Stabilizing heavy subs

[sutherpride59]

So I have a fancy new 230grn mold for my 300 aac and I’m trying to get it to stabilize in my 9” 1:7 twist barrel AR. Probably will never stabilize but I figure I should at least try before I start looking at 200 grain molds for it. My first attempt was sized .001 over bore at .310 using a soft red lube of unknown makeup(inherited from my father in law and works great on every rifle load ever, pretty sure it’s elmers red). The fist test was with 10bhn sitting over loads of Hodgdon CFE blk at 10,10.5, and 11 grains. All created a small tear off to the side At 5-7 yards but not what I would consider key-holeing. I’m going to try it again with a harder alloy that was oven baked and water dropped and is sitting at 22bhn. I will also try them at 10.5, 11, & 11.3 grains(11.3 is max load... pretty sure that’s only because of breaking the sound barrier doesn’t look like it would really be unsafe to go over but I won’t). If this works I’ll dial back the hardness till I get keyholeing again to set a benchmark of how soft the rounds can be in this gun before I run into problems. Does this all make sense or would the hardness have absolutely nothing to do with stabilizing the boolit? I was originally aiming for more of 14bhn but I miss judged how the temps work in my apartments oven and didn’t want to repeat the process twice at a reduced temp to get a softer bhn.

[M-Tecs]

Stabilization may not be your problem. Overspinning bullets pushes some bullet past their structural integrity limits. That can lead to accuracy issues or in worst case bullet blowup. This happens with both jacketed and cast. Tougher alloys may help.

http://castboolits.gunloads.com/showthread.php?208186-RPM-Threshold-barrel-twist-velocity-chart

[charlie b]

Bullet hardness is not directly related to stabilization. 5-7 yds does not test the stability of the bullet. It does test if the bullet is leaving the muzzle correctly. If you look at the bore can you see leading?

A soft bullet may 'skid' when shoved into fast twist rifling. This causes leading and will accumulate.

I would definitely increase the hardness of the bullets and keep the velocity low.

Then take some shots at 50 or 100yd and see if you have keyholes.

PS before you shoot it again make sure all the lead is cleaned out of the barrel.

[Wayne Smith]

Generally your twist rate/length of bullet and velocity will have a whole lot more to do with stabilization than hardness. A super fast twist and soft boolits could cause a loss of stabilization as the integrity of the boolit could be compromised as MTex mentioned, but that is on the edges of the issue.

[sutherpride59]

There was no leading in the barrel but the rounds were gas checked. I was shooting at 5-7 yards because I wanted to make sure the bullet was stable enough to shoot out of my suppressor without wrecking it.

[Burnt Fingers]

Is it the Lee mold?

Lots of guys over at the 300 Blackout forum have had problems with that boolit.

[Larry Gibson]

Length of GC'd bullet for stability calculation?

[sigep1764]

Consider going to 311 sized boolits instead of upping the hardness. I have found that in my experience yaw or keyholing can be attributed to two things, undersized boolits or under stabilization. There will be a speed where 230 grains works. Just need to find that window.

[Larry Gibson]

The question remains; is that bullet going to stabilize in a 9" twist and stay sub-sonic.

[M-Tecs]

The question remains; is that bullet going to stabilize in a 9" twist and stay sub-sonic.

Larry it's a 9 inch barrel in a 7 twist.

[Greg S]

Are you using gas checks?

Shoot at 50 and 100. 5-7 yards is not enough distance for the projo that is heavy for caliber to stabilize or as they say, go to sleep and the bullet spin is stabilized. Bullets can yaw when exiting the barrel and start to experience drag from the outside enviroment. First put it to paper before dabblIng with hardness and size.

There are some good slow motion vids on the tube of artillery projectiles exiting the muzzle yawning like a teter-totter for the first 25m until they finally settle down.

https://youtu.be/xpJ8EoGmLuE @ 8:15 into it.

[Harter66]

The 7" twist is plenty fast for the 230 . Those unenlightened "in the know " are running SMK 250s (I know Js ) in that twist .
The Lee suffers I think from bearing length and the associated ability to hold rifling . I had a 40 that required hardened bullets even at lower loads to make round holes .

[M-Tecs]

Length of GC'd bullet for stability calculation?

I don't have a clue as to what the OP has but this one is common and it fits the description. https://www.midwayusa.com/product/1010217751/ Bullet Length: 1.363"

[shootinfox2]

Check your can recommendations. Many state to not use a barrel shorter than 10” for that very stabilization reason.

[sutherpride59]

Sorry guys I just got done shooting for the day. I’ll measure it with calipers and look through the group buy page but it’s a recently run group buy from MP molds. I wouldn’t touch the lee with a 10’ pole after the stuff I heard about it. It has a .310 bore riding nose and I’m sizing them to .310 as well, gas checking them and living with a soft lube. It’s fairly stable out of my 16” but even then it’s yawing just a bit from touching the baffles. I fired some j words suppressed as well and they shot very well. I’ll get e data when I get home later tonight but I will add that making them harder did increase the stability quite a bit. Just need to figure out the other part of the puzzle.

[Larry Gibson]

Larry it's a 9 inch barrel in a 7 twist.

My bad, that is a very short barrel.

