Dillon SDB multiple problems

[jimbullet]

Hi

I have owned by SDB for over 10 years. Loading 40 S&W with Winchester 231 and 180gr TMJ projectiles.

 

This set up worked flawlessly until a few weeks ago checking all the settings and here is what I have found:

1. Powder dispensed has been inconsistent and it ranges +/- 0.2 grains either way - Having to load major power factor, I want to pass and dont want to be too over but I do put some leeway like targeting 175PF at least.

 

2. OAL slightly inconsistent - target is 1.158" but I find that this has been moving between 1.158 - 1.161. Should I be worried? This is with new brass

 

I have made sure that

- powder die is sitting all the way in so that it will flare the brass - but the brass doesnt really flare - starts at 0.419 and when I check its still the same but I can see the powder bar going all the way so should be dispensing full. I cannot adjust this anymore as the die is well seated in.

- the failsafe nut is snug and some tension on the spring when the press it at rest.

 

What am I doing wrong?

Any thoughts advice will be greatly appreciated

 

 

[Hi-Power Jack]

Powder usually varies by at least 0.1 grain so not sure 0.2 is much to worry about - very difficult to

accurately measure the difference between 7.0 and 7.1 grains with most reloading scales.

 

Same with OAL - that's not a huge difference ( ( 1.158" and 1.161").   

[jimbullet]

The problem is that when I chrono, the difference was the lowest being 896 fps to a high of 998 fps.

 

Admittedly the 8 rounds I chrono'd had a mix of new brass, once fired and old brass I have been using for 2 years now. Would it then be a factor of the brass and not actually the powder charge?

 

[Dirtchevy841]

I have a sdb and this is normal. Powder range from Dillon says .1-.2 variance and the oal is in range with mixed head stamp. If you want consistent oal to the T the same head stamp will get you that. 

[Hi-Power Jack]

6 hours ago, jimbullet said:

  the lowest being 896 fps to a high of 998 fps.

 

Might be other factors - do you throw the powder charge uniformly each time,

is your bench solid, perhaps there's a better powder for the application      

[perttime]

I had some belling issues just before the Connector Body Collar Assembly (#20642) broke. I lost the bracket that holds the Roller (#13793) on the bolt(s).

 

Have you checked your Seat Stem, that it is the right one for your bullet shape and hasn't accumulated much crud over the years?

[jhgtyre]

12 hours ago, jimbullet said:

The problem is that when I chrono, the difference was the lowest being 896 fps to a high of 998 fps.

 

Admittedly the 8 rounds I chrono'd had a mix of new brass, once fired and old brass I have been using for 2 years now. Would it then be a factor of the brass and not actually the powder charge?

Using brass with the same headstamp will help but there is a possibility that other factors are at play.  Did you weigh the projectiles?  You don't have to weigh them all but a sample of 20 or so might give you an idea of how consistent they are.  You might also measure the projectiles both for length and diameter.  Are these weights and measures consistent or are they all over the place?  Even really good bullets will have some variances.  Lastly you might want to check the load you are using.  Most powders are more consistent at one given charge weight than they are at another.  Maybe a little greater or lesser amount of powder will result in a better burn and lower deviation in velocity.

[jimbullet]

The projectiles are fairly consistent at 179.6 gr, 179.9 gr, 180.1 gr from a small sample I did. Diameter are consistent 0.401. Will have to check the length as that is something I havent thought about.

 

The seat stem, is that the seating die you mean? Yes its clean, I have put whisked a cotton buds through and only very minor dirt out of it and after two swabs, its pretty clean. 

 

Work bench - is that a factor? My workbench admittedly has some wobble, but how does that impact? 

[jimbullet]

On 8/26/2018 at 8:58 PM, Hi-Power Jack said:

Might be other factors - do you throw the powder charge uniformly each time,

is your bench solid, perhaps there's a better powder for the application      

 

I would like to think that I am throwing the powder consistently - What I mean is that I visually check that the powder bar goes all the way each time and that the crank handle goes all the way down.

 

 

[Hi-Power Jack]

4 hours ago, jimbullet said:

 

I would like to think that I am throwing the powder consistently - What I mean is that I visually check that the powder bar goes all the way each time and that the crank handle goes all the way down.

 

 

Also consistent speed  ….   going slower or faster can make a change also     

[perttime]

What powder are you using? What kind of granules? Have you changed powders?

 

Some powders measure better than others.

[jimbullet]

4 hours ago, perttime said:

What powder are you using? What kind of granules? Have you changed powders?

 

Some powders measure better than others.

 Winchester 231. They usually meter very well I would have thought. 

 

No I havent changed powder.

 

[jimbullet]

7 hours ago, Hi-Power Jack said:

Also consistent speed  ….   going slower or faster can make a change also     

 

This is the first time I heard this but what does speed of reloading gotta do with it? Powder gets into the powder charge bar (might be using a wrong terminology here) through gravity.

 

I doubt I will be fast enough that the powder has no time to come into the charger bar.

[perttime]

When I load, I tend to get a slightly high charge for the first one, if I take a break in the middle of loading. Maybe 0.1 or 0.2gr high for the first one, using Vihtavuori powders. I discard that one, and then I'm quite consistent until I need to top up or take another break.

[Hi-Power Jack]

1 hour ago, jimbullet said:

 

 what does speed of reloading gotta do with it?  

 

Not speed of Reloading   ...

 

The speed with which you pull down the handle (the force used).

 

If you pull slowly (less force) , you may get less powder fall into the charge bar,

and be different if you pull the handle quickly -   consistency of the pull could

cause some of your problem.

 

I also use a lot of WW231 - usually meters very well     

[jhgtyre]

3 hours ago, Hi-Power Jack said:

 

Not speed of Reloading   ...

 

The speed with which you pull down the handle (the force used).

 

If you pull slowly (less force) , you may get less powder fall into the charge bar,

and be different if you pull the handle quickly -   consistency of the pull could

cause some of your problem.

 

I also use a lot of WW231 - usually meters very well     

Really its the dwell time while the powder measure is open.  You want to pause, let the powder drop fully from the bar, and then push the handle back up.

[Hi-Power Jack]

4 hours ago, jhgtyre said:

Really its the dwell time while the powder measure is open.  You want to pause, let the powder drop fully from the bar, and then push the handle back up.

 

True, and also the sharp rap at the bottom will "shake" more powder out and into the charge bar.

 

Really two advantages of a uniform handle movement     

[dillon]

You should be flaring the case mouth at least .010" larger than the sized, unflared case mouth measures. Any variation in case length affects how far the powder bar travels. Be sure to start with the measure reasonably full, and throw and return 10-15 powder charges to settle the powder under the baffle before you begin weighing the charges..004" variation in overall cartridge length is actually very good. Don't worry about that at all.

[jimbullet]

Just an update, so it seems the square plastic (forgot the name for it) which rides on the powder bar has split and was fairly worn out. Thanks to Dillon for the replacement, now with it being new, it seems that my powder charge has become more consistent with no variance at all.