AR Question

[Baddog0302]

Don't see many AR questions here, but I'll ask, I'm thinking about replacing the bbl. on my AR, one of the slots on the form to order a bbl is GB location, my two choices are mid length and rifle.
The center of the present GB is 13.5" from the receiver. I'm replacing the 20" bbl. with a 26" bbl.

On the chamber it's Wilde or 223. ALL my loads are FL sized LC brass and I only load to an OAL that will function through a magazine.

Thoughts & opinions

 

[mac86951]

Lots of pieces of info there, but not quite a full story.

You are loading to mag length; what bullet, and for what purpose?

Barrel length, changing from 20-26"; this will indicate a need to change gas port length rifle at a minimum, bit would recommend a +2" over rifle length (White Oak arms for the tube). This recommendation is making assumptions on your intended purpose, which isn't a good thing.

What barrel twist will determine range of bullet weights; and recommended chamber.

-Mac

 

[Fast14riot]

Your current gas system is "rifle length."

Shooting a wylde chamber allows you to run 5.56 Nato pressure spec ammo as well as .223 Rem SAAMI spec ammo. 5.56 is rated to a higher pressure. Wylde chamber started as a "match" chamber for .223 rem shooters. It's basically a slightly longer free bore but tighter all around than a 5.56. It's a good place to start. I shoot a wylde chamber as well as a .223RemMatch chamber, both handle 5.56 pressure loads equally, but are slightly different dimensions.

FL sizing is fine, but pay attention to your shoulder bump. I usually bump .003" for my ARs and keep an eye on trim length.

What bullet/powder combination are you currently using?

-Xander

 

[johnfred1965]

If your two choices are mid or rifle length, you want rifle length. Mid length on that long barrel will push your port pressure way up. As one said above, if you order a custom barrel, you can have the port pushed farther out and this will lower the pressure and smooth out the action somewhat. Being farther out lets you use slower powders for more velocity or heavier bullets, hence the question about rifle use and ammo. The wylde chamber is kind of middle of the road chamber and will work with the widest range of ammo configurations. IIRC, Glen Zediker posted some info on this subject on the Midsouth Shooters blog, there is a lot of good info there on a lot of gun related topics.

 

[Sniper338]

Sounds like you got your info there...

 

[Baddog0302]

Mac & Xander,
Thank you, bullets & loads 75 Hornady bthp /24.0 TAC, This bbl. prefers 77 SMK's to the NCC's and 24.2 N 140,or 23.5 8208, all loaded to function through a magazine **. Intended use steel "varmints" at 300 yds. requiring 1.5 MOA or less.
** Might try ASA Mag. which allows OAL of 2.316

 

[johnfred1965]

http://www.mssblog.com/2015/12/18/r...es-for-semi-automatic-and-bolt-action-rifles/
http://www.mssblog.com/2016/01/01/reloaders-corner-pressure-curves-and-port-pressure-part-2/

If I did this right, these should be the articles I mentioned above, talking about pressure curves and position of the gas port.

 

[johnfred1965]

Sounds like you got your info there...

Those that can do, those who can't read about those that can

 

[wildfowler]

I always wondered about this, where can you get a longer than rifle length gas tube?

 

[mac86951]

With hot loads of heavy bullets, I'd recommend a rifle length and adjustable gas block at a minimum. White oak armament has +2" tubes which serve to delay the system further. The effect of either is simply to reduce wear and tear on brass; reducing the case head swipe or ejector wipe that is common with heavy bullets.

IME, mag length will jump far less with a 223 chamber not wylde; but then you won't be single loading 80gr if you want to shoot farther. I'm shooting 600y with a mag length 77 and an sufficiently challenged to be happy. Single loading 80s would make me feel better, but local club rules are mag feed only.

Correct about wylde chambering posted above, as a 24.2 N140 is a hot compressed load. I've dialed back to 23.0 for my wylde chamber, but it is 100+ out here during the summer.

A more exotic bullet is the Berger 70gr VLD. My testing has this one doing quite well at 600, and should be a ringer at 300; I'd recommend a standard chamber for this to keep jump minimal from mag.

Basically, if you plan on ever shooting bulk surp. Ammo, get the wylde chamber; or 5.56 match. If you are careful and 'handload' only, then from mag length I'd recommend a standard 223 chamber. I'm sure you know already, but a 1:8 or faster for the 77s is recommended.

Best of luck, happy shooting,
-Mac

 

[Fast14riot]

Hornady 75 or 77smk should be fine in a 26" barrel. 22.5 and 23.2 of 8208 in LC brass with CCI or Rem 7 1/2 primers are common accurate loads.

80 gr bullets should be single loaded only.

I wouldn't recommend a standard SAAMI 223 chamber, a wylde or 223RemMatch or CLE chamber are good options.

Standard powders are RL-15, 8208, Varget. H335 and 3031 will work well, but may not get you the velocity you want or expect.

-Xander

 

[jwink]

I put an adjustable gas block on mine, pressure issue taken care of and use the rifle length gas tube and issues should be minimized.

 

[Outrider27]

I'm with jwink. My Sunday go to meetin' upper has a Lilja barrel, Wylde chamber, rifle length gas tube and an adjustable gas block; it can be tuned for any load I care to run by tweaking the adjustable gas block, if necessary. The adjustable gas block has proven to be a real plus.