accuracy of AR-15 caliber choices

[socalbeachbum]

I'm thinking of swapping out my stock M&P 15 upper for a new one.

I've considered .300 Blackout, 6.8mm, .204 Ruger, and .223 Wylde barrels, and I prefer to use good off the shelf ammo.

Considering the ammo that's available, which of these would buy me the best accuracy for target shooting?

or is there another caliber to consider?

 

[The Big D]

A match/Wylde chambered .223 will probably give you the best accuracy. .300 BLK is a CQB cartridge, so not a lot of effort is going into accuracy. 6.8 SPC has suffered from manufacturers enlarging the chamber to try to run higher pressure loads - also not good for accuracy. .204 Ruger is a non-entity and may well die, which is bad for people who like off the shelf ammo.

 

[Hummer70]

I concur with Big D. A Match Wylde chamber would do the job. Barrel twist rate needs to be considered. If you are going to be using 77gr bullets and heavier you will need a 1-7 twist.

If you are going to be running M193/ M855 type ammo (55 and 62 gr.) you want a 9" twist.

If you are going to be using store bought ammo it will likely have ball propellant and is more erosive on barrels. If you handload with stick propellant your barrel life may be doubled.

 

[HKGuns]

Wylde as well.

 

[Mike C2]

The longer 6.8 SPC II is not the SAAMI chamber. It has a slightly longer leade in order to REDUCE pressure and is the choice you would want if you were interested in terminal performance.

As mentioned above, the .300 BLK is a CQB cartridge and would be my choice for an SBR, pistol, or if you were shooting suppressed.

.223 is certainly the answer you are looking for if a variety of off-the-shelf ammo for target shooting is the question. The .223 Wylde has a great reputation for accuracy and the ability to swallow any .223 or 5.56 stamped ammo. Consensus these days has the 1:8 twist as the most desirable for all bullet weights.

 

[socalbeachbum]

thanks guys. any thoughts on good match grade .223 ammo brands?

 

[fireman 9731]

I would take a look at 6.5 Grendel. It may very well be your most accurate option. Plenty of ammo available from cheap steel cased Wolf to Hornady Custom.

 

[socalbeachbum]

Grendel, oh ya, sure. Requires everything new, right, barrel, bolt, mags too?

Is a standard upper ok or does it need an enlarged ejection port?

 

[justin22885]

accuracy is about shot to shot consistency, as long as theres consistency in the ammunition manufactured, "accuracy" should actually be the same, but if youre talking about your ability to hit targets more easily then out of those id stick with a 75-80 grain 223

 

[COLOSHOOTR]

Have to go with Big D as well. The .300 BLK is not the most accurate round out there. Full power super sonic factory ammo doesn't seem to be very consistent and sub sonic is worse. The .223 Wylde is probably your best bet for accuracy coupled with quality heavier weight match ammo.

 

[cfullgraf]

I have found the 300 BLK not super accurate. Adequate for the purposes it was developed for.

My 204 Ruger AR-15s are 3/4" MOA at 100 yards or better depending on the shooter. But they have 24" barrels and tip the scales at 12 pounds plus. Not exactly carry friendly.

223 Remington Wylde chamber gives excellent accuracy.

 

[fireman 9731]

Grendel, oh ya, sure. Requires everything new, right, barrel, bolt, mags too?

Is a standard upper ok or does it need an enlarged ejection port?

Standard upper and ejection port. Standard bolt carrier, different bolt, barrel, and magazines. If you are building it yourself, the barrel and bolt usually come as a matched pair.

Or you can just buy a complete upper and a few magazines that are reasonably priced and very available.

Depending on how far you want to shoot, a 6.5 will significantly out perform any of the other calibers you mentioned.

 

[Itzdapig]

My preference is the 6.8. I have both the 6.8 and wylde chambered 223. Both are capable of under an inch @100 yds. If it purely paper targets I would go with the wylde as it would be a bit cheaper to shoot in the long run with factory ammo.

 

[Zerodefect]

.223 wylde to a certain range, then the 6.5 grendel after that point.

 

[bfoosh006]

What range do you intend to shoot at ?

100yds-500yds ?

 

[CarJunkieLS1]

Of all the common AR uppers available. The one that has been hands down the 6.5 Grendel. I own several and have shot several. And none of them are necessarily bad, but of the multiple uppers across all the calibers and multiple shooters the 6.5 Grendel has been the most consistent for 1st round hits from 100-500yards