Mec bushing chart compared to actual weights?

Els-

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Have a mec 600 and a 33 bushing that Ive been using with clays powder which normally dropped 18.4gr powder mec chart shows 18.6gr.

Switched to red dot powder and it drops 17.6 gr, mec chart shows it should be dropping 19.9gr.

Alliants 1 oz load at 1200 fps is 17.8gr 8000 psi, and 1310fps is 19.7 9400psi. In remington sts/gun club hull with cb1100-12 wad (which is what im using) So should be safe either way.

Weights were checked with a lyman accu touch 2000 that I use for all the brass reloading I do.

Curious if anyone else has similar readings and/or recommendations.
 
Use the MEC bushing chart as a guide only. I like to buy a bushing or two in either direction (eg. 31, 32, 33, 34, 35) and check the thrown charges. Could also be humidity as well, try throwing the same charge in the summer months.
 
Bushing charts are always close but not exact. Tolerances in manufacture make the bushings close but not perfect, differences between single stage and progressive presses, differences in operator technique and different lots of powder all add up to variations in what a chart says and what the bushing throws.
As said, they are a guide to get you close as a starting point and then you fine tune your selection with the scale from there.
 
I used to load shotgun on a 600 Jr, and I found my powder drops were more consistent if I kept the depriming and resizing steps separate from the rest.

In other words, I'd deprime and resize maybe 100 hulls first. That's the most violent part of the cycle and causes inconsistent vibration in the press.

The vibration is what causes powder to settle in the bushing, you want it to be as consistent as possible from load to load.

YMMV, of course.
 
Bushing charts are always close but not exact. Tolerances in manufacture make the bushings close but not perfect, differences between single stage and progressive presses, differences in operator technique and different lots of powder all add up to variations in what a chart says and what the bushing throws.
As said, they are a guide to get you close as a starting point and then you fine tune your selection with the scale from there.

How do you "fine tune" with bushings?? File some out or goop in some glue or something? I had what I thought were "issues" when I tried to set up an MEC for reloading 28 gauge - ended up getting rid of the fixed bushings and that bar, and installed a "universal" bar which had threaded adjustments for both the powder and shot cavities - I set them by repeated throwing and weighing on the scale that I use for reloading centerfire rifle. And, of course, never did adjust the cavities since then, because I have never changed the "recipe" - so likely could have spent the same amount of time fussing with fixed bushings and would likely be in the same situation today ...
 
How do you "fine tune" with bushings?? File some out or goop in some glue or something? I had what I thought were "issues" when I tried to set up an MEC for reloading 28 gauge - ended up getting rid of the fixed bushings and that bar, and installed a "universal" bar which had threaded adjustments for both the powder and shot cavities - I set them by repeated throwing and weighing on the scale that I use for reloading centerfire rifle. And, of course, never did adjust the cavities since then, because I have never changed the "recipe" - so likely could have spent the same amount of time fussing with fixed bushings and would likely be in the same situation today ...

You don't it is shotgun not rifle and doesn't have to be perfect
I check drops about every 25 when doing the 28ga but with the 9000g can do 400-500 a hour so a pain and also hate universal bars since they are worse in my experience with them but that is me
Steel reloading I don't use the bushing and weigh every one
Cheers
 
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You pick a bushing from the chart, check what it is dropping and get as close as you can and feel you need to by switching bushings. You can use glue/paint/tape or filing to adjust it closer if you really feel it is worth your time, but close is good enough in most shotshell loading. Universal charge bars are another option as well.
 
I had a Universal charge bar on a MEC but hated it as it was easily scored by hard shot and ignorant to adjust for powder.
 
Thanks for replys, I always resize/deprime and prime seperate. Scales also on a totally different bench not connected to the loading bench. And I never have much variation besides the odd 0.1gr.

As far as the fine tuning aspect, some of us are lucky enough to have a lathe and it isnt an issue. Others make do with a dremel, file, sand paper etc. I do have a bunch of other custom bushings. But Id assume its generally bad practice to go "close enough it'll be fine" just because its not a centerfire rifle cartridge. There are no signs of excessive pressure for shotshells like that you see in metallic reloading. The only sign you might sense is excessively loud report. The other sign might be the gun blowing up in your face.

