Leading On The First 1" Of Barrel??

[Foto Joe]

Okay I need some education here. I pulled my Uberti SAA down this morning after shooting about 50 rounds of COWW 160gr RNFP cast out of a Lee 2 cav and lubed with 45-45-10. Out of the 50 rounds there were two different powder charges both TrailBoss, one pushing around 930fps and the other around 980fps +/-. After running a brush down the bore a few times and then patching it out the barrel was immaculate except the front one inch or so which had some pretty good leading in it. I'm kind of confused as to why.

The leading starts just past the forcing cone and extends about an inch.

FYI, the bore slugs at .449, cylinder throats caliper out at .453 and I'm shooting unsized .452's

Any ideas?

[runfiverun]

that 449 tight spot under the frame could have something to do with it.

[Foto Joe]

Wouldn't this have caused leading previously though with store bought cast boolits?? This is a new problem.

[gray wolf]

If it's not a tight spot from over torquing the barrel your bullets may be to small.

[runfiverun]

so the difference is? lube, hardness, bearing length.

[btroj]

What? Not all bullets of a certain size are the same? Heresy!

Now that the sarcasm is out of the way....

Look at the loads that leaded and those tha didn't. What is different? What makes some lead? This is a great learning opportunity, make the most of it. Was it lube? Alloy? What else was different?

[Foto Joe]

Bearing length isn't something that I'd considered. I've shot a bunch of little 150gr boolits out of this thing but those were always really soft lead being pushed by Black Powder with a huge lube groove filled with SPG.

[detox]

At that velocity i would try water queching the boolits or slow the soft boolits down under 800fps

[atr]

as the boolit hits (slams) into the lands, the front end slows down but the back end keeps going due to inertia, in essence the back end is being compressed. The only place the material at the back end has to go is into filling the grooves, i.e. expanding in diameter. As that diamenter increases it seals off the hot gasses behind it. The gasses now don't have a way around the back edges of the boolit. Its the gasses blowing past the back end of the boolit that cause leading, and if this avenue is sealed off by the expanded diameter the changes of leading are reduced. NOW, if the boolit is too hard the back end of the boolit may not expand in diameter. I think the trick is to cast a softer boolit as see how that works...
just a though, hope it helps
atr

[btroj]

That is sorta right. Hard bullets have a harder time sealing the bore at low pressures.

The big issue often with revolvers is thread choke. A tightly threaded barrel can be choked down when threaded into the frame. This may be .001 to .002 decrease in diameter under the frame. Now that nice bore seal we just got suddenly ends after the bore opens back up after it gets past the frame. Now we get leakage and leading.

Is the lead at the very end of the barrel or does it start a 1/2 to 3-4 inch down the barrel? It matters

[John Boy]

the barrel was immaculate except the front one inch or so which had some pretty good leading in it. I'm kind of confused as to why.Chamfer the forcing cone

[Foto Joe]

I think ATR is in the right track here simply because the leading is only in the first one inch +/- of the bore. If it were a "thread choke" situation I would think that most of the barrel would be a mess. Now on to the fix...

I still need to determine which powder charge is causing the issue or if they both do, I suspect that it will be both. If this is the case would it make any sense to anneal the boolits to see if I can reduce the problem. And just out of curiosity exactly what is the accepted method for annealing lead boolits ?

[btroj]

Nope. Thread choke often causes it just at the end of the the choked area. After that the bullet can often expand back enough to seal the bore.

[runfiverun]

i'd look at the pressure of the loads you are using too.
yeah I read trail boss it's low velocity not low pressure.
real hard for 1/4" of soft lead to grab rifling with 25-k slapping it along.

[Iowa Fox]

I have to agree with atr

[detox]

You need a lead hardness tester to find out how hard your boolits are. I know my old COWW alloy has a BHN of 13. They say newer COWW has a softer BHN. My 20/1 alloy has a BHN of 7 and will shoot in most any revolver if velocity is kept under 800fps. I also use SPG lube.

[btroj]

Lets see. A 160 gr bullet that has very little bearing surface, a lube this OK but certainly not great, a powder this developing pretty good pressures to give those velocities. Thread choke is probably also an issues, it seems to exist in about every 45 Colt revolver out there.
You could try a better bullet, one with more bearing surface to grab the rifling and hold it. A softer bullet may make this worse, not,better.
You could use a better lube, one that can help maintain the seal you are losing as the bullet strip from the lands due to minimal bearing surface for the pressure and velocity.
You could use a better powder for the velocity. Something like Unique that gives those velocities at much lower pressures and with a gentler initial kick.

Look at it this way- you are sing a powder and bullet designed for 750 to 800 fps loads. You are well past that. If you want 900 plus fps then use a bullet and powder better suited to the job. Cowboy action bullets are designed to minimal velocities, not to be screamers.

[randyrat]

One more monkey wrench to throw in......Did you pull a bullet and check how much it was squeezed down by your brass?
Solving that problem- softer brass, harder boolit, larger expander button

[gray wolf]

************************************************** *********************
After running a brush down the bore a few times and then patching it out the barrel was immaculate except the front one inch or so
************************************************** *********************
The leading starts just past the forcing cone and extends about an inch.
************************************************** ******************

[Larry Gibson]

Add 2% tin to your COWWs, let the cast bullets age 7 - 10 days before use. Follow Lee's directions for LLA including sizing (.452 should be fine).

