Accuracy Trouble Shooting and Barrel Wear Pattern

[jwhittin]

All,

I hope everyone had a great Thanksgiving break!

 

I have an open gun with only about 3K rounds on it.  I checked the accuracy and did an inspection and would like to get some feedback. I did bench testing with 6 different loads at 20 yards and shot multiple groups with each load.  I’m getting random outliers from 2” to as much as 5” from the main group. I’m certain they are not due to me.  I also see varying group sizes using the same ammo (e.g., 1.5”, 1.6”, then 3” or more). And this happened 4 out of 6 times. 

 

I did an inspection and found uneven barrel wear patterns on the lower lugs (see photo). The top lugs look fine but the lower lugs have uneven wear (nitride is worn off one lug but not the other lug).  There are also a couple small dings on the outer edge of one of the lugs and I also found the barrel link is elongated by about 0.002”. 

 

The manufacturer no longer makes open guns but will repair at cost and do warranty if they deem it’s covered.  I am planning to send it back, but the initial feedback from the manufacturer was that it looks like normal wear.  This doesn’t seem like normal barrel wear to me.  I would appreciate your observations and thoughts.

Thanks!

[schaet]

That is not normal wear by any stretch on the imagination. The wear should be even across both lugs. Also on the non-wear side (as you mentioned) there looks to be an impact of some sort on the lower lug (it looks like a divot), wearing on the link an on the bottom of the ramp. This is concerning. 

 

As for the "elongation" if it is on the hole where the slide stop goes through; this is ok. 

 

Overall I'd venture to say (without seeing the whole gun) that the barrel is not fit correctly. (disclaimer: I am not pooping on someone else's work, just pointing out what I see as issues and remedy) 

 

I'd say start there. There are many other attributes that will affect accuracy (extractor, barrel fit to the slide, breech face ... ), but to start there are issues here to be addressed. 

 

[zzt]

That is not normal barrel wear.  An improperly fit hood can case that, and the dinging on the unworn side.  Alternately, the barrel was not perfectly centered in the slide or the jig when the bottom lugs were cut.  Maybe both are problems.  I would send the gun back and see what they say.  Warranty repair.

[schaet]

Looking at this even more analytically .. the wear/damage on the one side (non wear lug) is most likely caused from the barrel lug being too high on the wear (top) side causing the barrel to roll/twist to the opposite side; hence causing the wear marks on that side.

[jwhittin]

Thanks for the input.  Based on what I see, I also concluded the barrel was not installed properly.

 

I will continue working with the manufacturer and hopefully they will come around after they physically inspect the gun.  I don't know why they would say it was normal wear.  Maybe trying to lower my expectations...

 

[Kilrb]

1 hour ago, jwhittin said:

Thanks for the input.  Based on what I see, I also concluded the barrel was not installed properly.

 

I will continue working with the manufacturer and hopefully they will come around after they physically inspect the gun.  I don't know why they would say it was normal wear.  Maybe trying to lower my expectations...

 

Looks like this is why they aren't building Open Guns any longer. Don't think I would want them to touch this if they think this is normal. I would want full reimbursement or pay for repairs from a reputable shop.

[yigal]

8 hours ago, jwhittin said:

Thanks for the input.  Based on what I see, I also concluded the barrel was not installed properly.

 

I will continue working with the manufacturer and hopefully they will come around after they physically inspect the gun.  I don't know why they would say it was normal wear.  Maybe trying to lower my expectations...

 

Probably this is normal  for their professional level. Reminds me of similar things from the past.

[MikeBurgess]

As above the barrel is not fit very well, also the ding on the non worn side is likely from someone trying to insert the slide stop pin with the barrel not aligned properly. 

 

That said, a likely cause for flyers in an open gun is comp strikes, these are much harder to see in the comp than most people think, take a super close look at the comp and if you can see any differences in the look of the holes through the baffles its likely brushing the edge of a bullet every once in a while. 

 

 

 

[schaet]

Yes, the comp, forgot it was an open gun. The comp should of been bored aligned to prevent this. Judging by the other issues I'm going with what Mike suggested as an additional potential issue. 

[zzt]

3 hours ago, schaet said:

The comp should of been bored aligned to prevent this.

 

That doesn't help if the comp threads are loose.  If they are the odds on getting it clocked and aligned the same way are long.

