.40 s& w barrel leading up

[Gun Nut]

Ok , sorry about last post..stupid auto text on my phone obvisly doesn't work!!

I am shooting a .40 s&w sigma and have slugged it to.400 and I am getting lead in last half of barrel.I use 7 gr of HS 6. and 175 gr boolits
I have used tumble lube,lymans moly,and even carnuba red and still get lead. I dont crimp mine because they are so tight anyways when seated. The tl boolits were being swagged down by my sized case, even at 21 bnh!! Thanks to the small lee case expander!! So Doby45 sent me some regular 175gr grease grove boolits to try,witch had a bnh of 14-15, and when seated in sized case and then pulled,they come out to be .4005-.401 wich I think is alright,but I still get lead problems ? The drive bands are much stonger on the tc design, than the tl boolit design. All my dies ,molds and equipment are from LEE. Dobys boolits were more accurate than my original tl boolits. The only options that I can see that I have are to hone my boolit sizer out to .402 and or get a better case expander???
:confused: any more suggestions??:confused:

[Doby45]

I would say your powder is fine. I use 3.6-3.7gr of Clays in my 155gr MiHec HPs like the ones I sent you and they are an awesome combination. As I told you in PM I am looking at getting a 402 die for my Star ordered from lathesmith as I think my Storm Lake barrel will chamber a slightly larger boolit. The kicker is making sure you don't take that nicely oversized 402 boolit and squish it down either during the seating process or the crimping process. I would definently look into a M die that could expand your case to .001 smaller than your boolit size. So if you are using 402 boolits it needs to expand the entire seating area of the boolit to 401, THEN apply a light taper crimp until the round chambers with little to no effort.

[geargnasher]

Again, good advice from Doby on not squishing. I know it's a dead horse, but a very important one.

Yup, try .402, see if they'll still chamber. It ain't the powder, lube, or alloy. That pretty much means you still have a fit issue, i.e. undersized boolits or a bum/fouled barrel. I know you aren't pushing them too fast, I use up to 8.0 grains HS6 under a 175 Grain Lee TC. Doby's lube mix is about as good as it gets for your application.

HOW ABOUT COPPER FOULING? Are you 100% POSITIVE you have all of the old j-word fouling cleaned out? Have you used a good copper solvent until no more blue on the patches? Lead sticks to copper fouling like no tomorrow, the friction heat solders the boolit to it and smears as it tears away no matter how good your fit is. The lube acts as a wetting agent, enhancing the soldering effect just like rosin-core flux.

Gear

[noylj]

In general, leading in the last half of the barrel means your lube is gone. Besides not swaging down you bullet during seating and crimping, my first reaction would be to tumble lube them in LLA if they were lubricated in a lubrisizer.
One other question would be how severe is the leading. If you shoot 400 rounds, does it get progressively worse or does it stabilize? Do you notice deterioration in your gun's accuracy?

[RobS]

All good advise and if the leading is happening at the muzzle end then the lube is running out as already stated. However, this does not mean that you don't have an ample amount of lube or that your lube isn't good enough etc. it just means that in this scenario it is being burnt off the bullet as it travels down the barrel because you are pushing a bit too small of a bullet. Gas blow by is slowly working the lube from the bullet and if your bullet was much smaller in diameter then you would have leading issues much sooner in the barrel and would also be much more sever. There is only so much bullet lube can do and putting more lube on may help with leading, but accuracy will never be as it should. A larger diameter bullet, one that is of the correct diameter for your bore, will more than likely correct the leading issues you are experiencing and your accuracy should improve.