Mixed Headstamp for AR15 223/556 LOADS?

I would only use mixed brass for general plinking ammo, where I'm not totally concerned about maintaining really high consistency. In reality, the only way you're going to get really good consistency is by making sure all the components you're using are, well, consistent. In fact, it's not just the headstamp I would be concerned with there, but even whether or not all the brass came from the same batch out of the factory.

To answer your question, I would handle the load work up the same way as I would without using mixed brass, just with a few caveats. First, I might not work up quite all the way to the max load, knowing there will be some variance in pressure between rounds. I don't think it's a huge concern if mixing brass is the only variable, but it's for plinking anyway - I don't need a full-power load for that. Second, I would accept that I'm just not going to get perfect consistency. I'd be looking more for the round that feels the best to shoot while still getting on target than I would a really tight grouping - that's probably just not going to happen (although I have found a few impressive loads that seem to be accurate with most brass).

EDIT: Although, if you wanted to be a little more precise, you could probably work up each brand of brass separately and compare the results, i.e. use a five step ladder and load up five LCs, three of the other for each step.

Vettepilot555 said:

How, exactly, would you handle this on a load work up for the combined set?

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When I do my work ups, I use a single HS, it hopefully eliminates one of the variables. I typically use LC since I have a lot of it. Most of my loads are not near max, so after I develop on LC, I’ll run a mixed HS run and chrono those as well. If you’re looking to be at max, your IVI has less volume so I’d develop on those and then since the LC has a bit more volume, it’s likely it’d be a bit less pressure. I don’t see much difference in velocity between those two HS. Good luck.

Case volumns for 223 and 5.56 vary widely so it really depends on what you are expecting from your reloads. If I am working up a load to see what shoots best out of a particular rifle then I will separate my brass by lots for the test as you talked about above. Note however that case volumes do vary even within the same head stamp. Once I have a load worked up I really don't separate the brass unless I am trying to get a load that is more accurate that others. I have a varmint load that I use all LC head stamps and get consistent 1 MOA which is perfectly fine for my uses. Plinking ammo gets all mixed together but most of my plinking ammo doesn't come close to being loaded at max pressures. If I were looking to create a load for maximun accuracy then I would buy new brass instead of using range brass,

Use the case with the least internal volume... in your case, IVI... for load workup. Going to a case with greater internal volume won't be a problem.

I second loading the case with less capacity first.

Vettepilot555 said:

Thanks guys. Yeah, I understand most of the tenets for precision loads, and follow them. Actually, I'm pretty anal, so I REALLY follow them, even when it's not really necessary for what I happen to be doing.

But these in question, and any mixed HS, are just for plinking.

I was just wondering if there was a kind of rough formula out there; if case volume is (minus X), then reduce load (minus Y) kind of thing.

I want Quickload!! But dam it seems high priced...
:~(

Vettepilot

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I work up my loads with 1 head stamp, if LC same year. If it's a load developed for plinking I will take a 10 case average of the case volume. Then do the same thing to other mixed head stamps. Then I compare the numbers. If the volume is within 1% I mix them together. Those > or < I either adj the load as needed or just change the OAL if I'm not at max till I get the same average velocity. Normally on plinking I prefer to adj the OAL since its a easy change. Normally it doesn't take more than 0.010" if there relative close. If I want max accuracy you will end up adj the powder charge to get the same velocity.

What powder charge will reliably function the gun will depend on several things: size of gas port, how well sealed the gas system is, weight of buffer, strength of action spring...

Just have to test and come to your own conclusions.

Edit: I have a particular AR that refuses to properly function with even max loads of H335. Feed it BL-C2 however and it's 100%. This gun has a gas port I measured with a pin gauge at exactly .078" mid-length gas 16".

If you're tight on supplies.
Start at the minimum charge weight and load one in 2/10 increments.
Checking for bolt lock open by only loading one cartridge at a time.
When you get to this. Start looking for accuracy.
My AR was extremely overgassed so I could start at minimum charges.

If you are loading 55grn bullets, it seems like everyone winds up in the 23'ish grn range. Looking at Hodgdon's online data for comparable bullets, starting charges are around 21grn, which should work well enough, unless your rifle is picky.

I generally avoid mixed headstamps in any batch. I also usually weight the brass, sorting out anything outside of a 1 gr range.

I also convert a lot of 556 brass to other cartridges.

For LC headstamps, I usually mix years, but again I weigh the brass separating out stuff that is not within a 1 grain range.

For plinking loads, I don't worry about it much. For hunting loads, (which in my recent experience ended up as my 'go-to' recipe for plinking and hunting loads) I use LC, and stick to one year for workups. The 60 gr. Partitions I finally am going to start after several years of saying I would (Reason: That's all the bullets my LGS had left, and he had them at the same price he's always had them) will all be in LC 17 without the 4 pt. stab crimp. (those tended to be 18's in this batch of brass)
Next is selecting between the only two powders I have enough of to do 50 rounds; BL-C(2) or IMR 3031. I'd run test batches of each powder, laddered, but I only have 50 Partitions.

I find the weight and case volume is not the only big issue with mixed brass, it is also the brass alloy composition and annealing that effects neck tension.

joneb said:

I find the weight and case volume is not the only big issue with mixed brass, it is also the brass alloy composition and annealing that effects neck tension.

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I too found the neck thickness and annealing was more important than small variations in weight.

It's always better to sort. If you adjust your die for a "tight" case, you will likely end up a loose bullets @ some point.