Hi everyone. I have a question about the color of my 50 bmg brass. So I'm just getting into reloading the 50 bmg and acquired 1000 pieces of brass from a buddy. He purchased a couple of 50's with tons of reloading supplies. The brass in question has a rainbow color to them and I'm wondering if they are safe to load. The cases are LC 81-91 headstamp and i don't know if they were fully annealed or if the color pattern is due to sunlight/age? I live in Arizona and the brass was purchased here as well so summer heat might be a factor? I'm just not sure if the guy who sold it maybe placed the cases in the oven and potentially ruined them? As stated before, I am new to reloading 50 bmg but have been reloading multiple calibers for 18 years. I have never seen cases this color and don't want to load if they are unsafe. I don't want a hand grenade going off a foot from my face, haha. Any information would be of great help! Thanks!
50 BMG Brass questions
- Thread starter Andrew D
- Start date
rockhound78
Silver $$ Contributor
I would not want to touch off a 50 cal round where the brass might have been over-annealed in an oven. I would take them back to your buddy.
The only other time I have seen cases look like that was when I took freshly cleaned cases and swirled them in 99% isopropanol. They changed colors quickly
The only other time I have seen cases look like that was when I took freshly cleaned cases and swirled them in 99% isopropanol. They changed colors quickly
Fast14riot
Gold $$ Contributor
Error on the side of caution,of course, but those look more like oil staining than over annealed. My dad ruining a batch of 270 brass in the oven drying them, they all came out a very uniform grey.
I hope no-one is dumb enough to anneal in an oven. Looks like oxidation from just laying around??? Take a pair of pliers and squeeze the neck. If the brass is way over annealed you can squeeze the mouth ovel with little effort. Get some other cases you have laying around that you know were not annealed, sqeeze them to get a feel for how strong the neck resist deforming. If you are going to ue them just load one and shoot. Wear safety glasses. You should be OK?
How were those brass cleaned? I found the old way of cleaning with vinegar and salt in an ultrasonic bath affected the brass by dissolving some of the component metals, perhaps the zinc or copper, and the brass cleaned with that method was discolored and came out somewhat reddish. I had used that for pistol brass for many years, but now have switched to cleaning with a detergent solution and haven't had any problems. Here is the sequence I use for .50BMG military brass:
clean in ultrasonic bath at 30C for 50 mins.
decap with an arbor press
bevel the primer crimp away
anneal neck and shoulder
full-length size
trim to length 3.90"
bevel i.d. and o.d. of the trimmed neck
polish with Scotchguard red
ream flash hole
square primer pocket
As a side note, once-fired military brass is normally quite a bit oversize owing to having been fired in a loose M2 chamber. The brass is often 0.520" or more in i.d. at the neck as well as being .010-020" over length. The shoulder and case requires considerable sizing as well, and this is normally difficult.
Cleaning military brass in ultrasonic bath at 30C is necessary to soften the sealant that is used on the primers. Otherwise, the decapping operation is difficult or near impossible owing to the decapping pin punching right through a sealed primer.
Finally, the anneal is important because the sizing operation will work the neck quite a lot. The military chamber is so loose that the necks of fired brass will be 0.515 to as much as 0.525 i.d. Sizing reduces this to typically 0.490 so that the button expands to 0.505. Necks may fail in some brass after one or two firings.
clean in ultrasonic bath at 30C for 50 mins.
decap with an arbor press
bevel the primer crimp away
anneal neck and shoulder
full-length size
trim to length 3.90"
bevel i.d. and o.d. of the trimmed neck
polish with Scotchguard red
ream flash hole
square primer pocket
As a side note, once-fired military brass is normally quite a bit oversize owing to having been fired in a loose M2 chamber. The brass is often 0.520" or more in i.d. at the neck as well as being .010-020" over length. The shoulder and case requires considerable sizing as well, and this is normally difficult.
Cleaning military brass in ultrasonic bath at 30C is necessary to soften the sealant that is used on the primers. Otherwise, the decapping operation is difficult or near impossible owing to the decapping pin punching right through a sealed primer.
Finally, the anneal is important because the sizing operation will work the neck quite a lot. The military chamber is so loose that the necks of fired brass will be 0.515 to as much as 0.525 i.d. Sizing reduces this to typically 0.490 so that the button expands to 0.505. Necks may fail in some brass after one or two firings.
