View Full Version : Need some help with barrel lengths

05-25-2012, 3:25 PM
So I am at the point with my ar build that I need to research what kind of upper is best for me. I am confused about the 14.5",16",18",20" barrels.

My goal for this build is to be able to shoot reliable groups at 100 yds. I will be shooting it mostly with iron sights at 50 yds in the beginning, then in the future set it up with a Harris bipod and some quality optics, but by no means do I want a long distance rig.

1.Is this possible with a 14.5 barrel?
2.Is the 14.5 legal? I am not clear on barrel length legality.
3.What is the difference between a "carbine upper" and a regular upper?
Feel free to recommend any upper
4. Would it be worth it to build my upper instead of buying it?

Thanks in advance. I did search, but could not find specific answers to my questions.

05-25-2012, 3:44 PM
Well you need to be honest with yourself and what you intend to do with your rifle. If you are only going to use it at 50-100 yards then a short barrel is fine. And everything being the same....barrel profile...generally a short barrel if stiffer and thus (technically) should be more accurate then a longer barrel.
A shorter barrel has lower velocity then a longer barrel. But again...under 500 yards it is really not that big of an issue.

I have a 14 1/2" AR and shoot it to 300 yards on steel with very good results with non-magnified sight.
And speaking of 14 1/2"...it is legal if you have a permanently attached muzzle device that brings the barrel length to 16" and a OAL of the complete rifle to 30" in its shortest configuration (think collapsible stock in its shortest setting).

When you see rifle, mid length, or carbine they are usually referring to the gas tube length.
Since your building your upper, I recommend including a adjustable gas block. That was you can regulate the gas it will not matter what length gas system you use.

Buying vs building....buying your stuck with a pre-made upper. Building you can use the parts YOU want to make your rifle YOUR rifle. Depends on what your after and personal preference. I assemble my lowers but use JP uppers. Why? Because to be they are the best AR uppers you can buy. But that is just my opinion after owning quite a few of them.
If your interested in JP....I have a "low mileage" 16" JP upper for sale. PM if your interested. Below is a video of it and me shooting it to 600 yards.

Good luck on your search.


05-25-2012, 4:42 PM

Thank you for such an epic post. You basically answered my all of my questions. Your 16" upper is tempting, but I need to save up a little bit of money for my next purchase but thanks anyways! I think I am going to stick with a 14.5" barrel and a pre made upper for my first ar. For my second build I will probably assemble my upper from scratch and install a longer barrel. Thanks again.

One last thing, the only muzzle devices illegal in ca are supressors right?

05-25-2012, 6:27 PM
One last thing, the only muzzle devices illegal in ca are supressors right?

Thanks for asking that question. Until recently, I thought flash hiders were illegal as well.

05-25-2012, 6:38 PM
One last thing, the only muzzle devices illegal in ca are supressors right?

Use the flowchart at the top of the page. Short answer, if running a featureless build you cannot use a muzzle device that reduces flash. If you're using a magazine locking device flash hiders are ok.

05-25-2012, 10:23 PM
A previous poster is correct when asking how will the gun be used. I shoot at 100 - 300 yards, but used a very heavy (.920" muzzle) on a 22" long barrel. It is for bench accuracy only. You could get by with much less than 22". I opted for it because I liked the look, it does no harm, and the weight keeps it on the bags better and minimize a bit bipod hopping (when I use it).