Noob reloader question

[Deer_Slayer_90]

I found some Hornady ZMax bullets for sale and I noticed they say .310 and 7.62x39 123 grn. Will they work to load 300 Blackout? I assumed being 7.62 (.30 cal) they would work but most .30 cal say .308. FYI, I plan on loading into modified .223 brass, not designated .300 blk brass.

 

[red_zr24x4]

No, As .310 is bigger than .308
I suggest you buy a few reloading books and read them. Bad things can happen putting to large dia. bullet in a gun.

 

[Deer_Slayer_90]

Thank you, you just saved me a decent bit of money.

 

[shibumiseeker]

For 300BLK you need .308 jacketed or .309 cast. .310 will, as red said, do bad things, especially if you are using a sensitive powder and shooting them in an AR as opposed to a bolt action. Really the only way .310 or .311 bullets can be safely used in 300BLK is to swage them down to the proper size.

 

[noylj]

Oh God, not this again. I can almost guarantee that it would work just fine.
.310 and even .312 has worked in .30-06 for decades.
You know that barrels have tolerances, right?
If you don't KNOW the groove diameter of your barrel, you're only guessing any way. If your groove is larger than 0.308", then the .310 may even be a lot more accurate.
Load 2-3% below the starting load and see how they do.

 

[Broom_jm]

Noylj,

What you know, as an advanced reloader, should not be conveyed as "best practices" to a self-professed "Noob". Hopefully the OP is wise enough to understand that barrels intended for .308" bullets should not be fed .310" or .312" bullets.

What are the odds his NEW 300 Blackout has a .310" bore? Close to zero. How much will it drive up pressures for him to use a .310" or .312" bullet in his new rifle? Well, that is going to be a GUESS, for real.

The bottom line is this: When it comes to reloading, you either KNOW what you're doing, or you don't. If you're not 100% confident in what you're doing, stop and find out for sure, which is exactly what the OP did. Kudos to him, but shame on Noylj for espousing potentially dangerous "information" to reloaders with far less experience.

 

[shibumiseeker]

Oh God, not this again. I can almost guarantee that it would work just fine.

No, you can't. You haven't slugged the barrel he's using, and a 300BLK is pretty much guaranteed to have a barrel with tighter tolerances than older guns.

CAN it work? Sure. And an experienced reloader will know how and when it can work and what signs to watch for. But a novice reloader should NOT be screwing around with it, period.