Bullet Behavior Questions

I cast some 309-170 and 459-500-3R last week out of Lyman #2 alloy. Each design and batch has its own interesting quirks and issues.

1. For 459-500-3R, this is quite a hard alloy for the application of this mold. My bullets are dropping out at about .460. If my bore is at about .458, could I still choose a load developing low pressure and could still avoid leading?
After all, we are looking for a certain fit in the bore that minimizes gas cutting right? So technically, if the bullet's diameter is close to where you want to bump it, then bump it slightly with pressure, do you achieve a similar effect with a softer alloy and smaller diameter to maximize velocity and eliminate cutting?

2. Same with the .309, these bullets are dropping out at .309 or below, could I use a higher pressure and velocity load to bump the tail to a larger diameter needed to seal the bore, even with a gas check?

Am I asking the right questions? My guess is that these are the dynamics we are trying to mimic in our load development to control velocity and leading but I am not sure; its like we are just controlling the amount we bump our bullets to seal the bore.

Or for short, could these two situations achieve a similar effect: small, soft bullet bumped a lot or slightly larger harder bullet bumped a little?

shoe

Always been better for me to make hard and fit better, over groove a few thou.

your not really bumping anything unless you get an immediate pressure spike.[or a soft enough alloy with the spike]

you want enough diameter to seal the barrel off from any gas pressure.
but not so much diameter you damage the boolit getting it in the barrel.

Fairly hard bullets that are a little over groove diameter for your rifles, gas checked. Perfect! You can load anything from mild to wild with no worries about leading. Hard bullets and light loads can get you leading in a revolver. Not in a rifle where you are already sealing the bore with the slightly oversized bullet.

Something you might try would be to install the gas check on your 30 caliber bullets with a .310" sizer. I know the sizer won't touch the bullet but it does leave the check a little larger and might help with eliminating any leading.
Good Luck,
Rick

Quote:

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Originally Posted by RickinTN

Something you might try would be to install the gas check on your 30 caliber bullets with a .310" sizer. I know the sizer won't touch the bullet but it does leave the check a little larger and might help with eliminating any leading.
Good Luck,
Rick

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+1! This is exactly what I do, my boolits come out .310, I seat checks and lube in a .311 die and shoot them thru a .308 bore!

Quote:

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Originally Posted by centershot

+1! This is exactly what I do, my boolits come out .310, I seat checks and lube in a .311 die and shoot them thru a .308 bore!

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Darn, NO! As you seat the GC is larger and expands brass over boolit diameter that ruins tension. Never size a check larger then the boolit.

No it doesn't. The brass has ample springback to also hold the bullet. It actually works quite well. I think I would be correct in thinking that most people load cast bullets with too much neck tension anyway. .001 to .002 works well for me.
Take care,
Rick

I was having trouble for a while until I found I was using a Lee die too large. Just to remove excess lube without sizing the lead. .432" die on a .430" boolit. Accuracy trouble went away with a .430" die. The check WAS expanding my brass. Reverse "M" die!

In that application it very well may have. I deal mostly with 30 caliber, and usually 30-30. Installing the check in a die .001" over bullet diameter works well and sufficient neck tension is retained. How many times the cases have been fired and how long it's been since they were annealed could also play a part.
Take care all,
Rick

Quote:

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Originally Posted by RickinTN

In that application it very well may have. I deal mostly with 30 caliber, and usually 30-30. Installing the check in a die .001" over bullet diameter works well and sufficient neck tension is retained. How many times the cases have been fired and how long it's been since they were annealed could also play a part.
Take care all,
Rick

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That may be because you don't have to deal with the revolver throats, jump and recoil movement. I might worry with a lever gun and a tube magazine.

I was thinking exactly the same thing after I wrote the post above. In a revolver basically you are sizing the bullet (in the cylinder throat) before it enters the throat proper of the barrel. In rifles we don't have to contend with this jump and sizing. I work with revolvers very little but I can see that in a revolver without the cylinder throats matched you could actually be firing 6 different sized bullets through the barrel. That could certainly play heck with accuracy and consistency!
Take care all,
Rick

I have that 459-500gr mold, not seen any need for a specific alloy. Not like you will get a ton of velocity out of it to begin with. I use it subsonic in a H&R 45-70. More velocity I shift to a NOE 425gr/ 390gr w hollow points, powder coated it can be driven as hard as you care to fire it, 2200fps, but a bit hard on the shoulder for to many of them.

Ah gotcha. So it's back to the same theme again with velocity and pressure. For any .308 Load, it seems like if I just stick with a harder alloy, I am okay at most speeds as long as I size .001 to even up to .003 above bore diameter (with a gas check of course)? Since with .45-70 I don't plan on pushing anything above 1500fps in a 405gr or 1200 in 500gr, I can use any alloy I want technically right?

The former claim is subject to experimentation course and would yield some characteristic tailored to my rifle but I think it sound correct right?

shoe

The 45-70 is very forgiving and as long as pressures are kept in the BP range, you can shoot pure lead. Just see what you get.
Now the Lee 459-500-3R was giving some problems at the BPCR shoots. The fellas found they were slumping. I never got mine to shoot right either but how they recovered the soft boolits to see is a mystery. Maybe the soft berm at 500 meters would not mash them.
I found the old 500 gr gov't boolit still was right.

For your 30cal search beagling a mold on here that should drop them a little bigger and isn't a permanent alteration to the mold. Also try casting at a lower temp to prevent shrinkage.