Loss of Accuracy After Annealing

B

bill123

New member
I’m a prone shooter working on improving my 1000 yard precision. I just started annealing and processed my 3x fired 308 Lapua brass with a Bench Source annealer. All signs (tempilaq, flame color changing) were correct and the maker of the Bench Source assures me that I am doing the annealing properly.

At 100 yards, my un-annealed brass was giving me 3/8" groups. My annealed brass is now giving me 3/4" groups. I went back to the un-annealed brass and shot a few groups, just now to see if the 3/4" groups were me or the brass. I got 3/8" groups so I'm assuming the problem is the brass.

I neck turn my brass to .014”
My fired case necks are .340” diam.
Neck diam. of finished cartridge w/ bullet: .3355"
Bullets are .3075” measured diam.
I resize with bushing dies in 2 steps .336” then .332”.
My Sinclair mandrel measures 3.055” diam.
After expanding my cases, the neck diameter is .3335” (.002” neck tension)

The maker of the Bench Source unit recommended that I try different bushings to see if that brings the groups back down.

I loaded and shot 2 sets of brass. One with a .331” bushing and one with a .330” bushing. The precision with the .330” bushing was better but not great.

Has anyone experienced this before?
Should I continue to test with smaller bushings?
At what point and I over working the brass because I have used too small a bushing?
In other words, did the annealing make my brass so soft that I had to over size in order to get my rounds to shoot as well as they did before annealing?

One more thing, prior to annealing I was using an ultrasonic cleaner to clean the brass but I switched to SS tumbling at the same time that I started annealing. I know, I should have made one change at a time.
 
Hello Bill, welcome to BRC.
It is possible to over anneal brass making it a bit softer than we would like. I have been told that even when done properly, brass that has been annealed tends to shoot better after it has been fired and resized a couple of times, I'm sure that some of our more knowledgeable members will chime in on the subject.

Whether it's the softening of the brass from annealing or the change in your cleaning method, I do think that neck tension is at the root of your problem.

Good luck,
Dick
 
Hi Bill,
Welcome to Benchrest Central. I did my first batch of brass. And was really surprised. At uniform neck tension.
But, this brass had over well over 20 reloads. Maybe 50. And is 6PPC. Used in 2 Group tournaments and many Score matches.
I use Wonder cloth to clean necks. No tumbling. Tumbling I think changes the brass also. I knew some Off road race car guys, talking about, using a shaker to stress relieve their welding.
Or maybe your brass could have gone a little longer 8-10 reloads.
Custom rifle, custom barrel, and all that......Plus shooting 1000 y.........
I would try 5 shot groups at 200y.
 
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Bill,
I just reread your thread title. I don't think annealing is for accuracy. It's for uniform neck tension.
There is a lot to read on the subject. I read a lot before doing it. Goggle can be a friend or an enemy. Watch the videos.
By the way. That lot of brass might be wasted. Had a barrel go bad. Heavy bolt lift. Too much pressure on the web. Can't anneal the web safely.
Or so I have been told.
 
When annealing does the heat used burn the carbon out of the neck or make it so the release tension is not as consistent? I've had this suspicion for a while but have no evidence to prove or disprove it. Could you try lubing the base of the bullet with motor mica or something to maybe make the release more consistent?
 
Why lube your bullets?
Not sure about carbon in the neck. I used a nylon brush to clean the inside of the neck. So I guess no carbon.
When I seated the bullets they were all pretty close. All 95 brass. Results at the next VFS match were pretty good.
 
Do the annealed and un-annealed loads chronograph the same? You simply may have to retune. What seating depth have you been using? Annealing will reduce the bullet pull somewhat. You may have to play with charge weight and seating depth to find your tune.
 
If you got them too hot and ruined the brass is a possibility, If they looked dull at neck you may have. If you anneal you are better served doing it every time, do your load development with them and it should be a more consistent load. Neck tension will be more consistent……… jim
 
bill123 said:
At 100 yards, my un-annealed brass was giving me 3/8" groups. My annealed brass is now giving me 3/4" groups. I went back to the un-annealed brass and shot a few groups, just now to see if the 3/4" groups were me or the brass. I got 3/8" groups so I'm assuming the problem is the brass.
Click to expand...

Pretty much the same experience I had, fire them 3 or 4 times and they will return to normal.
 
Thanks for all of the replies.
Boyd & Jim. I have not choreographed the annealed vs annealed because I use a Magnetospeed and I suspect that it has some effect on groups size. I was planning on doing that after solving the group size issue. I was hoping that I would not have to do load development all over again after annealing but it seems as if that might be the case.
 
Dick Grosbier said:
Pretty much the same experience I had, fire them 3 or 4 times and they will return to normal.
Click to expand...

I've heard that as well but I stupidly processed all 500 of my cases. That's a lot of bad groups to get back to normal. Has anyone hardened brass by sizing and expanding multiple times w/o shooting in between?
 
