KKM or Kart

KC and others have described KKM barrels as [i]better for[/i] (read-more precise) jacketed barrels and Kart [i]better for[/i] lead.  I would like some more detail.  How much precision is lost when using lead with a KKM and similarly how much precision is sacrificed when shooting jacketed through the Kart?  This now creates four questions...
50 yd precision- KKM jacketed _______? 
50 yd precision- KKM lead       _______?       
50 yd precision- Kart jacketed _______?  
50 yd precision- Kart lead       _______?       

If you can estimate representative numbers, fine.  An alternate way of asking the same question is simply which scenario will lead to a higher score when equal shots (say fifty each of jacketed and lead) are fired with each barrel.  Neither number of shots nor distance should matter.  I realize that precision is less important at twenty-five yards and other issues in the real world such as lower recoil and the unequal number of rounds at each distance, play a role.  I'm not interested for purposes of this question - only the measured, mechanical precision of each barrel in a barrel test fixture with each bullet type.  This is really looking at "how much precision is [b][i]given up[/i][/b] when shooting the bullet type for which each barrel is [b][i]not [/i][/b]optimized." Jut another way of thinking of this.  The attached sketch shows a simple example of how the[b][i] amount of lost precision [/i][/b]can influence the overall winner.

Warm weather is coming so I promise to soon stop asking senseless, technical questions.  Thanks for your patience.  
Ed

I too was on the KKM/Kart fence and the math was easy; Kart Barrels were in stock and KKM were not.

Kart barrels barely short chambered and have fat chambers that do not always 100% clean up when finish reamed/chambered.
KKM short chambered and always comes out perfect!
Kart upper lug depth varies from barrel to barrel, KKM always the same.
Kart hood length can be too long on some slides meaning slide tolerances can affect final headspace dimensions. In other words headspace before finish reaming can be deeper/longer than match chamber. Fortunately 45 cartridge is very forgiving and will still shoot good.
On a SA RO I would use KKM 100% of the time. The SA RO tolerances are +side so KKM will always turn out better than a Kart (upper lug fit).
I prefer the KKM on 99% of old Colt builds. Colt’s tolerances we’re all over the place.
No one shoots good enough to tell the difference between a KKM vs Kart with lead or jacketed bullets. 
I use both KKM and Kart barrels, but use KKM 99% of the time. I favor the KKM because I have control of the entire fitting process. Kart is a crap shoot. 99% of the shooters out there wouldn’t know the difference, but as the gunsmith I do.
KKM is worth the wait.
So you might make your choice based on the base pistol.
Also I would never recommend the Kart Exact-Fit barrels in a BE pistol. Not enough upper lug engagement. Yeah they will group from a RR but will eat you alive shooting from hand.
My more than 2 cents.
Jon

I installed a KKM barrel in a 9mm I built and put lead through it. It was a great barrel in my opinion and once installed I sent it back and they chambered it for me at no extra cost. If I ever have to re-barrel any of my 45s I'll use a KKM.

Jon Eulette wrote:
...
KKM is worth the wait.
...
Jon

How long?

They’re running 8 weeks right now.
Jon

I have a kkm barrel in my latest 45 and shoot jacketed zeros at 50 and GASP lead bullets at 25...ive never felt I've lost points because of it.  Other factors cause point loss...

Better for jacketed or lead is generally based on overall comments and opinions for a number of barrels, builds, and reports over years from both gunsmiths and users.  For example, barrel X is better than lead, but then again that doesn't include a run quite a few years ago that really wouldn't group with either or that run of barrel y that was super tight.   It can be somewhat variable on an individual basis.  

Next, I generally listen to the gunsmith for the initial build.  I tell them my plans for that gun and listen to their response. They have an opinion for a reason and they can be different from gunsmith to gunsmith.  Each one has their on way of doing the build and their own opinions of their suppliers and that factors into the equation as well.     

Pursuing testing to determine probability of barrel X being some "delta" better better at y distance with bullet a versus bullet b is probably a long path to a lot of data with a multitude of variables (barrel, gun build, loads, bullet type, etc.) 

But, after getting the build / rebuilt gun, I've always listened to the gun.  Tried each new barrel / build out with known good loads (lead and jacketed) and let each barrel and build tell me what it wanted to shoot better.  You really should listen to what the gun wants no matter what the name is on the barrel.  

Most of the time its worked out as per the builders recommendations.  But one gun I had built with a barrel specifically recommended for "lead" turned out to be an absolute tack driver for jacked and just really good with lead.  You never know. 

There is one caveat to the above that's really important.  

No matter what the absolute difference in test groups was for each well built gun with the loads it preferred, all the points I ever lost were my fault.  

CR

Jon Eulette wrote:They’re running 8 weeks right now.
Jon

And Bar-Sto is running 10-12.  They're who I am going to for my next barrel, probably to replace the Kart that is in my wad gun.  KC says it wasn't chambered or fit correctly, but it would still group pretty well (solid 9-ring, maybe 10).  He throated and re-fit a new slide lock, so we'll see how much better it is.  There's little doubt it will outshoot me.

FYI KKM product page for 5".45 gov barrel says they are not taking 1911/2011 barrel orders at all until April 2022. 

Having lived through the last two years, I presume in April they will update it to say June or July.

