I just got a new 18" JP 308 barrel and want to properly feed it. I'm thinking 800yds max for designated marksmanship type matches and maybe some medium range hunting.

From my 3 gun AR10 I have HUNDREDS of (ZQI blasting crap) MKE marked turkish brass. I dont know if this is good for precision work or if I should just load it for 3 gun blasting or if its considered worthless.

I have somewhere over 100 each of Hornady and Federal brass. Most of which was fired in a RPR.

Also have another 200 or so of VERY mixed cases from both bolt gun and gas gun. I'd use them for blasting, but knowing different case volumes in 308 could cause drastic velocity and pressure swings i would guess thats a bad idea.

I would think I need more than 200 brass in circulation to properly feed a precision ish semi.

Note, I have a 1000 155gr Nosler CC's coming in tomorrow. Might use them for long range if they perform. Otherwise I plan the 175/178/180 gr route for long range and download the CC's for powder puff 308.

You won't know if the brass will produce acceptable accuracy unless you load a few and try. You may get 3-4 loading vs 10 loadings.

So MKE will have a short lifespan.  What will be the mode failure.  If its best I can fire some more factory Fed or Hornady just to get the brass count of either one to 200.

Also, is mixed brass for blasting rounds in 308 a good or bad idea?

I’ve got a bunch of MKE so I’m curious about this as well.

I recommend Lake City once fired brass for precision 308. A guy who reloads and shoots more in a year than I will in a decade told me that when it comes to .308, the only better brass is Lapua and it’s not worth the price. (He uses Lapua for most of his other calibers.) LC brass is CHEAP (like $150/1,000) and heavier and more uniform than most commercial stuff. I took his advice and I’ve been very pleased with the results.

ETA: here’s primed, unfired LC brass $169/1,000

I don't know I've never loaded it. But it may turn out alright and it may not. I got a bunch of IRI gave to me by a buddy. I loaded as blasting ammo and set 50 aside to play with. Well I'm on my eighth load with it and my primer pockets are holding better than my Fed brass. I just sorted it and uniformed the primer pockets after rolling the crimp out. If unsure sort 20 rounds out and load it. Your rifle may actually like it better than something else.

I wouldn't use it. I looked into it before doing some load development and found that the case capacity had too much variance for my liking. You may end up spend more in time and money chasing accuracy with sub par brass. I would pick up some starline which is a great price for the quality.

Did very limited trial of the brass because bought fair amount of the cheap rounds years ago.  If memory holds, it has similar weight to military surplus or federal brass.  Harder than Fed brass, but softer than military surplus.

Like others said, you won't know till you try it.  If trying for consistent precision, may be advantage to having same make and lot of brass that was shot through same rifle. This can minimize variance of head to shoulder datum.  Am reluctant to run any brass through semi auto more than 4 times with full powered loads.    Maybe try sizing the MKE brass so it will work with new barrel, trim it and try it.

I don't know about number of firings, but i worked my way up to the same charge level as i use with LC brass, 42.7 grains 4064 loaded to 2.810 COAL with Speer 168 grain HPBT's.  LC or ZQI brass, both shoot just under moa average 5 shot groups.  I bulk loaded about 500 rounds of the Zqi brass after working up the load and haven't shot my way thru that batch.  For the roughly $5 per 20 Walmart was selling it at, even if it only lasts 3-4 reloads it was well worth it.  Just work your way up, iirc i get 2630 fps average from my 20 inch barrel with that load.

I've loaded about 200 rounds of this brass.  So far I'm not sure.  It has a higher case capacity vs LC.  At same charge of 4064 powder the LC brass is 80-100fps faster due to this.   Primer pockets on some are very loose after 1-2 firings.   I'm not sure how it will hold up over the long haul.  Accuracy is still an issue, but I'll blame that mostly on me.   Compared to other brass I have, I cannot tell accuracy differences once I control for velocity etc...

Lake City brass is popular for your application.  If you would like to buy some new LC cases, they are about $40/100.  Or, another way to skin that cat is to buy cases as ammunition ($275/500 shipped).  Note, the ammunition has crimped primer pockets that you will need to deal with in order to reload it.  The new LC brass is not crimped (FWIW).

I reloaded a bunch of ZQI brass after the initial firing. After 3 firings (2x reloads) it was toast. If you want cheap brass capable of shooting well then get some LC and go that route. Getting 6-7 loading out of Plain Jane LC brass, and could do better if I bothered annealing it.

MKE is probably built like Lake City, to NATO specs.

Weigh empty unprimed cases, Lake City averages close to 180 grains. It requires a two (2.0) full grains reduction in powder charges.

Maximum powder charges in Lake City w/168 SMK's:

41.5 grains of IMR-4064
40.5 grains of IMR-4895
40.0 grains of H4895
39.5 grains of IMR-3031
43.0 grains of WW-748
40.5 grains of AA-2460
41.5 grains of Varget
41.5 grains of VihtaVuori N150

One half grain lower charges across this list works well and provides a reasonable load before trying full power loads.

MKE/ZQI ammunition is made in Turkey.

Most 7.62x51mm military brass, even foreign manufactured, is built for machine gun use. The average unprimed case weight is usually around 180 grains +/-.

The OP needs to weigh his cases and treat them accordingly. 180 grain cases need the lighter charge weights I posted above.

Commercial .308 cases weighing around 160 grains +/- 5 grains can be loaded using standard reloading tables from the bullet manufacturer's data base.

BTW - Hornady's "service rifle data" works great in semi-auto's.

Not arguing against that at all. The ZQI I loaded got the same velocities with 1.2gr less powder due to decreased case volume. Good rule of thumb is to start close to the min charge for commercial .308 and work your way up the ladder.

Sort through your brass by headstamp.  Various batches of brass may vary in weight or thickness, affecting overall load.