Why no 14.5" pencil barrel with carbine length gas system?

[Jay Cunningham]

So after figuring out that I needed to look at just the barrels and not barrelled uppers for weight listings, the BCM 14.5" M4 barrel is listed at approx. 1lb 10oz. The 14.5 lightweight mid length is listed approx. 1lb 6oz. The 16" lightweight mid length is listed at approx 1lb 7oz.

Brownells has a Daniel Defense lightweight carbine barrel listed at approx 1lb 5.6oz (Thanks to Kram for the link above)

I'm just looking to buy a complete upper sans BCG and CH though.

I feel your pain. The M4 barrel profile is really F'd up; a continuous taper is nice. I think Noveske used to make them. There's that phrase again: "used to"...

[schüler]

...
On a 16" barrel I would go mid length without hesitation. I don't doubt that the majority of the 14.5" run great, but I've heard of enough people having problems with lower power ammo that it gives me pause.

Running duty or 5.56 ammo it's never been an issue in Texas 16-106F. Keep with original carbine buffer and spring if you're wanting insurance.

[littlejerry]

I feel your pain. The M4 barrel profile is really F'd up; a continuous taper is nice. I think Noveske used to make them. There's that phrase again: "used to"...

Sionics sells complete uppers without BCG. I bought their mid weight continuous profile. Same weight as an 4 but with a continuous cross section. Been totally happy with it.

Not sure who makes their barrels. Haven't heard anything bad about them though.

[Bart Carter]

Colt now offering Colt Combat Unit (CCU) Carbine with mid-length gas system, 15" barrel. I guess Colt decided the reliability is OK on a mid-length.

Colt said it is light weight, slim line and softer shooting.

[Pennzoil]

Sionics sells complete uppers without BCG. I bought their mid weight continuous profile. Same weight as an 4 but with a continuous cross section. Been totally happy with it.

Not sure who makes their barrels. Haven't heard anything bad about them though.

Sionics is good to go!

A number of local agencies have switched to Sionics rifles. I met the owner Josh earlier this year at the range and the guy is genuinely passionate about the quality of product he was selling.

[Clusterfrack]

Thanks for your input and taking the time to post the numbers. It's not that I doubt BCM quality, far from it, but I'm just not sold on the idea of departing from the carbine length gas system on a 14.5" gun specifically. This is the configuration that has proven itself in US military service for so many years.

On a 16" barrel I would go mid length without hesitation. I don't doubt that the majority of the 14.5" run great, but I've heard of enough people having problems with lower power ammo that it gives me pause.

My experience is that uppers that run well with low power ammo (e.g. PMC Gold) are overgassed, and can be problematic suppressed. My 14.5" Mid-length BCM will occasionally short stroke with PMC Gold, but is perfect (suppressed and unsuppressed) with the 5.56-pressure ammo I use.

[ChrisLapre]

Look at Sionics. As Pennzoil mentioned, their quality is second to none. I have a 14.5 mid-length and it's as good as anything currently by the big name guys.

[GJM]

In a perfect world, wouldn't carbine length gas systems be with a 14.5 barrel, and mid-length with a 16 inch barrel?

[Rick62]

Look at Sionics. As Pennzoil mentioned, their quality is second to none. I have a 14.5 mid-length and it's as good as anything currently by the big name guys.

I wasn't aware that Sionics has ever produced a 14.5 mid length. Was it a limited run?

I'll add that my 14.5 mid length BCM has run well. I can't say that it runs any "better" than my Colts (carbine gas system) do, but it doesn't run any worse either. I don't run steel cased, or other ammo that is often noted for its lower pressure (PMC bronze etc). If that's a requirement, I can't offer any data there.




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[MSparks909]

In a perfect world, wouldn't carbine length gas systems be with a 14.5 barrel, and mid-length with a 16 inch barrel?

Assuming optimum gas port sizes and identical ammo, a 16" middy will feel softer shooting than a 14.5" carbine gas. Same reason a 20" AR will feel softer shooting than the 16" middy. While dwell time is important to reliability it isn't the only part of the equation.