6mm Creedmoor issue

[243winxb]

Id suggest getting it cleaned really well and testing again.

Yes, a good cleaning with a brush may help.

 

[Starlite]

That's y I showed the measure of the bullet diameter and the neck diameter. Just so I could show I measured.

 

[Starlite]

Here is the bore.
not good quality.

 

[243winxb]

The middle one looks more normal COL to me.

 

[Starlite]

The middle one looks more normal COL to me.View attachment 242779

The left is 2.640 (Hornady manual)
Middle is 2.460 (bolt over distance)

 

[25WSM]

Are you measuring the coal with an ogive insert? That's about the only way to get those numbers on those cartridges. Coal that the manual shows is from tip of bullet to the base. Not base to ogive. A manual can't give you a measurement to the ogive because ogive measuring inserts are not a standard size between manufacturers. Even inserts from the same company can give you different lengths. Vld bullets will have a much longer coal when at touch than a standard bullet. In the pic above the cartridge in the middle looks about normal the one on the left would need about .350 freebore to chamber and wouldn't fit your mag box.
shep

 

[Starlite]

Are you measuring the coal with an ogive insert? That's about the only way to get those numbers on those cartridges. Coal that the manual shows is from tip of bullet to the base. Not base to ogive. A manual can't give you a measurement to the ogive because ogive measuring inserts are not a standard size between manufacturers. Even inserts from the same company can give you different lengths. Vld bullets will have a much longer coal when at touch than a standard bullet. In the pic above the cartridge in the middle looks about normal the one on the left would need about .350 freebore to chamber and wouldn't fit your mag box.
shep

See photos 3&4

 

[243winxb]

The tolerances on tne SAAMI chamber drawing & different brass trim lengths, will make a difference in this measurement. But may be close?

Length of throat in chamber.

 

[Starlite]

Another wired thing is the minimum COAL is 2.550 for the 6mmCM
I know the bore photos aren't all that clean but. Think it's a carbon issue.

 

[jebel]

Think it's a carbon issue.

I agree. The scrapes on the bullet do not look like lands engraving to me. There's something in the throat, likely carbon build up.

 

[dragon798]

I think there are 2 things going on here. First of all, if you check the diameter of the Berger bullets, I bet you find the are .0005" smaller. So the Hornady are probably. 243 and the Berger are probably. 2425. Secondly, I will almost guarantee you have carbon build-up in the throat. It may not actually be a ring yet, but I bet if you soak the throat area with carbon remover and brush it well, use stiff nylon not bronze brush, you will see a lot of carbon come out and your bullets will fit better in the chamber.

 

[dragon798]

One other thing. Spend the $50 and buy a Teslong bore scope on Amazon. You will be amazed.

 

[JAYgs8163]

Get a chamber mop and work/soak that chamber with some good quality solvent. You must have a carbon build up. Did it chamber these type rounds before? Also, have you tried chambering the Berger rounds again and see if they continue to chamber ok?

 

[Creedmoor shooter]

I had the same issue. Same marks on the projectiles. Mine was a carbon ring