Dan

Do you think I could get any good info from doing the OCW at 75 yards. That is all that is offered at my local range. I do shoot at least monthly at a 600 yd. range but the local one is most convenient. The rifle is a .223 10FP shooting 75 gn. AMAXs. I just had it bedded and think it is time to try to work up a load.

With the 10FP's heavy barrel, you may not get enough dispersion at 75 yards... But, if I had to guess, I would say go for it.

If you're going to be looking at 1/2 MOA to 3/4 MOA groups, you should be able to see the shift.

If you want a good 55 grain load, work up to 26.6 grains of W748, and depth tune (seating depth adjustments) for optimal accuracy.

For the 69 grain Sierra BTHP, 25.2 grains of W748 should do it for you--again, work up to that level, and then depth tune to optimize.

You can shoot a round robin sequence with the varied seating depths after you've arrived at the OCW. Use .003" seating increments, and work on both sides of a caliber's depth into the case. In other words, seat .28" into the case, then .25" into the case, then .22" (caliber's depth), the go to .19" into the case, and finally .16" into the case. One of these should get you onto a stable vibration node.

Don't overlook the above mentioned charges of W748, they work...

Dan

With my current load it shoots 5 into ~.375" at that range. I use Varget and I wish the elevation dope would be more consistant. As an example I have used from 14 to 16 1/4 MOA at the same range over a one year period(temps from 30 to 90). I hoped the OCW may reduce this. Since I'm pushing the range of the round anyway I hope the OCW load works out to be close to max.

Thanks for the suggestions

I'm not sure how well the 748 load would work at 90 degrees. I like to keep that powder under about 85 degrees, max.

But it's uncannily accurate in the .223, and seems to be the powder against which all others are measured.

That said, the Varget is going to do you a good job, I feel sure. Hodgdon's new Benchmark powder should also be a good choice.

What bullet do you want to use?

Dan

I have always used the 75 Gn. AMAX in this rifle.

I use it to compete at a small 100 to 600 yd. match monthly. I guess I need at least 69 Gn.s to help keep the wind from blowing me around to bad.

Like I said before, it shoots fine but most of the other guys act like they use almost the same dope all the time and I must use different dope every match. I'm still "green" at this and don't have the experience to know what normal is.

If I understand the OCW idea correctly then the OCW load should be more consistant in POI with pressure changes brought on by condition changes.

"If I understand the OCW idea correctly then the OCW load should be more consistant in POI with pressure changes brought on by condition changes."

That's correct, your pressure tolerance (either up or down) will be increased significantly with an OCW load.

I don't know what powder to recommend with the 75 AMAX's, but the Varget should be about right.

Let me know how things go...

Dan

Will do!

Thanks again

If you're going to give the Varget a try, look for the OCW at or very near 25 grains.

Try loading 24.7, 24.9, 25.1, 25.3, and 25.5 grains of Varget, with the bullet seated a caliber's depth into the case. Shoot the OCW test with these charges (see the instructions at my website, linked below) and see if you can identify the center of the zone. This should minimize POI shifts to some degree.

Take care,

Dan

I've been using the max of 23.5 from the Hornady manual. I've saw maximums of 25 gn in other manuals but haven't went any hotter than 23.5.

I do have some primer cratering but my current brass with eight of these loads still have good primer pockets so I think I'm not pushing it to far yet. They only other sign is slightly flattened primers. These stay constant over the temp span mentioned before.

Now for the question sure to make you nervous. Do you think I could handle more powder?

Maybe that is my problem. I think you have mentioned the powder density with Varget needs to be high. I load these things to 2.545" and have some room left in the case.

Hodgdon's max is 25 grains with a 75 grain VLD, which should be pretty close for the Hornady bullet. Hornady and Sierra tend to have very conservative data, and generally publish maximums below the OCW zone.

You'll have to work up carefully, but I think you can probably get to the 25 grain area. I've had .223's and 22-250's crater primers with very conservative loads. Flattened primers show you that you're getting there, but you'll note that many factory rounds will flatten the hell out of primers. Check out some of the Winchester Varmint Pack .223 45 grain stuff, and you'll see what I mean.
If you're using primers without the nickel coating, they will flatten more easily than nickeled primers.

Work up carefully, and USE CCI-BR primers. The Varget will perform so much better with the CCI BR's that it's unbelievable. Try them and you'll see. These are also very mild primers, which should allow you to move toward the 25 grain point with a bit less concern.

Best of luck, work up gradually, and post your results...

Dan