Murom large rifle primers, anyone had problems?

[snayperskaya]

Is anyone using Murom LR primers and have you experienced any problems?.

I had a really strange problem today at the range with one of my 7.62x54r handloaded rounds.It had 48gr of Ramshot Big in a once fired PPU case and a 150gr PPU SPBT bullet and a Murom primer.

On squeezing the trigger I was met with a click rather than a bang so waited 30 seconds with rifle pointed downrange before extracting the round......at which point I was surprised to see no bullet in the case but a case full of powder that appeared to be lightly singed but bizarrely the primer had gone off with enough energy to move the bullet enough that it just started to engage the rifling but the powder was intact and unburnt!.

How is it possible for the primer to ignite and move the bullet, albeit a small amount, without igniting the powder?.The powder appeared dry and burned normally with a match to it.The other 19 rounds loaded at the same time to the same spec had a bearly perceptible delay between the click of the firing pin and the bang and on decapping the cases there was what appeared to be tiny flecks of unburnt primer material (like tiny bits of pink paper) in the tray my spent primers fall into.

The powder type/weight and bullet/case are my "pet" load and very accurate, I usually use RWS primers and never had a problem.After shooting off the 20 rounds with the Murom primers I fired a batch of ammo with the same powder/powder weight/bullet/case combo with RWS primers and there was no delay so I'm sure it was imagined

Anyone had the same or similar problems with Murom primers?, or any other primers for that matter?.

[rox]

Anyone had the same or similar problems with Murom primers?, or any other primers for that matter?.

I've had 1 misfire in about 30k. The bullet wasn't moved.

[dodgyrog]

Is that ball powder?
If so I'd recommend magnum primers.
I had the same problem in 6,5 x 55 ammo with Accurate 2520 which is a ball powder.

[snayperskaya]

Is that ball powder?
If so I'd recommend magnum primers.
I had the same problem in 6,5 x 55 ammo with Accurate 2520 which is a ball powder.

Big Game is indeed a ball powder

[snayperskaya]

Is that ball powder?
If so I'd recommend magnum primers.

Is that due to a ball powder charge being denser than stick powder?.

[dodgyrog]

Is that ball powder?
If so I'd recommend magnum primers.

Is that due to a ball powder charge being denser than stick powder?.

Can't say I know why ignition is difficult other than to say it is a known phenomenon!
I suppose 1gr of fast pistol powder next to the flash hole would do the job but only if the case were full and the powder didn't 'slosh' around. Don't use a filler!

[DaveT]

I can't really account for the symptoms that you describe but I have noticed thatbMurom LR primers need sesting significantly deeper than CCIs.
I had a session where on first trigger pull all I got was a click and a dented primer...... tried again and it fired perfectly.
When I measured the spent primers I noted that the cups where .007" thinner than the CCIs.
I had been seating the Muroms with the 'learnt' pressure needed for CCIs which appeared to insert them to the expected depth.
What was happening was that the first firing pin strike was completing the seating and bottoming the primers ready for a full strike 2nd time when all worked ok.
Since then I make sure they are fully seated by applying the extra pressure on my priming tool.... they actually look as if they are seated a little too deeply but work perfectly.

[dromia]

It is the coating on the ball powder that makes it hard to light, combine that with inconsistent bullet retention and the powder fails to ignite.

As it was a one off then I would say look to you bullet retention, if full length resizing then I hope that you have removed that abomination of an expander plug and had it destroyed.

I have seen it happen with slow burning stick powders as well when the bullet retention is poor.

Nothing to do with the primer, Murom is good kit.

[snayperskaya]

It is the coating on the ball powder that makes it hard to light, combine that with inconsistent bullet retention and the powder fails to ignite.

As it was a one off then I would say look to you bullet retention, if full length resizing then I hope that you have removed that abomination of an expander plug and had it destroyed.

I have seen it happen with slow burning stick powders as well when the bullet retention is poor.

Nothing to do with the primer, Murom is good kit.

Bullet retention seems to be good, Resized case mouth is 0.307" and bullets are .311"......the expander ball measures .309"

The expander that came with the die set was for .308" bullets and measures 0.3065", the .309" one I have been using is the one listed for .311"bullets.

Can a case be full length resized in a standard die with the expander removed or would that cause issues?.

[dromia]

Expander balls ruin cases and obviously it isn't giving you consistent bullet retention or you wouldn't be getting this intermittent issue.

Chuck the expander ball and just replace it with a decapping rod. I never ever use expander balls in my dies, I do use "M" die parallel expander plugs to give me controlled neck tension.

I would also anneal the cases as the god awful expander ball exacerbates the hardening of the case mouth, this creates spring back and I suspect if you were to measure all the cases mouths of you cases they would vary.