Alternative to 6.5 Grendel?

[320pf]

That was a .25-223 Bolt gun with a massive bull barrel.



Grendel has taken antelope at 752yd from a 22" AR15, DRT.

Sierra lists the .257" 100gr SBT G1 BC's as:

.355 @ 2800 fps and above
.333 between 2800 and 1600 fps
.310 @ 1600 fps and below

6.5mm 100gr NBT is .350
6.5mm 100gr Barnes TSX is .359
100gr Hornady A-MAX is .390
100gr Hornady V-MAX is .365
100gr Nosler Partition is .326

16" Grendel with preliminary load development for me pushed the 100gr NBT to 2700fps, and I haven't even tried more than 2 powders with that bullet.
I was talking about the .222 Remington with the shoulder blown forward, and a 30 degree shoulder angle, but staying at .222 Remington case length of 1.700".

That .25-223 sure is a nice little quarter bore, and I have always wanted a .257" since my grandpa loved it so much. I think the .30 Remington case necked down to .257" would be ideal for the AR15 for those that are wanting a .257". There is nowhere near the bullet selection for the .257" compared to 6.5mm, especially when talking target bullets and big game bullets, but it is a beautiful little medium game caliber.

That 110 Nosler Accubond would be awesome in the AR15, with a .418 BC. I think there is a void in the market right now that .257" is waiting to fill in the hunting AR15, and a .247x43 or 25 DTI would be awesome. A 16" hunting carbine should be able to spit the 110 out at ~2600fps with the right powder.

The .25-223 is certainly no slouch. You've done a lot of work with it, right? What powders are you finding to work the best with the 100gr? I think it's pretty efficient in the .223 Rem case, as it allows more pressure relief with the bore size, while facilitating nice speeds with the charge weights, powder types, and bullet weights.

Hi LRRPF52,

Sorry, I was not more clear in my post on the 25.223Ar. The brass for the 25-223Ar is made be expanding a 223 REM/5.56 to 25 cal. The case is then trimmed back from 1.76 to 1.70 (1.695 to 1.705). This is the same case length as the 222 REM. The result is a .222 Remington with the shoulder blown forward, albeit not with a 30° angle.

I have built a couple of 20-inch heavy varmint barrels (0.925 and 0.875) and I am now considering building either a 22 or 24 inch varmint weight upper. As I am sure you know, with a properly timed Ar the bullet is well out of the barrel before the B/C activates to extract the case. This is why Ar are generally pretty accurate rifles and the accuracy potential of the AR is similar to a bolt gun. I regularly hammer LaRue's and 12-in flashers out at 300-400 yrds with unmagnified EOTech or a 1 to 4 tactical scope.

My extreme/long range bullet of choice is a BIB Bullet Co. 88 g 25 cal bullet with a BC of 0.42. My 16-in barrel will drive this bullet to 2700-2750 fps. I did not list this bullet initially because these bullets are not used by the everyday shooter. From a 20-in barrel this number will clock at about 2800 fps. I also like to shoot the Sierra 90 g BlitzKings (at ~2700 fps) and 100 g MatchKings (at ~2580 fps).

The powders that work well with the 25-223Ar are basically the same powders that work with the 6.8 SPC. Both cartridges have very similar case volume to bore area ratios (~590-600 grains H2O/in^2). Accurate 168,0 RE-7, and IMR/Hod. 4198 work well for bullets less than or equal to 80 g. For bullets in the 85-100 g weight class, RE-7, Accurate 2200, and H335 perform well.

I feel the biggest problem with all of the Ar variants that are based on cartridges with a case head larger than the 223REM/5.56 (0.376") are compromised by the physical limitation imposed by the AR platform i.e. C.O.L limit of 2.26 and the bolt head diameter. Opening up the bolt face compromises the of the bolt, hence the chamber pressures these cartridges are derated to some degree. Secondly, the mags are different than the standard mil spec Ar mag. Thus they are less common and/or more expensive. In addition a 30-round length mag will only hold about 25 rounds.

So I still maintain that the 25-223AR can run with the Grendel out a distance.