Reumbo pressure spike below freezing!

[tbrice23]

I've opened a can of Reumbo before and was shocked to see it clumped into a singular mass. I expected to see something like that as I dumped the rounds but everything looked normal.

 

[J E Custom]

I still think it has something to do with seating the bullet very close or against the lands. The slightest change could cause this if the head space goes to zero or less.

It is a mystery, But you can eliminate that possibility by seating the bullet .010 to .020 off the lands
and using the same load.

Keep us posted

J E CUSTOM

 

[tbrice23]

I still think it has something to do with seating the bullet very close or against the lands. The slightest change could cause this if the head space goes to zero or less.

It is a mystery, But you can eliminate that possibility by seating the bullet .010 to .020 off the lands
and using the same load.

Keep us posted

J E CUSTOM

My load is .010" off the lands (jump).

 

[Trnelson]

Someone tell me I'm crazy.
I have worked up a load for 264wm with140vld and Retumbo up to 71.5 gr in 65° with mild pressure signs, so I backed down to 69.0 grains at 3250 fps average.

Today 30°F I shot some of the same ammo loaded 3 weeks ago and the velocity spiked to 3340fps and blown primers. This barrel is completely cleaned, no copper or carbon with a dry chamber verified with my bore scope.
Same lot of brass, primers, bullet and powder.

The only thing that changed is last week I did a several groups of RL 25, but I always clean to bare metal when I change to a different powder.

*** !! Help!

When I switch from one 100 pack of primers (in the same lot) to another package I randomly select five, load as usual and verify velocity over the magnetospeed. I used to do the same thing when switching from 8# powder to a new jug, they vary up to 10% lot to lot. Now I buy several and blend them together as soon as they arrive. Humidity control, or lack there of, in your powder storage can cause powder to react in a less than predictable fashion as well. There are several old threads that discuss that topic.

 

[tbrice23]

Thanks, I keep deseccnts in the coolers that I store my primers in. And a dehumidifier running by my powder storage.

As you know I was going to bring this rifle and these exact loads on my last hunting trip 2 weeks ago, if this would have happened I would have been mad. However, when I travel for hunts I always bring a second backup rifle.
If this is an isolated phenomenon that only happens with my particular barrel or cartridge and Retumbo interaction then I'll just go back to RL25.
Still, this will drive me mad if I never figure out WHY it happened. Then I'll be afraid of Retumbo forever.

 

[Trnelson]

Your powder could be too dry causing it to deflagrate more quickly and raise pressure. Let me see if I can find a link to the article I'm thinking of...

 

[Trnelson]

Your powder could be too dry causing it to deflagrate more quickly and raise pressure. Let me see if I can find a link to the article I'm thinking of...

I still had the article book marked, here you go

TECH TIP: Humidity Can Change Powder Burn Rates « Daily Bulletin

 

[tbrice23]

Seems logical to me. But this would have affected all my powder for all my rifes, right?? ( I keep meticulous records and chrono **** near every shot from all my rifles at the range).

Reading the article ,it seems we all would be better off loading by volume ( powder dropper) instead of scales.

 

[Michael Eichele]

Carbon ring or excessive heat checking.

 

[tbrice23]

Carbon ring or excessive heat checking.

I've been looking for one.
I checked again with my borescope today, its not a Hawkeye but I really don't see one.
Maybe it is in a shadow and i missed it, do you think I should do a JB bore scrub in the throat area???
I really don't like abrasives but may I'll give it a few dozen strokes with JB and Kroil.

 

[Michael Eichele]

I've been looking for one.
I checked again with my borescope today, its not a Hawkeye but I really don't see one.
Maybe it is in a shadow and i missed it, do you think I should do a JB bore scrub in the throat area???
I really don't like abrasives but may I'll give it a few dozen strokes with JB and Kroil.

Clean your barrel as you normally do. Then take a nylon brush and push it all the way out. Then pull it back towards the breach end gently and smoothly. If there's a ring, you'll feel it either stop or show a lot of resistance. It's usually abrupt. If it exits the breech easily and smoothly, it should be good.

 

[Michael Eichele]

I would try that before JB. If you do need JB, I would try 10-12 short strokes. Then clean it ALL out and recheck. Need be, repeat.

 

[tbrice23]

I'll try pulling out to see if I can feel it. I've been using Boretech carbon remover every 50 rounds, I know how dirty Retumbo runs. Been using it on every rifle for a few years now ,and never had a problem with carbon rings even in rifles that use 7828 . It also removes copper.

 

[Michael Eichele]

I'll try pulling out to see if I can feel it. I've been using Boretech carbon remover every 50 rounds, I know how dirty Retumbo runs. Been using it on every rifle for a few years now ,and never had a problem with carbon rings even in rifles that use 7828 . It also removes copper.

I have found with overbore cartridges, even when the 'carbon' gets cleaned out, a rock hard ring is near impossible to get out with any cleaner short of a mild abrasive.