Annealing opening up groups?

[MikeMcCasland]

Hey Guys,

I picked up an AMP last week and annealed some cases for a rifle that historically has shot very well, and very consistent. When I took it out to the range today, I shot some leftover match ammo that hadn't yet been annealed along with some annealed rounds I just loaded up; load data/everything identical except the cases.

The newly loaded rounds had their groups open up noticeably at 300 yards vs. the rounds I'd loaded up earlier. I also "Aztec'ed" another round just to make sure I didn't over-anneal the cases previously.

That said, I'm curious if you guys have run into this before? I'm thinking of dropping down .001 in bushing and testing again, but wanted to see if anyone else had any thoughts as to what happened.

For reference, this is a 6.5, and I'm running Alpha LRP brass. The cases I previously annealed were done using aztec code 152, and the machine just analyzed another piece of brass at 153...so I'm thinking I didn't over-anneal anything.

Thoughts?

 

[Ned Ludd]

How many times was the brass previously fired without annealing? I'm wondering if you changed the neck tension by annealing and it might have affected the load.

 

[MikeMcCasland]

How many times was the brass previously fired without annealing? I'm wondering if you changed the neck tension by annealing and it might have affected the load.

~4-5 times. That said it had shot very well, and very consistently, on all previous firings.

 

[spclark]

Annealing cases changes a factor affecting the harmonics associated with cartridge firing. It’s something that has to be factored in when changing variables, whether altering a load profile will be necessary.

A lot of new brass can be bought for the cost of high $$$ annealers (at least for most commonly used cartridges) to say nothing of the time it takes to process fired brass for re-use.

Annealing increases brass life, may be the single most significant benefit
over using cases just a few times before abandoning them.

 

[MikeMcCasland]

I guess I'll just redo load work-up; not trying to start a thread debating the merits of annealing.

 

[gambleone]

How many times was the brass previously fired without annealing? I'm wondering if you changed the neck tension by annealing and it might have affected the load.

Probably.

 

[KenOath]

I’ve done a similar thing with 6x fired BR brass, the annealed brass had much lower neck tension than it did before I annealed obviously and shot worse than the non annealed because I worked up a load with non annealed..I put another couple firings on the annealed brass without annealing again and accuracy came back. I believe if you are going to anneal do it from the start and anneal every firing, I rotate 200 pieces of brass per barrel and keep em on the same cycle..works for me.

 

[Mulligan]

I have found annealing to be just one more of the many things I test with each new barrel.
I think, it is related to what the powder "likes". Some powders like a lot of neck tension some, not-so-much.
To answer your question, Yes I have "seen it" before. If you search on this site, you are likely to find good informative threads focused on this very thing with lots of input from the long range crowd.
CW

 

[Ned Ludd]

I’ve done a similar thing with 6x fired BR brass, the annealed brass had much lower neck tension than it did before I annealed obviously and shot worse than the non annealed because I worked up a load with non annealed..I put another couple firings on the annealed brass without annealing again and accuracy came back. I believe if you are going to anneal do it from the start and anneal every firing, I rotate 200 pieces of brass per barrel and keep em on the same cycle..works for me.

That's what I was thinking. It's analogous to working up a load and then switching bushing size. The load might stay "in the window"...but it might not.

 

[varget204]

you said you used different cases; should anneal the cases you were using,do you check temperature on annealed cases /

 

[MikeMcCasland]

you said you used different cases; should anneal the cases you were using,do you check temperature on annealed cases /

I was using the same lot/box of 100 Alpha cases. Half were annealed, half weren't.

I obtained the correct annealing temperature by using AMPs "Aztec" mode, which analyzes the brass to give you the 'perfect' annealing temperature. I don't think this was a case of annealing too much, because afterwards I sacrificed another case to confirm my original aztec code; it came out 1 number off.

I just finished annealing the entire box of fired brass. I'm going to test with .001 and .002 smaller bushings, using the same powder charge.

On a somewhat unrelated note, it makes me think if annealing can push a load out of tune, it can also keep one in tune, provided you're doing the exact same thing every time.

 

[KenOath]

If you work up a load with annealed brass with same neck tension and anneal the brass every firing or enough to keep your neck tension the same I can’t see that being a problem, many shooters do it well..

 

[muleman69]

If you work up a load with annealed brass with same neck tension and anneal the brass every firing or enough to keep your neck tension the same I can’t see that being a problem, many shooters do it well..

Great info, even at my age I can learn something. Thanks

 

[Bc'z]

I was using the same lot/box of 100 Alpha cases. Half were annealed, half weren't.

I obtained the correct annealing temperature by using AMPs "Aztec" mode, which analyzes the brass to give you the 'perfect' annealing temperature. I don't think this was a case of annealing too much, because afterwards I sacrificed another case to confirm my original aztec code; it came out 1 number off.

I just finished annealing the entire box of fired brass. I'm going to test with .001 and .002 smaller bushings, using the same powder charge.

