Carbon ring and bolt lift??

[Texas Solo]

I have a 6 Dasher I built a few months ago. This rifle has shot better than anything I've ever seen.
But an issue has risen I can't figure out.

After 15 or so rds, I get a slightly heavy bolt lift. Not too bad, but definitely noticeable. New rounds chamber as easy as the first. Issue only occurs after 15 +/- rounds.

Chamber is clean. Rifle now has 375 rds on it. Alpha brass, Berger 105's, Varget.
FPS is 2890 with 31.3 Varget.
104 freebore, 272 neck. As said, subsequent rds chamber perfectly.
Accuracy is still amazing.

One person said it "could" be a carbon ring forming. I'm not sure if that would only cause an issue with bolt lift and not chambering? I checked with scope and I do have a carbon ring just starting to form. I'll have to research how best to remove it. Can the reamer be used for this?

Any insight would be appreciated.

 

[6BRA]

Are you cleaning case lube off good? Bolt grease migrating? Carbon ring won't form in 15 rounds. How much are you bumping shoulders?

 

[madmixerman]

Possibly from the Alpha brass? I experienced heavy bolt lift when I tried Alpha brass in a bra.

 

[Texas Solo]

Are you cleaning case lube off good? Bolt grease migrating? Carbon ring won't form in 15 rounds. How much are you bumping shoulders?

Yes, brass is tumbled after sizing.

Don't use bolt grease

Rifle has 375 rds on it, not 15.

Shoulder bump is .002.

Again, issue only occurs after 15 - 20 rds.

 

[Texas Solo]

Possibly from the Alpha brass? I experienced heavy bolt lift when I tried Alpha brass in a bra.

Don't think so. Alpha chambers perfectly. Growth is minimal.

 

[JFrank]

What does the loaded round neck OD measure ?

 

[Texas Solo]

What does the loaded round neck OD measure ?

.269

 

[Hal]

Do you grease the back side of the bolt lugs, the firing pin camming , the threads on the inside, at the back of the bolt , and the bolt handle/ extractor cramming surface ?

 

[Texas Solo]

Do you grease the back side of the bolt lugs, the firing pin camming , the threads on the inside, at the Bach of the bolt , and the bolt handle/ extractor cramming surface ?

No. I don't use grease. I use oil.

 

[Hal]

Does the oil stay in place ?
Spray some on a vertical surface and see if it stays in place. If not use a grease.
On the back of the bolt lugs use a high pressure grease.

Hal

 

[Bob3700]

U need to keep the bolt lugs greased. Oil does not create a sufficiently durable lubricating layer. A quality synthetic grease will ensure smooth bolt lifts n prevent galling. I would try the grease and see if that helps. Cheap easy fix to try.
If there was a detrimental carbon ring that has formed, the first rounds would have the same bolt lift issues as the later rounds.

 

[pilediver]

Lots of people have trouble with Alpha brass, especially in 6 bra for some reason, was the chamber cut with an Alpha designed reamer?
You could try a different brand of brass, my first 6 bra didn't work well with Alpha or Norma brass but Lapua and peterson work fine.
Something about the .200 line at the base

 

[Texas Solo]

Lots of people have trouble with Alpha brass, especially in 6 bra for some reason, was the chamber cut with an Alpha designed reamer?
You could try a different brand of brass, my first 6 bra didn't work well with Alpha or Norma brass but Lapua and peterson work fine.
Something about the .200 line at the base

It's not the brass. Alpha has been fine for the first 300 rds.

 

[G Liles]

What do the lands look like from the throat out to 4 inches? I’m asking because it could be a build up of carbon on them.

 

[Texas Solo]

What do the lands look like from the throat out to 4 inches? I’m asking because it could be a build up of carbon on them.

Very clean. How would that cause a heavy bolt lift anyway?

 

[Bill Norris]

Very clean. How would that cause a heavy bolt lift anyway?

He is probably referring to potiential pressure.

 

[Gabe22BR]

Carbon ring !

I have 325 rds. On my 6 dasher. It shoots incredibly well. I decided to bore scope to ensure my cleaning routine is working. The bore looks very clean. But...I see a carbon ring starting to form. I'm confused how it's happening. Brass chambers very well, has never been trimmed. Alpha. Berger...

forum.accurateshooter.com

Hoping you found your answer after the last post & 50rds later…

 

[mikecr]

After 15 or so rds, I get a slightly heavy bolt lift. Not too bad, but definitely noticeable. New rounds chamber as easy as the first. Issue only occurs after 15 +/- rounds.

That's not from a carbon ring.
Sounds like it's an action warming up normally, but bringing an action issue to surface with that.

 

[Texas Solo]

If there was a detrimental carbon ring that has formed, the first rounds would have the same bolt lift issues as the later rounds.

This makes sense.

 

[jr600yd]

JB it and see if it persists