Larry Gibson

[detox]

Read Lyman Cast Bullet Handbook# 4 article on Barrel Leading written by Brian Pearce

Throat sizing can contribute to barrel leading. Excessively large ones can allow powder blow-by and fusion, especially when the cast bullets are too hard to obturate (slug up to fill the throat), or features of a bevel-base, a design that is not prone to slugging up to offer that important gas seal. The chamber to bore alignment is also critical ,this not only causes excess "spitting" in the barrel cylinder gap, but also can deform one side of the bullet, while allowing fusion (melting from hot gases) on the opposite side.

Use a larger diameter bullet with flat base to fit cylinder throat and SOFT alloy (7 bhn) so bullet can slug up better. Keep velocity between 700 and 900.

[Foto Joe]

I'll pull that article. Alignment isn't a factor on this gun.

I'm still way new to this and I'm getting quite the education. My wife calls me a "Jack of all trades and a master of what ever interests me at the moment."

[fredj338]

Pull a loaded bullet & measure it, make sure it is still 0.452". It sounds like early leading is a larger dia throat in the bbl & maybe the bullet is a bit too hard for the pressure involved. Still, back in the day I used to shoot lino in my CAS loads, no leading, so check your bullet size after crimping.

[Foto Joe]

That is a possibility for sure. I'm used to shooting .454 soft lead boolits with Black Powder out of the gun. Normally I never resize 45 Colt but I wound up doing so when I started loading these .452 160's simply because they would just fall into the brass. I really think this whole thing would have been a non-issue if I could have found a .452 mold but no such luck. Never the less, I'm learning new tricks. I won't have any clue as to what works and what doesn't until this weekend. For some reason work is getting in the way of my play time this week.

[detox]

Slip one of your boolits into and thru cylinder. It should not fall thru, but have tight resistance.

The RCBS Cowboy mould is a verygood mould and it comes in two sizes .452 (82244) and .454 (82234). I can send you some samples of the .454 version. These are cast using softer 20/1 alloy (7 bhn) and lubed with SPG. This boolit fixed my Ruger Blackhawk 45LC

[Foto Joe]

When I do a search on those numbers it gives me a sizer not a mold. What weight boolits does this mold drop?

[detox]

When I do a search on those numbers it gives me a sizer not a mold. What weight boolits does this mold drop?

You are correct only one size 82308. My 20/1 boolits weigh 231.4grs

[detox]

RCBS Cowboy boolit third boolit on the right
http://www.midsouthshooterssupply.com/item.asp?sku=0004482308

[Foto Joe]

The thing is I already have a 230gr mold. I'm basically looking for something lighter that doesn't throw that much lead down range to make a half inch hole in a peace of paper. I used to get a boolit called an El Paso Pete's Ultra Gamer that weighed in at 150gr. It was a Big Lube that came prelubed with SPG and worked great for Black Powder 45 Colt Gallery Loads. What I'm trying to accomplish I guess is to replicate those for smokeless. If nothing else I'm gaining experience and I do appreciate the suggestions.

[detox]

The thing is I already have a 230gr mold. I'm basically looking for something lighter that doesn't throw that much lead down range to make a half inch hole in a peace of paper.

Then you need a 38 Special or 357 Magnum. The longer bearing surface really helps with accuracy. I like the RCBS 158 or 140 Cowboy. Problem solved

[Harter66]

453 throats w/calipers and 449 groove my money is on thread choke.

Apples and oranges here. My RBH had cyl throats 1@454 4@4532-6 1@ 4515 w/ them all matched up to 454 the flyer and 1 harder recoil closed to a 5'' 50yd group. Before lapping to match I had leading mostly in the breach end . the bbl is 451/445 end to end w/no choke,even under the Bi-Centennial roll stamp. The commercial cast were too hard my alloy now comes out water dropped at 12-14 and w/Darrs Lube will go to 1200 and as low as 600 w/RCBS 45-200 SWC, 452-252 SWC and 452-255 RNFP Lee's.

[Foto Joe]

What everybody needs to keep in mind and something that I may not have gotten across effectively is that this whole thing with the lighter boolits isn't a "make or break" deal for me, it's an "experiment" so to speak. If it works then it's cool, if not as has pointed out there are many other options. I'm not a competitive shooter any more (shotgunner), I just happen to be considered a little eccentric once in a while.

One of the things I do need to figure out is how to slug both ends of the barrel. Namely how to get a boolit into and out of the throat, out really isn't a problem on the throat as a dowel through the muzzle will work. Out on the muzzle end is another matter though. Any thoughts?

[detox]

I run a slug thru barrel several times (line up rifling) thru muzzle until it begins to be easily pushed by hand with dowel. If there is a restriction you will feel it.

I would not over think this. I believe your problem is with boolit fit, velocity, alloy. A softer boolit will obturate even if there is a slight restriction. What is BHN of your alloy? Under 10 bhn works good between 700-900fps. Boolits should be slightly larger diameter than cylinder throat.

You also may wany to try a lighter weight 45acp boolit with flat base. My 200 grain RCBS boolits measure .454" unsized. Its the second boolit in picture above. RCBS also makes a 185gr version.

Montana bullets will sell you custom bullets to try with lube of your choice. Give them a call and tell them your problem.

IMO Lee moulds are very cheap and not very durable. I buy the higher quality RCBS moulds.

[runfiverun]

I shoot the 165 rnfp for fun and for taking grouse during the hunting season.
so I know it is possible, even with that miniscule lube groove they have.
before I got too overly wrapped up i'd try a different load.
something like 5 grs of clays or 6 of titegroup or 7 grs of unique.
I might even tumble them in some 45/45 lube after lube sizing them.
or even all of the above, now if one of those magically makes the leading disappear you have some thinking to do.