Hey guys,
I'm new to the site but not to weapons in general lol. My question, in Florida BTW:
I currently have a Windham AR in the M4 configuration with a 16 inch barrel. When I TAC up and hit the course reliving the good old days, I've found that this particular weapon is a bit long for my purposes. The longest shot I'll be going for with this weapon (in any situation) is maybe 200m. So I'm thinking of a 12 inch barrel instead of 16.
Suggestions? Comments? Concerns?
Thanks in advance guys!

10 3/4 is mo betta. Pure sex with a short titanium can. 

A lot of platform experts consider 12" the perfect length for an all-around AR, all-around including CQB/house/car stuff.
11.5" is widely considered the minimum length to ensure supreme reliability with various ammo under any environmental conditions when dirty and worn.
With 62gr Federal Fusion MSR and 77gr Sierra Tipped Match Kings you'll have your barrier blind and non-barrier blind, accurate, and very destructive ammo bases covered to at least 300yds with full projectile performance from a 12".  

Be sure to be aware of NFA laws when going to that 12" barrel.

What he said.  Limit for a rifle is no less than 16".  12" is considered a SBR, which is okay if allowed in your sate and you complete the Form 1, mail your $200 Check and wait for your tax stamp before you change anything.

10.3's are awesome!  

I did some research on the 12" barrel. Velocity decrease is not that bad, only 200-300fps (youtube videos). At 0-200 yards that decrease in velocity is great for unarmored personal because it greatly increases the chance of bullet yaw and tumble.(greater damage)

12" barrels are great. I actually bought a 16" to be safe at greater ranges and I am looking to sell mine since I prefer being able to go out to longer ranges. I only shot 9 rounds through it (.223/5.56 wylde with quad rails)

Here's a good resource that I bookmarked
https://www.ar15.com/forums/t_3_122/480476_.html&page=1

FWIW, I didnt think that thread was much to write home about as far as knowledge.  Im not trying to be confrontational.  If you just want a 12" pistol or SBR, go for it.  If you are asking for advise, you need to say what you are trying to accomplish.   I am still not sure that I understand what you are going to be using the rifle for.  And what your want to accomplish.  You said longest shot, meaning? at a range on paper for groups? or 8"steel?  If so, length has little to do with accuracy to a point.  Ballistics?  Stopping power? What?

If you are looking for supreme manuverability, on a tactical course with shots out to 200 on steel, I'd go 10.5 or 10.3.  Although, I can hit steel at 200 all day long with my 7.5" SBR PDW Build. but there is the muzzle blast.

I still dont know that you picked up on what we were saying about going below 16" on a rifle either.  You ask for concerns, and then when they are given you do not acknowledge them.  When we are just trying to keep you on the correct side of the law.

Here is a good link:
https://www.ar15.com/forums/t_3_118/693858_Molon-Reference-Links-2016.html

My 7.5" VSeven Match Barrel 5.56  PDW Build.  This is extremely maneuverable, and accurate, It just suffers in the velocity department meaning the projectile will become subsonic ( this is where bullet stability concerns really begin) earlier.  

IMO, if you're relying on velocity dependent wounding quirks of military ammo-- Don't forget fleet yaw! --as a civilian, you're doing it wrong.

Not ignoring by any means, I was just never alerted to the thread response. I don't do anything for purely paper targets my life revolves around tactically, emer responses & real life scenarios but you can't train for real life scenarios with real life targets so paper training for real life purposes is what we're delegated to. After speaking with my local NRA/CJSTC & SWAT instructor in FL it's not legal to privately own an M4 configured AR with less than a 16" barrel unless it's certified as a pistol as stated above by another member. Which tho that's a possibility (building an SBR pistol) I guess I'm going to be training around the 16 incher lol. I appreciate all the responses & have looked into some of the configurations stated above & think I'm going to build an AR pistol. So unless I need to start a new thread, I'll take whatever advice on that anyone is willing to offer