On a somewhat unrelated note, it makes me think if annealing can push a load out of tune, it can also keep one in tune, provided you're doing the exact same thing every time.

If I'm not mistaken your un annealed brass has more springback creating a lighter neck tension.
Might I suggest going up in bushing size by .001 and not down. As the annealed brass is more malleable and going down would create more neck tension.
Correct me if I'm wrong

 

[MikeMcCasland]

If I'm not mistaken your un annealed brass has more springback creating a lighter neck tension.
Might I suggest going up in bushing size by .001 and not down. As the annealed brass is more malleable and going down would create more neck tension.
Correct me if I'm wrong

You could be (probably are) right. I didn't pay attention to neck springback prior to annealing. Either way, I just finished up loading up a bunch of rounds, so we'll see.

 

[michaeljp65]

Mike, how many cases did you sacrifice to get the correct Aztec mode number for your lot of brass?

 

[MikeMcCasland]

Mike, how many cases did you sacrifice to get the correct Aztec mode number for your lot of brass?

Two cases. One came up a 152, and the other a 153. At the time of 'sacrifice' both had ~4-5 firings on them; not sure if that helps.

I opted to anneal at 152 to avoid over-annealing.

This seems pretty consistent with other testing I've done. I have a few thousand fully prepped/neck turned LC .223 cases, and I sacrificed about 20 of them just trying to get a feel for how much variance Aztec needed to alter the code; I only ever got a +/- 1 number deviation in that testing.

Same with some old .260 Lapua brass that had ~12-15 firings on it.

 

[David Christian]

@MikeMcCasland. Overall, annealing brass is a major change to your load development process. I think you found yourself anchored to your old load, yet you changed a major ingredient in the formula. If you are going to consistently anneal going forward, I might suggest that you start over from scratch with your load dev process.

Neck tension is the combination of three things: interference fit (i.e. bushing size, mandrels or gage pins), neck hardness (anneal or not), and the surface condition of the inside case neck and bullet surface (lube, graphite, carbon, steel wool, etc.).

Annealing brass will continue to be debated until the cows come home, but I anneal after each firing and also gage pin each case post full length sizing so that I have a consistent inside neck dimension. If you follow this technique you will find that no matter what bushing size you use or gage pin/mandrel you use, the case springs back 0.005 each time.

For example, on a .284 use a .309, .310, or .311 bushing to size the neck. Assuming that bushing adequately sized down the neck to a smaller dimension, use a mandrel/gage pin of .283 and the case will spring back to .2825. Use a .284 gage pin and your final dimension will be .2835.

The consistency of the springback is directly related to the neck hardness from annealing. I would hypothesize that your node opening up has a high correlation to the change in this variable.

Let us know how your future tests go.

Best,
DC

 

[MikeMcCasland]

@MikeMcCasland. Overall, annealing brass is a major change to your load development process. I think you found yourself anchored to your old load, yet you changed a major ingredient in the formula. If you are going to consistently anneal going forward, I might suggest that you start over from scratch with your load dev process.

Neck tension is the combination of three things: interference fit (i.e. bushing size, mandrels or gage pins), neck hardness (anneal or not), and the surface condition of the inside case neck and bullet surface (lube, graphite, carbon, steel wool, etc.).

Annealing brass will continue to be debated until the cows come home, but I anneal after each firing and also gage pin each case post full length sizing so that I have a consistent inside neck dimension. If you follow this technique you will find that no matter what bushing size you use or gage pin/mandrel you use, the case springs back 0.005 each time.

For example, on a .284 use a .309, .310, or .311 bushing to size the neck. Assuming that bushing adequately sized down the neck to a smaller dimension, use a mandrel/gage pin of .283 and the case will spring back to .2825. Use a .284 gage pin and your final dimension will be .2835.

The consistency of the springback is directly related to the neck hardness from annealing. I would hypothesize that your node opening up has a high correlation to the change in this variable.

Let us know how your future tests go.

Best,
DC

David,

Thanks a TON for the in-depth response! I fully agree with your assessment. I will absolutely be incorporating annealing into my standard load process (I paid way too much money for this thing; you better believe I'm going to use it! ). I suspect once I get the load re-tuned it won't be a big deal, and I'm guessing I don't need to go back to the drawing board completely, as I know this powder/bullet will shoot. Probably just play with bushing size and seating depth?

More than anything, this change just caught me by surprise. I figured it would go back to 'like new' brass; and from the very first round on virgin brass, this barrel has produced excellent groups.

Like with any new reloading toy purchase, I'd spent many hours reading AMP user reviews, annealing theory etc. In all of that 'research' I didn't come across someone annealing their load out of tune. Given some of the posts in this thread, it may be more common than I thought.

Live and learn I guess!

Thanks again,
Mike

 

[Bc'z]

Mike I'll be shooting some loads I just finished last week that I too annealed the cases after numerous firings. It will be interesting to see if I too have a grouping issue.