AR-15 1:7 twist

[sureYnot]

Hey guys. About to come up short against a brick wall here and need some advise from you experienced fellers before I go throwing money in the wrong direction.

Some history:

I'm an experienced reloader. Been through a couple rounds. I've always bought my bullets in the past and only got into casting a few weeks ago.

Current issue is in regards to my AR-15.

16-inch barrel. 1:7 twist.

Works great for my favorite plinking round...55 grn fmj from RMR, 24 grn of IMR4895, winchester small rifle primer, and whatever brass I find laying around. Although what I've read online suggests I should have some problems with that combo, it puts the metal on target.

Had some issues with powder coating at first. First batch was total ****. Leaded so bad, the muzzle looked like a Christmas star.

Got that worked out. No more leading. But...I can't keep it on an 8X11 sheet of paper at 25 yds. (fmj reloads are going right where I want them)

I'm down to a small window of powder charge. Between 20 and 24 grns. I'm a little worried the sweet spot won't be in that range since my group is so massively out of whack so far.

If someone can tell me they've had luck with PC 55grn cast in a 1:7 twist, I'll happily continue the experiment. There is that window, after all, but I'm not very hopeful any more.

Question is, do you think (know, preferably) that I could get 'er done with heavier boolits (which I'd like anyway. as heavy as will still fit in my mag.) or am I going to be stuck swapping out the barrel for a slower twist?

note: no leading, no keyholing with any charge I've tried so far (except for my epic failure at PCing). Just massively wide grouping. Alloy is COWW. PC is HF red. No gas check (but that shouldn't matter as it's all about leading?).

[earlmck]

No gas check? Well no wonder. Put the danged gas check on and then report back.

[44Blam]

I was talking to a friend about reloading cast for .223 and he said if I do, make the boolits HARD. He said to use pure linotype or harder.
That's when I decided not to cast for the .223...
He said that the tight twist will rip soft boolits apart.

[Bigslug]

No gas check? Well no wonder. Put the danged gas check on and then report back.

Ditto. You're running WAY too hot and WAY to fast a twist for an unchecked bullet. The check is not only about sealing; it's also about "keying" the bullet into the rifling and preventing the softer lead from stripping out in the lands

[sureYnot]

No gas check? Well no wonder. Put the danged gas check on and then report back.

What's the purpose of the gas check? Thought it was to prevent gas cutting. Not having that problem.

Sent from my XT1710-02 using Tapatalk

[sureYnot]

I was talking to a friend about reloading cast for .223 and he said if I do, make the boolits HARD. He said to use pure linotype or harder.
That's when I decided not to cast for the .223...
He said that the tight twist will rip soft boolits apart.

Not having that problem either. When I get up close and hit the target, they're making nice, round holes.

Sent from my XT1710-02 using Tapatalk

[sureYnot]

Ditto. You're running WAY too hot and WAY to fast a twist for an unchecked bullet. The check is not only about sealing; it's also about "keying" the bullet into the rifling and preventing the softer lead from stripping out in the lands

There's no leading.

Sent from my XT1710-02 using Tapatalk

[JimB..]

Conventional wisdom is to use a gas check in this application. Maybe it doesn’t make sense, but try it anyway. If you aren’t setup for them just post a WTB for some for testing and someone will probably help you out.

[sureYnot]

I will give it a go. Seems a logical first step. Even if it doesn't fix my problem, I will have a new option for other applications. I will report back with the results. It'll be awhile as I need to order some gear. Any favorite places to purchase gas checks?

[earlmck]

Any favorite places to purchase gas checks?

I'll pay a bit more to get the Hornady checks for their crimp-on feature. I usually get them from Graf's. And I also use Linotype for those little fast boolits because I know it works.

A number of theories out their about what gas checks accomplish. All I know for sure is they have been absolutely necessary for my rifles as soon as I get over somewhere around 1400 fps velocities. And some boolit designs wont shoot at any velocity without their check.

[Larry Gibson]

Not having that problem either. When I get up close and hit the target, they're making nice, round holes.

Sent from my XT1710-02 using Tapatalk

Obviously the bullets are stable, not stripping in the rifling nor coming apart. It's simply about to much RPM for the cast bullet you're using. Some here will say it's not so but you've found the proof it is so. A heavier GCd cast bullet of 60 to 75 gr weight will work better. Drop to a start load of 14 gr 4895 and work up in 1/2 gr increments until functioning is just 100%. You'll also probably find accuracy will be the best you'll get at that point. RL7 may be a better powder to use with out using a dacron filler also.

