Lead strength for AR casting

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zhughes posted this 20 May 2017

Hi all, Looking to cast for my AR. I've heard it's a hard caliber to cast for, so challenge accepted. Anyway, I'll be working with the recipes in Lymans Reloading for the AR handbook.

So to the point, I don't know if my alloy is hard enough to take on the task. I'm using wheel weight lead, nothing else added, water quenched. I've seen some folks do a thumbnail dent test to estimate bhn, not sure if that's legit or not. I really don't want to do the cash on a bhn tester since they're pricey. Any idea if wheel weight lead is hard enough or if the thumbnail thing really works? Thanks!

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45 2.1 posted this 20 May 2017

What you did will work fine up until you get into the 2,700 fps range................ that depends on which caliber and pressure range you get into though. Picking a powder that gives a pressure high point / spike in it's curve will reduce that number......... a powder with a long pressure curve gives better results.

Picking a good design bullet will give you good accuracy..... not all designs will though. Do not pick something that engraves on loading as it will cause problems.

 

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Ken Campbell Iowa posted this 20 May 2017

keep in mind that .... as most other rules for cast bullets .... "" harder bullets shoot better "" ....is a pretty flexible rule ... 

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that softer bullets might sometimes shoot better seems to go against common sense ... being that mj bullets are harder and statistically shoot better than cast .  as they might say in the movies>>  cast bullets are " complicated " ...

ken

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onondaga posted this 20 May 2017

 

zhughes   Can you do $15 for a good testing method? Here is a video that demonstrates using various high quality lead pencils with a scratching method to determine lead hardness very well. Get the pencil set at an art store or on Amazon. It works excellently and is CHEAP. Study the method in the fun video and you are set. Video:

  I have done this method and have a Lee hardness test kit also. Both methods agree very closely.

Hardness does matter a lot! use the method in the Lee book, Modern Reloading Second Edition, to determine lead hardness needed for your load level and you won't go wrong.

Personally, I use a BHN15-16 recreational alloy from 1:1 Jacketed bullet scrap : Linotype Scrap or commercial certified  Lyman #2 alloy or Commercial certified Hardball Pistol Alloy, all  air cooled only and the lowest level load that will cycle my action reliably with AA2230 or H4895. My bore is polished and I have zero leading. Actually bullet fit is more important than hardness to eliminate leading. That is a lot harder to learn if you are new at shooting cast bullets in an AR.

Your drop quenching significantly raises BHN beyond needed for an AR. Bullets too hard OR too soft are more critical to fit and reduce accuracy potential. If your bullets fit with an ink test slide fit on chambering then that excellent fit gives more leeway in bullet hardness. If you don't get the correct fit then problems are magnified. I use the Lyman #225646 mold and gas check/size at .225 for an ink test fit for my AR, it shoots >1.5 MOA with cast consistently and it slams competition steel silhouettes down easily at 100 yards. I tumble lube 45:45:10 once lightly before size/check and twice lightly after.

  Gary

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onondaga posted this 20 May 2017

My AR loads:

Note the 45:45:10 dries clear, hard and tack free and ready to load in 5 minutes when applied warmed to warmed bullets. My load massacres big snapping turtles easily at 100 yards too.

 

Gary

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JeffinNZ posted this 20 May 2017

I am driving air cooled clip on WW (9.8 BHN) at 2300fps out of my .223 burning 13gr H4227.  Accuracy is 1.5-2.0 MOA.  Minute of bunny to 150m.

Cheers from New Zealand

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M3 Mitch posted this 4 days ago

Gary,

Are you using a load hot enough to cycle the AR action, or just using it as a "straight pull bolt"?

Ed has posted up on loads that will "run" in a Garand, I am not aware of anyone getting good accuracy in a load that will "run" in a .223/5.56 AR.

Thanks,

-Mark

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358156hp posted this 4 days ago

Here's a really good article on cast bullets in ARs, written by Ed Harris, who is a regular contributor here. I've passed this on to a number of people who tried these guidelines, and swear by them.

http://www.hensleygibbs.com/edharris/articles/Cast%20In%20an%20AR.htm

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