Extraction issue. Need advice.

[joe.canada]

Extraction issue. Need advice.

New custom barrel from renowned maker. Chambered in 6mm Creedmoor with a 1:8 twist. Only 120 rounds through the barrel, break in and load development. Reloder 16, CCIBR4, Peterson SRP brass new and the 108 ELDM. Developed a load with avg velocities 2955 fps with no pressure signs. Then all of a sudden, very stiff bolt lifts, brass and primer show no signs of pressure. Load has not changed and environmental temperatures aren’t at extreme opposites (fairly consistent). I tested lighter loads and they still produce stiff bolt lifts. I tested the load in another 6 Creedmoor I have and no issues. Barrel is mounted on a Rem 700 Stainless steel action, brand new.

Additional info: I’ve kept data on fired brass measurements and nothing has changed. Load development has always been performed within recommended powder charges, I’ve never loaded hot and been reloading since 2009. Competed in PRS and Sniper competitions with my handloads. Never had an issue. I’ve inspected the bolt to the best of my capabilities and the chamber using a bore scope and nothing odd was seen.

Worst part, is that the stiffness of the bolt lift is now at a point where I have to slam the bolt handle to get it to go up. I’ve stopped shooting

Any advice would be appreciated.
Thx

 

[AllenOne1]

Your barrel has probably started to speed up. Back your powder charges off some more and see if it corrects the issue.

I'm going through the exact same thing right now, barrel sped up at least 20 ft/sec at around 120-150 rounds.

 

[DIBBS]

what's your cleaning regimen? It's possible you have developed a carbon ring that is jacking pressures up.

Have you changed the lot of bullets recently... maybe a slightly different profile that are touching the lands?

New lot of powder?

 

[Pat McGroin]

See anything that looks like this with your bore scope?

 

[joe.canada]

what's your cleaning regimen? It's possible you have developed a carbon ring that is jacking pressures up.

Have you changed the lot of bullets recently... maybe a slightly different profile that are touching the lands?

New lot of powder?

I bought some C4 Carbon Cleaner and will give that a try.

Same lot for all components.

 

[joe.canada]

View attachment 8116067
See anything that looks like this with your bore scope?

Nothing like that no

 

[Pat McGroin]

Nothing like that no

Ok. That’s a carbon ring in my own 6cm that presented similar to what you’re describing.

 

[ShtrRdy]

Do you have any factory ammo you could try?

 

[joe.canada]

Do you have any factory ammo you could try?

I’ll go buy some tomorrow and see if it yields same bolt stiffness

 

[joe.canada]

Ok. That’s a carbon ring in my own 6cm that presented similar to what you’re describing.

I’ll double check…just in case I missed it

 

[Hardholder439]

Based on your "all of a sudden" revelation, a carbon ring sounds likely but... in the explore all possibilities line of thinking before shipping it off to a gunsmith...

Did you FL resize the new brass before loading? If not, why not? Try it. I know. Peterson brass is the best but try it anyway.

I purchased a custom rifle chambered in 6 Dasher from a well known benchrest shooter that is a gunsmith as well. I fired about 85 rounds before deciding something was just wrong. Closing the bolt on new Alpha brass that was .002 under Saami spec took more effort than it should but the Kelbly Panda action was new. Lifting the bolt on under maximum loads took a sharp slap. I was unhappy to say the least. I then experimented with chambering new unfired empty brass .002 under Saami. To my surprise, bolt close was stiff. Extraction of the new case was just as difficult as any fired case. WTF? It is a very tight chamber. Fired brass only expanded .001. A friend told me to use a small base .308 die to size the case before the FL Dasher resizer. Said he had to do the same with a custom Dasher built by the same smith. I didn't have a small base .308 but ran 5 new cases through a standard .308 die. Chambered the empty cases and harder than normal bolt close and very difficult extraction problems disappeared. They were still were run through a FL Dasher die with a neck bushing before loading. Bolt lift was normal after firing. Don't ask me to explain. It's above my pay grade. I don't understand why either. It would be worth buying a:

Buy 6.5 Creedmoor Small Base Taper Crimp Die Set - AR Series and More | RCBS

Shopping for the 6.5 Creedmoor Small Base Taper Crimp Die Set - AR Series - Learn more about the latest 6.5 CREEDMOOR RELOADING ESSENTIALS and other hunting or shooting gear at RCBS.

www.rcbs.com

Run some new cases though the SB die and see if it helps. If it is not a tight chamber the only other thing I can think of is a reamer with a short neck. Trimming the neck may help but you should show high pressure if that were the case. Best of luck and let us know what you find.

