Velocity increase on 6 month old ammo

[The Oregonian]

I didn't remember to seat the bullets farther bc I'm an idiot, but I did pull them and some were fairly easy with noticeable extra effort needed to free the bullet right at first, though some, probably 2/3, needed extra effort right at the beginning.

While I have no scientific way to measure I am pretty certain it was cold welds that caused the higher velocities / pressure.

Here are a few I pulled. The bullet in the first vid was one of the tougher ones.

 

[crkckr]

I've had some experience with cold (or worse, corrosion!) welded bullets. A buddy left a couple hundred 7.62x39mm factory ammo in his basement in their cardboard boxes and several of them refused to fire. I pulled the bullets on the rounds that wouldn't fire and found the bullets corroded into the neck, requiring some serious bashing with my inertia puller. I've also had old ammo that was cold welded but most was 10 years + in age. But I could see it happening on ammo only a year old with cases that had been cleaned well, especially cases that hadn't been cleaned with something like corn cob grit & Brasso, which leaves a film on the brass. Chemical or pin tumbling gets the cases down to bare metal and leaves them perfectly clean, setting up the bullet to case neck weld over time. Reloading is part science with a bit of voodoo thrown in for good measure and that's the part that bites at times.

To the OP, did you you have any pressure signs with the new velocities? If not, I would guess your POI might change a tiny bit but otherwise,you're probably good to go with the faster rounds, as long as they still shoot to your accuracy requirements. If they are, pulling all those bullets seems a waste of time to me... I hate to pull bullets!
Cheers,
crkckr

 

[LDHunter]

I think we all get caught up in the need for everything to be scientifically exact when we handload and shoot ammo and it simply isn't happening.

I've yet to meet anyone that can predict bullet velocity and accuracy well enough to make them happy from day to day much less season to season. Rifles and ammo simply have too many variables. Literally hundreds.

We all strive to minimize variables but in the end it will literally drive you batty and waste your sanity away if you expect true repeatable precision from a rifle or ammo.

It's not true science. It's an art form with scientific foundations.

One more thing.... Once we get as close as we possibly can to eliminating variables in rifle accuracy and velocity we then have to deal with the elephant in the room. The human being trying to actually put a bullet where he or she wants it to go.

No boys and girls... This is not science. It's an art form. LOL

 

[LDHunter]

This post will be a little more on topic. If you get a chance to go to a real sho nuff benchrest match you might want to watch how much cleaning of brass the competitors do. How squeaky clean do they want their brass?

I've always wondered at how handloaders obsess over how shiny their brass is and it appears that the way I learned to clean brass over 50 years ago still applies. Corn cob media in a vibratory cleaner for an hour is enough and perhaps even best. If I want bright and shiny I save that for my rifle not my handloads.

 

[hogheadv2]

I recall reading part of a old reloading manual... [Photo of press and stuff set up on tailgate of pick-up.] Warning that loads worked up and shot right away may differ over time. This had to be from early 70's my dads few books. (I'll say Speer or Redding, maybe not the Sierra as that was notebook style if memory is serving me)
** Now try to search it...

*** BTW, I came across this thread wondering if anyone used their bore scopes to check the inside of the brass on occasion?

 

[aushunter1]

Same here. Cold welding of the brass to the bullet.

I suspect this.
Especially after just trying to scrap some of my old 22-250 rounds that I couldn't use in a new rifle I just purchased.

I was pulling projectiles using a RCBS collect puller & I was astounded in how much effort it took to pull them.

They were produced with redding bushing dies as well!

 

[WildRose]

I had maybe 30 extra rounds from hunting season last year....i hadn't shot that gun since then until a week ago, and had put it away clean. To my surprise, velocity jumped from 3010 avg to about 3070 avg. i cleaned the rifle again and used simichrome to check for carbon ring (there was none). I loaded down a grain with the same jar of powder (N560), same primers (F210), same brass, etc. temp wasn't really any different from my sessions last fall - all in the 60's and 70's at the same location.

Today I worked back up and got 3020 with the same powder charge on ammo that was loaded yesterday...I also shot 2 more of the old ammo and got 3070 again. No pressure signs the other day or today so I felt comfortable with those old rounds.

My guess is that brass springback is what led to the velocity increase...I go .003 under with a FL bushing and then .002 with a neck turning mandrel, so it could come back tighter over time. I anneal with AMP after each firing so the brass isn't worked hardened.

Nothing else changed...could it be springback? Or could it be bullet and neck getting sticky? I tumble with STM and then coat with graphite powder prior to neck expanding and thought that would cover any metal stickiness issue.

Gun is a 280AI with 168 hunting VLD's. Ammo has been kept inside where temp range is normal with heat and AC.

My first guess would be temperature difference.