Lee autodrum and a tooth brush

[martin_b]

Gents,  the two groups below were shot with rounds made using the Lee Autodrum.  the first set without the toothbrush mod the second with.

Number 2 on the first set could have been my fault. and the breeze was a bit gusty on the second set but brushing seems to help!

Gun was a 6.5CM @ 900 yards on Stix.

[Triffid]

Nice shooting.

I've Googles the AutoDrum toothbrush mod, but cant find anything, so please tell more. . .

I'd really like to get the Autodrum to be more consistent and I've done quite extensive trials using different baffles and throwing techniques. But using N140, the best I can manage is a 0.5gn extreme spread (charge weight 44gn, n=20). Which models to about 25fps difference in MV using Quickload. Which models to a 9" vertical spread at 1000X using Shooter ballistic app.

Triffid

[martin_b]

The idea is you buy the cheapest electronic toothbrush you can find (think Ebay&China). remove/cut the head off then tie-wrap it as tight as possible to your autodrum ( it also should work with anything similar). Then turn it on while you load.

The idea is the vibrations stop kernals sticking internally and help granular powder to pack evenly. (I was using RS62)

I dont think it will ever be consistant enough for benchrest, but it good enough for what I do and its a damn sight faster.

[martin_b]

just to be clear.. cut the head off and throw it away, tie-wrap the rest of the toothbrush to the powder thrower.  😀

 

[Triffid]

Ah, thanks. I'll give that a go. I've got lots of data to compare it with.

Triffid

[Kipper]

I just use a cheap toothbrush and "masage" the cases in the tray before seating 

[Andrew]

20 hours ago, Triffid said:

Nice shooting.

I've Googles the AutoDrum toothbrush mod, but cant find anything, so please tell more. . .

I'd really like to get the Autodrum to be more consistent and I've done quite extensive trials using different baffles and throwing techniques. But using N140, the best I can manage is a 0.5gn extreme spread (charge weight 44gn, n=20). Which models to about 25fps difference in MV using Quickload. Which models to a 9" vertical spread at 1000X using Shooter ballistic app.

Triffid

I doubt if you'd see that in the real world of actual shooting.~Andrew

[Triffid]

19 hours ago, Andrew said:

I doubt if you'd see that in the real world of actual shooting.~Andrew

You might well be right, it's using the results from one computer model (Quickload) as the input into a second (Shooter ballistic app). The chronograph will soon tell!

However I'd like to get my extreme spreads down. And as charge weight variation is within my control, it seems like one of the more straightforward ways of doing this.

Triffid 

[Andrew]

3 hours ago, Triffid said:

You might well be right, it's using the results from one computer model (Quickload) as the input into a second (Shooter ballistic app). The chronograph will soon tell!

However I'd like to get my extreme spreads down. And as charge weight variation is within my control, it seems like one of the more straightforward ways of doing this.

Triffid 

I understand. I'm just saying that you shouldn't' hang your hat on these numbers.

Neck tension and (resulting) ignition have more influence: Intangibles that QL can't model which is why I'm suggesting that you won't see this in the open air of the range.  Computer modeling too often considers things like component weight and case capacity as a constant which, unless you are sorting your identically prepped cases by weight, and bullets by weight and diameter, it isn't.  ~Andrew