Coated cast (bought) 203 and 215gr. OAL

[taymag]

Not sure if this is allowed here but I figured you guys would know best.

I have some 203gr and 215gr 300 blackout rounds that I am trying to load up and was wondering how I get my OAL for them?

[runfiverun]

from your magazine.

[taymag]

from your magazine.

I've read that a lot and that's what I don't understand.. My magazines can hold and cycle (by hand) 2.200" easily, but the only cast info I've seen "published" for 300 blackout is from Palmetto Projectiles and they say load at 1.95" which seems to be way shorter than any magazines "max length" for these rounds.

Those 203's shoot great but I am loading up some 215gr now and planned on just going a little longer which I am sure will be fine but what if you had zero info to work off of, how would you determine OAL for a new cast load? For example, if Palmetto Projectiles didn't publish 1.95" I probably would have loaded way longer just because people say "from your magazine", so how was 1.95 suggested? Strictly from testing and based off accuracy?

[shooter93]

It could be that 1.95 is the length that would work in any rifle's magazine. There are several way to get you OAL such as using a leaded steel insert in an empty case, dropping a bullet in the chamber and measuring with a cleaning rod that measurement and then another one with out the bullet and the cleaning rod against the bolt. I sometimes load a dummy round very long and slowly ease the action closed until I feel resistance and then seating a little deeper and so on until the bolt closes with no resistance. If it's a gas gun or you want just off the lands then seat a bit deeper. Hope that all made some sense to you.....lol...... and welcome to the site....I would suggest you run from here as fast as possible before the enablers here get hold of you and you go broke "saving money" like the rest of us.....lol.

[Jupiter7]

Better Answer: from your chamber. Most the successful 300blk heavy loads run around2.10-2.14". Shorter if they won't chamber.

[taymag]

It could be that 1.95 is the length that would work in any rifle's magazine. There are several way to get you OAL such as using a leaded steel insert in an empty case, dropping a bullet in the chamber and measuring with a cleaning rod that measurement and then another one with out the bullet and the cleaning rod against the bolt. I sometimes load a dummy round very long and slowly ease the action closed until I feel resistance and then seating a little deeper and so on until the bolt closes with no resistance. If it's a gas gun or you want just off the lands then seat a bit deeper. Hope that all made some sense to you.....lol...... and welcome to the site....I would suggest you run from here as fast as possible before the enablers here get hold of you and you go broke "saving money" like the rest of us.....lol.

Man... I am fairly new to reloading and it has a tighttttt grip on me, stronger than the 4 year NFA stuff obsession. I have 9 tax stamps and 3 are from these last 2 months and I haven't even touched them. I am fully addicted to reloading and now more than ever since I jumped into cast.

[taymag]

Better Answer: from your chamber. Most the successful 300blk heavy loads run around2.10-2.14". Shorter if they won't chamber.

With 9mm I figured out I wasn't crimping the bell all the way back to spec and all lead rounds have been perfect ever sense but with 300blk its not as easy since the "clunk" test doesn't work as good. I dropped 2 different factory 300blk rounds to try and replicate it and they seem to be similar but its hard to tell.

When you say they wont chamber, I feel like if the slide is released anything close will smooch in, especially if its just touching the lands by a little

[taymag]

IF I am loading too short and not getting any pressure issues and its cycling fine are the only things to worry about accuracy at that point or is there another negative loading too short?

[runfiverun]

none.
your gonna jump across the throat anyway.
when I said from the magazine that means that is the maximum length you can go.
start at that length and go shorter until you have 100% feeding.
now that you have this number you can start your load work up.
work that from the other direction start at the bottom and come up.
once you get to 100% ejection you now have a starting baseline load to work from for accuracy.

2.2 is where I run most of my jacketed stuff for the 223/5.56 round in my AR's.
it is as long as the magazine will take and it still feeds 100% of the time.
I play with the powder weight from that point on to see how the groups do.
I do the same thing in my 9mm, 45 acp, m-14, whatever moves a round from a magazine to a chamber.
function takes priority over everything else.

[taymag]

none.
your gonna jump across the throat anyway.
when I said from the magazine that means that is the maximum length you can go.
start at that length and go shorter until you have 100% feeding.
now that you have this number you can start your load work up.
work that from the other direction start at the bottom and come up.
once you get to 100% ejection you now have a starting baseline load to work from for accuracy.

2.2 is where I run most of my jacketed stuff for the 223/5.56 round in my AR's.
it is as long as the magazine will take and it still feeds 100% of the time.
I play with the powder weight from that point on to see how the groups do.
I do the same thing in my 9mm, 45 acp, m-14, whatever moves a round from a magazine to a chamber.
function takes priority over everything else.

Ok, that is what I wanted to hear and seems a little easier. I am going to load up for this weekend and give that a shot.

Your signature says hmmm but your long post says you still have all your fingers :drinks:

[runfiverun]

I come close to losing a couple but that was not reloading related.
some guy with a beard a turban, and a machete, didn't like where I was at the time.

I'm usually pretty short worded, but can go into detail if it's required.
sometimes too much detail.