In this case being within 0.2gr for one published powder and off by 2.3gr on another published powder is abit of a raise of concern to see if its wide spread, or just a variation of this specific batch of powder.
 
Negative, I dont personally have any powder inconsistency's. It will drop 18.4-18.5 gr clays all day long, and 17.5-17.6gr red dot all day long. The only variation is mec's reading for red dot compared to mine.
 
Negative, I dont personally have any powder inconsistency's. It will drop 18.4-18.5 gr clays all day long, and 17.5-17.6gr red dot all day long. The only variation is mec's reading for red dot compared to mine.

You will if you reload enough and I assume you are measuring after a complete machine reloading cycle?? A lot of the difference depends on how one operates the loader. Single stage requires 6 pulls of the handle for a complete cycle and packs the powder tighter in the bushing. An operator that is more aggressive will also pack the bushing tighter.

Also you will never blow up a gun with 2 extra grains of powder in shotgun and lead shot not even 5x that. Reloading steel the pressures get up there so those I watch closely and do those one at a time

Also not my words but agree 100%
Mec Bushing charts can be off a fair bit always on the low side but it kind of depends on what you mean by "off." The problem is that we are using a volumetric measure and expecting to get a consistent weight. If the density of the material being measured is consistent, things are good. If the density varies, the weights dropped will vary. A lot (but not all) popular powders are flakes. When subject to more or less vibration they pack down more or less. The density changes. The volume of the bushing is the same, but the weight of the powder packed into it changes. You actually can get many flake powders to drop real close to what the charts say. IF, the press is mounted loosely and you really slam it up and down a few times between drops. Bolt it down solidly to a solid bench and operate smooth and gently and you might have to use one to two bushings up from what the chart says.


Cheers
 
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I've always found my Mec Jr to throw slightly underweight, by a bushing size or two. I've always attributed this to the fact that MEC has probably put in some "margin" in their sizings. I've started to weigh my charges instead of using bushings, only because I got tired of collecting and swapping bushings.
 
I remember years ago asking Mec and got something like this back

Mec Bushing charts are a guide only and a rough starting point and no replacement for a scale . MEC is on the side of caution when it comes to powder.
 
Great topic right now. My 32 bushing throws an average of 18.2 grains of red dot on my 600 mec JR (over what the chart states). I just got my brother a single stage Mec 600. The 32 bushing it came with throws 20 grains average. Wow. We went to a bar that it came with, with integral 31 bushing and it throws an average of 18.0. ALWAYS double check them in each press.
 
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Operator technique is a very important variable. If I have a small batch of shells to load with a slightly undersize bushing, I sometimes bump the handle twice just to settle a bit more powder into the bushing, then check on a scale after a full loading cycle. I can change the charge by half a grain with this technique.
 
Great topic right now. My 32 bushing throws an average of 18.2 grains of red dot on my 600 mec JR (over what the chart states). I just got my brother a single stage Mec 600. The 32 bushing it came with throws 20 grains average. Wow. We went to a bar that it came with, with integral 31 bushing and it throws an average of 18.0. ALWAYS double check them in each press.

This is the info I was looking for, for the most part. Thanks.
 
Like the powder manufacturer's have always said since I pulled my first handle doing shotgun with MEC over 50 years ago not sure what is new here?? In those days the bar was the bushing and the entire bar had to be changed imagine

Powder Bushings Charts

A reloading scale is required to check the nominal weight of a powder charge. Powder bushings can vary in the charge weight they drop and could vary as much as several grains under certain conditions. Powder density, moisture content, and loading technique can cause a variation from the bushing weights listed on the charts. Also, the loading machine vibration affects charge weights. A complete loading cycle should be completed to assure an average powder charge weight. The information in these bushing tables has been supplied by the reloading machine manufacturers and is not a reloading recommendation or a result of Alliant’s testing
 
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Operator technique is a very important variable. If I have a small batch of shells to load with a slightly undersize bushing, I sometimes bump the handle twice just to settle a bit more powder into the bushing, then check on a scale after a full loading cycle. I can change the charge by half a grain with this technique.

Agree 100%
 
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