38 Super Bullet Diameter

Currently fitting a Kart 38 Super barrel to a Colt Competition 1911 9mm pistol. Kart said this barrel has the same internal dimensions as their 9 mm barrels.  

My question is what diameter bullets should I use?  .355 vs .356 jacketed.  The bigger question is with lead bullets. I would think .356 for 9mm and .357 for 38 super, but the barrel is the same. 

I read the forum regularly, but based on the difficulty making this post I don’t post very often. 
Thanks

Rush

For lead bullets .357". I switched my KART 1x16 barrel for a KKM 1x10 shooting 145gr bullets. Much more accurate.

Bill

I’m using .358 Brazos 150’s with 3.5 BE.

The 38 Super and 9mm both have the exact same SAAMI barrel specifications of groove diameter .355" + .004.  So, you should expect them to be the same whoever makes them - that is, within the same range as specified by SAAMI.

Your gun will tell you what it likes.

Here's a source for 38 Super data: https://www.shootingtimes.com/editorial/super-accurate-38-super-loads/326242

SAAMI specs: https://saami.org/wp-content/uploads/2023/02/SAAMI-Z299.3-2022-Centerfire-Pistol-Revolver-Approved-12-13-2022.pdf

we ran the old 126gr dardus(now gone) in .356 in both Kart and KKM barrels with very good results.

In my 38 super, I have a KKM 1-10 twist and I shoot the 150g Brazos in .357 with 2.8g BE.

Michael C wrote:In my 38 super, I have a KKM 1-10 twist and I shoot the 150g Brazos in .357 with 2.8g BE.

 
I have the same barrel and tried all of the Brazos bullets. The best one I have found is the flat nose. The best bullet by far I have used is the GT 145gr RNHP.

https://www.gtbullets.com/index.php?main_page=popup_image&pID=3

Bill

messenger wrote:

Michael C wrote:In my 38 super, I have a KKM 1-10 twist and I shoot the 150g Brazos in .357 with 2.8g BE.

 
I have the same barrel and tried all of the Brazos bullets. The best one I have found is the flat nose. The best bullet by far I have used is the GT 145gr RNHP.

https://www.gtbullets.com/index.php?main_page=popup_image&pID=3

Bill

Bill,
Those look like nice bullets. I just looked up the hardness and they’re on the soft side. Have you loaded/chambered and ejected and looked at HP nose for deformity from feeding/chambering? Just curious. I will have to try some.
Jon

Bill, 
Forgot to ask what diameter you’re using? KKM is 0.355” bore.
Jon

With the demise of the Dardus 126gr TC bullet, I reached out to our local N GA caster, The Cast Bullet Shop, to see if they would be able to get a mold made to recreate the bullet. They did, though these drop a little heavy at 128 using their alloy.

Tony hasn't put them on his website yet, but if you are interested, send him an email. I think they are just as good as Dardus. He'll size them to whatever you say- I have liked these in .357", though .356" is the typical size.

Jon Eulette wrote:

messenger wrote:

Michael C wrote:In my 38 super, I have a KKM 1-10 twist and I shoot the 150g Brazos in .357 with 2.8g BE.

 
I have the same barrel and tried all of the Brazos bullets. The best one I have found is the flat nose. The best bullet by far I have used is the GT 145gr RNHP.

https://www.gtbullets.com/index.php?main_page=popup_image&pID=3

Bill

Bill,
Those look like nice bullets. I just looked up the hardness and they’re on the soft side. Have you loaded/chambered and ejected and looked at HP nose for deformity from feeding/chambering? Just curious. I will have to try some.
Jon

Never had a feeding problem. Never hand ejected a round to check. I posted a picture of a five round group @ 50yds a few months ago that you could cover with a quarter and got quite a few comments that it wasn't enough rounds for a true accuracy test. Maybe so but when I am testing 20 different load combinations it saves a little time. I used a Lyman M expanding die, a Redding taper crimp die. COL of 1.45", Crimp of.377" and 3.0gr WST. Hope this helps.

Jon Eulette wrote:Bill, 
Forgot to ask what diameter you’re using? KKM is 0.355” bore.
Jon

 I am using .357". I know this sounds big but they work great.

Bill

I have had some on order from GT for a while. They are about three months behind. I placed my order May 27th. Tomorrow will be three months. They charged my credit card the day I ordered. 

Bill

Jon,

Like I previously stated GT is three months behind. I however have a pretty good stock. I have both .356" and .357" diameter bullets. I can send you 100 of each if you want to do some testing.

Bill

Bill,
That’s very generous, how about 50 of each? Thank you. I once bought from GT Bullets several years ago and it was a several month wait. 
Jon

Jon Eulette wrote:Bill,
That’s very generous, how about 50 of each? Thank you. I once bought from GT Bullets several years ago and it was a several month wait. 
Jon

Let me know where to send them.

Bill

PM Sent

messenger wrote:

Jon Eulette wrote:Bill, 
Forgot to ask what diameter you’re using? KKM is 0.355” bore.
Jon

 I am using .357". I know this sounds big but they work great.

Bill

Just ordered the GT bullets in .357 for my 38 Super. Also ordered some in .358 which will work in 38 Special and may work in the 38 Super. 

Thanks for the input. 

Rush