Merick wrote:FYI KKM product page for 5".45 gov barrel says they are not taking 1911/2011 barrel orders at all until April 2022. 

Having lived through the last two years, I presume in April they will update it to say June or July.

I ordered a FoMoCo Maverick. I know the feeling.

Nothing negative to say about Kart, BUT my customer service experience with KKM has been awesome over the last decade, have bought a dozen or so different barrels and they have done a lot of unusual stuff for me, willing to take the time to patiently discuss things with me and and never in a huge hurry to get me off the phone which seems to be the norm these days. They have my business for life. And they they are built like spaceship parts, dimensionally perfect.

Kart:  I'm not familiar with their gunsmith barrels, but I installed a couple of the "Easy-Fit" that were the predecessor to the "Exact-Fit." One was in a wad gun and off the bench I could get 10 shots in two inches at 50 yards.  One time I shot 10 into 1.75 inches, testing some Nosler ammo that Neil Kravits had built.  Dave Salyer tested just the barrel and got just under 1 inch at 50 yards for some of my ammo.  After he re-bushinged the gun, I shot 100-98-100 for the Center Fire Slow Fire targets in the next match.  The other Kart E-F barrel went into my ball gun and I never really tested it, but it took me into the 280's for EIC matches.

KKM:  My only experience with KKM was with a stock Beretta 92FS.  I did put a trigger stop in the gun, but otherwise it was factory.  It would hold the ten ring at 25 yards, but not the repair center at 50 yards.  I bought a drop-in KKM barrel and it started holding the ten ring at 50 yards.  But, that was with a gun that hadn't been fired much and since it was not accurized, I didn't expect it to stay tight in the long run.

Jon Eulette wrote:Also I would never recommend the Kart Exact-Fit barrels in a BE pistol. Not enough upper lug engagement. Yeah they will group from a RR but will eat you alive shooting from hand.
My more than 2 cents.
Jon

Jon...so full/proper upper lug engagement helps keep the barrel locked as it begins to move backwards (before unlocking), and that friction/drag helps dampen recoil? I was thinking about also trying the next longer link. As I understand it, a link that is too long could cause excessive wear on the lugs. I'm trying to learn 1911 "mechanics" with a SA RO 9mm "project" gun. Lots to learn!

I can't answer the question directly, but I can add a little bit of data. David Sams built me a wadgun back in 2020, and I had him rebuild/rebarrel a very special pistol who belonged to a mentor of mine. In both cases, David used Kart barrels. He tests with Atlanta Arms load that the AMU uses, 10 shots per target. The first one on the new build he measured out, the second one on the rebuild is a little bit better than the first. 



There is no reason to believe that a lead bullet won't do well in either of these guns, once sprung to the load, etc. I haven't asked, but it wouldn't surprise me if David tests his barrels first and selects the top cut for his builds. He does manufacture a barrel tester, so would be weird if he didn't use one.

I do use jacketed bullets in the new build, and lead bullets in the other. I am not limited by equipment. Can you get a bad barrel? Maybe. It's more likely that the failure mode in this particular scenario, regardless of jacketed or lead, is having the barrel improperly mounted. After all, if the barrel is in like poo, then no amount of good barrel or ammo will make it shoot better.

My two cents.

-Chase

tovaert wrote:

Jon Eulette wrote:Also I would never recommend the Kart Exact-Fit barrels in a BE pistol. Not enough upper lug engagement. Yeah they will group from a RR but will eat you alive shooting from hand.
My more than 2 cents.
Jon

Jon...so full/proper upper lug engagement helps keep the barrel locked as it begins to move backwards (before unlocking), and that friction/drag helps dampen recoil? I was thinking about also trying the next longer link. As I understand it, a link that is too long could cause excessive wear on the lugs. I'm trying to learn 1911 "mechanics" with a SA RO 9mm "project" gun. Lots to learn!

In my experience deeper upper lug engagement along with maximum bottom lug engagement will reduce felt recoil. Link length “should” be determined by barrel fit. The proper length is dependent upon this. Arbitrarily using a longer link to just use a longer link is counterproductive. It will affect timing of both going into and out of battery. On loose poorly fit barrels it was common to use a longer link to get “link lock up” which is minimal in comparison to actual barrel lug engagement. That same longer link could actually be the correct link length for a properly fit barrel. Many details to consider when fitting a barrel. The receiver, the slide, the bushing and the link all play a role in the fitting process. I just saw a $5k+ pistol that the upper lugs were not fit, the hood had end-shake and excessive hood side cuts, and the slide stop pin was not contacting the bottom barrel lugs. But it was purty! Guns owner said it kicked like a mule when I asked him. I wasn’t surprised. Also told me 50 yds couldn’t call his shots. Also not surprised.
I don’t take barrel fitting lightly. It is an art and their aren’t many artists.
Jon

In my mind the link is there to pull the barrel down out of battery, not much more. The lower link lug legs controll vertical lockup.

Where most gunsmiths screw the pooch is by using a link that is too short. Barrel needs to ride the link to just before going back into battery ( hitting the flats on the lug). Otherwise you get battered barrel lugs and slide stop pin. See it all the time. Even on $5k pistols.
So link has two missions!
Jon