New to rifle bullet casting

[BLACKTALON]

I have cast for pistols for about a year now, 9mm and 45. I am looking into casting for 5.56 and am finding myself buried in information that may or may not be absolutely relevant. The rifle is a colt 6920 with a 1/7 twist barrel. I am thinking that bullet weights in the 62 to 70gr range would be best. what are the recommended available bullet mold options out there?

My lead is range scrap so I get a good mix of the alloys that everyone is shooting in their pistols. I have no idea what the hardness of the lead is and would like to avoid GC's if possible. plan to keep velocities just above those required for cycling the action.

Please correct and advise

[RickinTN]

I cast for rifles, but never anything as small as .223. I also don't cast for an AR, so take what I say with a grain of salt. I don't think you're going to get a bullet with no gas check to cycle your rifle and give any accuracy at all. Usually a plain-based bullet needs to be kept in the less than 1,200fps. or so range for any accuracy. Also, I don't know what your range scrap consist of, but I'm thinking most range scrap won't be hard enough. Water dropping or heat treating may get you there? Just have to try and see. I do think you've chosen quite a challenging combination for your first attempt at rifle casting. I'm sure more experienced folks will be along to offer advise more based in experience.
Good Luck,
Rick

[JonB_in_Glencoe]

my 2¢
You are gonna need a GC for an AR. PB boolit molds in 22 cal are kinda rare, I have one, a Ranch Dog 50gr, but it was a special request to have the GC shank reamed...and this one is way too light for your 1:7

Range scrap will not be hard enough, but maybe if you heat treat or water drop them.

You are right about the weight boolit you want.
Good Luck,
Jon

[MUSTANG]

BlackTalon:

+1 concerning gas checks on your boolit.

Be prepared to spend some time and experimentation on developing an accurate load. Even if your doing mostly man size targets at 100 yds and less, you are going to want to know what groupings you can achieve from the bench so as to to determine if you or the loads are at fault if shooting results in open groups or misses.

You might review the following two threads and see if the 65 Grain and 75 Grain molds might strike your fancy. Both Group buys are in the near closing phase, so you might want to add your name to the list soon if interested.


65 Grain
http://castboolits.gunloads.com/showthread.php?188864-Fourth-Run-for-MiHec-22-Nato-%2865-gr-version%29-brass-four-amp-six-cavity-solid

75 Grain
http://castboolits.gunloads.com/showthread.php?188868-MiHec-22-Nato-Heavy-%2875-gr-version%29-brass-four-amp-six-cavity-solid

Mustang

[runfiverun]

keep us posted on the whole outcome.
i'll advise trying for about 700 fps with the peramiters you outline for how you wanna do it.

[BLACKTALON]

Those molds look great! I am very tempted to sign on. Is .227 a cast and shoot dia or do the bullets need to be sized? For all my pistol casting the finished product is about .001 over their jacketed counterparts and are ready to shoot right after lubricating. .227 seems extreme over .224



BlackTalon:

+1 concerning gas checks on your boolit.

Be prepared to spend some time and experimentation on developing an accurate load. Even if your doing mostly man size targets at 100 yds and less, you are going to want to know what groupings you can achieve from the bench so as to to determine if you or the loads are at fault if shooting results in open groups or misses.

You might review the following two threads and see if the 65 Grain and 75 Grain molds might strike your fancy. Both Group buys are in the near closing phase, so you might want to add your name to the list soon if interested.


65 Grain
http://castboolits.gunloads.com/showthread.php?188864-Fourth-Run-for-MiHec-22-Nato-%2865-gr-version%29-brass-four-amp-six-cavity-solid

75 Grain
http://castboolits.gunloads.com/showthread.php?188868-MiHec-22-Nato-Heavy-%2875-gr-version%29-brass-four-amp-six-cavity-solid

Mustang

[BadDaditood]

as i understand it, to gain hardness by water drop or with heat treating you need a small amount of arsenic. clip on wheel weights have some arsenic, not sure about range scrap.

cast a few and check in a week if water dropped are harder than air cooled.

(20 mins later) after some thought, commercial cast are usually harder than what we cast- how do they do it? i assume arsenic/heat treating is cheaper and gets harder than tin... i'll have to cast up some range scrap and see if they respond to water drop

[cbrick]

as i understand it, to gain hardness by water drop or with heat treating you need a small amount of arsenic. clip on wheel weights have some arsenic, not sure about range scrap.

Antimony is needed for HT, arsenic is frosting on the cake and will allow HT well beyond what the percentage of Sb would suggest.

Most commercial jacketed bullets will have varying percentages of Sb, a few as high as 5%.

Rick

[Larry Gibson]

BLACKTALON

You've picked one of the hardest cartridge/rifle combinations to begin with. I doubt anyone but a hardcore Colt fan knows what a 6920 is. Probably a lot that have a sililar AR but based on that description don't know what you are talking about. I suggest a bit more common description would help......just a suggestion.

Your range scrap is useable if it the atypical mix of mostly cast and jacked bullet alloy. I suggest you make it much better for the application at hand by adding 2 -3% tin to it and add 20 - 30% tin. Then the bullets cast hot and WQ'd will be "hard" enough to withstand the 7" twist at a reasonable velocity. There will already be enough arsenic in the mix so adding more isn't necessary.

There is no way to avoid the use of GCs if you want reliable functioning with your AR. If you want to manually cycle the action for each shot then a PB'd cast bullet will do. Either bullet will do but I would get one that allows magazine use with the GC not seated below the case neck. You will want to use a medium to slow burning powder that ignites and burns well at lower psi. I suggest starting with H4895 and then move to Varget, RL19, AA4350, H4831SC or RL22. With any of them use a 1/3 gr dacron filler when load density is less than 80%. Start low and work up until the action just function reliably. that is where your best accuracy will be with the 7" twist.

Larry Gibson

[oldsgm]

A while back I posted a thread here about a 500 round cast bullet test I completed for my AR-15. Using cast bullets can be done in an AR without any of the eye of newt, and wing of bat kind of recipes. Standard casting and bullet prep practices along with finding a reduced load that will function the gun and not lead the barrel excessively.

http://castboolits.gunloads.com/showthread.php?156326-AR-15-500-Round-Cast-Bullet-Test