In-accurate autoloader. How to fix it?

Today I got out my P9 Ultra. This is an older Springfield clone of the CZ75 in 40S&W. I have had the gun since the middle 90's and I have shot it just shy of 9000 times. I remember the gun being accurate when it was new, but maybe my standards are changing. Today, at 15 yrds, I was putting up 6" 50 shot patterns. At the same time I was shooting 1" 50 shot groups with my 610 and 1" 50 shot groups with my 41's so I don't see operator error.

I tried many different reloads and a bit of factory ammo. All was this way. It does not seem to matter if the bullets are light or heavy, fast or slow, it is just a pattern.

I just got done scrubbing the tar out of the gun. It is as clean as I have ever seen it. Most of the gunk was from the AA5 reloads I was shooting which got everywhere.

Looking at the barrel, the crown is not the best, but I don't see any particular nicks or anything. I do see that some of the rifling is missing little bits toward the end of the barrel. Not much but enough that you see it. The gun is ported (at the factory) and you can see the effect of the porting has pulled some of the rifling off. Also looking down the barrel you see a fair amount of tool marks and scraps in the barrel. The odd thing is that some seem to go straight toward the front of the barrel and not follow the rifling. I figured if I had did it, the marks would follow the rifling around but not straight. It is definitely not the mirror finish of one of my Les Baer's.

In the slide, the barrel locks up so so. You can rock it front to back when you have the barrel fully engaged in the slide lugs. When you put the barrel into the frame with the slide lock it is pretty loose in the link down lug.

I have a Briley fitted barrel put into it right now. I had them put a barrel in it a few years back because it was not that accurate but I never shot it much. I just went back to the ported barrel because my wife likes to shoot the ported barrel. The Briley is tight in the frame and link down lug and tight in the slide and the crown looks good. Also the Briley barrel looks pretty close to a mirror in it with just a few marks in the bottom of the rifling.

My current thought is this barrel is just shot out and worn out. I should give up on the original Springfield barrel and shoot the Briley.

Opinions? Thoughts Suggestions?

I honestly don't remember. I had it done about a decade ago when I heard that briley was going to stop doing P9 barrels. So I had them fit it and then I packed the barrel away and did not think about it for a long time.

I will take it out next weekend and try the other barrel.

The problem though is I would like to try and figure out what makes my current setup "not worK". I am trying to understand why this barrel and pistol combination is not accurate.

I looked at the crown under a magnify glass and it looks very clean. I could not find any dings or wear on it that would indicate improper cleaning was the cause. Looking at the chamber end I did not see any problems either that would indicate the cleaning was the problem over the years.

When I said I scrubbed the tar out of the gun, I was referring to cleaning and cleaning it to make sure that it was properly cleaned and nothing was left in the barrel.

Thinking about it, I think the answers along the lines of just plain loose fit are the likely cause. The Briley is fit "tight" and is actually difficult to put in the slide and the slide on the frame. It has to be done just so and it will work otherwise no go. The springfield barrel just slides on no matter what.

I will try to test the Briley barrel tomorrow and see how it odes. It all depends on the rain here though.

I measured the link down lug when I was putting it in and found it was 8 thousands thicker then the springfield. I did not measure the barrel but the lugs on the top of the barrel are tight. It does not have any movement when you grab the front of the briley barrel.