[jwhittin]

It’s an integrated comp but I’ll check. 
 

I sent them new pics and I asked them to re-evaluate there initial assessment.   They sent me an RMA no questions asked.  

[konkapot]

Nobody ever comes BACK once it's been resolved. Please let us know how the story ends. 

[zombywoof]

Send it back to STI

 

They've been very good to me on warranty issues

[davsco]

10 minutes ago, zombywoof said:

Send it back to STI

 

They've been very good to me on warranty issues

ditto here (assuming the OP's gun is STI).  my dvc open was having hammer follow issues.  the first time, whatever they did (i think played with sear spring), didn't work for long.  but the 2nd time they changed out all the fcg and it's been working fine in the handful of matches since.

[jwhittin]

I'm packing it up now to send it back.  I'll post updates.  I don't have a backup so will be running COs in the meanwhile. 

[jwhittin]

Hi All,

 

Here is an update as promised! 

 

I spoke to the manufacturer today (yes STI).  They had to order more 9 major ammo before the Holidays to test my gun and apologized for the delay.  The Smith did acknowledge the uneven lower lug wear pattern as a concern. He checked the lockup and said it was still in factory spec.   He mentioned the wear pattern favoring a side can be more pronounced due to rotational forces (from barrel twist).  I’ve never heard that but yes, there will be rotational forces.  I will have to think about that some more. 

 

As far as the elongated barrel link, he explained that sometimes they intentionally elongate a  link hole a small amount to fine tune the lockup.  It has a #4.5 link and I measured a 0.002” elongation in the slide stop hole. 

 

He also noted that the slide stop has some unusual wear that could explain the degraded accuracy.  The stop had some areas that were flattened so he replaced the side stop with their new more durable part. I suspect it might have a slightly larger diameter too.

 

Bottom Line:  He said what he found doesn’t meet their threshold for a complete barrel replacement. 

 

WORK COMPLETED

Replaced the slide stop with new, more durable slide stop

Inspected pistol and checked barrel lockup - Was still within factory spec.

Test Fired 4 groups of 3 shots each at 20 yards.  All groups measured less than 0.5" center to center and there were no fliers.

 

It’s already on the way back.  I will check the accuracy and see what I find.  I know they have their process to follow.

 

I’m really glad they stand behind their products!  

 

 

Edited January 24, 2023 by jwhittin

[Superkaratemonkeyfighter]

[jwhittin]

I checked the accuracy and I'm getting about 0.5 to 1." at 15 yrds. So far it looks good.  I noticed the wear on the slide stop but didn't think it was enough to cause an issue.  I will keep checking it from time to time.  Hope it lasts.

[sharko]

While that wear was certainly suspect you might also want to check the chamber, throat specifically, to see if it's cut evenly.

[CHA-LEE]

“Rotational Forces” the root cause of unevenly cut lower lugs? Rotational force exists while the bullet is traveling down the rifling but is mostly gone before the slide even starts to move back. So the whole ware surface on one side of the lower lugs getting exclusively worn due to “Rotational Forces” is BS. It’s odd that they wouldn’t own up to cutting the lower lugs wrong. 
 

If it’s only locking up on one lower lug then the duration of the lockup quality (rounds fired) will be half of what it should be. The lockup tightness may be In Spec now, but how long that will last is TBD.

 

 

[jwhittin]

Thanks Charlie. I wasn’t buying the torque tale. Yes it is very disappointing. Was tempted to have the lug laser welded and refit it myself.  I suspect it won’t take long for the issue to reappear. Maybe at that point they will address it properly.  

[ltdmstr]

Pretty much everything they told you is B.S.  Not sure if they actually believe all that, or just like to make stuff up to avoid warranty repairs.  But, bottom line is, the gun wasn't built correctly.  Either they don't know how to do it, or just don't care.  Pretty sad that even with the rebranding and various other changes, they still suck.

[mrvip27]

I would be upset with what that gunsmith told you!

[shred]

The barrel torques rotationally as the bullet engages the rifling.  If there's play in the system (loose hood/lower lugs/etc), it can roll some amount.  A tighter slide stop should improve things in that regard although I'd look at the hood fit too.

  

[jwhittin]

I understand that.  Clearly the one lug was not cut properly when it was installed and they should have corrected it.  Instead they decided to put a Band-Aid on it.  Thanks