RCBS Powder Thrower

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I picked up a used thrower and it looks like it is near mint condition. I assembled it following the directions and tried to use it with IMR 3031. It would throw very inconsistent weights, sometimes dropping powder when thrown and other times throwing powder on the return as well. I ran about 1Lb through it just to be sure, weighing every throw. It would do 5 -6 good ones then that many that were either way above or way below weight. I also tried the handle mounted on left and right sides.

Any thoughts?

Geoff
 
Sounds like what is happening is the powder is hanging up in the drop tube. When you rotate the handle, allow it to bump at the end of its movement on the fill stroke and the dump stroke.

IMR 3031 is an extruded powder, and although it is finer than some extruded powders, 3031 still will not feed as consistently as ball powder. Ball powder is the only powder I will throw a number of charges with, without weighing every charge.

As the powder height in the reservoir drops you can expect changes in the weight of your thrown charges. Powder measures as a rule measure more consistently when you operate them in exactly the same way from throw to throw. If you allow the tumbler to bump at the end of its travel every time, your thrown charges will be more consistent, but not so consistent with extruded powder that you don't have to weigh each charge.
 
Another factor is that you will cut one or more strands of extruded powder with almost every stroke. This jars the measure, giving a difference to each dump depending on how consistent your stroke is and how much is cut. Also depending on how solidly your measure is mounted.
I use an RCBS measure for all ball powders and a Lee for extruded. The Lee does not cut granules and is therefore much more accurate.
On the other hand the Lee has gummed up with a couple of ball powders when it wasn't set up perfectly.
 
With extruded powders I just use my RCBS Uniflo to get close ( a little under) and use a trickler to top off to an accurate weight. This is still a lot faster than hand weighing the entire load. With ball or flake powders you should have no problem if you are consistent with how hard you throw each stroke and the volume of the powder in the storage tube. Try keeping between 3/4's and 1/4 full as more or less powder seems to mildly affect loads in my experience.
 
Boomer's right--you've got powder in the drop tube. Check to make sure you don't have the 'narrow' tube installed; that one only seems to work with fine ball powder, at least for me.

IMR 3031 is a bit on the long side, I have trouble getting it to meter accurately through my RCBS as well, where shorter-grained powders do just fine.
 
I read your thoughts and decided to call RCBS coustomer service. They stated that the powder throw does not work well with extruded powders and should only be used with ball and flake powders. Confirms what you experienced guys knew :)

So if we (the wife and I) want to use the throw we need to work all all new loads for all our guns - worse things to be doing I would say.

Thanks
Geoff
 
Ruger No.1 said:
With extruded powders I just use my RCBS Uniflo to get close ( a little under) and use a trickler to top off to an accurate weight. This is still a lot faster than hand weighing the entire load. With ball or flake powders you should have no problem if you are consistent with how hard you throw each stroke and the volume of the powder in the storage tube. Try keeping between 3/4's and 1/4 full as more or less powder seems to mildly affect loads in my experience.
Click to expand...

I do it the same way. RCBS recently released a trickler that attaches directly to the uniflo, I've got one. Speeds up the process a little more.
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I haven't had a problem throwing consistent charges of IMR4064 in my RCBS thrower. It will cut grains, but I've never had a problem with the weight. I never use my trickler. The only issue that I notice is that no matter what powder you use, the charge weights tend to get a little lighter as the powder reaches the bottom of the
reservoir (say 1/2 grain at the extreme). The easy solution is to keep the powder topped-up as it's consumed. I weigh about every tenth charge - no worries. Perhaps it needs a cleaning? Sometimes dust-bunnnies can gum up the works.
 
OneBarfly said:
I haven't had a problem throwing consistent charges of IMR4064 in my RCBS thrower. It will cut grains, but I've never had a problem with the weight. I never use my trickler. The only issue that I notice is that no matter what powder you use, the charge weights tend to get a little lighter as the powder reaches the bottom of the
reservoir (say 1/2 grain at the extreme). The easy solution is to keep the powder topped-up as it's consumed. I weigh about every tenth charge - no worries. Perhaps it needs a cleaning? Sometimes dust-bunnnies can gum up the works.
Click to expand...

I used an old Lyman 55 (with the little "knocker") for decades...honest! Never had a problem with it except the small capacity. Next up was the Lee, and I loved it until I found that it had to be dissmantled for a cleanup after a lot of use with ball powder. And again, small capacity.
The RCBS gave me problems from day one with extruded powder. In light of what you and others say I'm going to strip the it, examine everything, and try again.
Your comments about hopper level and weight are interesting: With the Lyman the charges would get marginally heavier as the level went down. With the Lee it doesn't make much if any difference from full to near empty.
 
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