I think that you should simply retune your load. Over time, I have come to realize that many shooters seem to regard a load with a lot more reverence than I do. I load and test at the range, and find that doing so allows me to pretty quickly resolve this sort of a problem. I would guess that playing with seating depth and perhaps powder charge should put you back in business, but of course only testing will determine that.
 
Boyd Allen said:
I think that you should simply retune your load. Over time, I have come to realize that many shooters seem to regard a load with a lot more reverence than I do. I load and test at the range, and find that doing so allows me to pretty quickly resolve this sort of a problem. I would guess that playing with seating depth and perhaps powder charge should put you back in business, but of course only testing will determine that.
Click to expand...

I'm one of those who's stuck in the mindset that once I determine the load, I don't mess with it. Probably need to get over that. Any recommendations on how far from my old depth & charge I should start testing? Thanks.
 
First of all, you will waste way too much time, barrel, gas and components doing this by loading at home. I would do a full, from scratch workup, shooting over at least a couple of flags, using a chronograph for all shots. I would pick a seating depth that has, in the past, worked well for that particular bullet, and do what I call a pressure test, which is really a short range ladder test of sorts. I would drop down to a load that while safe, is below my desired velocity range, and shoot one shot per load with increasing charge weights, until pressure signs told me to stop. In your case, I would fire each shot with a different case, since we want to hold neck hardness, or lack of it constant. I would shoot all shots at the same target, noting the evolving pattern of bullet impacts, using the same point of aim, and using the flags to try to shoot all shots in the same condition, or as close to it as I could manage. What I would be looking for is how the impacts moved and perhaps clustered as the test progressed. Hopefully, there would be at least a short range of loads in which there was not much movement of bullet impact. If that happens, I would load three with the middle charge, and carefully shoot a group. If that looked promising, I would do some trials of two shots, seating slightly longer and shorter in increments of .002. I usually choose a starting seating depth somewhere around .006 longer than touching. Obviously this would not be appropriate for a semiautomatic. For a .308 I would use .4 grain charge weight steps for the initial test.
 
Boyd Allen said:
First of all, you will waste way too much time, barrel, gas and components doing this by loading at home. I would do a full, from scratch workup, shooting over at least a couple of flags, using a chronograph for all shots. I would pick a seating depth that has, in the past, worked well for that particular bullet, and do what I call a pressure test, which is really a short range ladder test of sorts. I would drop down to a load that while safe, is below my desired velocity range, and shoot one shot per load with increasing charge weights, until pressure signs told me to stop. In your case, I would fire each shot with a different case, since we want to hold neck hardness, or lack of it constant. I would shoot all shots at the same target, noting the evolving pattern of bullet impacts, using the same point of aim, and using the flags to try to shoot all shots in the same condition, or as close to it as I could manage. What I would be looking for is how the impacts moved and perhaps clustered as the test progressed. Hopefully, there would be at least a short range of loads in which there was not much movement of bullet impact. If that happens, I would load three with the middle charge, and carefully shoot a group. If that looked promising, I would do some trials of two shots, seating slightly longer and shorter in increments of .002. I usually choose a starting seating depth somewhere around .006 longer than touching. Obviously this would not be appropriate for a semiautomatic. For a .308 I would use .4 grain charge weight steps for the initial test.
Click to expand...

Thanks for the reply. I'm beginning to wonder if I should have just stuck with the un-annealed brass. It was actually working very well.
 
I think that we all have 20-20 hindsight, but don't get too discouraged, just get busy and see if you can get the accuracy back with your annealed brass. Doing it the way that I outlined, you should have your answer in one morning. If I am shooting a well built rifle, with a good barrel, off of a good bench and rest setup, over flags, on a day when the wind is easy, I try to get off two shots as fast as I can shoot them correctly, and if the wind held, I believe what they tell me.
 
Boyd Allen said:
I think that we all have 20-20 hindsight, but don't get too discouraged, just get busy and see if you can get the accuracy back with your annealed brass. Doing it the way that I outlined, you should have your answer in one morning. If I am shooting a well built rifle, with a good barrel, off of a good bench and rest setup, over flags, on a day when the wind is easy, I try to get off two shots as fast as I can shoot them correctly, and if the wind held, I believe what they tell me.
Click to expand...

Thanks. I'll give it a try.
 
Hi Bill,
I would load up a few pieces (6 or 9) of your annealed brass with your regular load, fire and re-size them three or four times to see if accuracy returns. You may have gotten the necks a bit too soft to hold consistent neck tension. Working the brass by firing and re-sizing should bring it back.

Dick
 
Just came back from range. Shot 2, 4 shot groups at 100yds w/ 42.8-44 grains Varget in .4gr increments. Shots were randomly scattered w/ no group better than the rest. I'm concluding that I over annealed. Thanks for all of the input.
 
Bill, If you got them too hot and they are flat looking you will be dead soft and will have no neck tension……. jim
 
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