Barrel the culprit

[John-ny]

So today I shot a steels match after shooting a gssf match yesterday.  Had alot of accuracy issues to the point one of the club members asked to shoot off the bench. And hits were a good 3 inches apart at 10 yards. The loads tested were factory boxed american eagle 147gn fmjfp. And handloads 147gn blue bullets with 3.2gn titegroup. Also tested montana gold 124gn hp, 4gn titegroup

Ae147gn chrono 913,914,908,891,918

Blue bullets chrono 872,872,878,875,878

Montana gold124hp 1079,1051,1006,1041,1038

Factory glock barrel had no issues.  With all 3 loads through the wilson combat barrel the groups were bigger then the factory glock gen4 g19

One old time said maybe the barrel isn't sized properly and its loose. So I just measured dimensions that are pictured below.  What's your thoughts. Cause I'm thinking about sending it back.

 

[Bkreutz]

Measuring the outside of the barrel is meaningless, you need the inside dimensions. There are different sizes of 9mm bullets, and there are different bore sizes. (I know, it sounds stupid) The two most common 9mm bullets are .355 and .356 inches, some people who shoot cast lead bullets size them to .357. If your Wilson fits tight in the gun when it's in battery, it's probably not the accuracy problem. Couple of things to check first. 1. make sure there is no buildup in the barrel (lead or copper), It's possible that your barrel is sizes to .356 and you're using .355 bullets. Only way to tell is measuring. Good luck.

[John-ny]

7 minutes ago, Bkreutz said:

Measuring the outside of the barrel is meaningless, you need the inside dimensions. There are different sizes of 9mm bullets, and there are different bore sizes. (I know, it sounds stupid) The two most common 9mm bullets are .355 and .356 inches, some people who shoot cast lead bullets size them to .357. If your Wilson fits tight in the gun when it's in battery, it's probably not the accuracy problem. Couple of things to check first. 1. make sure there is no buildup in the barrel (lead or copper), It's possible that your barrel is sizes to .356 and you're using .355 bullets. Only way to tell is measuring. Good luck.

I took all external measurements cause the old timer pressed on the rear of the barrel while the slide was forward and he noticed a little downward play where the factory barrel was tight.  

How would you suggest I measure the inside of the barrel. And yes. Montana gold and blue bullets are sized to .355 according to the boxes.  I think bayou are. 356 

[Talon75]

 

 

 

[Bkreutz]

You can "slug" the barrel. It's a material that you pour into the barrel (after plugging part of it. It hardens, gets removed, and then measured to see the size. If you look at Brownells or Midway, they have the materials (or they used to). As far as external measurements, it's hard to get accuracy with a drop in part. It should be fitted for maximum accuracy. There are machine tolerances on all pistols and they have to allow for this variation between parts. It's kind of a crap shoot when you buy a drop in part as to if it will fit and give you accuracy. Have you called Wilson and see what they say?

[John-ny]

4 hours ago, Bkreutz said:

You can "slug" the barrel. It's a material that you pour into the barrel (after plugging part of it. It hardens, gets removed, and then measured to see the size. If you look at Brownells or Midway, they have the materials (or they used to). As far as external measurements, it's hard to get accuracy with a drop in part. It should be fitted for maximum accuracy. There are machine tolerances on all pistols and they have to allow for this variation between parts. It's kind of a crap shoot when you buy a drop in part as to if it will fit and give you accuracy. Have you called Wilson and see what they say?

I have not called them yet. Wanted some opinions before I dialed in. 

[rooster]

The dimensions that matter are hood length,  hood width, and barrel lug height, that is measured from the top of hood to bottom of lug. Hood length in your drawing is from point c to end of hood.  Hood width is the part that fits into slide at the breach, and barell lug is measured from top of hood to bottom of lug.  Drop in barrels have to fit every slide and frame made for that model, so accuracy is minimal over factory.  The best barrel for improvement is a Barsto because you have to fit it to your frame and slide.  The next best way for accuracy improvement is load development.  Find a load that your barrel likes.

[John-ny]

22 minutes ago, rooster said:

The dimensions that matter are hood length,  hood width, and barrel lug height, that is measured from the top of hood to bottom of lug. Hood length in your drawing is from point c to end of hood.  Hood width is the part that fits into slide at the breach, and barell lug is measured from top of hood to bottom of lug.  Drop in barrels have to fit every slide and frame made for that model, so accuracy is minimal over factory.  The best barrel for improvement is a Barsto because you have to fit it to your frame and slide.  The next best way for accuracy improvement is load development.  Find a load that your barrel likes.

So the width should be measurement d in my drawing correct. And the lug measurement should be E if I understand correctly.  And I've been working on loads that's why I included the data. With multiple weights. The wilson is a 1:16 twist I believe which should have done better with the 124gn hp but still the factory glock barrel that is I believe a hair under 1:10 twist did better.

[rooster]

Hood width should be the measurement across the little “ears” at top of barrel that goes into slide.  Barrel lug should be measured from top of barell to bottom of barrel lug.