IMHO, the 223 cartridge is more prone to larger ES/SD spreads than other cartridges. If you plan on shooting it at 1K, then those spreads will certainly take you out of the X ring...
Yes! ES values of 40-50 fps are not at all uncommon even with carefully loaded ammo.
The CCI br is a good primer but like any brand primer, that particular lot might not be working well for you...
When I shot 223 with 90s at long ranges using VarGet or Re15, I got much poorer results from the BR4 than its sister CCI-450 SRM, or best of all, the Russian Murom SRM, mine sold in Europe as PMC, better known in the US under the Wolf brand. My lot of BR4s were too hot for the cartridge giving ~40 fps higher MVs than the other two and more than doubling ES. Reducing powder charges to return to the 450 / PMC MVs didn't reduce ES values. (These same BR4s work very well in 6.5X47L and .308 Win / Palma brass with their much larger powder charges.)
Everything has to be perfect in .223 to use it at long range. I only used recent manufacture Lapua Match brass, gave the necks a light 'clean-up' turn and batched them by weight and neck thickness. Primer pockets don't need touching, but uniform flash-holes with a tool like the Sinclair reamer which cuts them slightly larger to 0.081". You meet the occasional case even with Lapua that has an undersize flash-hole and needs a lot more effort to ream it out. If you use Winchester brass, full preparation and batching is essential - necks, primer pockets, flash-holes including deburring the exit end, etc, etc.
I found with 90s in my chambers at any rate, that very light neck tension worked well, just enough to stop a carefully chambered round having the bullet pushed back into the case by the rifling. VLDs always worked best 0.015" or so 'in', tangent ogive bullets like the 80.5gn Berger Fullbore, 80gn SMK and 90gn Berger LRBT generally worked best the same amount 'out', but seating the SMK 'in' could usefully be tried to see what it does both for groups and ES. I found that I got my ideal neck tension using a Forster Bushing-Bump die with a bushing size that was 0.001" smaller than needed, followed by neck expansion using a Sinclair mandrel die and the company's E22 expander mandrel designed for neck-turning preparation, but giving me just the right amount of neck tension on the bullet. Lube the inside of the neck. Shoulders were bumped by 0.001-0.002", any more will not help your efforts.
Weighing charges to less than 0.1gn is important in .223 as gstaylorg says. With 90s, 0.1gn = 10 fps MV change, and it'll likely be a bit more with an 80. I did a lot of research a couple of years back on powder measures and also what sort of consistency I could get using my best efforts with the traditional measure + weighing / adjusting charges on a set of good beam scales (RCBS 10-10) and found that while most of a 50 charge run would be within 1.5gn, a few would take the spread out to nearly 3gn. The issue is your head / eye position looking at the scale beam prodiucing parallax changes. For LR ammo, I used an Acculab and worked to a single kernel of Varget or Re15, that is plus or minus 0.02gn. A beam scale with an automatic cut-off electric trickler can be very consistent. I love my RCBS Chargemaster, but scale drift over a session risks producing far too large charge-weight variations to use charges as thrown.
223 bullets, especially SMKs, used at extreme ranges benefit a lot from trimming followed by pointing. This produces both noticeable BC improvements and also reduction in elevations. ~5% BC improvement is easily obtained. I've not loaded the 80gn SMK in a long time, but most MKs exhibit a fair bit of variation in the base to ogive measurement (180gn 7mm MKs that I'm currently loading in .284 have a >0.005" range and need batching, that compares to around 0.002" for Berger 180gn VLDs out of the box), so measure and batch if needed using a comparator.
Don't use the 77gn SMK, or any other 77, for anything other than short-range matches. These bullets are wonderfully designed, but for a specific purpose - to be loaded to less than 2.26" COAL for magazine and semi-auto operation in High-Power Service Rifle tuned AR15s for the 200 and 300 yard stages. They're amazingly tolerant, accept huge jumps to the lands (as they must), but are relatively low BC having short, blunt nose sections. The 80gn SMK is no great shakes at 0.217 G7 BC, but the 77 is worse at 0.190. They compare to the Berger 80gn VLD at 0.228, 80gn Hornady A-Max with 0.231, and the recently introduced 80.5gn Berger BT Fullbore with 0.234. A near 20% difference between 190 and 230 is a lot given that the 80s start to run out of steam beyond 600 yards compared to a good 155 in .308 Win, never mind a good 185 or 200.