 

[Rocketmandb]

I bought some C4 Carbon Cleaner and will give that a try.

Same lot for all components.

I've found that C4 Carbon Cleaner is a good general cleaner, but doesn't work all that well on caked on carbon. If you do have some carbon forming, look at Wipe Out foaming cleaner. Night and day. You still have to really work at it, but it pulls carbon off very well.

 

[Rocketmandb]

Extraction issue. Need advice.

New custom barrel from renowned maker. Chambered in 6mm Creedmoor with a 1:8 twist. Only 120 rounds through the barrel, break in and load development. Reloder 16, CCIBR4, Peterson SRP brass new and the 108 ELDM. Developed a load with avg velocities 2955 fps with no pressure signs. Then all of a sudden, very stiff bolt lifts, brass and primer show no signs of pressure. Load has not changed and environmental temperatures aren’t at extreme opposites (fairly consistent). I tested lighter loads and they still produce stiff bolt lifts. I tested the load in another 6 Creedmoor I have and no issues. Barrel is mounted on a Rem 700 Stainless steel action, brand new.

Additional info: I’ve kept data on fired brass measurements and nothing has changed. Load development has always been performed within recommended powder charges, I’ve never loaded hot and been reloading since 2009. Competed in PRS and Sniper competitions with my handloads. Never had an issue. I’ve inspected the bolt to the best of my capabilities and the chamber using a bore scope and nothing odd was seen.

Worst part, is that the stiffness of the bolt lift is now at a point where I have to slam the bolt handle to get it to go up. I’ve stopped shooting

Any advice would be appreciated.
Thx

Questions:

- Are you FL sizing or neck sizing?

- Are you sure you're bumping the shoulders enough?

- How many firings on the brass?

 

[joe.canada]

I've found that C4 Carbon Cleaner is a good general cleaner, but doesn't work all that well on caked on carbon. If you do have some carbon forming, look at Wipe Out foaming cleaner. Night and day. You still have to really work at it, but it pulls carbon off very well.

Thx for the tip. Will do.

 

[joe.canada]

Questions:

- Are you FL sizing or neck sizing?

- Are you sure you're bumping the shoulders enough?

- How many firings on the brass?

- FL with bushing die + expander mandrel

- bumping shoulders 0.002. Never had tension on bolt when chambering.

- 3rd firing on the brass. Annealed after each firing

 

[supercorndogs]

Sounds like a classic case of what happenns when a die isn't sizing brass enough at the base of the case. What's the diameter at the base on new, fired, and fired and sized 3 times.

 

[joe.canada]

Sounds like a classic case of what happenns when a die isn't sizing brass enough at the base of the case. What's the diameter at the base on new, fired, and fired and sized 3 times.

I’ll measure that and confirm. But wouldn’t that result in a stiffness of the bolt when chambering a round? Because i have no stiffness of the bolt when chambering new or resized brass, only on extraction.

 

[spife7980]

I’ll measure that and confirm. But wouldn’t that result in a stiffness of the bolt when chambering a round? Because i have no stiffness of the bolt when chambering new or resized brass, only on extraction.

Depends on where exactly in the spectrum of too big they are. Not too big to chamber but too big to spring back enough.

Write the case dimensions down each firing and sizing and you’ll be able to track where the problem is occurring.

