Cast Bullet Keyholing and Tumbling

[ChrisG]

Hi All,

I am new to the forum but have been casting for about 10 years now. I have been casting the Lee 310 GC boolit sized to .431 for my 4" Ruger Redhawk that I just bought 6 months ago, and loading it with a 19.0 grain load of Alliant 300 MP (Well below even the 10% under max rule). I started with 19 grains of H110 and got yaw so I got the 300 mp to slow down the burn thinking it would solve the problem. Anyhow, 4 out of 5 bullets are still keyholing at 15 yards and tumbling at 25. The throats of the gun are .431 and the bore is .430. I am not getting any spitting and it looks like the bore is fairly well aligned with the cylinder. If it is off, it is not off by much more than a couple thousandths. The gun seems to shoot the bullet well with a light load of trailboss at about 620fps. But anytime I go to a magnum powder I get yaw or just a complete tumble. I thought maybe it was the pressure curve so I even tried HS-6. With 13 grains of HS-6 (about 900 fps) I still got yaw but not quite as bad. I know people are going to suggest the crown and leading but neither is a problem.

I am getting to my wits end with this. The bullets are cast of quenched range scrap. I am not sure of the BHN but they are not easily scratched with my fingernail. The only thing left that I can think of is that they are too soft and when pushed at 30,000psi, the rifling strips off the bullet and doesn't stabilize it. It is gas checked so I thought that wasn't easily done. I know there are people here who have a lot more experience than I do troubleshooting this sort of thing. I bought some foundry lead (23% Antimony and 12.5% Tin) to mix in and see if that hardens it up. Is there anything else I can try?

Thanks for any advice.

[Tim357]

Have you tried pushing them harder? Perhaps they need more rpms to get stable. IMO and IME heavy projectiles need more spin to get and stay stable. Have you tried a 240-250gr boolit for comparison?

[44man]

Need to spin. My load with the Lee is 21.5 gr of 296 and a fed 150 primer. The boolit has proven accurate beyond 200 meters.

[oteroman]

Vary crimp. Easy to do.

[ChrisG]

Hi Guys, Thanks for the replies. Yes I have 240 grain cast boolits but I only push them to about 1000fps. They seem to shoot pretty well. About the spin rate, according to the Berger spin calculator and the 1:20 twist in the rugers barrel, they should stabilize down to about 200 fps. My own loading bears this out. I loaded these with trailboss to 620fps and they seemed to stabilize just fine. I have shot 180 grain .358 cast boolits in a GP100 1:18.75" .38 special at 550fps and had them stabilize just fine so a bigger diameter bullet that is only slightly longer shouldn't have a problem stabilizing at 900 fps.Thats why I am so puzzled.

[ChrisG]

Vary crimp. Easy to do.

Are you saying I should go with more or less crimp? Because currently they are crimped pretty good so that they don't jump and bind the cylinder up.

[oteroman]

Not knowing where you are now hard to say. Test 10 rounds with a bit more crimp, then try less, but test for no bullet setback.

[ChrisG]

Thanks! I will give it a try!

[44man]

Crimp should only be folded to the bottom of the groove, More will buckle brass and ruin case tension.
NO, NO, a heavy boolit will NOT shoot at 200 fps. The 310 needs around 1300+.
Toss the charts and figures.

[runfiverun]

umm obvious question.
but you are using gas checks right?

[ChrisG]

umm obvious question.
but you are using gas checks right?

Yes I am. Hornady .44 gas checks to be exact. I'm going to try and catch a bullet to examine. I'll slow it down with some wetpack and then sand.

[osteodoc08]

There is no way that boolit would be stable at 200 fps.

As 44 man suggests, step up the velocity. Get a good GC boolit and put the throttle
down with some 296.

[runfiverun]

un-stabilized boolits are caused only by one thing.
the boolit isn't spinning fast enough.

if the twist is on the slow side you need enough velocity to make up the difference.
if you have enough twist and velocity then you have skidding so the boolit isn't engraving the rifling properly.

I think I'd try going faster as my first step with the slower powder.

