Kart XACT 1911 Barrel Leading with Zero SWCHP?

Hi guys,

At 50 yards I’ve seen my groups open up quite a bit after shooting Zero 185 SWCHP.  Shooting on call becomes significantly less

I’ve noticed this after shooting a 900 last Monday, 60 rounds were with 3.7gr WST 185 SWCHP 0.463.  During the next 900 all my 50 yard shots were incredibly dismal with few of them being on call.  I looked into the barrel and saw a lot of streaks from the chamber going down. It didn’t come out with dry patches so I tried FP-10 soaking for 20min followed by patches till dry but it still remained.  Did the same with BoreTech Eliminator with minimal improvement.  Soaked in Eliminator and chore boy’d it quite a bit to clean up the streaks but some remained along the grooves through first part of the barrel.

I saw it again recently after shooting 25 rounds of, what I think are, hot loads while working up a load—4.3gr WST 185 SWCHP 0.464”, 805fps. First 25 shot great, everything after felt wild and seldom made call regardless of ammo.

Came out with 50 strokes of chore boy and FP-10 soak.

Am I having leading issues?  If it is, it’s at the chamber of the barrel which I read is a sizing issue, my bullets may be undersized for the barrel.

Bullets are from Zero 185 SWCHP and 0.452”, although I just realized I haven’t measured the bullet diameter myself.  This was all done with two separate batches of Zero 185 SWCHP bullets

Barrel I’m using is a Kart XACT fit

Photos of barrel with new streaks from yesterdays session

The bore scope photo with a silver streak along the groove and new silver just after chamber

Current plan is to get rid of all the streaks along grooves and shoot again Tuesday.  The ones not along the groove are removed but some remain next to the groove

1) Shoot long line with a load that looked good from before.
2) Shoot sustained with 3.7 WST 185 SWCHP 0.463  for 60 rounds.  
3) Then try the long line again.  If shots aren’t on call, clean barrel and shoot long line again



I also haven’t slugged the barrel, can I do that with my Zero 185 0.452” diameter bullets?

Greetings,

My "guess" is that 3.7 WST is too light a charge to obdurate the bullet. 

Gas is getting forward of the bullet Lead fouling the bore.

Load a few rounds with 4.3 WST and see if the Lead fouling diminishes.

Cheers,

Dave

I don't get leading worth mentioning in my rock river with the SWCHP at 4.1gr and ~.464 crimp. All comes out after a few hundred rounds with a kroil soak followed by a few strokes with a bronze brush

fc60 wrote:Greetings,

My "guess" is that 3.7 WST is too light a charge to obdurate the bullet. 

Gas is getting forward of the bullet Lead fouling the bore.

Load a few rounds with 4.3 WST and see if the Lead fouling diminishes.

Cheers,

Dave

It was after shooting 28 rounds of 4.3WST did I start noticing my groupings opening up. I was shooting 48 rounds of 4.3 WST total


I did shoot 90 rounds of JHP before shooting 4.3WST, so next time I’ll start with just 4.3

Don't just measure bullet diameter before loading.  Pull some bullets after loading and see if they have been scrunched smaller during seating.  Use a micrometer, not a Vernier caliper, to measure.  

I would expect a Kart barrel to have a correct groove diameter, but anything can happen, so it would be useful to slug your bore.  You could also just have a loose spot, so run a tight patch through the bore and see if you can feel any difference anywhere.  

You could find some larger bullets and see if you get different results, and also hollow base bullets.  I have tried the latter (185gr HB SWC) in a S&W 25-2 with .455" throats with better results.  If you will PM me an address I will send you some to try.

Some time ago I purchased a booklet Getting Jacketed Performance from Lead Bullets. Guy did quite a bit of testing as to what caused leading.  He found that the leade angle was the cause. Simply put when the round is fired and soft lead engages the rifling a strip of lead is cut like and cutting tool will do. That lead chip is then pushed down the barrel smearing itself onto the barrel surface. Kart being the worst offender due to having a sharp and greater angle. He recommended using 3° leade angle.
 Also to lube about 100 bullets with JB bore paste and shoot them to polish the leade. I made a lap and lapped the leade. Leading ended! Being lazy I didn't cast my bullets but local gun shop didn't stock much lead 45acp bullets. I would get all of his 200gr (150 or so) but if I needed more I tried lower weight. Got 175gr they didn't shoot good at all. When I  lapped the barrel I took those 175gr bullets and removed the lube and relubbed with JB. I was supersized to see that accuracy improved with the 175gr bullets. Though they were only shot at 25yards. However not only leading was eliminated 200gr accuracy improved too.

I was told that Kart barrels always need finish chambering/reaming as the leade is not cut. 

I did so with my Kart barrels and have never seen even a trace of leading. They were also short chambered from Kart.

DA/SA is correct. if a finish reamer has not been used to set the throat, there in lies your issue. A throating reamer can also be used.

DA/SA wrote:I was told that Kart barrels always need finish chambering/reaming as the leade is not cut. 

I did so with my Kart barrels and have never seen even a trace of leading. They were also short chambered from Kart.

I had to take off quite a bit of hood to fit the barrel into battery. So I used a finish reamer to have the cartridge actually fit. Any tests on leading in regards to finish reaming?

Not a Kart barrel but I do shoot the Zero 185 SWCLHP bullets and have tried 3.5gr to 4.3gr of WST with a .465" taper crimp. 
I found that they would lead the throat of my barrel with all powder charges I tried. 
I tried resizing them and that helped some and did improve the accuracy a little but the leading was still there.
I thought about getting some Lee liquid bullet lube and dip them in that but found some Rooster Jacket liquid bullet lube at Mid Way and bought a couple of bottles to try and picked up a plastic bowl with snap lock lid so I wouldn't accidently dump everything out when coating the bullets.
The Rooster jacket lube is poured into the bowel with just enough to coat the bullets, about 1oz and then swirled around to get an even coating. I pick them out of the bowl with a pair of large tweezers and place in a mesh basket over night to dry so you can handle them to load. Keep them separated so they don't touch and stick together as they dry.
The lead particles left in the bottom of the bowl is a lot and could help to contributing to the leading problem.
The lead particles/dust is left over from swaging the bullets and then held on the bullets by the factory lube process.

you can also use 45/45/10  from White Label lubes.. just coat right over the old lube. works great.

lengthening  your throat will also work

I've never had a problem with Kart Barrels using jacketed bullets. As a matter of fact I had 2 gunsmith fit Kart barrels tested, I'm not willing to say who but they are a very reliable source to test group size. Atlanta Arms 200gr JHP loaded ammo 10 shot group was about 1" at 50yards. Test was two 10 shot groups for each barrel.
 Sharp edge on high angle leade cuts rifling into soft lead that's smeared in the bore by the next round that then also leaves a cut chip to be smeared.

Froneck wrote:
When I  lapped the barrel I took those 175gr bullets and removed the lube and relubbed with JB.

I remember reading this on this forum from a Dad who shot and reloaded for his son who ended up joining the AMU!

So is lapping the barrel just shooting lead that has JB on the lube grooves or did you use a bronze brush and stroke it back and forth with JB on it?


Going to load some JB lead rounds when JB arrives tomorrow