223 loaded Long with heavies?

[Alpine]

Planning to build a 223 and using either 77-gr SMK, TMK or the new 75-gr ELD-M's. I want to load the bullets out longer to that ideal boattail - neck shoulder junction to maximize performance. Measuring a TMK at that length gives me a COAL of around 2.49", which will not be a problem with my detachable magazines.

Anyone here doing that? I'm assuming guys who shoot FT-R 223 may be doing this?

FYI - The build is for a specific tactical match that limits barrel length to no more than 18", and bullet weight no greater than 77-gr. I plan on running suppressed, which may give me some additional speed, if any.

I will be shooting very small steel targets out to approx 600-yards, with bonus targets sometimes placed further out. Trying to get the edge in accuracy, and trying to beat the wind by increasing velocity. I usually shoot the match with a Precision AR, with 77--SMK loaded to mag length, and velocity is usually around 2660-fps. Accurate load out to 1000-yards, but the wind sure pushes the bullet around, and where this match is held, it gets windy.

Any input appreciated.

Thanks!

 

[slm9s]

I built a heavy barrel fast twist 223 as a "trainer" for cheaper LR shooting practice. I chose the Nosler 70 RDF as its BC is almost the same as the 77smk and shooter's pro shop usually has 2nds for around $15 per hundred. I shoot them in 3 rifles and they do well.

 

[Alpine]

Had a few PM's suggesting this and that bullet over the other. What I was really looking for was performance figures for those seating the 75 - 77 class bullets long over the standard factory length load.

 

[watercam]

I shoot 80.5s and Sierra 90s seated waaayyy out so that the bullet shank/boat tail corner sits right at the neck/shoulder junction of brass when bullets are jumped .020". 24.8 gr. Varget for 90s @ 2800 fps and 25gr. V. with 80s @ 2950 fps.. 75s should make 3000 fps with that much case capacity.
Case mouth to lands measures .265".

 

[ShaunBrady]

I shoot the 75 ELDm from a RPR I rebarreled with a 26" Bartlein Heavy Palma 1:7. Using H4895 and a loaded length of 2.525" that is 0.025" off the lands, it gives 3037 fps at 8-10 loadings pressure. I'm using LC 556 brass I bought new.

The gun was built to effectively extend an ELR training range we built. It's somewhere between a 308 using 175smk class bullets and a 6.5cm at 1200 yards. Much closer to the 6.5 on elevation and wind.

The 77smk uses a short nose to maximize performance out of an AR15 magazine. Once you loose that constraint, there are other bullets it won't compete with if the gun has enough twist. I've used them to 1060 yards at AR15 mag length. I used to use a compressed load of Varget, but I'm getting better velocities out of H4895. The temperature stability and velocity spreads are similar. I've used the 77smk with 9 twist barrels to that distance at about 1000' elevation. They transitioned well.

What else were you looking for?

 

[Alpine]

Thanks guys, that's the kind of info I was looking for.

 

[CharlieNC]

I run the 75Amax in a standard freebore chamber so the length is pretty short. No mag issues and good performance at 1000yd when I can properly dope the wind.

 

[alf]

I run 75 Amaxes at 2.240" OAL in a 700 short action in regular BDL bottom metal.