 

[Bugholes]

switch back to virgin brass and see if your issue persists.
-if you still have pressure issues look at your barrel. Either shavings in the chamber or cleanliness of the bore. Also consider taking out your ejector (this would be unlikely unless you’re having stiff bolt close on a virgin case)
-if your issue goes away (temporarily) the look at your dies, you may not be sizing the cases enough

 

[supercorndogs]

I’ll measure that and confirm. But wouldn’t that result in a stiffness of the bolt when chambering a round? Because i have no stiffness of the bolt when chambering new or resized brass, only on extraction.

Your bolt cams into battery, it can force them in without much effort.

 

[joe.canada]

Depends on where exactly in the spectrum of too big they are. Not too big to chamber but too big to spring back enough.

Write the case dimensions down each firing and sizing and you’ll be able to track where the problem is occurring.

Will do. Thanks for the advice. Going this week so I’ll have the data to compare.

 

[FisherT&C]

I also recommend trying the small base sizer. Also, check the bolt lugs for galling.

 

[joe.canada]

Based on your "all of a sudden" revelation, a carbon ring sounds likely but... in the explore all possibilities line of thinking before shipping it off to a gunsmith...

Did you FL resize the new brass before loading? If not, why not? Try it. I know. Peterson brass is the best but try it anyway.

I purchased a custom rifle chambered in 6 Dasher from a well known benchrest shooter that is a gunsmith as well. I fired about 85 rounds before deciding something was just wrong. Closing the bolt on new Alpha brass that was .002 under Saami spec took more effort than it should but the Kelbly Panda action was new. Lifting the bolt on under maximum loads took a sharp slap. I was unhappy to say the least. I then experimented with chambering new unfired empty brass .002 under Saami. To my surprise, bolt close was stiff. Extraction of the new case was just as difficult as any fired case. WTF? It is a very tight chamber. Fired brass only expanded .001. A friend told me to use a small base .308 die to size the case before the FL Dasher resizer. Said he had to do the same with a custom Dasher built by the same smith. I didn't have a small base .308 but ran 5 new cases through a standard .308 die. Chambered the empty cases and harder than normal bolt close and very difficult extraction problems disappeared. They were still were run through a FL Dasher die with a neck bushing before loading. Bolt lift was normal after firing. Don't ask me to explain. It's above my pay grade. I don't understand why either. It would be worth buying a:

Buy 6.5 Creedmoor Small Base Taper Crimp Die Set - AR Series and More | RCBS

Shopping for the 6.5 Creedmoor Small Base Taper Crimp Die Set - AR Series - Learn more about the latest 6.5 CREEDMOOR RELOADING ESSENTIALS and other hunting or shooting gear at RCBS.

www.rcbs.com

Run some new cases though the SB die and see if it helps. If it is not a tight chamber the only other thing I can think of is a reamer with a short neck. Trimming the neck may help but you should show high pressure if that were the case. Best of luck and let us know what you find.

I’ll order a set. Thx for the advice. Well explained.

 

[iceng]

This is also my guess. Custom barrel and chamber, resulting in a tighter base of case. "Normal" dies are not sizing it enough.

it enough at the base, and as such, when you are sizing the brass and doing shoulder bump, it's marginally swelling the base of the case. Nothing to be scared of, just need different dies. It happes.

Also speak to your 'Smith about primary extraction. Rem700 actions such for that. Get that fixed and its a WORLD of difference. I've fix loads of Them.

 

[Eurodriver]

Are there small base dies easily found for 6mm CM? I’ve seen them a lot for .223 - I have some - but not the newish 6mms.

 

[iceng]

Source for a 6.5 CM small base resizing die?

I just picked up an LRP07 from JP in 6.5 Creedmoor. Ive been told that the chamber is tight and a full length resizing die with a small base is suggested so that the cartridge will feed properly. Finding one has been another issue altogether......anyone know of someone off the beaten path...

www.snipershide.com

 

[DeathBeforeDismount]

Sounds like New custom barrel from renowned maker needs to buy you a new barrel if you eliminate bad sizing from the culprits.

