The 6UM

Joined
Jul 20, 2019
Messages
464
Location
A Free and Sovereign Nation
I ordered the dies back in August from UM, I don't think ordering them from Whidden directly would get them to me faster. However, I've pretty much decided to bail on the 6UM and go 6 SAUM.

I started the project trying to get a DTAC going over 3200 since I couldn't get there in my .243 AI. Looks like the 6 SAUM will easily do what I want and I can use the same dies with a different neck bushing if I decide to do another SAUM down the road (I think 25 SAUM would be fun and I already have a 6.5).

As far as brass I thought the 6 UM brass was just a 6.5 SAUM necked down to 6mm, I'd bet that's the case as that's a relatively simple change to the process compared to a whole new set of case dimensions. A run through the sizing die would fix it anyway.

The whole idea of the 6UM was great when it first came out, buy the reamer (which was not proprietary at first) and take it to your local gunsmith and have them cut a barrel. Now that it's all proprietary it's a tougher proposition.
There have been some changes to the first released reamer. Clickers were developing in fired brass past the .200" line of the chamber, so they widened the reamer .002" to solve the problem.
 

Elkster23

FNG
Joined
May 26, 2019
Messages
1
I ordered the dies back in August from UM, I don't think ordering them from Whidden directly would get them to me faster. However, I've pretty much decided to bail on the 6UM and go 6 SAUM.

I started the project trying to get a DTAC going over 3200 since I couldn't get there in my .243 AI. Looks like the 6 SAUM will easily do what I want and I can use the same dies with a different neck bushing if I decide to do another SAUM down the road (I think 25 SAUM would be fun and I already have a 6.5).

As far as brass I thought the 6 UM brass was just a 6.5 SAUM necked down to 6mm, I'd bet that's the case as that's a relatively simple change to the process compared to a whole new set of case dimensions. A run through the sizing die would fix it anyway.

The whole idea of the 6UM was great when it first came out, buy the reamer (which was not proprietary at first) and take it to your local gunsmith and have them cut a barrel. Now that it's all proprietary it's a tougher proposition.
I jumped on the wagon bought the dies ordered a reamer. I have the rifle finished but didn't have brass. I ended up going with 6.5 saum adg brass. I'm still waiting on my "6um" brass I was told would be here in October, then first part of December. Still waiting. While I have shot the rifle and got a load worked up. It's shooting the dtac at 3250 in an 18in 1-7.5 twist. If I had to do it all again I'd go the 6 max from sherman wildcats. They have everything in stock, dies, brass, and reamer. Since I bought the reamer I'll stay with the 6um for now.
 
Last edited:

khuber84

WKR
Joined
Jun 6, 2019
Messages
1,727
There have been some changes to the first released reamer. Clickers were developing in fired brass past the .200" line of the chamber, so they widened the reamer .002" to solve the problem.
0.552 is the best dimension for Saum chambers at the 200 line, and a good tight sizing die like the micron, or matchmaster FL bushing die. The other option, buy Cortinas small base mandrel die, which is cheap, and use that to size the base tighter after or before FL sizing.
 

The Fish Box

Lil-Rokslider
Joined
Aug 31, 2020
Messages
102
The 6UM might at well be a unicorn at this point, I have been waiting for my rifle since February almost starting to get impatient. Hope to at least have the whiden dies when the gun shows up and then neck down the 6.5 sauna brass until my 6UM brass shows up.
 
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