Rebuild Launched: .243AI from .308W - LR Load Discussion

[BallisticsGuy]

I usually compete in 200-1000m long range matches with my .223 but when the winds get above 20mph or highly erratic I like to pick up a heavier load instead of just wasting .223 cal projos. I have been using a .308win chambered Savage 10FPSR for those occasions but I'm the owner of 2 completely destroyed shoulders in various states of decay and reconstruction and the .308 has been beating me up too much lately. When I shoot .308 I'm not working toward my goal of running the course clean (50:50) with my .223, and I'm officially out of the Tactical class so I'm lumped in with the highest scoring shooters that are almost all using 6CM/6.5CM/.260Rem/6XC which puts me at a huge disadvantage. So since I only have the .308 barrel to allow me to shoot in .308 specific tactical matches, I ordered myself a new barrel from Columbia River Arms / Black Hole Weaponry. Got myself an 8-twist 26" MTU profile with threaded muzzle chambered for .243AI (Ackley Improved, 40deg shoulder) and ordered a crate of 108gn ELD-M's and several hundred Hornady cases and dies. Can't seem to get 115 DTAC's so the 108's will have to do.

Given the long pipe and relatively heavy bullet I'm definitely going to be served by slower burning powders. H1000 seems to be well liked so it's looking like it wants really slow stuff suitable for overbore magnums and heavy bullets. I've had good luck with powders like N550 and US869 in some combos that are similarly overbore and heavy bullet using like 7mag with 180's and 7br with 168's and .223 with 80's. Curious if anyone has any data particularly for US869. Viht already has N550 data posted which looks promising but there's nothing out there about US869. I fear it might be too bulky for the application.

 

[ATH]

I use Re22 and Re26. I have a nice 3200fps load with Re22 and 105 Amax that went under half MOA vertical at 1K in competition out of a medium sporter barrel. More recently I wirked up Re26, I can get similar 100yd accuracy but anout 70fps faster with similar pressure signs.

 

[BallisticsGuy]

I ended up settling on RE23. So far I've only been working with fire forming loads but it's been a heck of a shooter with those. The first load was 39.3gn under a 108gn ELD-M which netted right at 2800fps, so still a little soft for my money but the shoulders are coming out distinct and it's a laser to 500m. SD's were kinda tall, 30fps over 40 rounds, early on but it must have settled after I stopped taking chrono data and headed up to the long range line because I was nailing 8" plates at 900yrds really reliably with 'em. Now that I know what is basically my minimum fire forming load I can start to work up a load I can use for matches till my brass is all fireformed and at the same time I can work up a full house load on my newly fireformed brass.

Random thought: I already hate Reloader 23 with a passion. Random granule lengths from darned near ball to 1/4" long. The stuff bridges like mad and won't meter basically at all so I'm having to use a Lee dipper and then trickle every load which is its own special hell. The shame of it is the round seems to like it and I have 8lbs of it.

 

[BallisticsGuy]

Final report on the load development.

Settled at 45.5gn RL23 & 108 ELD's or 115 DTAC's. Both run 3180fps with single digit SD's. Hornady brass. Winchester primers made much lower SD's than CCI LRP's or Federal 210's. Both bullets liked jump under .080" all the way down to .010". Didn't test touching lands or jamming.

Barrel life wasn't spectacular. I got to just over 1000rnds before it started opening up enough that I have to re-work the load. I'll be doing some tweaking of the load and I'm going to try to squeeze another 200 rounds from it while my & coach's new 6XC barrels are being set up but I'm not optimistic about my likely match scores till the new barrels are fitted.

 

[APDDSN0864]

I'm resurrecting this thread as I am doing the same thing that the OP did, except with a Savage 10PC in .308.

I also bought a 1:8 twist pre-fit barrel from Columbia River Arms/Black Hole Weaponry because they make great barrels that use Caudle Polygonal Rifling in a great variety of twists that are easy to clean and are very well machined.
Getting a custom barrel from them right now is a 6+ month process and don't expect any communications with them in the waiting time as everyone, and I mean everyone, that works there is on the production floor due to the tremendous backlog of orders that started as the pandemic hit.

So, back to the build, I presently have a two .243Win rifles and one NULA .243AI rifle. There are some loads I am going to start with that are accurate in all three of my other rifles and see where they go.

I have settled on Retumbo or the heavier weight bullets, and have turned away from Re26 due to pressure spikes in hot weather (>95F ambient) and use Superformance for my varmint needs with Varget and Win760/H414 as my backups.

My favorite projectiles right now are 105gr Lapua Scenar-L and Speer 75gr TNT.

Ed