I'm not sure this is correct.  I am not an attorney, and do not live in Florida, but a quick search online reveals numerous references that it is legal to own a short barrel rifle in Florida.  It also appears to be legal to own a fully automatic weapon.  But either of these has to be done in accordance with federal law (NFA).    So if you want the 12" barrel AR, you have to either submit a form 1 where you are the manufacturer or buy the SBR on a form 4.  This requires the $200 tax stamp as mentioned (and a lengthy wait).  If you don't want to go that way, then you have to build an AR pistol.  This will probably require a new receiver as you most likely have already had a stock on your current AR, therefore rendering it a rifle forever.  If you think you can skirt this with a sig brace, you should read this.

Florida is GTG as far as all NFA items are concerned, with the POSSIBLE exception of DDs. That advice you received is incorrect, as far as I can tell.

Something you could do is assemble a 12" barrel pistol, send in a Form 1, and only attach a stock after all the paperwork comes back. A lot of folks do that as an interim measure.

OP you seriously need to educate yourself as to what the National Firearms Act is, and the realities of firearms that are regulated under that act.

What you are describing is an NFA regulated firearm configuration, to wit a "Short Barreled Rifle".

What you were told is both true and untrue. An SBR is not legal to just make one, or go down to the store and pick one up. They are legal once you go through the substantial Federal regulatory scheme, which involves paperwork, a $200 tax, fingerprints, and an 8 to 12 month wait. The NFA firearm is then registered to you personally and you must take precautions to prevent it being accessed by anyone else. Technical violations have severe legal penalties.

Many find the regulatory scheme surrounding NFA firearms to be too imposing, and choose to limit themselves to non-NFA firearms like long guns and pistols.

No, your rifle cannot be made into a pistol, you will have to start from scratch either with a stripped lower or buying an already-made pistol configuration, if you choose that route vs the NFA process. 16" barrel and 26" overall length are the non-NFA minimums for a rifle which is why you see so many in that size.

Your NRA CJSTC & SWAT guy has no idea what he is talking about (this is typical for most LEOs when it comes to firearms laws from my experience). You can own a SBR without issue in Florida just need to fill out a form 1 and send it to the ATF with your $200 tax payment. You cannot build a M4 with the happy switch though. You could buy one but going prices are in the 20K+ range plus the $200 stamp

You can however build a pistol. (but it cannot be made from your current lower) while you wait the 9 months to a year to get you stamp back, just remember not to shoulder it. There is no such thing a "SBR Pistol". You have Rifles, Pistols, Non NFA firearms, and SBRs. May want to look up the definitions on each.

Another option is a 14.7" with a pinned and welded A2 Flash hider top bring it to 16" or a 14.5" with a number of aftermarket muzzle devices pinned and welded to achieve the same purpose. I know it doesn't seem like much but that 1.5" is a lot.

That's what he (I) meant, I can't put a shorter than 16" barrel on my current AR. I can build the SBR ground up and file the paperwork no problem. And yeah, if only we could have a happy switch on our personals (even after getting vetted and qualed). In a perfect world, right? lol

You have to file the paperwork and have it returned before you complete it, just want to make sure you understand that. Unless you build it as a pistol and wait for the stamp to come back before putting a stock on it. You can have a happy switch all you want too if you do the paperwork etc for that too....oh and have the cash for it (little more complicated than an SBR though and expensive)

If you register your rifle as an SBR, once you get the stamp and engrave your maker info then you can change the barrel to a shorter length.

Staring from scratch is to assemble a pistol (short barrel and no stock). If you register the pistol as an SBR, once you get the stamp and engrave then you can add the stock.

Also to add in FL there is no requirement to have an AR pistol certified (whatever that is supposed to mean).  For a pistol start with a virgin lower and build what you want.

I think that's the route I'm going. Between my FFL dealer (and friend) and my instructor buddy I think that's the best option. Once completed I'll turn my AR with the 16" into more of LD tasker instead of the CQB but can reach out multi tasker. I'm getting excited already