300BlkTalk

Hey, all,

I need some help. I have been shooting the Lee 312-155 bullets for a few months with GC and have been getting lead marks on my AR flash suppressor. I am also getting a ton of lead around the bolt and the three gas washers. The barrel doesn't show much leading at all as I use HiTek coating. I was originally sizing to .309 but thought maybe the bullets were still too big for my AR-15. I got a .311 sizing die and it still is leading the rifle. I think it may be the lead is simply too soft as I use straight wheel weights and range lead. Is that the issue? What can I add to make it harder? I do quench as I cast. I'm using the rounds for short range plinking 25-50yds. I recently downloaded a lead excel formula, but don't know how hard I should make the bullets on the Brinel scale. I'm using 17 gr of LilGun to get 1972 fps at 2.00 oal as that has been the most accurate load. Again help!!! Thanks.

Tattoo

Antimony and tin are added to harden lead. But beyond that I can't help you.

You're near or over max pressure for the bullet weight, 55,000 PSI, so cast your bullet accordingly. Probably in the neighborhood of 30 BHN.

Then you need to worry about start pressure, speed and twist rate. Here's what happens to a powder coated bullet that is pushed too hard.


The bullet needs to be hard enough to not shear in the rifling. A fast start with a powder like Lil'gun will do that.

Your alloy might be OK. Are you quenching AFTER applying the Hitek?

I run that bullet with conventional lube over H110 for 1920fps avg across the chrono with no barrel leading, but those bullets are quenched and sized, not subjected to another heat cycle that might anneal them.

I'm shooting another bullet about 140gr over a compressed load of 4227 and the barrel has remained shiny. Those bullets were quenched, powder coated, and quenched again after a 30 minute bake at 450F. Immediately after cooling they get shoved through a .309" die. They still need at least a week to precipitate harden before shooting.

From what I've read, powder coating is tougher than Hitek. I chose to NOT deal with a solvent carrier, so went powder coat.

Lilting burns hot. HiTek cooking results in AC hardness. Need to quench after cooking. You need 3% Sb for what you are trying.

might be worth putting a borescope down the tube to check if there's a chip at the gas port too.

cant hurt to check since you're troubleshooting anyway. worst case you can cross that off the list.

First off, thank you everyone for your responses. I have not tried quenching after the hitek coating has been put on. I think I will try that next and see what happens. I’ll Also see if one of my friends has a borescope to take a look at the gasport. I’ll update in a few days.

some folks are using cheap endoscopes that plug into USB's as a borescope.

you can get them on amazon for $20 or so, often less.

https://smile.amazon.com/Seesi-Endoscop ... 07PBF6DX5/

just one example