RR Test with KKM 1X10 38 Super Barrel

In looking for a CF pistol with lower recoil to give my arthritis a break I had my friend build me a 38 Super. It had a Kart 1X16 barrel. Shooting the Dardus 125gr SWC I had decent results but nothing to right home about. I bought a KKM 1X10 barrel to give it a try. I played with different loads and bullets until I felt I had something decent. I made up 20 five round loads using two powder weights, two seating depths, and three different crimps from two different dies. ( Redding & Lee ) The best load was new StarLine brass, Winchester primers, 3.0gr WST, 1.244 Col, .377 crimp from the Redding profile crimp die. The bullet was the 145gr LHP from GT bullet company. Unfortunately when setting up my Labradar Chrono the batteries lasted about two minutes.

25 yd?

james r chapman wrote:25 yd?

 Nope, 50yd.

Bill

Shoot 5 more. If you get 10 close to that grouping, that's a hell of a gun.

Dave

messenger wrote:

james r chapman wrote:25 yd?

 Nope, 50yd.

Bill

Excellent!

Just by going up 1/10gr it opened up a bit. The crimp made the biggest difference. This was .377". .375" would open it up to 2"-2.5".

5 shots is not enough to make an accurate assessment of accuracy. Here's why:

https://www.ssusa.org/articles/2019/9/25/accuracy-testing-shortcomings-of-the-five-shot-group/

Here's a followup article:

https://www.ssusa.org/articles/2021/2/17/accuracy-testing-how-many-shots-in-the-group

5 shot groups are a screening exercise.  Statistically, 15 shots are better.  Fortunately, for pistols 15 shot groups can be done more easily than in rifles.  What you want to get is a 15 shot group at 25 yards to be a nice round blob.  See James Chapmans picture for an example in this thread https://www.bullseyeforum.net/t19944-loss-of-accuracy-between-25-and-50-yards-diagnostics#172971….

When your 25 yards group like that test at 50.  Too many will shoot a 5 shot group, all in the x from one side to the other of the x and think they have a group.  Then at 50 they’re going from 9 ring to 9 ring.

It way I'd look at it is the small count group pictured above failed to disprove its accuracy.

Often times if I am trying something it will not work immediately.  If the first 5 shots are big as the repair center, there is no point firing another two boxes to see if it actually makes an acceptable distribution around the center.

Please update this thread with your findings. I am interested and have been considering a 38 Super build for a few years.