Those look like they were cleaned in a mild acid, as some people do. I briefly played with an old NRA recipe for dilute citric acid brass wash, and mine had that same rainbow appearance.
coldboreshot
Silver $$ Contributor
This statement^^^^^^^^
Andrew D,
If you do not know the reliable source where they came from, discard them. Don't be that guy that we all read about in this forum where it is used as a safety summary. Everyone can look at the pictures and arrive at their own conclusion but you are still the determining factor if you want to chance it. Get yourself a fresh inventory of brass whether it is surplus Winchester, LC, or even new RWS or Lapua. That way, you have full control. Good luck, I'm sure you will make the right call.
I say put some in a tumbler with the stainless pins lemishine/ dawn. After they come out clean they could look like new. It looks like a harmless surface tarnish. I'm not positive but an oven can only reach 500 degree temperature max. Annealing necks the temperature is 800.+ Or thereabouts. So i dont know for sure but i don't think an oven would ruin cases. ? Google would be helpful to see temperature / annealing / brass.
Last edited:
I thought the melting point of brass was around 1650° F
Could be lets Google
I have been corrected, it seems annealing temperature for necks is more around 800 degree temperature. Thank goodness for Google.
Thanks for pointing out this. I googled and you are right. Annealing necks are somewhere around 800+ . at least that's what one article said.
rmr
Gold $$ Contributor
its been quite a while since I've been to a FCSA match, but I've reloaded extensively for 50BMG.
it looks like the brass was just outside in a bin for months (or years) and that was where it picked up the oxidation. but who knows without knowing the source.
generally speaking, surplus brass is a crap shoot because of the headspace adjustment on an M2. as long the gun (M2) was properly adjusted, the brass is fine but that rarely seems to be the case. The end result here is that some cases are so severely stretched that you need to be popeye with some spinach to resize the cases, and then they will only last one or two firings. After two attempts to make surplus brass work, i gave them away and just bought new.
I've always used IMI cases for competition, but new Winchester, and CBC should still be available. I have a bunch of new CBC cases that I'll sell if you happen to be interested. (500+)
Annealing 50 cases is super easy. I would just pick them up by the base with thumb and forefinger. use a propane torch to evenly heat at the neck / shoulder junction while rotating the case. you will see the heat anneal ring start to move down the case. once you feel the base of the case *start* to heat up, simply put it down on the bench to air cool. you only have about 2 seconds for this last step, or the case will end up on the floor, along with a couple of new four letter words. once you get the hang of it, your anneal rings will be on the upper 25% of the case, about 1/4" past the shoulder junction. I have neck turned cases that have 15 firings on them (annealed every 4th shot).
it looks like the brass was just outside in a bin for months (or years) and that was where it picked up the oxidation. but who knows without knowing the source.
generally speaking, surplus brass is a crap shoot because of the headspace adjustment on an M2. as long the gun (M2) was properly adjusted, the brass is fine but that rarely seems to be the case. The end result here is that some cases are so severely stretched that you need to be popeye with some spinach to resize the cases, and then they will only last one or two firings. After two attempts to make surplus brass work, i gave them away and just bought new.
I've always used IMI cases for competition, but new Winchester, and CBC should still be available. I have a bunch of new CBC cases that I'll sell if you happen to be interested. (500+)
Annealing 50 cases is super easy. I would just pick them up by the base with thumb and forefinger. use a propane torch to evenly heat at the neck / shoulder junction while rotating the case. you will see the heat anneal ring start to move down the case. once you feel the base of the case *start* to heat up, simply put it down on the bench to air cool. you only have about 2 seconds for this last step, or the case will end up on the floor, along with a couple of new four letter words. once you get the hang of it, your anneal rings will be on the upper 25% of the case, about 1/4" past the shoulder junction. I have neck turned cases that have 15 firings on them (annealed every 4th shot).
Thanks for all the replies. I have a feeling the cases were left outside for years and are completely fine. I will try and track down the original owner to see what he did/didn't do. That being said, I don't think I'm comfortable with a potential grenade ruining my new rifle.
Again, thanks for all of the input.
Again, thanks for all of the input.
rockhound78
Silver $$ Contributor
Rifle can be replaced, its YOU that I am more concerned with.
hoz53
Gold $$ Contributor
this is a good thread OP to remind me if i ever get a 50 ill just get new brass. had always thought about LC brass but for the money we spend on a 50 rifle and all the rest of the stuff we need new brass isnt much. of coarse safety first.
Thanks, that is also a huge concern
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.