7.62 Mk316-ish hand load expectations

Barrett.

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Minuteman
Jan 22, 2023
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GA
A buddy and I have been tinkering around with some reloading recently and after a sort of expensive learning curve, we ended up finding the Mk316 Mod 0 recipe which worked perfect since we had a solid line of (relatively) cheap 175gr SMKs and IMR 4064. I was able to aquire some LC machine gun brass through a local shop that is all the same lot and then we've tried both CCI #34 and some Winchester military primers. The load has worked very well for us, landing about .75 MOA out of an LMT MWS and closer to .6 out of my custom R700. Honestly I'm almost comfortable using every component I have with this recipe, but the only thing holding me back from doing it is the fact that once in about every 10 or so rounds, I'll get a flier in a random direction that puts it at about a minute or sometimes a little worse. We're pretty exacting with our loading for our standards and what were expecting, cases all trimmed to within ±.002 case length, powder charge to the tenth of a grain, COAL measured on each round to be within a thousands or so. What would yalls best guess be for that error? Obviously there shooter, but between the two of us and 3 rifles, we can call our shots to be a solid string and still both end up with about that 1/10 figure. Maybe the brass has some inconsistency and we just discard that piece of brass for the next round of loading? I haven't been able to do more loading after firing it from our rifles, so maybe results will differ with a 3rd run. We're very much amateurs so any advice or ideas is appreciated.
 
I too found a large batch of LC machine gun brass (LC 07) several years ago. As I began processing my brass I added the step of weight sorting the brass. I recall weighing 10 random cases for a weight average then settled with a 1.5 gr plus/minus limit. This yielded a little over 400 pieces. Using Dan Newberry’s OCW method, I found my Mk118 load and was very happy with it.
Later I found a large batch of FC 12 brass. This brass proved to be better in weight consistency than the LC 07.
My rifle has a fairly new barrel (<160 rds) but both old and new barrels, 175 SMK’s, IMR 4064 and FGMM primers along with a bit of attention to the loading process leaves me with a big smile after a range session.
 
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The Mod 0 was not loaded at Lake City as far as I know but it actually used Federal Brass and standard FGMM primers.


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Could be normal shot distribution. You could easily be interpreting this "error" incorrectly.

How often are you actually observing this? Recorded sample sizes? Thought: If you printed (10x) 10-round groups, you're saying every single one has a "flier"?

If you're actually concerned with a single component then change out one component at a time and see if it makes a measurable difference. Use large enough sample sizes so you're not fooling yourself.
 
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Honestly I'm almost comfortable using every component I have with this recipe, but the only thing holding me back from doing it is the fact that once in about every 10 or so rounds, I'll get a flier in a random direction that puts it at about a minute or sometimes a little worse.

Could be normal shot distribution. You could easily be interrupting this "error" incorrectly.
Most likely this is the load & shooters' capabilities. How does it do at distance, like 300-600yds?
 
Could be normal shot distribution. You could easily be interrupting this "error" incorrectly.

How often are you actually observing this? Recorded sample sizes? Thought: If you printed (10x) 10-round groups, you're saying every single one has a "flier"?

If you're actually concerned with a single component then change out one component at a time and see if it makes a measurable difference. Use large enough sample sizes so you're not fooling yourself.
I haven't been keeping as meticulous detail as i probably should with round counts of this load, but it's been a consent observation across the probably 80-100 rounds I've loaded of the stuff. The only good example i have with me at the moment is this battleship target my buddy and I shot at 100 yards
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There's normal movement up and down left and right, but you can see 15/18 rounds landed within about half an inch with the majority trending to be nearly right on the left line of the box, but then the three circled ones flew nearly an inch wide. Those are the ones I'm wondering about. Maybe it's a matter of just taking those peices of brass and discarding them and seeing how that group of rounds do after loading again. Also, I know I could do for an adjustment to my zero lol.
 
Most likely this is the load & shooters' capabilities. How does it do at distance, like 300-600yds?
It does well. We can hit a full size steel IPSC 100% of the time out to 600 but usually the steel at the range is shot up enough that you can't spot impacts super well. The 1/3rd IPSIC at the same yard line is about in line with what our 100 yard shows, the majority of rounds will connect but here and there you'll have a same wind observed all the way down range and the same hold and then it just won't connect how you'd expect. We haven't been able to strech it any further unfortunately.
 
The Mod 0 was not loaded at Lake City as far as I know but it actually used Federal Brass and standard FGMM primers.


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As i was, then. I don't know where the distinction comes in exactly but the "Mk316" is more the fact were loading a 175gr smk with 41.7 grs of 4064 in a 7.62 case and getting similar velocity and all to what the military round has. I'd rather have the Federal brass and primers but you work with what you have lol
 
I too found a large batch of LC machine gun brass (LC 07) several years ago. As I began processing my brass I added the step of weight sorting the brass. I recall weighing 10 random cases for a weight average then settled with a 1.5 gr plus/minus limit. This yielded a little over 400 pieces. Using Dan Newberry’s OCW method, I found my Mk118 load and was very happy with it.
Later I found a large batch of FC 12 brass. This brass proved to be better in weight consistency than the LC 07.
My rifle has a fairly new barrel (<160 rds) but both old and new barrels, 175 SMK’s, IMR 4064 and FGMM primers along with a bit of attention to the loading process leaves me with a big smile after a range session.
You don't recall any consistency issues at all once the LC 07 brass was all prepped and trimmed? Would you discard cases outside of that 1.5gr threshold or was that purely your observed average?
 
LC machine gun brass

Did you do load development or just 41.7gr like in that spec sheet?

Lake city brass is decent, the machine gun fired can have wonky necks every now and then making weird tension or fliers, my loads with it and 175smk were 43gr IMR 4064, 43gr RL15, and 41.5 H4895. The mk316 load in that sheet never shot well for me I even had the fed brass, fed match primers too.
 
Did you do load development or just 41.7gr like in that spec sheet?

Lake city brass is decent, the machine gun fired can have wonky necks every now and then making weird tension or fliers, my loads with it and 175smk were 43gr IMR 4064, 43gr RL15, and 41.5 H4895. The mk316 load in that sheet never shot well for me I even had the fed brass, fed match primers too.
Honestly we just kind of sent it at 41.7, got 2600fps out of a 22 inch barrel and the groups you see in that battleship target which aren't bugholes, but its what we were hoping for. I'm reloading more to have 1 load that works well in 3 rifles more than 3 exact recipes to shoot perfect in 3 rifles. With that neck tension, I guess that wouldn't be fixed by fire forming would it, which would just lead back to discarding the flier brass?