I think I'm going to have to admit defeat.

I read but didn't retain over the last day or so .......
Have you tried segregated brass, primers , LG vs sm and aberrantly hard alloys ? As many trials as it sounds like you probably have . My current experience with acp class cartridge rifles is limited but currently the revolver isn't sharing a load/bullet with the carbine there are a couple close but none that are great in both.

I suggest the alloy because I had an alloy that was great for a 9mm and 357 AC but it had to be WC to work in a 40 S&W . I had a 45 Colts RBH and 92' . The the RNFP 255 was a ringer in both hot or deference loads in both but the 1st SWC wouldn't shoot for beans in the 92' in more than a cowboy load . It was the bullet. I've had several occasions where a gun just didn't like a particular case or primer also. Have you tried heavy weights or lights in it . It might surprise you with a "back pressure" hum solution by going to a heavier bullet that better mimics the acceleration curve of the jacketed 230 gr ball.

In my little time spent with the AR platform it seems to be in some cases driven by what a nominal load should do in terms of the maximum nominal loads that are consistent. If the acceleration curve is close and the pressures are correct they tend to be more consistent.
Maybe a lighter bullet with a faster powder loaded to a barely cycling load or even a heavyweight with a fast powder loaded to +P vs a square nominal load .

I've done too many things to go over again. The only thing mentioned, and a whole lot of things not mentioned on this thread but others thatI haven't done is use really really hard alloy.

Tonight I slopped together a load with Rainier 230 ball profile plated bullets over 5.1 HP-38, some old CCI-300 primers I'm trying to use up, and mixed brass that's been loaded dozens of times. Set the die at 1.250-60-ish COAL (didn't really care) and cranked out enough to go shoot. Scrubbed the bore with a bronze brush, one patch and some spray penetrating oil I had laying around just to get some of the BLL scum and antimony crusties out from prior adventures. Spent an hour getting the lead chisled out of the BCG and out of the gas rings and bolt. Last time I shot it it took less than 50 rounds of BLL-coated WW+2% Sn to foul the gas system into submission. Hosed it with oil (didn't clean the receiver) and went shooting. All of them (16 I think), including the first shot down a wet, oily bore, all went into under an inch at 25 yards.

WTH. They're just plated, that's all. Same load wouldn't work with ten other CAST bullet designs, eight powders, three lubes, two or three other alloys, bullets from 200 to 260 grains. So plated and any kind of jacketed bullets, factory or otherwise, work great and nothing cast works.

Where's that "bang head" emoticon????

I know it goes against everything we do but "every gun is .....Yada Yada yada".....

If it works it was worth a shot.

Works great. Problem is the ammo now costs four times as much. Not as bad as jacketed, though.

I STILL don't know why. My RCBS seating stem has a little dimple in the center and these bullets were soft enough to take the full impression of the machine marks in the stem, plus the crimp bit the case mouth into them easily. Not sure how thin the plating is but I'm sure it's not more than a few thousandths. This all tells me it isn't a straight start that was the problem, or size, it was the alloy engaging the lands that was the issue, somehow.

I'll probably blow through the rest of these and strip the bolt for inspection. I'd say a harder cast bullet might work, but it might make for obturation issues.

Add 2% woodpecker lips?
Like bass said, it only matters when it does.

sumthin is mattering here.
now I wonder if the gas hole ain't slightly tearing up the boolit's base and it's getting thrown crooked at the muzzle..
[the plated bullets are usually straight lead or 2/6/92.]
I think I'd look for some plain base gas checks to try, or maybe you could beg/borrow some powder coated ones from someone.
that might could answer some questions anyway.

I've been over a small pile of various recovered bullets with a 20x loupe and the mark from the gas port is so tiny as to seem insignificant. If they got thrown crooked at the muzzle due to a gas port defect, I'm inclined to think it would be in the same way each time, maybe not though.

My first AR in BLK had an undersized gas port. I drilled the hole larger and larger until I got it to function reliably with the load I wanted to use (.120" ended up being big enough). Evidently I used too much pressure when punching through and made a helluva burr in the bore. There's a huge scrape the length of every bullet right next to on of the land engraves, deep enough to show on the base, and a variety of washed out marks on the edges of the bullet bases....and it groups a solid 1.5 MOA as far out as they can fly. I don't understand how it shoots that well, makes no sense. I can do everything right to a "t" and it makes no difference to how badly the .45 shoots, except giving the bullets a tougher skin. Recovered bullets fired out of the .45 look perfect. The squib I had that stuck in the throat had wedged in there nice and straight and had no lube washed out of the groove whatsoever (very soft SL-68.1). The suppressor doesn't seem to help or hurt accuracy, which is also confusing to me since the groups with cast bullets are so terrible. I'd think the bullets would be coming out practically sideways to group so poorly. I just con't get it.

