It did not have what I would call a pencil barrel.

chris in va · August 9, 2022, 12:14 AM

It's more of a 'middle ground' diameter, definitely not pencil.

On a side note the Melonite carburization is external and internal, and the rifling is what is referred to as '5r' also used in Thompson/Center rifles. The barrel is quite good.

bamaranger · August 9, 2022, 12:31 AM

Wrong forum.......sorry

**Spats McGee** · August 9, 2022, 08:31 AM

Quote:

Originally Posted by bamaranger

Wrong forum.......sorry

Don't sweat it. I'll move it.

bamaranger · August 9, 2022, 03:52 PM

Had a bit of time now to research the original Sporter Gen I barrels and managed to find a few pics, I think I can live with the barrel taper. Again, I have not yet handled the carbine being discussed, but believe it is an early model with the desirable T/C 5R 1-8" melonite barrel. The Sport II added a duct cover and forward assist, but discontinued the Melonite 5R barrel.

The dust cover and forward assist are just extra hardware to me, but if indeed this rifle has the 5R barrel, that would be a real plus.

GJeffB · August 9, 2022, 07:53 PM

MP15 sport 1:
Yep, I also have the gen1. No dust cover or forward assist (yawn, others disagree) full profile barrel, not pencil, not bull/varmint profile.
Understand the 5r barrel is/was a variable twist, aka gain twist (?). Sorry, I don't recall the specifics, I want to say 1:7 to 1:8? The idea is the ability to stabilize a wider range of bullet weights. Mine seems to be more accurate than I am, very happy with it.

-jb, bought during the 1st pre-panic, 2nd to come

chris in va · August 10, 2022, 12:59 AM

Right, I forgot about the gain-twist rifling.

kymasabe · August 12, 2022, 05:33 PM

Anderson used to make a slick side upper with no forward assist or dust cover but they no longer have access to that forging. Their new slickside has a dust cover, but still no forward assist thankfully.
I've built some uppers with pencil or lightweight barrels. Faxom gunner is great, Ballistic Advantage now has a pencil barrel, RightToBear has their house brand pencil which I'm pretty sure is made by B.A., I've had good luck with (and currently own) the KAK lightweight, and the BFI/Bushmaster lightweight barrel (Bushmaster calls it the QRC barrel) and its available thru RightToBear and CDNN.
My suggestion is build exactly what you want. Parts are readily available again and prices are coming down.

August 8, 2022, 09:50 PM	#1
bamaranger Senior Member Join Date: October 9, 2009 Location: North Alabama Posts: 8,804	barrel profile on MP15 sport 1????? Can anyone advise on the barrel profile on a S&W MP15 gen 1? I am considering purchase of same, used, as the basis for a lightweight build AR. The semi slick side upper is a plus for me, but the owner cannot advise on barrel profile. At present, neither of us are in proximity of the rifle, which is stored in a different location. Ideally, I would like the rifle to have a factory barrel of pencil like dimension, or at least lighter than the GI/A4 style. I would prefer not to invest in a new barrel. The carbine in question is all factory, sporter carbine, with front sight tower and carbine handguards, picatinny receiver, semi-slick side, and what appears to be a MagPul rear sight. If the barrel profile is lightweight, I would remove carbine handguard , front sight tower and rear sight, add new low gas block and mod-lok free float lightweight handguard.

August 8, 2022, 10:21 PM	#2
TunnelRat Senior Member Join Date: May 22, 2011 Posts: 12,427	I had a Sport Gen 1. It did not have what I would call a pencil barrel. __________________ Know the status of your weapon Keep your muzzle oriented so that no one will be hurt if the firearm discharges Keep your finger off the trigger until you have an adequate sight picture Maintain situational awareness

August 9, 2022, 12:31 AM	#4
bamaranger Senior Member Join Date: October 9, 2009 Location: North Alabama Posts: 8,804	Oops! Wrong forum.......sorry

August 9, 2022, 03:52 PM	#6
bamaranger Senior Member Join Date: October 9, 2009 Location: North Alabama Posts: 8,804	research Had a bit of time now to research the original Sporter Gen I barrels and managed to find a few pics, I think I can live with the barrel taper. Again, I have not yet handled the carbine being discussed, but believe it is an early model with the desirable T/C 5R 1-8" melonite barrel. The Sport II added a duct cover and forward assist, but discontinued the Melonite 5R barrel. The dust cover and forward assist are just extra hardware to me, but if indeed this rifle has the 5R barrel, that would be a real plus.

August 9, 2022, 07:53 PM	#7
GJeffB Member Join Date: February 26, 2009 Location: Southern Colorado Posts: 78	MP15 sport 1: Yep, I also have the gen1. No dust cover or forward assist (yawn, others disagree) full profile barrel, not pencil, not bull/varmint profile. Understand the 5r barrel is/was a variable twist, aka gain twist (?). Sorry, I don't recall the specifics, I want to say 1:7 to 1:8? The idea is the ability to stabilize a wider range of bullet weights. Mine seems to be more accurate than I am, very happy with it. -jb, bought during the 1st pre-panic, 2nd to come __________________ Spyros: People who talk little listen a lot. Which is why they're wise; it's harder to learn while talking

August 9, 2022, 12:14 AM	#3
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	It's more of a 'middle ground' diameter, definitely not pencil. On a side note the Melonite carburization is external and internal, and the rifling is what is referred to as '5r' also used in Thompson/Center rifles. The barrel is quite good.

August 10, 2022, 12:59 AM	#8
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	Right, I forgot about the gain-twist rifling.

August 12, 2022, 05:33 PM	#9
kymasabe Senior Member Join Date: June 10, 2005 Location: SW Florida Posts: 2,748	Anderson used to make a slick side upper with no forward assist or dust cover but they no longer have access to that forging. Their new slickside has a dust cover, but still no forward assist thankfully. I've built some uppers with pencil or lightweight barrels. Faxom gunner is great, Ballistic Advantage now has a pencil barrel, RightToBear has their house brand pencil which I'm pretty sure is made by B.A., I've had good luck with (and currently own) the KAK lightweight, and the BFI/Bushmaster lightweight barrel (Bushmaster calls it the QRC barrel) and its available thru RightToBear and CDNN. My suggestion is build exactly what you want. Parts are readily available again and prices are coming down. __________________ God's creatures big and small, eat them one, eat them all.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search