Bore Scope Chamber Questions

[CMP70306]

Good Evening Everyone,

I recently got a bore scope and a new 6.5 PRC barrel, since I toasted my first PRC barrel in 1100 rounds I decided to take some before pictures so I could compare the wear later down the road.

However when I went to take the pictures something seemed off with the lands and grooves.

So I decided to back out at take a picture of the whole lead.

Now this is the first new barrel I’ve bore scoped but something doesn’t look right with this chamber. I would have expected it to be more uniform and I’m confused as to how the reamer can cut the grooves but not the lands right next to it. Any ideas as to what is going on here?

 

[AleksanderSuave]

Im just here for the inevitable comments that will be coming soon, telling you to throw out your bore scope and how someone has had a barrel that looks like absolute dog shit inside, and shot "lights out".

 

[Supersubes]

Good Evening Everyone,

I recently got a bore scope and a new 6.5 PRC barrel, since I toasted my first PRC barrel in 1100 rounds I decided to take some before pictures so I could compare the wear later down the road.

However when I went to take the pictures something seemed off with the lands and grooves.
View attachment 7789317View attachment 7789318

So I decided to back out at take a picture of the whole lead.

View attachment 7789319
View attachment 7789322
Now this is the first new barrel I’ve bore scoped but something doesn’t look right with this chamber. I would have expected it to be more uniform and I’m confused as to how the reamer can cut the grooves but not the lands right next to it. Any ideas as to what is going on here?

This is super simple, you just have to think spacially. The lands are tall, and the reamer is tapered at the lead, so the cut “reaches” further down the bore on the lands. The more interesting thing is the radius of the groove doesn't match the radius of the cut. The groove radius is larger. In relation to the reamer longitudinal axis, the center of the groove is closer than the edges are. What you're looking at is normal. The cut overall is a little off axis, but its very difficult to say whether its bore geometry or the gunsmithing work.


Cut rifled barrel?

 

[CMP70306]

This is super simple, you just have to think spacially. The lands are tall, and the reamer is tapered at the lead, so the cut “reaches” further down the bore on the lands. The more interesting thing is the radius of the groove doesn't match the radius of the cut. The groove radius is larger. In relation to the reamer longitudinal axis, the center of the groove is closer than the edges are. What you're looking at is normal. The cut overall is a little off axis, but its very difficult to say whether its bore geometry or the gunsmithing work.


Cut rifled barrel?

The barrel is button rifled.

Also I understand the lands should be cut farther down the barrel due to the taper in the reamer. What I was referring too was in the first picture where it looks like only part of the grooves are cut and there is an uncut spot between the land and the cut in the groove.

In the second picture the cut in the groove blends right into the lands at the same place on both sides which is what I would expect for a symmetrical cut.

 

[CMP70306]

So after shooting the new barrel a few times I noticed that I get these marks on the shoulder.

Looks to me like the reamer is getting worn and scratched the chamber shoulder.

Honestly out of the several prefits they have done I have not been thrilled with any of them. They pressure out significantly lower and slower than any of the proof barrels I’ve used and 2 of the 3 have had chamber issues, one of which was so bad it needed to be rechambered to a larger cartridge to get the marks out.

At this point I’m debating if it’s worth sending it back or to a different smith to rechamber it.

 

[JBoomhauer]

That’s not good. Out of curiosity what’s the shoulder in the chamber look like with the borescope.

 

[wadebrown]

Ouch! Send it back and maybe ask that they get that reamer sharpened (requalified), or better yet a new reamer.

 

[Steel head]

Years ago I had a prefit that ringed the shoulder a bit but it was far milder that that

That’s pretty bad.

 

[b6graham]

that barrel is shit.

send it back, on their dime, and get a new one

 

[Steel head]

that barrel is shit.

send it back, on their dime, and get a new one

Kinda shocking it got out the door!