I would try bumping .003-.0035. Give yourself some more margin of error with dirty chambers, wet chamber and inconsistent sizing. Yes it will work the brass a little more but as long as you are annealing it shouldn't be much of an issue.

 

[kthomas]

Out of curiosity, is this "renowned" barrel maker from Canada or the US?

 

[joe.canada]

UPDATE

I performed a full cleaning of the bore, once using a carbon remover and again using a copper remover, which resulted in no more stiff bolt on extraction. I believe the issue was a nasty carbon ring. I’ll be performing a carbon ring removal (with C4 Carbon remover) after every outing.

Thanks again for the help and advice. Learned something new.

Joe

 

[DeathBeforeDismount]

RL16 and Varget are very dirty. My theory is they burn cooler so they leave more residial carbon in barrel and are a culprit of carbon ring.

Running a hotter powder like H4350 will elivate this issue. I sold off all my varget and run H4350 from 6gt to 6.5cm up to 300wsm. Never have carbon ring issues and cleaning takes about 10 minutes with 8 of that waiting for solvent to soak.

 

[joe.canada]

I’m in Canada and H4350 has become unobtanium ! Have to do with what I can get, and for the moment, that’s RL16 and Varget.

 

[DIBBS]

Glad that you were able to get the problem resolved!

 

[wind gypsy]

RL16 and Varget are very dirty. My theory is they burn cooler so they leave more residial carbon in barrel and are a culprit of carbon ring.

Running a hotter powder like H4350 will elivate this issue. I sold off all my varget and run H4350 from 6gt to 6.5cm up to 300wsm. Never have carbon ring issues and cleaning takes about 10 minutes with 8 of that waiting for solvent to soak.

What do you mean “hotter”? Varget has a significantly higher heat of explosion value than h4350 if that’s what you’re referring to.

 

[robb_va]

What do you mean “hotter”? Varget has a significantly higher heat of explosion value than h4350 if that’s what you’re referring to.

He's clueless.

 

[supercorndogs]

RL16 and Varget are very dirty. My theory is they burn cooler so they leave more residial carbon in barrel and are a culprit of carbon ring.

Running a hotter powder like H4350 will elivate this issue. I sold off all my varget and run H4350 from 6gt to 6.5cm up to 300wsm. Never have carbon ring issues and cleaning takes about 10 minutes with 8 of that waiting for solvent to soak.

Varget is a hot turing powder famous for toasting throats.

 

[supercorndogs]

I’m in Canada and H4350 has become unobtanium ! Have to do with what I can get, and for the moment, that’s RL16 and Varget.

RL16 was pretty popular here. Varget is probably better for the 120 class bullets.

 

[Elite_KG]

UPDATE

I performed a full cleaning of the bore, once using a carbon remover and again using a copper remover, which resulted in no more stiff bolt on extraction. I believe the issue was a nasty carbon ring. I’ll be performing a carbon ring removal (with C4 Carbon remover) after every outing.

Thanks again for the help and advice. Learned something new.

Joe

Just to note - the pressure increasing under 200 rounds or so could be a result of generally fouling of the barrel. I would expect if cleaning the barrel resolved the heavy bolt lift your barrel may require cleaning every 100-200 rounds since your load was developed on a new cleaner barrel.

Pretty sure AllenOne1 meant the same thing when he stated “your barrel has probably started to speed up”.

Your barrel has probably started to speed up. Back your powder charges off some more and see if it corrects the issue.

I'm going through the exact same thing right now, barrel sped up at least 20 ft/sec at around 120-150 rounds.

The barrel speeding up is a result of more pressure being generated as the barrel begins to foul from new and generate some firecracking (normal). The fouling and roughness from firecracking results in more pressure drop, resistance, or “back pressure” that translates to increased chamber pressure and higher velocities usimg the same load.

Did you see higher velocities in the shots that had extraction issues vs the earlier firings that did not?

Bryan Litz from Applied Ballistics discusses and explains this phenomena in the “Believe the Target” podcast #56.

If you do not wish to clean that often, then you may need to back off the powder some.