Leading help

[pipehand]

I've been shooting several different 45 Colts with the 45-270 RCBS bullet. I've been using maily 20 grains of 4227 in Starline brass which clocks around 925 from my Mountain Gun. This load produces little to no leading.
I've got the issue of Handloader that lists loads using this bullet to three different pressure levels. The 4227 load is supposed to operate in the 20kpsi range. A load of 7.5 grains of Hodgdon's Titegroup is supposed to deliver the same velocity, but at two thirds the pressure, for roughly 14kpsi. Sounds like a no brainer-- lower powder cost, easier on the gun, use same powder in 45acp...
What's not to like? Well, the only time I've seen worse leading was when I was new to this CB thing, and heat treated some .452 diameter 230 grain 45acp bullets, and loaded them up in an early Blackhawk with .455-.456" cylinder throats. The mountain gun doesn't have that problem. In fact, I had to open up the cylinder throats, so a .4515" cb had to be pushed through. That's the size my bullets come out of the Star- I asked for a .4525" die, but I believe they alow for springback using Taracorp alloy. My raw material is half wheelweights and half range scrap which seems relatively soft and doesn't have much springback after going through the sizer die.
Lube is a concoction you could call a modified Felix formula- made with ATF and olive oil, with all sorts of odds and ends of 50/50, Lithi-Bee, LBT melted into the mix. Its pretty stiff, but didn't need the sizer to be heated during the 100 degree days we had earlier this month.
What's puzzling me most, is that Titegroup, being a faster powder would obturate the bullet sooner/better than the 4227 and be less likely to lead.
Has anyone else had a similar experience with this powder/cartridge combo?
I know there are a lot of CAS/SASS guys out there that shoot the harder commercial cast bullets with this powder and at lower charges.
Any suggestions? I'm thinking: cast softer, size bigger, use a bit more of the same powder. I'm trying to come up with an economical and effectice load for when (not holding my breath) the 45-283 group buy mould arrives.

[Char-Gar]

If you had no leading with a load and changed only the powder charge and got leading that tells me you need more pressure. As you stated, you can use a softer alloy or more powder.

I am not a walking ballistic calculator, but I have been shooting the 45 Colt round for 45 years and much of that with 4227 and Unique. Having said that, I don't think 20/4227 and 7.5/Unique are comparable loads. You will need 8 to 8.5 grains of Unique to equal the 4227 load in velocity.

I shoot the RCBS 270 SA (actual weight 280 grains) over both 20/4227 and 8.5/Unique and have no leading problems with either. This loads are safe in a good Smith and Wesson, Ruger (including New Vaquero), the Colt SA or any non-Italian clone. They are safe in the Italian clones, but might give too much wear due to the softer steel.

I size all of my 45 Colt bullets to .454. This makes them larger than the throats but they will size down as they pass through. No..this won't cause pressure problems. You can size the bullet in a die or in the cylinder throats. When you size in the throats (by firing) you know you are not shooting undersized bullets.

My RCBS 270 SAA mold throws bullets .435 to .454 so when I run them through a Lyman 450 with a .454 die, all I am doing in lubing the bullets.

Works for me!!!!

[Bass Ackward]

PH,

Somebody lied to you.

You can't simply go by pressure amounts. What you have to look at is the rate of pressure. The 4227 is going to come up way slower and not have as much obturation on the base. That load is a gradual increase that peaks in .280 of bullet travel at 17,000 psi. These figures are computer generated, but since the velocity is close, I would say the pressure calculation is ballpark.

The 7.5 grains of Tightgroup is 21,500 psi and it peaks in .244 of travel by the same program. Says your velocity in a perfect world should have been @ 900 fps. Because you were leading, my guess was pressure was higher than that which adds to increased leading and the velocity should have climbed on the chrono. You were probably smoking like an old coke plant too. :grin:

In short, it looks like you need a harder bullet for the Titegroup load.

[leftiye]

Pipe,
Not much probability of a faster powder reaching a given velocity with less pressure than a slower powder. B.A.'s computer workup gives you a good picture, especially as the powders relate to each other. Not only are the pressures higher and the pressure rise faster with a faster powder, but gas cutting is more violent (especially with lead that might not obturate).

[pipehand]

Thanks for the reply, Chargar. I've experimented with the Unique loads before, then found the 4227 load to be more consistent, and have a "different" recoil impulse than the Unique. I suppose that for the reason of frugality, the Unique loads would serve as well as Titegroup. I was just surprised at the amount of leading. 4.8 grains of the same powder and an RCBS 45-230cm shoots great out of my 625-2- at 920fps to boot. The same load in my 1911 goes =/- 870fps, and neither gun exhibits any leading. The 625-2 has almost identical bore/cylinder dimensions, yet shoots to "black bore condition." I would imagine that the ACP load is making 3-4kpsi more pressure. The same Scoville article lists 20k psi loads with the same bullet at 10 grains of Tightgroup, right up there with twice as much 4227. I'll have to try it.

[pipehand]

BA and Leftiye- what you're saying makes sense, and makes me wonder about the pressure testing methodology used to work up the loads for the article. Article says 14kpsi for the 7.5 load. BA says 21kpsi for the same. If so, I wonder what the real pressure for the 10 grain load is! Is anyone having great success with that boolet with anything other than 8.5gr Unique or 20 gr. of 4227?