Need help with my AR15 & Mihec Cast bullet

Boolit Buddy Join DateJun 2010Posts53

Looking for some help in shooting cast bullets out of an AR-15. I have spent considerable time on CB looking at previous threads to gain info on the subject, and it seems like shooting cast bullets out of an AR15 can be troublesome.

I spent the last 5 months (and 10 visits to the range) doing load development and still can’t get the accuracy I am looking for. My requirements are pretty reasonable: for my needs I need to be able to shoot and get all cast rounds into a 4” paper circle (see picture) from a bench rest at 50 yes.

I shoot a lot of steel standing, sitting, and kneeling from 50 yds, and the above criteria would work well for me.

What I am shooting: Noveske 11.5” barrel with 1/7” twist (I know not a good twist rate, but that is what I have to work with); flattop receiver with a Super Sniper magnified scope on a LaRue Mount. I zeroed the gun at 50 yds with some good quality Hornady FMJ reloads and got a 1.5” 5 shot group.

The bullet is from the Mihec mold (62gr) with a Freechex III GC (.008” lith plate). Lube is BAC. Sized .225 on a Star Sizer (Lathesmith sizing die). Alloy is 60/40 Lino/Pure lead. Bullets look clear of defects, etc.

The case is 1X fired IMI 5.56mm case with proper sizing for the barrel. COAL is 2.182”. I initially set them to mag length and ended up with the bullets jamming into the lands…a no go.

I did OCW load development and settled on 20grains of Tac powder.

What is driving me crazy are the flyers that I can’t account for. One of the flyers I called due to jerking the trigger, the other two I have no idea. These flyers seem consistent in the other powder charges/test loads as well. I know my GC’s are seated well and square. Does anyone have any ideas on what I might have missed at this point? I hate to waste 5 months of testing….

Thanks-

Are you weight sorting the bullets?

The first thing I'd try would be to swap out the pure in that alloy for WW's and water drop them. I'd want some really hard bullets in a 1:7".

Is the bullet being deformed as it's chambered? If you make up a couple dummy's and feed them from the mag a few times are they bumped and scratched?

It is hard to fail, but it is worse never to have tried to succeed.

Theodore Roosevelt

Boolit Buddy Join DateJun 2010Posts53

Are you weight sorting the bullets?

The first thing I'd try would be to swap out the pure in that alloy for WW's and water drop them. I'd want some really hard bullets in a 1:7".

Is the bullet being deformed as it's chambered? If you make up a couple dummy's and feed them from the mag a few times are they bumped and scratched?

I have not sorted them. I am currently out of bullets, but am going to cast some more tomorrow, and will weigh them into groups.
So I took your advice and chambered a dummy....picture attached. That scratch wasn't there when prior to me putting it in the magazine.

I'm going to pull the barrel and polish the feed ramps, and try a harder alloy like you mentioned. Hopefully this is solve the problem. Thanks for the help, much appreciated!

I'd change the alloy to 80/20 lino/lead and AC them for 7-10 days before doing anything with them. Then I would get a few Hornady GCs (some one might spare you some, if not PM me). Try them on the new alloyed bullets with the same load. If that solves the flyer problem then you're good to go with probably thicker GC material. If not then the flyer problem is from pushing the bullets too fast for the very short 7" twist barrel. A slower powder may be needed. However, are you using a dacron filler? If not drop back to 14 gr TAC and use a 1/2 gr dacron filler. You'll want to work up to just have reliable functioning and no more. The best accuracy will more than likely be at that point.

Larry Gibson

Are you trimming your brass?
How are you crimping?

It is hard to fail, but it is worse never to have tried to succeed.

Theodore Roosevelt

Boolit Master Join DateFeb 2010LocationFinland, west coastPosts549

Yeah get one of those plastic sorting boxes to keep them separate, my mold dropped in the 62gr range and I found it varied from 61.9 to 63 grains. I sort the bullet to .1 grains difference.

Boolit Buddy Join DateJun 2010Posts53

LG: I used .010" AL GC before with the same results. Any suggestions on GC thickness? I will check (get it check) into the Hornaday's and see about getting some. I liberated a stuff dog toy from my killer mutt and will give the dacron "stuffing" a try. I'm sure in the end, a slower powder may be the answer to my problem.
Doc: I am trimming my brass (1.752") with my Dillon 1200RT trimmer on my 550. Brass is consistent in length. No crimping of the bullet. At one time I measured the bullet tension, and found it adequate. I use a .223 case expander from 21st Century shooting after trimming (4th station).

Don't worry about the scratch. My 308 carbine (1:10) does the same thing and does 1.5" @ 50 with 4895, close to TAC. You are running ~ 2400 fps in a 1:7, so I agree with Larry, alloy problem. Add some shot and HT or add Cu and reduce the Sb. Or slow down and use doggy stuffing if it will cycle properly.

You may not post new threadsYou may not post repliesYou may not post attachmentsYou may not edit your postsForum Rules

Abbreviations used in Reloading
Pointed Soft Point "Core Lokt"

View the original article here