AMP Annealer- they say their machine does not create spring back?? HELP me understand

[XikoPlavi]

I just got one. What does this mean?

From thier notes in the insert you get:

B/c amp anneals the neck and shoulder, you will have zero spring back when full length sizing or shoulder bumping.

Therefore you may have to back your die a fraction from previous settings to size exactly

For the same reason you may have to use slightly larger bushing for neck sizing

*****so, for 6.5 Creedmoor I use a .289 bushing. Should I use a .290 since I use the AMP???

Am I not getting the point here????

 

[straightshooter1]

I just got one. What does this mean?

From thier notes in the insert you get:

B/c amp anneals the neck and shoulder, you will have zero spring back when full length sizing or shoulder bumping.

Therefore you may have to back your die a fraction from previous settings to size exactly

For the same reason you may have to use slightly larger bushing for neck sizing

*****so, for 6.5 Creedmoor I use a .289 bushing. Should I use a .290 since I use the AMP???

Am I not getting the point here????

When necks of brass that has not been annealed and are sized, there is springback. For example, if you're using a .289 bushing, the outside diameter will spring back by something like .0005 maybe even .001 depending on how hard the brass in the neck is leaving you with an outside diameter of ~.290 if that's what going to give the neck tension one is after.

The brass in the neck has to be soft in order to not have any springback and that is what full annealing does to the brass. So, what they're saying is the AMP is fully annealing the brass so that there is no springback. And if one is looking for a .290 outside diameter for neck tension, then for a fully annealed neck, one needs to use a .290 bushing since there not going to be any springback.

Hope this explains it well enough.

 

[XikoPlavi]

Thanks for your reply. Yea that does explain it perfectly. I suppose you eye rolled me b/c you think I’m a moron, but that’s OKAY. I get it now and honestly that’s what I kinda figured but I have never really annealed. I always just threw away my brass after 3 loads, but won’t be doing that anymore.

So, the factory Sierra ammo I have that is VERY accurate in 6.5 CM in my ar10 measures .291 and I have .289 & .290 bushings. So, I was gonna start to mimic that load with the .289 being already annealed BUT now im gonna start with the .290

Which is what I figured anyway. I don’t want to much tension. I may even want to get a .291 but I’ll start with the .290 and see what it ends up measuring once seated

 

[straightshooter1]

I suppose you eye rolled me b/c you think I’m a moron, but that’s OKAY.

No! I was eye rolling my explanation because I didn't feel I explained it well enough.

 

[XikoPlavi]

No! I was eye rolling my explanation because I didn't feel I explained it well enough.

Nope perfect.

 

[Rocketmandb]

This concept of "no spring back" is not really accurate. "Spring back" - or more appropriately brass elasticity - is what holds the bullet in place. No spring back, no hold - and it usually means you've over-annealed brass.

You always need some.

 

[spife7980]

The harder the brass gets the more the grains grown and stress and want to return to its prior positioning, thus “spring back.”
When you anneal you relieve the stresses in the grain and size and that reduces its desire to go back to the prior positioning when sized.

So when you want to size hard brass down one step you actually have to go two steps down gross and it springs back one step for a net of one step. By annealing and reducing its stress you only have to size down that one step and it stays there.