SP101 leading issue

[unique]

My Sp101 has leading issues and wondering if you might offer some suggestions what to try. The cylinder throats are all consistent at .357. My bore slugs at .355 , maybe closer to .354, which I consider tight. My boolit is 358156 with gas check, sized to .357. Javlin lube. Load is 6.5gr Unique.

No discernible tights spots in my bore which is smooth. I tried my own poured from WW and also tried commercial boolits which where quite hard (but w/o GC). Brass is 357Mag (not 38spcl). Tried alox as well for lube.

Pretty much run of the mill load and shoots well in my other 357Mag's. I do not have .358 sizer or I would try that but having a hard time believing that would solve the problem.

The leading is heaviest right after the cone. Cone is fine. Leading is consistent even if I vary lube or boolit type. Not horrible terrible leading but much more than I am accustomed to.

Any thoughts?

unique

[FLHTC]

I believe the load is too light. Eight grains of Unique is a stout load for 158 grain bullets

[LUCKYDAWG13]

my new SP101 3" barrel shoots a 358477 sized .358 just fine no leading
i used a upper mid level load of Blue Dot you might try and up your load
a little bit

[unique]

Thank You for suggestions, can't hurt to try...well the 8.0 grs of Unique might.

Does anyone think the .355 bore is tighter than normal?

[cheese1566]

I never slugged my 2", but I am running my Lee 358-158-RF's through them sized to .358 using Magma hard lube and 4.8~ grains of WW 231 in 38 spec loads.

No issues.

[Highgravity]

I have the same gun, I slugged it and discovered that it is a 5 groove. That said, I couldn't get a good measurement. So I
size to the throats and have no leading. My pet practice load with 158 grain commercial cast is 4.5 gr. of Titegroup in
magnum cases.

[runfiverun]

the tight bore measurement and the leading tells me you have a tight spot under the frame.
the name ruger on the side of the gun tells me you have a tight spot under the frame.
where the leading is tells me you have a tight spot under the frame.
once you fix the tight spot under the frame going to 358 boolits should make the gun a decent shooter.

[unique]

So I followed a hunch and was able to reduce the leading significantly. I basically filled the exposed portion of the crimp groove with resizing lube after the cartridge was load. My resizing lube is 50:50 castor oil & lanolin.

These particular boolits are commercial hard cast with hard lube and if I can get this not to lead than I suspect when I lube my own and fill the crimp groove than I am on my way.

[FLHTC]

Its extremely doubtful that you have a tight forcing cone. I've owned SP101's in 22, 9mm, 32 mag, 38 and 357 and never had a leading issue that couldn't be corrected with the load.

[cbrick]

Let's see, commercial hard cast bullets, commercial hard lube, a lite charge of a fast powder and bullets possibly sized too small.

I don't think you have a lack of lube problem that filling the crimp groove will fix.

Rick

[unique]

Let's see, commercial hard cast bullets, commercial hard lube, a lite charge of a fast powder and bullets possibly sized too small.

I don't think you have a lack of lube problem that filling the crimp groove will fix.

Rick

The lube in groove did help.

I am having a hard time following you, but to iterate I have had leading problems with my own poured from WW (gc no less) and javelin lube as well. I didn't go into it but also tried the alox+jpw combo and blue dot and 2400 powder. I am wanting to know if someone thinks my bore to sizing ratio is wrong. I sometimes have trouble following an innuendo so please do explain.

Bottom line is I am just trying to learn as I figure with only 40 years of casting I still have a lot to learn and I really do mean that.

[unique]

So next thing I tried was waxing exposed portion of boolit with JPW, all else being kept the same. Even less leading to point where I am no longer concerned. I have always wondered about driving band not being lubed. I mean that is what smacks into forcing cone and then into the lands and where slip is going to occur so why wouldn't lube help out at this point.

There is the theory that a previous shot pre-lubes bore for next shot but I never bought into that. Oh, I do suppose it happens but the question is to what degree. If you look at sequential flow down the bore you have lead, lube and hot gases. I figure the smoke I get on each shot is hot gases blowing away the pre-lube. I suspect it depends upon lube factors relative to hot gases meaning Unique burns hot relative to other powders so more inclined to burn away pre-lube.

So then if this theory holds it makes sense that a 'dry' driving band would be inclined to lead. I did try tumble lube with alox previously and did not help prevent leading. I suspect the the JPW leaves harder & slicker surface.

[Grump]

Well, it still could be a tight spot forward of the forcing cone which some more creative lube options is adequately addressing.

Slugging a barrel and relying on "feel" is not a very precise way to quantify a bore's diameter profile. It's about 1,000 times tighter than trying to nail Jello to the wall, but still in that arena of squishy endeavors. That's why the air gage was invented.

[Case Stuffer]

Common issue


see post #7.

cylinders one size ,forcing cone another, right in front of forcing cone another size (smaller) then bore get another size.

[unique]

Well, it still could be a tight spot forward of the forcing cone which some more creative lube options is adequately addressing.

Slugging a barrel and relying on "feel" is not a very precise way to quantify a bore's diameter profile. It's about 1,000 times tighter than trying to nail Jello to the wall, but still in that arena of squishy endeavors. That's why the air gage was invented.

I am not sure there is a tight spot and if there was I wouldn't not know what to do other than live with it. I ran my slug backwards and can't detect a tight spot. I have other revolvers where there definitely is a tight spot so I know what I am looking for.

Basically the way I slug a bore is to place a cartridge loaded with 0.5gr BE and shoot into 3 feet of water. Gives me a clean undamaged bullet that can tell me a lot about what is going on. Anyway I take that and place into muzzle (the way it came out) and pusher back on thru to forcing cone. Changes in resistance tell me bore condition meaning tight, rough, loose.

Probably not as precise as an air gage (whatever that is) but it is all I have.

Having said all that, I certainly do appreciate your thoughts and is why I posted originally...to get other thoughts.

[texassako]

Slugging that way will not tell you if there is a tight spot, only the smallest dimension in the bore. Drive a dead soft, unfired, greased lead slug in the muzzle 1" with a wood dowel and drive it back out the other way, and see if it still measures .355".

[unique]

Slugging that way will not tell you if there is a tight spot, only the smallest dimension in the bore. Drive a dead soft, unfired, greased lead slug in the muzzle 1" with a wood dowel and drive it back out the other way, and see if it still measures .355".

I don't understand...Ok I can drive it into the muzzle but then you say drive back the other way? How do I drive it in from cone side since I don't have straight on access?

[texassako]

http://hgmould.gunloads.com/casting/sluggingthebore.htm for reference, especially the bottom portion on revolvers. A c-clamp using a piece of the same dowel you drove it in with and a little scrap of wood over the muzzle with a hole drilled large enough for the slug to come out works for snubbies. Wrap the clamp in tape if you think it will scratch. I did that once, but don't bother anymore. Tightness at the frame when driving it all the way through from the muzzle means it gets firelapped. PDF version if you want to save it: http://www.castpics.net/subsite2/HowTo/Slugging%20the%20Bore.pdf

[unique]

Wow, thank you for that. Good Stuff.