Cast boolit too much pressure?

[sutherpride59]

So the data first, I have an AR in 300 AAC with 16” barrel. Using Lake city converted brass H110 powder, Winchester small rifle primers, trimmed to 1.360” with a Lee 312-155-2r projectile has checked and lubed with Felix lube at 22bhn using 17lbs pure lead, 2lbs super hard and .8ounces pewter...oops on that more than I meant to lol.

So I was working up a load in .5grn increments, I started with 14 grns and worked my way all the way up to 17grains. By 16.5 I noticed light cratering and a slight impression on the brass from the ejector. So I fired one 17 gen and I noticed slight cratering, flattened primer but slight impression from the ejector. Here’s the problem, 16 grns is the last load that didn’t show high pressure signs but my groups didn’t show any improvement till I hit 17 grns. That load shot a .78” group at 50 yards. The rest were at 1.78” at 50 was the secon best at 14grns, probably a fluke. These were all 5 round groups.

My question is with 300AAC being such a low pressure round yet creating these high pressure signs should I lower the load to 16grns and just cast like 18bhn rounds. Also at 16 grns I was averaging 2013fps, at 17grns I was averaging 2104fps.

I based my data off of hogdons website for jacketed data.

[S.R.Custom]

Cast a bit softer... Like 18 bhn. That should tighten groups with a lighter charge.

[Boolit_Head]

17.2 is max for a 150 grain bullet with around 50k pressure so not suprising you are seeing signs with what sounds like hard cast bullets. 50k is not exactly low pressure.

[Grmps]

one of my sources says 15.3 of H110 1800 Max Vel

[Stephen Cohen]

I have never loaded for that cartridge but if it was me I would lower the load to 16 gr and be happy with the loss of 80 odd fps and have peace of mind. I just wish we still had the right of owning such firearms again. Regards Stephen

[Rcmaveric]

22 BHN is pretty hard. Probably the reason you got better accuracy at higher pressures is because the bullet obutarated at the higher pressure. Soften the bullet. 12-10 BHN runs just fine in my gas gun. Back off the BHN and try a lighter load. Besides that an expensive alloy

[sutherpride59]

Y’all confirmered what I thought, I’ll back it down to 16grns and shoot for 18bhn next time. I had some 14bhn rounds and anything last 14grains went to heck. The 15 grain groups were everywhere.

[sutherpride59]

22 BHN is pretty hard. Probably the reason you got better accuracy at higher pressures is because the bullet obutarated at the higher pressure. Soften the bullet. 12-10 BHN runs just fine in my gas gun. Back off the BHN and try a lighter load. Besides that an expensive alloy

Well the alloy was after 5 minutes of mind numbing math saying to heck with it 17lbs lead 2 lbs super hard with some tin should be harder than my previous bullets. I accidentally melted a bit more pewter than I anticipated, by that I mean I dropped an old flattened pewter cup on accident when I meant to just melt the bottom quarter off lol.

[BK7saum]

I have never considered the 300AAC a low pressure round. It is meant to be pushed hard with supersonic jacketed bullets to achieve the ballistics and numbers to compete with the claim of 30-30 and 7.62x39 ballistics. I have ran mine pretty warm in the bolt gun. Same loads in the AR will sling brass 30 feet.

Also, depending on the gas and powder used, if it unlocks with more pressure, you can still get some burnishing by the ejector cut, especially if there is a burr or rough edge.

[Rcmaveric]

Well the alloy was after 5 minutes of mind numbing math saying to heck with it 17lbs lead 2 lbs super hard with some tin should be harder than my previous bullets. I accidentally melted a bit more pewter than I anticipated, by that I mean I dropped an old flattened pewter cup on accident when I meant to just melt the bottom quarter off lol.https://m.youtube.com/watch?v=KgGXiwkskEE

I prefer the mixing cross or table method. Simple subtract and division.

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