Amp Aztec question

[SDDasher]

I’m going to analyze a piece of Lake City once fired 308 (762) brass to anneal 500 pieces. My question is the 500 pieces are various head stamp years ranging from 10-14; will one program analysis be sufficient for all years? Just trying to prolong life of my M1A brass, not for competition. TIA

 

[rardoin]

Wes, I suggest sacrificing 3-5 cases to analysis and use the average of those readings.

 

[SDDasher]

Thanks Robin. I was hoping some of our ATC friends using the M1A might have an opinion on the consistency of LC brass over the different head stamps and damn that stuff is getting expensive.........hahaha

 

[PopCharlie]

You could also weigh 5 random cases of each head stamp and see how close they are. Then calculate the average across all head stamps. Pick one that is very close (say, less than 1%) to the average. Then analyse it. More work, but it will save a few pieces of brass. Only issue is that if the weights are all over the place, you'll end up analysing several pieces. I've used this method on different batches of Lapua 6.5x47, 6br and .223 when I first got my AMP annealer.

PopCharlie

 

[SDDasher]

You could also weigh 5 random cases of each head stamp and see how close they are. Then calculate the average across all head stamps. Pick one that is very close (say, less than 1%) to the average. Then analyse it. More work, but it will save a few pieces of brass. Only issue is that if the weights are all over the place, you'll end up analysing several pieces. I've used this method on different batches of Lapua 6.5x47, 6br and .223 when I first got my AMP annealer.

PopCharlie

Sounds like a good plan. Thanks for the info.

wes

 

[rardoin]

I think you will have more accuracy by measuring neck wall thickness since weight will be influenced by areas of the case that have no bearing on the setting needed for the desired state of anneal. I would choose a case with the median wall thickness and run an analysis. You will likely end up with a setting that will keep most, if not all, of your necks from work fatigue splitting.

 

[rijndael]

I think you will have more accuracy by measuring neck wall thickness

I suspect he'll find that LC brass is pretty consistent in thickness.

 

[dgeesaman]

I would separate by head stamp and test one from each group. But that could be overkill.

 

[SDDasher]

Thanks to everyone for their suggestions. Here’s what I settled upon; I segregated (can you even use that word in today’s world?) twenty pieces of each year ‘10,’12,’13,&’14. Interestingly there are none for ‘11. I then pulled five pieces randomly out of each year, weighed and averaged weight. I then took the four average weights and averaged them. That weight was 184.5 grains. I searched for a piece of brass at that weight and ran the analysis. The program recommended was 0150.
Not scientific, but close enough to help prolong life of the 500 pieces I have. The weight across all twenty pieces varied by .06 of a grain so I feel pretty confident in the suggested program.

 

[Webster]

I’m going to analyze a piece of Lake City once fired 308 (762) brass to anneal 500 pieces. My question is the 500 pieces are various head stamp years ranging from 10-14; will one program analysis be sufficient for all years? Just trying to prolong life of my M1A brass, not for competition. TIA

You couldn't go too wrong by using one of the lower settings for all of the cases.

 

[INTJ]

You couldn't go too wrong by using one of the lower settings for all of the cases.

Except if you don't anneal enough, then you don't gain anything from annealing. After five firings I was noticing increased seating pressure on some 6 BRA brass. I burned another case and the new setting was a little bit higher than the old. That fixed the issue.

I suspect that my initial Aztec setting was just a bit on the too little side, otherwise the necks wouldn't have started work hardening. However, I freely admit to knowing more WHAT works vs WHY..........

 

[SDDasher]

The M1A is notoriously rough on brass so any longevity gained by annealing the once fired Lake City brass will be a plus. I de-crimped the primer pockets, full length resized with a small based die, trimmed to length, and chamfered the necks inside and out; then loaded twenty Barnes 165 grain TTSX hunting bullets over IMR 4895 to mag length. I will take some to the range for function, accuracy, velocity test next week.