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'Clumping' Retumbo--Kirby/anyone?

 
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  #1  
Old 09-04-2013, 02:10 PM
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'Clumping' Retumbo--Kirby/anyone?

Shot some 338AX rounds loaded with 100g Retumbo under a 300 Berger lit by a 215M. These had been loaded last spring with no pressure signs evident upon shooting at that time. I use dry lube in the necks before seating. Now they are showing pressure signs with every shot. Temp controlled as I keep them in a 40F cooler if I'm shooting in warmer weather than that to try and simulate more typical hunting temps in an effort for consistency. Haven't gotten the over pressure loads over the chono yet.

I decided to pull a bullet to see if I somehow put too much powder in. Right at 100g with same scale--checked with flashlight to make sure no powder left in case. But, to measure this, I had to wack the edge of the case head pretty hard several times to loosen the powder so it would drain out. Only one kernal came out before doing this.

What is going on? Is this contributing to my over pressure issues? This is the second 8lb jug of Retumbo that I've had clumping. When I called Hodgdon several months ago, their tech said it's not a problem, but that was before I had this overpressure issue after having powder sit in the case for several months.

Perhaps I should give every loaded case a couple of good wacks on the edge of the case head...??
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Old 09-04-2013, 02:42 PM
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Re: 'Clumping' Retumbo--Kirby/anyone?

If this is a compressed load, clumping is normal with extruded powders, when you pull the bullet and tap the powder out.
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Old 09-04-2013, 04:17 PM
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Re: 'Clumping' Retumbo--Kirby/anyone?

That may be it. This load is 100% density. Still not sure of why the load is doing what it's doing in terms of pressure. Gave the barrel, lugs (bolt and action) and chamber a good cleaning. Chamber and action lug area was more dirty than I like to see.
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www.wildsidesystems.com - Shelter for Your WildSide - http://www.youtube.com/watch?v=tYwgo...&feature=g-upl
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Old 09-04-2013, 08:35 PM
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Re: 'Clumping' Retumbo--Kirby/anyone?

My load of 101 gr of 50 BMG in a 338 RUM is compressed behind the 300 OTM and does cake pretty solid.

However, pressure isn't a problem either immediately loaded and shot or if they set for as much as several months.

With Retumbo in the 375 AM with Kirby's std load of 142 grains and the 350 SMK which has been quite a moderate load considering my nature , the last time I was in Townsend and not on a very hot day, she blew a primer.

It's no way a compressed load.

I haven't shot her since.

Maybe there's something going on with Retumbo???

We'll see next week.
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Old 09-04-2013, 10:15 PM
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Re: 'Clumping' Retumbo--Kirby/anyone?

I'm starting to wonder about Retumbo as well, Roy.

I loaded some Kirby fireformed Lapua brass tonight to 99g (dropped 1g) and -.015 (standard load, just dropped a grain), same as the other load that ave. 2954fps MV. After two foulers to foul a clean barrel it went 2930fps 3x. Still had too much pressure. Will drop to 97g and try that tomorrow. Quite frustrating. It's as if the powder became a faster powder, whether loaded in a case or in the powder container, in the last 4 months since I worked with it. Seems to be pressuring out at lower charges and velocities.

Is this a Retumbo thing? Anyone else besides Roy and I noticing anything with Retumbo lately?
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"And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are the gift of God?" Thomas Jefferson - Notes on the State of Virginia

www.wildsidesystems.com - Shelter for Your WildSide - http://www.youtube.com/watch?v=tYwgo...&feature=g-upl
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  #6  
Old 09-05-2013, 04:57 AM
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Re: 'Clumping' Retumbo--Kirby/anyone?

If it ain't one thing it's another!

My problem is going to be, if things are wonky, I have a several hundred loaded and ready to go.
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Old 09-05-2013, 05:55 AM
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Re: 'Clumping' Retumbo--Kirby/anyone?

I use Retumbo exclusively in my 300WM and 6,5x284. The caking at the mouth of the case has always occurred, particularly of the load is compressed. There was definitely a a change in the Retumbo formulation 2-3 years ago that required a decrease in charge of 1.5gr in my 6.5x284, from 59 to 57.5 to get my velocity of 2970 FPS. There were no pressure signs, just the velocity change. This has maintained constant for the last few lots I have purchased since then. Having read this post, I'm a little suspicious that I might have a problem as well. My 300WM loads are OK, but they have been only recently loaded up over the last couple of months. I recently shot some of my 6,5x284 ammo that was loaded two years ago and noticed a velocity increase of 30-40 FPS. My recently loaded ammo is fine. I wrote it off the higher velocity loads as lighting effects on my chronograph, but will now go back and double check it. There were no pressure signs and the loads gave the same POI and group size. If there is a change over time it's not good news.
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