[Oklahoma Rebel]

now, I haven't even tried cast in my ar, yet, but wouldn't COWW's with just a bit of lino, heat treated or quenched, be hard enough ( considering the use of a gas check)?

[sqlbullet]

Obviously the bullets are stable, not stripping in the rifling nor coming apart. It's simply about to much RPM for the cast bullet you're using. Some here will say it's not so but you've found the proof it is so. A heavier GCd cast bullet of 60 to 75 gr weight will work better. Drop to a start load of 14 gr 4895 and work up in 1/2 gr increments until functioning is just 100%. You'll also probably find accuracy will be the best you'll get at that point. RL7 may be a better powder to use with out using a dacron filler also.

This.

You can try gas checks, but I am with Larry. You aren't experiencing any of the symptoms that would indicate a gas check is needed.

Chances are the fast twist + fast velocity is magnifying the natural asymmetry all cast bullets have. The result is big groups.

http://castboolits.gunloads.com/show...lanced-Bullets

[dragon813gt]

Go to Sage Outdoors if you want to purchase gas checks. I make most of mine. But for the oddball stiff where I only have one rifle in that caliber, I know it’s horrible , I buy from them. They sell Gator and checks they make themselves. All of them are high quality and the price is a lot more reasonable.

[sureYnot]

Was thinking that. 1:7 is for heavier/longer pills. But I've read a lot about high velocity performing better with a gc, despite the PC. Figured it might be worth a shot. Ultimately, I want to come up with a round where PC will suffice without gc. Was thinking around 75 grn fp might suffice. FYI, bolt doesn't operate under 19 grns powder. And then, still not 100%.

Obviously the bullets are stable, not stripping in the rifling nor coming apart. It's simply about to much RPM for the cast bullet you're using. Some here will say it's not so but you've found the proof it is so. A heavier GCd cast bullet of 60 to 75 gr weight will work better. Drop to a start load of 14 gr 4895 and work up in 1/2 gr increments until functioning is just 100%. You'll also probably find accuracy will be the best you'll get at that point. RL7 may be a better powder to use with out using a dacron filler also.

Sent from my XT1710-02 using Tapatalk

[Larry Gibson]

The heavier bullets require less powder to function the action.

[sureYnot]

55 grn is what I have ATM. I have to choose which thing to try next...gc or heavier bullet. If I were single, I'd just eat less this month and buy everything at once.

The heavier bullets require less powder to function the action.

Sent from my XT1710-02 using Tapatalk

[sureYnot]

Ordered some gc's and a tool today. Will report back whichever way it goes. If no joy, will order a mold for heavier bullets and report on that. Worst case scenario, will report back that I couldn't get cast boolits to work in a 1:7 twist barrel. Really hoping to file a different report though....But, if I do end up swapping the barrel, I wanted those tools anyway. If that happens, I will report back with what I managed to get away with in that barrel. This might take a few weeks. Wife and kids think food and electricity is more important than gun stuff...weirdos...I have 12 quarts of beef tallow that would make perfectly fine candles and/or food.

[sureYnot]

Had a new thought (probably a dumb one, but still something that should be said....maybe). If I recall, the first 3 or so rounds with 18gr behind them (before the barrel became a beautiful silver color) had decent grouping. But, the rifle wouldn't load the next round. I could take one or two of the weights out of the buffer and be able to use that load...perhaps. Any opinions on if that's a fair-to-middlin', or completely stupid, idea? For the time being, the short-term goal is a plinking round that will allow the wife to shoot the 100-200 rds/wk that she likes without breaking the bank on my "gun stuff" account.

[seetrout]

Alloy is COWW. PC is HF red. No gas check (but that shouldn't matter as it's all about leading?).

Are you sizing the bullets after casting? Unless they are way oversize try them as cast. You don't say if you are water quenching or not. If not quench the bullets as they drop from the mold to increase hardness. I currently cast 10 different bullets from .308 cal to .458 and only size 1. It is a 2 cavity 300gr Lee .45 pistol for my .454 Casull that drops out of round bullets that mic from .452 at the mold seam to .462 at 90* from the seam, everything else is shot as cast. With a 7 twist you will probably have to use a GC on any cast bullet.