100 fps MV increase on annealing?

[carlsbad]

So last week I got my new AMP annealer and I annealed my once fired 6 slr brass:

winchester 243, neck turned to .012.

The MV Before annealing was 3030 with 46.0 gn of H1000 with an SD of about 15. After annealing it was 3130 with an SD of 7. I actually reduced the load to 45.8 trying to find a velocity that the barrel likes better. Barrel is 30" brux 1/7 .236/.243. 300 rounds thru it.

Before you suggest I keep this load, I had hard bolt lift and crappy groups. No cratering or primer perfs since I run a .059 firing pin in all my rifles. Any ideas on how to explain this?

thanks,
Jerry

 

[mikecr]

One contributor: MV shift from new brass to once fired.
Before the added change (annealing) could be reasoned through as another contributor, we would have to know all about your neck sizing.

 

[1shot]

Depending on the type of chronograph you are using, the amount of light and the direction of the sun can make large changes in the readings as well.
I hope this helps,

Lloyd
Buckeye Bullets and Brass, LLC

 

[carlsbad]

No change in neck sizing. I'm using a .266 bushing and no expander ball.

Velocity change is real. Using a lab radar. also, Streelock predictions were right on at 11 moa at 600 yds for 3030 and 9.75 moa at 3130.

Seems hard to believe. I agree.

--Jerry

 

[jlow]

It’s hard to figure out since there could have been be a lot of stuff going on here. First, as mikecr mentioned, it’s comparing new brass to once fired brass. On top of that, you probably did a bunch of things to the brass prepping it that you did not do to new brass so it’s not just annealing.

 

[savagedasher]

I'm from Missouri -- I need to be shown .
Larry

 

[carlsbad]

I'm from Missouri -- I need to be shown .
Larry[/QUOTE

I'm from MO too. Born in Mexico. Went to grade school in Braymer, went to high school in Versailles. I'm also a physicist and Nuclear Engineer. I have 35 years experience solving problems others couldn't so I don't miss much.

Everything was the same except for the annealing and reducing the powder charge by .2 gn. I think the annealing trumps the change from new to once fired brass.

I used the same dies on the same rock chucker press with the same stop rings. I verified coal etc after the first round. I double weight my charges on a Chargemaster and a sartorius laboratory balance. I did add the holland primer seater to make sure all my primers were seated about .004" below flush. LMK if you think that can add MV.

I know you're used to getting silly questions from newbies but this isn't my first rodeo. Tomorrow I'm headed back to the range. I've yet to decide what to load my rounds for tomorrow's varmint match. I'm thinking somewhere around 44.5. I'll report back.

--Jerrry

 

[AckleymanII]

Jerry, were you using the same lot# of primers?

Also, spring back was more on the brass before it was annealed, and once the brass was annealed, the amount of grip on the bullet may have been increased...brainstorming here with you here...

 

[dkhunt14]

I would presume the chamber is getting sealed quicker and better. When I annealed my Dasher, the load I had always shot got sticky. Not bolt click at top, but sticky upon bolt lift. I was in a match so I don't know velocity but I presume it was more. I believe it takes energy to move the brass, now if brass is soft it takes less energy. Matt

 

[carlsbad]

I would presume the chamber is getting sealed quicker and better. When I annealed my Dasher, the load I had always shot got sticky. Not bolt click at top, but sticky upon bolt lift. I was in a match so I don't know velocity but I presume it was more. I believe it takes energy to move the brass, now if brass is soft it takes less energy. Matt

Matt,
That's all I can come up with. although I can't find anyone reporting this much increase from annealing. Also, my barren seems to be incredibly fast...

I live my labradar because it gives me data even in a match. I"ll be shooting an informal varmint match tomorrow but I'll get data.
thanks,

--Jerry

 

[Ned Ludd]

I'd assume the opposite. He said he annealed once-fired brass. That means it was virgin before that, so I'd have guessed the previous velocity data came from virgin brass. If so, mikecr already pointed out the effect of virgin vs fire formed brass on velocity in the first response to this thread.

A certain amount of the energy goes to expanding the case to fit the chamber in virgin brass. It takes much less for fire formed brass because it is much closer to the chamber in its external dimensions. In my hands, .308 Lapua Palma brass loads speed up 10- 15 fps when using fire formed vs virgin brass, all else identical. The OPs 100 fps seems like a lot to account for solely due to blowing the case walls out, but who knows. I'd certainly think that would account for some part of the increase, if virgin brass was used initially.

