I have a national match rifle I never use I want to modify for 3 gun.  Flat top and threaded barrel are definites for tac optics.  I'm going to keep it 20" and keep the stock float tube and hand guard, maybe use the magpul hand guard if I need to attach something .  

My main question is what diameter to turn the barrel?  It's about .9 something under the free float tube.

What brakes work well with a 20" barrel?

I used my DPMS m4gery this year and it's not too bad for me, but I can use some more accuracy and a little more weight for the precision targets.

Thanks!

My .223 barrel is government profile in my 18in midlength. Very light compared to a standard HBAR. Go to http://www.ar15barrels.com/profiles.shtml - he has the skinny on all the different barrel profiles.
I ran a Miculek Comp for two years - it's a great comp and relatively inexpensive. I just upgraded to a SJC Titan.


 

+1 on both of these.... Gov't profile and Miculek will work great.  ?for the OP..... will a Magpul rifle length forene fit right on to the "free float" tube?  In theory I guess it should but just wanted to make sure.  Thanks.

20" is okay, but will tell you that you're going to want to chop that down to 18".  The amount of velocity you lose is not enough to matter and you gain portability and weight savings which you're going to want on 3-Gun stages.  

As for a brake, the following are pretty standard:

- DPMS/Miculek:  Cheapest and very effective
- JP-Bennie Cooley, Rolling Thunder, SJC Titan:  All (in my opinion) are about the same and all are effective.  These are definitely nice to haves, not need to haves to start.

Get a free float tube.  JP's are great, but also look at the carbon fiber tubes from Carbon Arms.  The longer the better.  

Adjustable gas block.  There are two different camps on this.  I'm in the group that likes them because I can tune the action to the load that I'm using.

Reduced weight bolt carriers.  Simply awesome and I would say they're required, but I'd be a bit of a hypocrite.  In my 16" rifle, I run a JP-LMOS with lightweight buffer.  On my 18" rifle, I run a standard carrier and buffer.  I parse to reliability and not that the light stuff isn't reliable.  The reason I haven't switched on my 18" rifle is that it flat out runs, so if it ain't broke....

Barrel contour.  Normally I'd say the lighter the better, but I lean towards a simple .750 or medium contour just to make life easy.  You cut weight, but still have enough for good balance of the rifle.

Trigger.  JP's are awesome.  Some friends are running the new Timney's and Gisselle's are doing well with the NST guys and their record speaks for itself.

Good luck and welcome to the addiction.

Rich

Your most important mod is a good zero!  But if you are a highpower guy you will have no trouble with that!

I used to shoot an Accuracy Speaks Highpower sevice rifle in 3 gun Limited Division.  It also had a HEAVY barrel which was not ideal but I never really had any trouble with it.    

I would not place the magpul forward grip on it though.  I watch many a new shooter struggle with them when shooting off barricades.  I don't see any big dawgs struggle with them as they don't have them on their rifles.

I've had 2 Timney triggers go south (and with hardly any rounds over them) and seen several others do so.  I have to say get the JP.

Kelly - I'm glad you said you've also had problems with the Timney's.  I've trashed 2 of them between a couple of rifles.  The JP's keep on tickin'.

Rich

Thanks All.

I can use the standard handguard on the free float tube, I actually like it.  

What's the options for a rifle length stock besides the A1, which I'm considering now?

I'm partial to the ACE/Doublestar Skeleton.  Light, comfortable and it looks cool.

those Timneys cant be any worse than Jards.

JP makes a great trigger, but I gotta have some slack to prep, so I have about 300rds on a geissele, so far so good.

great info , just what I was looking for.  Trying to buy once and this will help to avoid unreliable  equipement.