[randyrat]

I run that bullet (Super Red Hawk) gas checked with WW or softer a little hotter, 21 grains of H110 and get no tumble or leading. I think that bullet is long enough to get by with a softer alloy. It's a Thumper!
If you go softer, be sure you are not sizing the bullet down when you seat it, in other words, be sure your expander plug is fat enough for cast.

[Mal Paso]

Are you chronographing your loads or going buy the load chart? Alliant used an 8.25" test barrel and as slow as 300-MP is a 4" barrel will produce a lot less velocity.

When I tested I was using a 250g NOE 429421 and never got close to the performance Alliant stated with my 4 & 6 inch guns.

[ChrisG]

Are you chronographing your loads or going buy the load chart? Alliant used an 8.25" test barrel and as slow as 300-MP is a 4" barrel will produce a lot less velocity.

When I tested I was using a 250g NOE 429421 and never got close to the performance Alliant stated with my 4 & 6 inch guns.

I am chronographing the loads. I'm going out today to try 5 different loads for speed and shooting them into tightly backed paper for evidence of yaw. The loads are as follows:

Lee 310, 6 grains trail boss
Lee 310, 13 grains HS-6
Lee 310, 20 grains 300 MP
Lee 240 RN, 9.5 grains Unique
Hornady 240 XTP, 23.5 grains 300 MP.

I tried to vary the loads as much as I can to see what seems to work and what doesn't. I also crimped the first three enough to curl the mouth into the crimped groove and the last two with as little crimp as I can get away with. I will update the thread when I get back later. Thanks for all the suggestions so far!

[44man]

I think MP 300 is too slow, can't get enough in the brass.
My home made boolit weighs 330 gr and has done this at 200 yards. 21 gr of 296 and a Fed 150. However taking it down to 1100 fps does this at 50 yards.
My sweet spot with the Lee is 1316 fps. Fantastic deer boolit.
It takes very little velocity loss to change things. I can see even 50 fps changes.
Use of a magnum primer in the small case will move a boolit and increase air space before the pressure can build with slow powders.
Even with a 330 gr, you can see the case tension I use, look at my loaded round. Python with a cow inside! Crimp does nothing for burn, only need enough to aid tension so boolits don't pull from recoil. The wrong primer can still break my heavy boolit loose as will a slippery lube.

[Sasquatch-1]

Is this a used gun? Could the barrel be heavily leaded? The only other thing is an undersized bullet. Have you slug the barrel and chambers?

I have a Redhawk 7.5" barrel that I shoot 240 to 260 grn bullets through. I use 7grns. Unique pushing around 750fps. Makes for a accurate and pleasant to shoot round. When loading 110 or 296 it is full bore at 21.5.

[stubert]

Listen to us, that 310 grain needs to go faster. Forget the crimp, forget the crown, go buy some 110 or 296 and have fun. I shoot that bullet in a 7.5" Redhawk with 20.8 grains of 296 seated to 1.71.

[ChrisG]

Thank you for all the advice everyone. I got home from the range on Saturday (My friends back yard) and everyone who is telling me it needs to go faster is probably right (yes you can all pull an "I told you so"). The boolit looked perfect. It definitely skids a bit when slamming into the rifling, but by no means is it a lot. I went back to the loading bench and loaded up some 21, 21.5 and 22 grain charges of 300mp (sorry I know everyone says I need you use H110, but it is all I have for now until I go to the shooter's supply) I am going to try them out sometime this week. The best shooting load I had was the 20 grains of 300mp. I couldn't tell if it was yawing, but when I found it in the box of sand, It showed some deformation on the nose. In order for that to have happened, it would have had to pass through 2 feet of water & wetpack, 6 inches of packed cardboard and slammed into the sand nose first. To my mind that means it must have either been a) a fluke or b) been relatively stable so as to not tumble through all the barriers.

BTW, even at the 1000 fps that it was travelling, It still almost punched through the foot thick box of sand after going through all of the previous barriers! This thing penetrates! Not as well as my .375 H&H with Solids, but still pretty impressive!