Chargemaster Link problem

[DonkeyHote]

I never considered my RCBS Chargmaster accurate enough, +-.1grain at best.
Honestly, I tried many scales to end up with the 2 I have , one to throw and the second to fine tune.. Using a second scale for fine tuning to +-.02 grains about 1 kernel of Varget ,
If your load window is wide , regarding POI than staying in the middle could work, if all else remains consistent.

 

[hogpatrol]

Whitetail deer hunting. My first loads was 10 rounds. All loaded with manual powder drop. The last were 20 rounds made with the Chargemaster. That was all the bullets I had. The powder, and primers were all from the same lots. Used the same R-P brass (All processed as I usually do). So the only variation was the fact that the powder load was -.1gr. I am still scratching my head on how the groups went from great to lousy with that little of a powder variation.

Have you checked bases, rings, and the scope? If the bases and rings are ok, it might be a help to try another scope.

 

[RegionRat]

Whitetail deer hunting. My first loads was 10 rounds. All loaded with manual powder drop. The last were 20 rounds made with the Chargemaster. That was all the bullets I had. The powder, and primers were all from the same lots. Used the same R-P brass (All processed as I usually do). So the only variation was the fact that the powder load was -.1gr. I am still scratching my head on how the groups went from great to lousy with that little of a powder variation.

There are a few possibilities.

One is that the first impression was just incomplete and fooled you. It happens a lot that folks think they are in tune, only to find out they really were not. Within that cause can be under-sampling, as well as temp and water sensitivity affecting a narrow node. It happens that some nodes are too narrow and won't repeat unless everything is perfect, which they seldom are.
Also, the condition of the barrel can change. There is wear and fouling states that can affect tune.

My suspicion is that the tune was not very wide to begin with and you caught a small sample on the edge. When the sample grew and the situation shifted, the group fell apart.

A CM is only good for so much, so you would want to know 1) the water content of the powder is always the same, 2) the temperature must be taken into account, and 3) the condition of the gun must be accounted for as well. 4) the tune node must be forgiving to within more than the capability of the CM charge, so figure on at least 0.5 grain range when all other factors are taken into account at random.

Many folks get 1 - 1.5 MOA from hunting rigs that they thought were tight, so keep at it but keep an open mind. It takes more testing and experience to know if the tune is forgiving within 0.3 - 0.5 grains, and work to keep it there with pre-loaded ammo. YMMV

 

[J_idaho]

My chargemaster has a feature that auto zeroes up to .2 grains. So that means if you have .1 drift it zeros out. There is no end to how many times it can do this. So if you bump kernels into tray it will zero before load starts. Main problem is temp stability to control drift or any small air flow like a furnace. I started writing the tray weight on bottom of tray to compare to the negative number when you lift the tray after every charge. I will say without modification to feed tube it was very hard to get consistent loads. Because you have a point where it gets rounded off from .01-.09 as mentioned by someone earlier. If you can slow the kernels down it will always break closer to the same number. Good luck. I check by weighing out 10 loads and weighing overall this should tell you how far off you are on an average.

 

[762willdo]

How long have the rounds been loaded? is the “weld” causing the problem ?

 

[Propbndr]

Have you checked bases, rings, and the scope? If the bases and rings are ok, it might be a help to try another scope.

I honestly did not consider the rifle as a possible source of the problem. The bases and rings are in good shape. The scope was bought at the same time I bought the rifle. I could swap it out for my slug gun scope. That is the only other one I have that handle recoil.

How long have the rounds been loaded? is the “weld” causing the problem ?

The rounds were loaded just before Christmas so, not old at all. I am not sure What “the weld” you are talking about.

 

[762willdo]

Copper jacket will weld to the brass case over time

 

[Propbndr]

Copper jacket will weld to the brass case over time

I have never looked for it. It must take a long time for that to happen.

 

[Homerange]

I have never looked for it. It must take a long time for that to happen.

Yes and no.
Some benchrest guys load long and seat to depth the night before a match.
Search the forum for Cold Weld for more info.
Yes, it's a real thing !

 

[M-61]

I honestly did not consider the rifle as a possible source of the problem.

Of course not.
And 1/10 of a grain will turn a 1/2 moa into a 1.5 in a hunting rifle.
Not a chance

 

[Propbndr]

An update.

I heard back from RCBS. They sent me a troubleshooting guide. It was no help. Most of it was for the 1500. A few steps were generic.

Now for the weird. I tested it with 2 ball powders and 2 stick powders. Win 748, BL-C2, Varget and IMR-4064. It threw 20 perfect charges for each. I ran some H4831SC again. All 20 charges were -.1gr. Go figure. I guess I will just have to add .1 to my load whenever I use a SC type powder.