I picked up some 155grn lead rn's for 40 s&w (couldn't find any 180's anywhere).  I ran some of the first batch over a chrono and they were averaging about 950 fps.  Is this too fast?  Too fast meaning I'm going to cause excessive leading in the barrel.  My 180's are usually about 800 fps and never a leading problem...



Thanks

You have all the information already. Was it to fast? I don't know. Did it Blow up the gun? Did it group well enough to meet your needs? Did it lead the barrel? You are the only person that can answer your questions.

lead bullets are great if you keep them under 1000 fps and if you want to go faster fps put gas checks on them if you roll your own or buy them that way.

There wasn't any noticeable leading but I only fired 25 rounds or so.



There's a "rule of thumb" out there somewhere, I just can't remember it.



Thx

OK, thanks.  It's plenty fast for me and functions well.  No gas checks used.





 

Depends on how hard they are and if they are the correct diameter.

.401 on all I measured.  No way to measure hardness that I know of -- is there a "home brew" hardness test?



 

Yes.

You can use pencils http://castboolits.gunloads.com/showthread.php?75455-Testing-hardness-with-pencils

Or you can use a number of other hardness testers like this http://leeprecision.com/lead-hardness-test-kit.html

I shoot home cast Wheel weight 40 cal bullets at 1200-1250fps out of my 10 MM's without any leading issues.  It's not about speed, it's about fit and lube.

Yeah, I shoot water dropped 50/50 WW/Pb in my .40 to 1050 with no issues.  At this low Sb level, I'm not sure water dropping does much though.

This. Pressure and duration. (How hard is the powder pushing and for how long is the spike in pressure.) Lead likes to be accelerated slowly and for a longer amount of time, which usually goes hand in hand. Bullet skidding is mostly from the bullet not fitting well and being pushed too fast over the riflings. Lube is always good.

There is no majic number.

In my experience I have observed the folowing

A barrel with any jacket material in it will tend to shread lead bullets. Start with a nice clean barrel (with stinky copper solvent)

Hardness of the bullet should be matched to the use . Most commercial cast lead bullets are too hard because customers insist on it.
Many of the hard bullets out there only shine when you push them fairly hard like in a 44 mag

Another decideing factor is the smoothness of the barrel and how the rifeling is cut. I have some fairly warm 44 mag loads that work very well in my S&W revolvers and my Marlin cowboy (cut ballard rifeling,not micro-groove). These are plain base commercial cast bullets, no gas check.
These same loads are horrible in my Ruger Blackhawk . Not sure if it is the smoothness of the barrel or just the way it is cut but it doesn't like these loads.

The powder selection is another variable. Two loads with different powders pushing the same bullet at the same velocity can be different in how they lead things up.Has to due with flame tempeture behind the bullet and also different presure curves that can affect how the bullet seals


Short answer is your load seems resonable- try it and see


I avoid gas check bullets in most cases, they add expence and are a pain to work with if you are casting