Blowing Primers and other signs of high pressure in a mild load

[the long shot]

long shot

while you have a moment, pull 2-3 of the loads and check the powder weight just to make sure.

Bob

Though my brass did not have shiny spots on the mouth of the brass I believe the brass stretched too far over a group of this brass. This lot of brass seem to stretch easier than my last batch.
Planning on pulling a few. Went out and bought a collet puller so I didn't have to hammer them all out.

pulled a few and the charge is within .1 grains of 54.3 consistently. brass is a few thou long on several samples.

I think in the first post and this one the problem could well be identified. Long brass can increase pressure. Trim those cases and I bet the issue will go away. Worst case I have seen of this was at the range one day, guy next to me was blowing primers and the case mouths had a bright area on them where they were hitting the end of the chamber. Cases that are long might not have enough room to release the bullet until pressures spike beyond where they should be. Not that it could not be any or several of the other suggestions.

 

[CaptainMal]

Don't buy case length. Buy what Donovan and Larry (SavageDasher) told you.

My take is time and NOT using C4 and Iosso allowed carbon to slowly build up with your moderate Varget loads. If you did not clean to deal with carbon fouling, forget all said about cleaning. Most solvents are not worth a "tinkers damn" dealing with carbon.

Over time the pressures with your Varget slowly built up and loosened the primer pockets. Sure you should have been trimming after every use of the case. Maybe you are not sizing right? They could be factors. My take is carbon fouling causing increased pressure that took out your cases was a big factor.

Bore scope and obscene scrubbing with Iosso and Bore Tech C4 probably can deal with the fouling. New cases should deal with the case problem. Maybe a new barrel also?

 

[jsthntn247]

When I think pressure problems on lower charge weights these 4 things come to mind 1. Not enough neck clearance 2. Brass too long pinching case mouths causing bullet release issues 3. Possibly a larger diameter bullet in a tighter sided bore 4. Carbon ring

 

[the long shot]

Don't buy case length. Buy what Donovan and Larry (SavageDasher) told you.

My take is time and NOT using C4 and Iosso allowed carbon to slowly build up with your moderate Varget loads. If you did not clean to deal with carbon fouling, forget all said about cleaning. Most solvents are not worth a "tinkers damn" dealing with carbon.

Over time the pressures with your Varget slowly built up and loosened the primer pockets. Sure you should have been trimming after every use of the case. Maybe you are not sizing right? They could be factors. My take is carbon fouling causing increased pressure that took out your cases was a big factor.

Bore scope and obscene scrubbing with Iosso and Bore Tech C4 probably can deal with the fouling. New cases should deal with the case problem. Maybe a new barrel also?

I plugged the barrel and let it soak a couple hours filled with brake clean before I did my Chrony test. I will try plugging the chamber and using Boretech C4 and also try a chamber brush as well to see if there results in some carbon removed. I have cleaned it aggressively with boretech eliminator in the past. I cleaned it with some Montana Extreme. I have never gone after the carbon ring as part of my routine. In the past I have just used a mop to clean the chamber.

I do not have a bore scope. Is there another way to inspect for a carbon ring?

 

[JRS]

A properly corrected loupe. You aren't going to examine the rifling half way through the barrel with it, but, it will clearly reveal everything you want to see in the chamber and throat area. They're also available lighted, for an additional cost.

 

[the long shot]

Update...

I continue to explore the carbon problem due to some doubt that my 110 chamber is tight enough to warrant problems with 16 thou over brass.

Even after getting clean patches out with Montana extreme and Boretech eliminator I took a brush and Iosso to the barrel. The barrel yielded black tarry patches for both successive Iosso treatments. I decided to triple down and inserted a chamber plug and tip the barrel up. I filled the barrel with Boretech C4 to see if i could milk out some more of the carbon.

 

[the long shot]

Hopefully this finally fixed it. I soaked the gun in Boretech C4 for 24 hours. It must have taken something out because the C4 dissolved the paint off the chamber plug. I did not have the yield of black tar like I did with the Iosso but I did have about 6 solidly dirty patches come out of the bore after I drained the barrel. I have Kroiled the barrel and will take her out for testing again soon and see if I get pressure signs again.