[sutherpride59]

http://castboolits.gunloads.com/showthread.php?360311-CLOSED-MIHEC-300-Blackout-311-230-GRN-hollow-point-4C-HP-and-6C-Solid

[sutherpride59]

1.20” long projectile with .32” of driving bands with an aluminum gas check

[popper]

Hardness may be the problem as well as Al GC. Do they mike at 310 or just a 310 sizer? Could be riveting the base if it is below the shoulder. You load should be good.

[megasupermagnum]

I know nothing about heavy subsonic bullets, but one thing that sticks out to me is the nose on that bullet. It has a rebated area. Maybe this was a feature to make nose sizing easier? Is this causing you to seat the bullet extremely deep into the case, or does the bore riding section fit as it should?

[sutherpride59]

Bore riding section fits just fine, I seat at or just past the crimp groove by a hair. The AL GC mic right at .397 the AL is annealed before I make the checks with the pat marlin. I’ll make another test run as looking at the rounds fired without the suppressor they seemed to be just fine so now my thoughts are shifting to taking the brake the suppressor attaches to off and removing the shims that I used to time the muzzle brakes. Perhaps somehow the shims are making the bore out of alignment just enough for the round to graze a baffle and get thrown off. My groups with my 16” seem to be 3 in a 1” hole at 50 and the other two an inch away from the rest of the group with slight key holing.

[sutherpride59]

So I went shooting Friday and I cast and loaded some 200grn rounds as well. The 200grn were great and at 50 yards gave a little more than an inch group, will work to shrink those later. The 230’s now loaded to 12grn of CFE BLk have about a 2” group with one flyer that was probably caused by a round touching the baffles just a tiny bit. I’m guessing that my first loading were moving too slow to stabilize the bullet which is what was causing my issues. I also loaded some up to 12.5grn and 13grn to see what point they went super sonic and I forgot them at home in my excitement to go shooting. So in the next few weeks I will post my results but I concur that hardness doesn’t help much with stability unless rounds are PB and too soft. These are way too hard but for target practice I’m not worried about it. Once I can get acceptable accuracy and determine a set powder weight I’ll worry about fine tuning the other components. Also I’ll dig my chronograph out of storage and take it on my next trip. If I had it the first time it probably would have saved a lot of guess work.

[tomme boy]

You might lose the alum checks in the suppressor. They don't stay on at all. Seat a bullet with a aluminum check then pull the bullet. Do this a few times and tell me how many checks were still on the bullet. The Hornady checks actually grip the bullet.

[sutherpride59]

Idk what might be wrong with the material you use but my home made checks using the pat marlin stay on just fine. I’m not worried about losing a check in the can, mine is user serviceable and it would only be $50 to replace a baffle according to maker. Besides when the round leaves the casing with check in place the check is further swaged into the bullet when it engages the rifleing. Heck I can’t even get them off with my finger nail after sizing! A more accurate test would be to check recovered bullets not putting them in a bullet puller. I don’t mean to argue but I disagree with your opinion. The only real risk would be the check being ripped off by an unstable round making contact with a baffle but at that point the round itself would be damaging the baffle along with the GC so either way there would be damage. I’m more worried about stabilizing my ammunition than I am about the GC.

[tomme boy]

I have recovered bullets. None of the bullets with alum checks had them on the base. The ones I used were from Sage. They are made just like the old lyman's that would fall off. Even picked up a few from the snow that did not have the alum checks on them. Not all but some. There is a reason the manufacturers don't want you to shoot gas checked bullets. This is it.

[sutherpride59]

That may be true of the checks you purchased but the ones I make using my pat marlin check maker have always been attached when I have recovered them. That being said I have aluminum strips I use in the making that fit very snug. It might be a good idea to start adding a dab of cheap super glue though just in case.

[sutherpride59]

I hate when the conclusion to a thread is never posted. After weighing these I noticed something must have been wrong with the alloy or the more likely I was running the melt too hot. I won’t go into details but the 230’s were dropping at 213grains and were a little undersized as well. I will try again at a later time with a different alloy and running my melt at a lower temp.

[charlie b]

I hate when the conclusion to a thread is never posted. After weighing these I noticed something must have been wrong with the alloy or the more likely I was running the melt too hot. I won’t go into details but the 230’s were dropping at 213grains and were a little undersized as well. I will try again at a later time with a different alloy and running my melt at a lower temp.

Glad you might have found your issue. I usually run my melt hotter and have to keep my casting pace lower to prevent issues. Your weight might be ok depending on what the mold mfg uses as a baseline for weights. Many use COWW alloy for that and harder alloys will be lighter, but, only by 5gn or so usually.

[bld451]

I got that MP 311-235 recently. If that is the same mold, it should be fine in a 1:7 twist. My 8.5" 1:8 twist does fine with the pb version. Have you tried it without the checks? Might be worth a try. I'd bet you won't have leading either at 1100 fps if they are sized .001 over bore dia. Mine don't accept conventional checks, so I don't know but when seated, are your checks hanging out in powder space, or supported by the neck?

[sutherpride59]

Bld451 I’m not going to bother with any of that. I’ll try again after I melt these back down and try again with a different alloy.

[pacomdiver]

i load the NOE 311 247 FN PB, powder coated, sized 311 with 8.2g H110 in LC cases with CCI 200 primers. runs good and locks back on last round in 2 1in7 TW 10.5 inch AR uppers and a 16" rem 700 AAC SD all thru a silco harvester can, all stay sub