Confused!!

[4xforfun]

Shooting friend had a 300WSM rifle built a couple of years ago. I had a brand new .334 Reamer that he wanted to use. When the gun came back it was obvious that the reamer was wrong. There was almost zero freebore and the 215 was WAYYYY deep in the case. like SAMI deep He shot it for a year or so and found a good load @59.7 H4350 and a 215 Hybrid. Last year I got back into comp and had my smith chamber up my HG with that same reamer and simply run a throating reamer in for the desired free bore using a couple of dummy rounds. He also ran a throating reamer in my buddies tube using the same dummy rounds.

Results are on record for my HG, but his went to hell. Still shoots good, but now shows BIG psi. Primers flat and cratered and very hard extraction.

Backed off to 59.0.......no help...same.
Triple checked neck clearance...... .3306
Checked head space......less than .002.
Checked scale....spot on.
Took his bolt apart and made sure it was lubed in all the right places.
Made sure his chamber was dry.



Just grabbed a new piece of neck turned WSM brass that I had laying around for my comp gun...... loaded to 57 H4350. Flat , cratered primer and hard to open bolt.

What am I missing?

Go!!!

Tod

 

[gunsandgunsmithing]

Carbon ring in ....3....2....1

 

[shoot4fun]

I have felt the same way after having a used 6 Dasher barrel recut to 6 Creedmoor. The barrel had probably 800 or more down it and showed some cracking and throat erosion but, after studying the differences between the Dasher and Creedmoor, we decided it would all clean up and leave a fresh throat. The job went smoothly and I screwed it back onto my BAT B for testing. I loaded a known good load that had never shown pressure signs in any other 6 Creedmoor we put it thru but immediately began blowing out primers in this barrel. Closer inspection showed there was still some roughness left in the new throat so we cut off the tenon and did it again to see if that changed anything. All was well with it afterward.
So, likely there is some roughness in there now on your buddy's throat that is causing pressures to be excessive.

 

[shoot4fun]

BTW, I tried using some JB Bore Brite to really polish out the throat but it made no difference. It had to be cut off the length of the tenon and redone.

 

[gunsandgunsmithing]

I have felt the same way after having a used 6 Dasher barrel recut to 6 Creedmoor. The barrel had probably 800 or more down it and showed some cracking and throat erosion but, after studying the differences between the Dasher and Creedmoor, we decided it would all clean up and leave a fresh throat. The job went smoothly and I screwed it back onto my BAT B for testing. I loaded a known good load that had never shown pressure signs in any other 6 Creedmoor we put it thru but immediately began blowing out primers in this barrel. Closer inspection showed there was still some roughness left in the new throat so we cut off the tenon and did it again to see if that changed anything. All was well with it afterward.
So, likely there is some roughness in there now on your buddy's throat that is causing pressures to be excessive.

I ran into that a few years back on one. It was a hunting rifle and I don't remember the details but I did as you, rechambered to a longer cartridge and it fixed it. I think it's unusual to see a big psi jump like that but I suppose it can happen.

 

[4xforfun]

Carbon ring in ....3....2....1

Well...it COULD be, but the PSI started immideatly after the new throat was cut, and.....wouldn't lengthening the throat remove the carbon ring?

Just spitballing here!!

 

[gunsandgunsmithing]

Well...it COULD be, but the PSI started immideatly after the new throat was cut, and.....wouldn't lengthening the throat remove the carbon ring?

Just spitballing here!!

Yes. I missed the part about it starting immediately afterward

 

[Fast14riot]

Did it ever get bore scoped?

 

[4xforfun]

Did it ever get bore scoped?

Not yet.....On my ta-do list. I don't have a scope, but should be able to talk someone into bringing theirs to one of the up coming 600 yard matches.

Thanks,
Tod

 

[4xforfun]

One more thing.....Primer pockets. They are tight as new!! Can live with flat primers and some cratoring.....but very hard bolt lift is unacceptable!!