 

[jlow]

I'm from MO too. Born in Mexico. Went to grade school in Braymer, went to high school in Versailles. I'm also a physicist and Nuclear Engineer. I have 35 years experience solving problems others couldn't so I don't miss much.

Everything was the same except for the annealing and reducing the powder charge by .2 gn. I think the annealing trumps the change from new to once fired brass.

I used the same dies on the same rock chucker press with the same stop rings. I verified coal etc after the first round. I double weight my charges on a Chargemaster and a sartorius laboratory balance. I did add the holland primer seater to make sure all my primers were seated about .004" below flush. LMK if you think that can add MV.

I know you're used to getting silly questions from newbies but this isn't my first rodeo. Tomorrow I'm headed back to the range. I've yet to decide what to load my rounds for tomorrow's varmint match. I'm thinking somewhere around 44.5. I'll report back.

--Jerrry

How is everything the same?

I mean if you neck turn to 0.012 before you shot, you had to have size the case neck using the expanding mandrel so that the neck is the correct size for turning. I don’t think you would do that on the once fired brass. Also, after you shot the case the first time, did you full length resize? Did you FL resize the virgin brass?

These and other differences are what we are trying to point out. You came here to ask for help and we are trying to help. Despite Larry’s joking around, you don’t need to show us any credentials or take our input as insults.

 

[carlsbad]

Yes, I full size resized both the virgin brass and the once fired/annealed brass.

I formed the brass from 243 to 6slr before turning. I turned it on a .2430 mandrel on the lathe. Then I resized it with the same dieset/bushing taht I used on the once fired brass. Indeed, the necks were sized twice and turned before the initial firing. but the final preparation was exactly the same.

I do have some once fired un-annealed brass from another batch that I didn't think my neck turning was up to my expectations. I can load a couple of those without annealing and see what happens.

--Jerry

 

[Alex Wheeler]

100 fps is a lot. In no way can I see annealing doing that. If the velocity increase is real and everything was truly the same, lot#s exc. I'd say your barrel sped up late in its life. Normally expect it to happen in the first 100 rounds, but your barrel may have been lapped a little coarse and it took longer.

 

[carlsbad]

Thanks alex. This barrel has been acting a little wierd to me. Hard to explain but speeds up from beginning of day to end of day. Come to think of it, there were a few fast rounds (3060 or so) toward the end of the previous session.

--Jerry

 

[Alex Wheeler]

Have a bore scope? Is it fouling unusually? Was the bore diameter normal when you chambered it? What does the lapped finish look like? If its speeding up the more its shot, something is causing pressure to increase. Simplest thing would be excess fouling.

 

[carlsbad]

Bore scope died and I haven't replaced it yet. lands were a bit tight. I had to find a .2358 bushing. Cleaning it seems to have a routine amount of fouling. thanks.

I think I'll go back to .237 barrels.

--Jerry

 

[jlow]

Yes, I full size resized both the virgin brass and the once fired/annealed brass.

I formed the brass from 243 to 6slr before turning. I turned it on a .2430 mandrel on the lathe. Then I resized it with the same dieset/bushing taht I used on the once fired brass. Indeed, the necks were sized twice and turned before the initial firing. but the final preparation was exactly the same.

I do have some once fired un-annealed brass from another batch that I didn't think my neck turning was up to my expectations. I can load a couple of those without annealing and see what happens.

--Jerry

That’s the thing. The more you size the brass, the more work harden it gets, and work harden necks will spring back more which means with the same size bushing your ID is going to be larger so less neck tension.

Once you anneal, the bushing will size it down more and reduce your ID which means more neck tension, and perhaps more MV. FWIW, ’ve seen neck tension causing 100fps MV change.

It’s a bit odd to think annealing will give you more neck tension but trust me it happens. This is a good example of why "precision annealing" is important.

 

[carlsbad]

OK. I should not have said it was the same. What I should have said was the differences that I saw were not significant enough to explain the 100 fps. I like what alex has had to say above about the barrel.

I've decided to go with 44.7 grains and lengthening the COAL by .010 for tomorrow. I was jumping about .020. Gonna try .010.

I'll be at the loading bench for a couple of hours.

--Jerry

 

[Ned Ludd]

As I mentioned, although I typically see increased velocity between fully prepped (meaning I first open up the necks with an oversized expander mandrel, then FL resize with bushing die) virgin brass and fire formed brass, it's on the order of 10-15 fps. You likely have additional contributing factors. Barrel speeding up could be one of them.