MAJOR Savage 11 6.5 Creedmoor Problem: HELP NEEDED

[md7989]

Good morning guys, this is my first post here and it's a bit of one at that. Have read many threads on here but decided to join to maybe get some more opinions on this subject. I posted it on the ar15 precision rifle forum as well...here it goes:

I went to shoot my Savage 11 6.5 Creedmoor this past weekend since I recently installed a B&C M40 stock and PT&G bottom metal. The gun ran great and shot great for the first 24 rounds. I shot 20 rounds of factory 140 gr AMAX (4, 5 shot groups) then switched over to the factory 120 gr AMAX. Shots 21-24 of the day (1-4 of the 120s) produced a 0.46" group, better than the 0.61" I got with the 140s

Then trouble struck...

I went to chamber the 25th shot of the day (5th 120 gr) and it would not chamber the round. The bolt is like an 1/8" shy of going forward enough to close. So I brought it home and looked in the chamber, and all appears clear with no obvious obstructions. The bolt face is clean and debris free. I then measured my chamber length using a modified case and a 140 gr AMAX and that's when things got really strange...

Before shooting this gun, the chamber length when using the modified case and a 140 AMAX was 2.2155" to the ogive (using comparator). NOW it is only 2.049" to the ogive using the same modified case and same 140 AMAX.

I HAVE LOST 0.1675" OF CHAMBER LENGTH!?!?!

I have checked everything multiple times, cleaned the gun, made sure nothing is obstructing anything and it's still the same. I even took it out of the action and made sure my barrel it isn't loose, and everything is tight as it should be so I do not believe headspace has changed but rather some obstruction/burrs/buildup is present. The gun cycles fine and bolts closed without any ammo present. The gun only has 49 rounds through it for its entire life and every round chambered as smooth as the other. This hit all of a sudden.

DAY 2 UPDATE: After reading many suggestions from the other forum thread, I cleaned the gun very well and regained the chamber length that I had before this issue arose. But now I am getting scarring and marring on the bullets. And let me clarify...I was getting the scarring/marring before the thorough cleaning took place that helped get back the length, so I know I did not "burr it up" with my cleaning. When I chamber a factory 120 gr AMAX, it makes a scar/scratch down the length of the bullet from just under the polymer tip to right before the case starts. When I load a factory 140 gr AMAX, I get marring on the leade area of the bullet and the bolt is hard to close with noticeable resistance on closing and opening the bolt. The bolt cycles fine with no ammo present and also cycles fine when using a spent piece of brass I previously fired. It's almost like some type of buildup is there around the leade area that I can't get out but it only developed in those 4 shots with the 120s.

Below are some pics. The first pic shows how the bullets were looking right when it happened before I cleaned and regained my chamber length with the one on the left and middle being 140 gr and the right being 120 gr. The second pic shows the 120 gr after I cleaned and how they're being scratched up. The third pic is of the 24 pieces of brass fired this range trip, all of which look fine. And the bullet I used when measuring chamber length with the modified case also got some marring on the leade area, although not as much likely due to be being more gentle inserting it with the overall length gauge vs. the bolt twisting and inserting it with a legit round of ammo.

Anyone have any idea what happened? This is very baffling to me. I have a borescope arriving in the mail this afternoon and will be peeking inside the bore for a better look. The barrel seems great to shoot a 0.46" group...but something odd is going on or did go on with those 120 gr AMAXs. Your help is much appreciated.

-Mike