New to me issue with brass

[R2rr]

The bullet leaves the barrel too fast and creates a vacuum, causing the brass to collapse. My Creedmoors do it all the time.

So, what's the cure for this? Slower burning powder to maintain positive pressure behind the bullet? Or a charge weight change?

 

[asd9055]

So this is what I found when a did a search...its from another site...read comments by
Patrick Chadwick

Dimple in Brass Cases

Had two strange occurrences while shooting some reloads at a range last week. I fired 10 reloads each of a 7.62x54R load using Varget, IMR 4895 and BL-C(2) and ten reloads of a .303 British using BL-C(2). The last fired case for the 7.62x54R using 41.0 gr. BL-C(2) (starting load as listed...

www.milsurps.com

 

[338 dude]

Its interesting that none of my loading manuals list H4350 for that combination. Hodgdon website will show for 175 and 180, and depnding one which one you select, could be either below or above minimum.
I tend to start a little below max my self and work up. That's probably why I have never seen it

Probably not the best match so they don't invest the money to do tests and publish it

 

[338 dude]

So, what's the cure for this? Slower burning powder to maintain positive pressure behind the bullet? Or a charge weight change?

Both!

 

[Pointman]

Looking at the photo closely, these brass look like the photo is after sizing. Assuming this is the case, you are getting too much lube on the shoulder area of the brass. Clean your dies well and keep the lube off the shoulders if you are using a lube pad

I agree that some of us, myself included, have neglected cleaning or sizing dies regularly. I have abandoned the lube pad for Imperial wax manly due to wearing out my last pad. I did occasionally see a dented neck when using the pad but I did learn to religiously ensure the shoulders had little or no lube accumulation of lube.

 

[RUFFIAN R - NY]

What lube you using and keep die clean and air hole open . Clean dies make a difference

 

[Mike Matteson]

First you never answered if the dents are showing up after sizing or after firing the round. If the dents are showing up when resizing, then the die is dirty. You are using 215 primers. So the is about right. With 165gr bullets I am using 75.5grs of H4350, but a 210 primer @ 3300fps. If nothing else clean the sizing die. Just to remove that possible problem.

 

[Veteran]

Good afternoon,

I have been reloading for a few years and have not had any issues like I am seeing in my new gun. I am looking for a little expert advice. I am loading 64 grains of H4350 in my Bergara 300 Win Mag shooting 178 grain Hornady ELDX with a Federal 215 Primer. In the 3rd reload with these cases, I started getting the following dents In the neck/case. This is by no means over max load. Also, these pieces of brass have not been annealed.

View attachment 379138
In doing some research, it is possible that I am loading too close to the lans and not giving the brass enough time to expand out creating a pressure issue. I am not an expert by any means and I am hoping that someone can give me some good advice or point me in the right direction.

Thanks for any and all information.

Respectfully,

The other way you can get these dimples on a belted 300 WM is by having imminent or actual case head separation up on the case head above the belt.

In these pictures, I cannot see the belts or case heads, to look for telltale cracks in the brass.

I have had case head separation on .300 WM brass in 3 firings on Hornady Brass.

Gas leakage there will pooch shoulders and necks in like that too.

 

[2buffalo]

First you never answered if the dents are showing up after sizing or after firing the round. If the dents are showing up when resizing, then the die is dirty. You are using 215 primers. So the is about right. With 165gr bullets I am using 75.5grs of H4350, but a 210 primer @ 3300fps. If nothing else clean the sizing die. Just to remove that possible problem.

He did in post 16.

 

[Veteran]

I appreciate all the comments. The data I am using is from the Hornady guide for that particular bullet. Those loads are coming out at 2925 ft per second already so they are a pretty fast bullet. It is happening at the chamber, not resizing. I am going to go up a bit on the charge and check again. Are these cases safe to use again?

Thanks again,

Grub

If you see any crack or a tell tale ring above the belt on the case head, you may have case head separation...Be careful to rule that out.

 

[volunteer06]

The other way you can get these dimples on a belted 300 WM is by having imminent or actual case head separation up on the case head above the belt.

In these pictures, I cannot see the belts or case heads, to look for telltale cracks in the brass.

I have had case head separation on .300 WM brass in 3 firings on Hornady Brass.

Gas leakage there will pooch shoulders and necks in like that too.

That's my assumption as to what happened here. 4th firing Hornady brass with a decent load

 

[Sheldon Root]

I would say you have to much lube and or a clogged vent hole in your die. Your load for that bullet and caliber is just under max so not under pressure in my opinion. There would also be loads of carbon all down the side of the cartridge where the dent is. It takes a very small amount of excess lube to give you this dent, die tolerances are pretty spot on to caliber size. Dismantle the die, clean well and reset. Should be good to go. IMHO

 

[Powell]

I've seen dents like that with case head separation. Any cracks about 1/4" up from base?

 

[ntsqd]

I am not questioning that you have seen it, I am trying to wrap my head around the physics. the moment the bullet leaves the case, if there is not a total seal, the pressure inside and outside the case is the same.

Just in case no one addressed this yet, the common thought is that if the pressure is low enough that the neck doesn't fully expand and form a seal. Then that neck clearance that you worked so hard to minimize is pressurized too, and that pressure pushes on the case shoulder forming that dent.

The way that I use the lanolin spray is I have a cookie sheet with one of the "garage service" type paper towels doubled up and laying in it. I spray that, and then roll the cases on it to lube the case sides without getting any on the necks and shoulders.