Leading in my Ruger GP-100

[robertbank]

Well i have a problem and hope you guys have some answers.

I am shooting 160 gr RCBS RN boolits cast from WW, air cooled. My load is 2.8gr of Clays making a PF of about 115 for IDPA. Velocity is 700fps. Boolits are sized .358. Lube is a soft commercial lube requiring no heat to flow freely through my RCBS lubricator.

I have reamed all the cylinders to .358. I have yet to cut the forcing cone to 11 degrees.

I am getting leading in the first 1/8th" of the rifling. I get some in the forcing cone but I attribute that to the 5 degree angle on the forcing cone.

I plan to try water quenched boolits to see if harder is more better. My head says it may not be a case of to soft a boolit but I am not sure at this point.

The gun has approx. 500 rds through it, virtually all lead shot from both .38spl and .357mag cases.

Take Care

Bob

[462]

Are you able to make a softer alloy? My handgun leading experiences have all been caused by too hard of an alloy.

Another remedy might be to use a slower powder, like 2400. My only form of competitive shooting is against myself, so don't know if that will affect your power factor rating.

[big dale]

I would try sizing to .359 first. I must caution that I have never owned a 357, but have been loading primarily for 41 mag, 44 mag and 45 acp for over 40 years and have never had a leading problem with air cooled wheelweights when driven to about 1,000fps. I have also loaded a bunch of 357 sized to 359 for a friends Redhawk thru the years and it always worked fine as long as I drove the loads very hot in that particular gun. If I backed off on the load this gun shot patterns instead of it's usual 1 inch at 25 yards. I don't reccomend that others load that hot, but that gun was very unusual and it had no leading problems.

Have fun with this tuff.

Big Dale

[robertbank]

For IDPA SSR Division all I need is a PF of 105 so I really don't want to go over 700 fps using .38spl cases. No need for a hot heavier recoiling load. I'll try going harder than cast some softer boolits. The gun is a shooter but the leading in the first 1/8th" has got me stumped right now.

Thanks for the repies. Any other suggestions are surely welcome.

Take Care

Bob

[CWME]

Ran into a similar issue with a 44 mag. Too hard of an alloy for the velocity I was pushing them. When driven hard the leading went away.

If it were me I would try driving them harder to see if the issue cleared up. If it did then I would know I needed to use a softer alloy for the slower velocity. This test only burns a little powder and some lead without buying a new sizer "just to see" so to speak.

You could try a larger dia but these may not chamber easily. For IDPA I assume you need to reload quickly... Could try some and see if you already had a .359 sizer. However depending on how many rounds you need to fire your chambers may foul up and make chambering dificult faster...

[Bass Ackward]

Boy, I would take the easy way out. I would add a little LLA to the slugs to see if it is friction related.

Then if it was, I'd shift to a .... cooler burning ( dirtier ) powder for the extra bit of help until the gun broke itself in.

And I would NEVER re-cut the forcing cone unless there was no other way. You can ALWAYS go to a less angle but you can't go UP and clean up a forcing cone without setting the barrel back because you will make it dangerously thin (pressure) at the back.

Hard to beat WW231 for this purpose. Covers a lot of sins.

[robertbank]

Boy, I would take the easy way out. I would add a little LLA to the slugs to see if it is friction related.

Then if it was, I'd shift to a .... cooler burning ( dirtier ) powder for the extra bit of help until the gun broke itself in.

And I would NEVER re-cut the crown unless there was no other way. You can ALWAYS go to a less angle but you can't go UP and clean up a forcing cone without setting the barrel back because you will make it dangerously thin (pressure) at the back.

Hard to beat WW231 for this purpose. Covers a lot of sins.

I won't touch the crown but the forcing cone should be 11 degrees for lead, it presently is 5 degrees. I may try Unique and 231 to see if that helps. Like I mentioned earlier I don't want to go over 700fps for these loads.

Take Care

Bob

[RayinNH]

Barrel restriction from the threads perhaps? See if you can feel one with a tight cleaning rod...Ray

[RobS]

Have you pulled a boolit after reloading it to ensure the very edge of the base of it is .358 as you intend. Case Swage does happen quite often especially if a person loads up air cooled WW boolits before they have a chance to age harden enough to keep from swaging down. I've seen many here cast up, lube and load air cooled boolits in the same day or within 24 hours which causes issues. It takes a week or two for WW boolits to age. Even worse is when a person loads up boolits like this having them swage down in the case then the boolits age harden to a small diameter and with a loaded charge that doesn't have enough pressure to bump up or obturate the base of the harder boolit the result is similar to what you are experiencing with the leading in the forcing cone/barrel throat/first start of the barrel. I don't know if this is what you have there or not but thought I would throw it out there at you.

