11.5” Mid Length Barrel Discussion

[01svtL]

That I couldn't tell you as i've never compared the two. Theoretically, yes, and more so suppressed.

So, again, what's the hangup on my chosen parts? Not being a smart@ss, I'm genuinely asking. I'm here to learn.

[FaxonNathan]

That I couldn't tell you as i've never compared the two. Theoretically, yes, and more so suppressed.

Not just theoretically, practically.

[JG007]

Especially because you are new to this you should buy, or at least try to replicate, what is proven to work. The BCM, Colt, Daniel Defense,etc use a regular barrel and regular Bolt carrier group.

Deviating from that should be for a specific purpose with understanding of the potential negatives.

It is never a good idea to be exotic just for the sake of being exotic, especially when it comes to self defense.

[fledge]

01, the main change in your list is the BCG. Make it standard. The barrel should work with quality ammo and simple to tune with adj gas block. If you can't make the system reliable, swap out the barrel for carbine gas barrel as most recommend (BCMs is 18oz). You get to learn as you go. Don't sweat it.

(Personally, I think 11.5" is long for a pistol and would consider an 8.5" in 300blk... then build the 11.5 gunner when you have your sbr).

[01svtL]

01, the main change in your list is the BCG. Make it standard. The barrel should work with quality ammo and simple to tune with adj gas block. If you can't make the system reliable, swap out the barrel for carbine gas barrel as most recommend (BCMs is 18oz). You get to learn as you go. Don't sweat it.

(Personally, I think 11.5" is long for a pistol and would consider an 8.5" in 300blk... then build the 11.5 gunner when you have your sbr).

Thanks for the suggestion. Yea I thought about 300blk after I bought about 1500rds of 223/556. I can't afford to switch now, really. Especially with 300 being more expensive than 223/556. I'm 6'1 with long arms, so I think 11.5" will be fine until/if I go SBR on it.

The suggestion to buy what's already been proven does bring a question to mind, though. Alot of those companies build 10.5 or 10.3" rifles, which seem to run just fine. So why haven't they adopted BCM's thoughts on the 11.5 being better? ETA: feel free to PM me in order to keep this thread about the Faxon 11.5.

[JG007]

There are a lot of threads on barrel length, I remember doing way too much research when deciding on a 10, 11, or 12 inch barrel.

My first SBR was the 11.5 BCM and then I added developed or A5 buffer, the longer barrel and buffer system provide a theoretical reliability advantage (although you do not hear of the 10 inch Daniel Defense with carbine buffers, or Colts/etc , having issues, but I figured why not)

There is no downside to getting a proven 10 or 11 inch SBR in 556 first, then you can do something different or unusual for your next rifle, but stick with the basics and there is nearly zero chance you will have any regrets

Figure out your hierarchy of needs and start at the top then work your way down

[nml]

1. BCG is not where you save weight. The short barrel and short rail is.
2. Unsuppressed get a 10.3-11.5 pencil barrel from a known quantity. They will both be loud if your hearing is intact. BCM's statements about 11.5 are true but from almost a decade ago. There is no point to running a midlength under 14.5 unsupressed.

[FaxonNathan]

1. BCG is not where you save weight. The short barrel and short rail is.
2. Unsuppressed get a 10.3-11.5 pencil barrel from a known quantity. They will both be loud if your hearing is intact. BCM's statements about 11.5 are true but from almost a decade ago. There is no point to running a midlength under 14.5 unsupressed.

We disagree fully with both statements, assuming one knows what they are doing in tuning a rifle. *If one does not, of course one should stick with standard components.

The needed weight of the carrier is directly correlated to two items 1-weight of buffer and 2- amount of gas. Assuming one has correctly metered both, the carrier is certainly able to afford weight reduction.

There is a point to running a mid length unsuppressed, assuming the same variables. We have multiple rifles (with full weight carriers too) in our shop that function with everything from Tula to Federal 5.56 loads. Is it a more limited envelope? Sure, but its not a non-existent one.

[nml]

I am sure the parts and builds function quite well. I was addressing 01svt regarding an unsuppressed build (although I now noticed it is not for an SBR and instead a pistol! ...just buy a 16 midlength so you have a gun you can shoot dude). Within that context he mentioned cost and so while a LW BCG and adjustable gb and midlength 11.5 would function I think my parts would do so at a lower price point with no impact on reliability or measurable impact on muzzle velocity.

I like people making different things and hate people who complain about price for no reason , so that is not what I am saying. Just that he sounds budget limited and needs to put it into ammo.

[tom12.7]

We disagree fully with both statements, assuming one knows what they are doing in tuning a rifle. *If one does not, of course one should stick with standard components.

The needed weight of the carrier is directly correlated to two items 1-weight of buffer and 2- amount of gas. Assuming one has correctly metered both, the carrier is certainly able to afford weight reduction.

There is a point to running a mid length unsuppressed, assuming the same variables. We have multiple rifles (with full weight carriers too) in our shop that function with everything from Tula to Federal 5.56 loads. Is it a more limited envelope? Sure, but its not a non-existent one.

Look, the BCG requires an amount of work for function. We all add in a factor for that function to insure that the cycle can complete, many times in less than ideal circumstances. There are timing events that we can choose to take advantage of to reduce the quantity of work required for that. Take away sprung tension, then you need more mass for a similar factor. Adding tension can reduce that mass for the same required work as a result, but timing and strains are altered towards the negative. Note, that I'm not talking about altering the energy applied to the system from the gas port.
There are timing events that may require more work with the associated tensions with their respective stresses and strains for their timing events and other issues.. Adding stress and strains is not something that we drive towards. We would rather look into these negative events towards looking into solutions. Reducing time outside of that hurts other events, i.e. carrier free non camed travel towards unlocking, magazine function and trigger function, among other, etc..
Let us say that we have an 11.5" DI AR, with that a possible can that drives the BCG similar to a 3" extension in barrel length. Would a carbine gas length fit better into that role, or a mid gassed one? Let's assume that we, to keep it simple that we are looking at 14.5" barrel with that same porting for either to relate to the two. Would you think that one may have an advantage over the other?