Recoil Spring and Vertical Stringing?

I was doing some load development today from the bench at 50 yards. I was using 180 SWC and WST. I had a 10# spring in from a prior session with 160s.

Shooting 3.5 and 4.0 of WST, the stouter charge made several groups that were 2 1/2 wide but 7 inches vertical. The 3.5 was much rounder. I even had a fluke group that had 7 rounds touching. I forgot to bring my spring pack with me to see what effect a 12 or 14 might have.

Was the 10# spring the cause of the 4.0 groups vertical stringing?

Short answer...YES. A friend of mine just went thru the same thing a couple of weeks ago.

Most 1911’s if the bottom barrel lugs are not fit well, will vertical string with lighter recoil springs. They rely on the recoil spring to keep them in battery. Not really what you want but unfortunately it’s a common reality. Bottom lugs are supposed to bear on slide stop pin.
Jon

Jon Eulette wrote:Most 1911’s if the bottom barrel lugs are not fit well, will vertical string with lighter recoil springs. They rely on the recoil spring to keep them in battery. Not really what you want but unfortunately it’s a common reality. Bottom lugs are supposed to bear on slide stop pin.
Jon

It is a fairly low use Clark with a tuner. I adjusted the tuner to just kiss the barrel, as opposed to having the tuner be the limiting factor in lockup and slide travel. I received it with both the sight and tuner loose. I wonder if that is the reason the prior owner got rid of it.

Most older Clark's will come out of battery in 0.010-0.015” in my experience. I just rebarreled a Clark that was 0.075” when I was finished. Yes it makes a difference. Also affects recoil; less lockup equals more felt recoil.
Jon