What was the bullet number on the 300 BLK? Was it a gas check design? Perhaps the length compared to diameter is a factor. Perhaps the smaller port made just enough difference? I believe you indicated the port in the 45 is .125"?

Say hello to powder coating?

even soft copper is like 35 bhn.
so it's resisting something in there.

Do you have a crown cutter? I have found numerous factory crowns to be very definitely
NOT concentric when I put a hand turned piloted Brownell's crown cutter into them.

Now, can I point to that rifle which would shoot 5" at 100 before and 1" at 100 afterwards?

Well, no. But I have found several that were not impressive - maybe it isn't as big a deal as
we might think.

How about selling the barrel and trying another? IMO, some barrels are just damned to shoot
badly, no matter what they LOOK like. Get a new bbl and pop it in. They are easy to
change out on an AR.....OTOH, why a gas gun for .45 ACP? Why not blowback? I think
many pistol cal ARs use blowback, but may be wrong.

The spring thing is really bad. I suspect nitrogen or hydrogen embrittlement. Hydrogen is
usually caused by plating of high strength steel and failing to oven bake it afterwards to drive
out the hydrogen which diffuses into the steel during plating. Nitrogen can come from any
source of nitrogen when the steel is hot, but it has to be real hot, like during heat treat, which
should best be done in a vacuum.

Bill

The barrel is a totally custom job turned from a blank by the maker of the upper. I wish I could just swap it out, but he won't well the parts and it would cost a fortune to have one made, IF I could even find someone to make one.

Yes, most of the .45 AR uppers are blow-back, and I might buy one before I'm through with this. I've shot several of them and they are very clunky, recoil is much more noticeable, they're filthy, don't suppress as well, and generally aren't as fun to shoot. However, I don't know how they shoot cast bullets, and if the basic design is more suitable, I'd consider it. Still mulling this whole thing over. If I hadn't already invested in registering and making a suppressor for it, I probably would have abandoned the project long ago.

L1A1Rocker said:

Say hello to powder coating?

Click to expand...

It hit me last night that if I started doing that, I could shoot cast bullets through the Miranda. Evidently your Jedi mind tricks work on me.

Ian said:

It hit me last night that if I started doing that, I could shoot cast bullets through the Miranda. Evidently your Jedi mind tricks work on me.

Click to expand...

What, no powder coat? But I gots this perfect mould for it, already have close to 90 pound of bullets cast up, a big oven at work that would be perfect for it, and I read Dolomite Supafly's lengthy threads on several forums about how he's refined the technique of tumble-coating.......And besides all that, the guy who turned me into a 300 Blackout fanboi, turned me into a stamp collector, and got me to finally warm up to AR-15s is now using his power of suggestion on this........

Lawdy I must be getting weak.

Stamp collecting? Really? Doesn't that cut into time you could be shooting or do home improvements?
Ian, be careful with that guy. Next thing you know he'll have you voting for Hillary.....

Well, no, actually those little blue, $200 stamps let me shoot lots more, even at night, without any complaints from the neighbors. It's freaking wonderful, like moving to a new piece of land big enough that nobody cares what I do.

I know you did the Hi-Tek thing, but did you ever try powder coated bullets? My understanding is it's different stuff, maybe I'm wrong. The tumble method of applying the powder seems to somewhat mitigate the issue of uneven coating thickness that spraying can have. Ought to be good enough for pistol bullets and maybe that undersized Lee Blackout mould I bought.

Heck, I'm gonna try it. Jedi mind tricks and a chiding naysayer is all it takes to push me over the edge.....

What's your favorite color?

Oh, THAT kind of stamps.

I'm partial to blue actually.

Powder coat has a place I suppose. I just didn't care for the variations in thickness or the extra effort some colors require for sizing.

Hi-Tek worked well enough for me but I still had some leading issues with it. It certainly is fast and easy.

I've never even seriously considered the coating route until now, just never had a need and was always a bit skeptical. But I have a commercial .45 caliber pistol silencer that is sealed and cannot be taken apart to clean out lead and lube (not my choice), and a .45 carbine that likes skin on the bullets, so that's two good reasons to try the coating. A third might be being able to load a few thousand rounds and never having to worry about the lube causing issues. Except with Titegroup, that is. I won't be mixing polyester and Titegroup.

I have been eyeballing a method that uses a tumbler and BB's or lead shot to apply the powder.
you run the tumbler and let it impact coat the boolits then cook them.

get your powder from smoke 4320 over to the boolits site.
airc he does multi-color sample packs for like 20 bucks..