[Bass Ackward]

I was just cutting a crown, so that was what was on my mind. I meant forcing cone and have since changed it.

[robertbank]

Have you pulled a boolit after reloading it to ensure the very edge of the base of it is .358 as you intend. Case Swage does happen quite often especially if a person loads up air cooled WW boolits before they have a chance to age harden enough to keep from swaging down. I've seen many here cast up, lube and load air cooled boolits in the same day or within 24 hours which causes issues. It takes a week or two for WW boolits to age. Even worse is when a person loads up boolits like this having them swage down in the case then the boolits age harden to a small diameter and with a loaded charge that doesn't have enough pressure to bump up or obturate the base of the harder boolit the result is similar to what you are experiencing with the leading in the forcing cone/barrel throat/first start of the barrel. I don't know if this is what you have there or not but thought I would throw it out there at you.

Thanks Rob. No my boolits sit for quite awhile befoer I size them. I am going to try harder than softer cutting my WW alloy to 50% with pure lead. I will report how I make out later next week.

Take Care

Bob

[RobS]

Thanks Rob. No my boolits sit for quite awhile befoer I size them. I am going to try harder than softer cutting my WW alloy to 50% with pure lead. I will report how I make out later next week.

Take Care

Bob

So you pulled a boolit to check???

[robertbank]

So you pulled a boolit to check???

Yes I checked this morning. Boolit miced out at .358, the same as it was sized. I seated the boolit in a re-sized Win nickle brass with a slight roll crimp.

Take Care

Bob

[truckmsl]

Rob - I have the exact same issue with my GP100 so I'll be watching with interest. I've tried soft and hard lead, Unique and 2400. I'm running .359 boolits and the cylinder throats are all 358. I'm thinking it may be a forcing cone issue. As you, I am considering going to 11 degrees.

[robertbank]

Rob - I have the exact same issue with my GP100 so I'll be watching with interest. I've tried soft and hard lead, Unique and 2400. I'm running .359 boolits and the cylinder throats are all 358. I'm thinking it may be a forcing cone issue. As you, I am considering going to 11 degrees.

How soft of an alloy did you run?

I am thinking 50% WW alloy, 50% lead.

Take Care

Bob

[truckmsl]

I've run from 12 to 20 BHN, using carnuba red lube and alox at different times. Leading is only at the forcing cone.

[WARD O]

I have been having a similar problem with my 586 Smith Wesson except that in my case the forcing cone was visibly rough. Leading about the first quarter of the barrel. I had the cylinder throats opened to .358 previously to see if that would help but it did not solve the problem. I have since done the forcing cone to 11 degrees and while I am still in the middle of testing, it does seem to be helping quite a bit!

Ward

[robertbank]

Well I knew this pretty much already but hard boolits isn't the answer so I am going to cast some 50% WW 50% lead boolits tomorrow and see how they work out. I have a ton of WW alloy boolits that will now go through my Rossi. LOL. I'll test them before doing my forcing cone.

Take Care

Bob

[btroj]

I had that problem with mine and eliminated most of it by fire lapping. I now get hundreds of rounds sized .359 with minimal leading.
You want leading? Try some commercial cast that are hard and undersized at .355. Now those suckers leaded. After 50 they Hit the target sideways!
I have found my leading goes away with softer bullets more often that with harder.

[GP100man]

Bob , been on the road all wknd & just now catching up !

Are you shooting the 2.8 gr. load in 38cases ???

2.8gr. is too lite in 357 cases .

I load my 357 plinking with 3.2-4.3 in mag cases .

My throats are also .3585" also .

I`ve found this combo worked on 3 GPs with a 10.0 bhn boolit.

[robertbank]

No out of .38spl cases.

I think the alloy is just to hard using WW. I get a build up of leading in the first 1/16th to 1/8th of the rifling and it is a begger to get out. I;ll try using my 50 -50 alloy before cutting my forcing cone to 11 degrees. I really don't want to up my charge as I want to keep the recoil as low as possible, if possible.

Welcome back.

Take Care

Bob

[GP100man]

Hey Bob , ifin ya lookin for some bunnt poot loads look at castpics Round Ball loads for the 38/357.

I even take a little alox & seal the ends & to help with leading a bit . I can shoot 75 with very minimal leading this way . I seat em a little deep so the blast from 1 cyl does,nt blow my lube away.

Quiter than a 22 (less crack) & recoil is non existant !!

Me & the girls have a blast until there gone !!!!