6mm Creedmoor question

[spudgun]

My 6mm CM is starting to loose accuracy. Used to shoot 3" groups at 600 yds but now getting 10".

I have about 1000+ rounds down the barrel at 2900 +/- 25 FPS.

Nothing has changed on my loads for the past 10 months.

I am thinking that maybe the barrel is going on me but was going to try some different OAL of my loads to see if I can get it back on track.

At this time I am or was getting the best groups at .03" off the lands. Was going to bump it up to .02" or .01" jump.

Yes, I have cleaned the barrel and removed carbon deposits. The necks of the brass look good after being fired, a little soot around the neck and not on the shoulders.

If I get an improvement in accuracy does this mean a new barrel is coming soon?

Is this the way to go?

 

[lawman29]

Check all the "screws"... If all torqued to spec you could try a different scope to see if that went south.

 

[Ranger188]

The 6 creed does go thru barrels quicker that others.
I would recheck your lands, pretty sure they have eroded
and you need to at least adjust the jump.
Some get 1000 rounds and others a little more, but
your throat has changed in that amount of rounds..

 

[eric32]

What bullet are you using? You may want to jump more.

Also have you check the carbon ring right where the neck/bore meets?

 

[Dgd6mm]

What bullet are you using? You may want to jump more.

Also have you check the carbon ring right where the neck/bore meets?

This exactly. I've let my .243 carbon up on me a bit and it will open up like a shotgun. Clean it properly and go back to .5 moa accuracy easily.

 

[spudgun]

What bullet are you using? You may want to jump more.

Also have you check the carbon ring right where the neck/bore meets?

Hornandy 105gr, ELD

Didn't see any carbon with the bore scope I have (not very good one though) Have a new scope coming..


Yeah, my next move is to try different OAL of the bullet

 

[eric32]

You shoot 6.5 or 6mm?

 

[spudgun]

You shoot 6.5 or 6mm?

Both, 6mm and 6.5 CM

Oh, I see what you mean.

Sorry, 6mm is 105 ELD, Hornandy not 140gr.

I shoot the 140's in my 6.5 CM

 

[eric32]

Yea check your jump but i think you might be near the end of its life.

 

[Hohn]

Might want to switch to another powder and see if barrel life improves.

 

[mike a]

My 6creed with 1100 rounds still doing 3” at 500. R16 and Berger 105 Hybrids. Shilen stainless select match prefit. Hoping for 1500. I do have new spare under the bed just in case though.

 

[Capt. Oblivious]

That throat would have moved quite a bit after 1000 rounds

 

[spudgun]

Back to my orig post

The 6 creed does go thru barrels quicker that others.
I would recheck your lands, pretty sure they have eroded
and you need to at least adjust the jump.
Some get 1000 rounds and others a little more, but
your throat has changed in that amount of rounds..

Well i tested some loads today at 100 yds. I loaded the same loads that I have been using for 10 months now and extended to OAL to .001 off the Ogive. (data from my orig measurement)

I tested my old loads (2.72" OAL) to my new loads (2.74" OAL)

The results were some what promising and my groups moved down to 1 MOA but not close to what it used to shoot when new.

Tonight I measured my chamber with a OAL gauge and found that what used to be 2.75" to the Ogive of my bullet was now 2.93" with my Hornandy 105 Match bullets.

I then measured using some Berger 105 target and found that what was 2.92" to the Ogive was now 3.02".

Looks like I picked up about .11" of extra throat.

So I thought can I load my bullets out to the new length to get back my .03 jump.

Seated a bullet and then pulled it. Not much left in the neck to hold the bullet.

I think my barrel is going to need replacement.

 

[fotohunt]

If you are going to get a new barrel, and the old barrel was a good one, why not have the new one chambered/threaded/crowned, and have the old one set back enough to rechamber and still use it? I bet your smith would do it if the rest of the bore looks good. Just a thought.

-Darrell

 

[spudgun]

If you are going to get a new barrel, and the old barrel was a good one, why not have the new one chambered/threaded/crowned, and have the old one set back enough to rechamber and still use it? I bet your smith would do it if the rest of the bore looks good. Just a thought.

-Darrell

I was thinking of that too.

I asked my GS about set it back and cut a new chamber. The cost was just about $100 cheaper than a new barrel (he needed to rent a reamer for that chamber).

I am not going to throw the barrel out, and may do that or what the heck, go to 6mm something else.

 

[gman47564]

That isnt that much wear really.. my advice would be to use the same charge weight as before and start seating your bullets deeper into the case by .005 at a time.. it will roll into the next seating node and go to shooting good again for ya..

 

[6ShotsOr5?]

The 6 creed does go thru barrels quicker that others.
I would recheck your lands, pretty sure they have eroded
and you need to at least adjust the jump.
Some get 1000 rounds and others a little more, but
your throat has changed in that amount of rounds..

My last match my 6Creed shot 1.545” for a 5-shot group, shots 1186-1190, which is still competitive in my neighborhood. The replacement barrel is on hand but not quite there yet.

 

[KMart]

My last match my 6Creed shot 1.545” for a 5-shot group, shots 1186-1190, which is still competitive in my neighborhood. The replacement barrel is on hand but not quite there yet.

1.545 is one of my groups at 100 yards. But since you shot it at 400 yards, it's not that shabby.

 

[6ShotsOr5?]

1.545 is one of my groups at 100 yards. But since you shot it at 400 yards, it's not that shabby.

Yeah, I forgot an important detail.

 

[Aceball]

Check your optics and mounts.