The 6UM

[Clarktar]

ADG is saying October for the brass

The dies will be here late July early August. Preorder or you won’t get one.

Preordered. Thanks.

 

[khuber84]

ADG is saying October for the brass

The dies will be here late July early August. Preorder or you won’t get one.

Deets on the brass? 30° shoulder? 6mm neck? I remember adg making Sherman brass, and the only diameter they'd make a 40° was 7mm or larger. I shoot standard 6saum, so 30° and 6mm neck would do me just fine!

 

[Arithson]

Good to know. I have a 300 Win Mag Tikka that I am constantly fighting the urge to change to something more exotic. I was thinking of keeping my eyes open for a 243 barrel for something like this.

I have one that will be twisted off in a few weeks if you’re interested

 

[JBradley500]

I might be if it's fast twist, fluted, and stainless. I have a "type".

 

[Tx_300wsm]

After debating for the last year I finally caved and ordered dies and brass today. Gonna buy a UM tikka prefit and Rostock when funds allow. Have a Scythe Ti in jail. Hoping to get everything put together around December/January and might get to try it out on some hogs and whitetail before the season ends.

I’m thinking of doing an 18” barrel, but am undecided on contour and twist. Most of my hunting is in Texas and Louisiana, barely above sea level, occasionally go out west. Right now my thought is to use the 108/109 eldm. I’m thinking an 8 twist would be fast enough?

 

[Tx_300wsm]

The wait begins! Went ahead and put in an order for a Rostock and an ace prefit. Ended up doing an 18” 8 twist #3 contour.

Has anyone used H4831 in the 6um? I know it’s going to be too fast but I plan on using it at least for my fire form loads, curious what kind of velocity to expect with it.

 

[khuber84]

The wait begins! Went ahead and put in an order for a Rostock and an ace prefit. Ended up doing an 18” 8 twist #3 contour.

Has anyone used H4831 in the 6um? I know it’s going to be too fast but I plan on using it at least for my fire form loads, curious what kind of velocity to expect with it.

55ish grains should net you somewhere 2900-3000 I'd think.

 

[Ryan Avery]

The RokStoks just looks better with a 6UM in them.

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[mtnbound]

What has the velocities been out of the 18” barrel?


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[bojangles808]

A 1-7” twist at UM speeds is over 320,000 rpm. A 1-7.5” or better a 1-8” twist will keep RPM below 300k.

Is going over 300k a little but at 303,000 a big deal with a 7twist or you wouldn't worry about it with 108 eldm (6cm not 6um).

 

[Formidilosus]

Is going over 300k a little but at 303,000 a big deal with a 7twist or you wouldn't worry about it with 108 eldm (6cm not 6um).

No it is not. A 1-7” twist with a 6cm is just fine.

 

[The Fish Box]

Deets on the brass? 30° shoulder? 6mm neck? I remember adg making Sherman brass, and the only diameter they'd make a 40° was 7mm or larger. I shoot standard 6saum, so 30° and 6mm neck would do me just fine!

@Ryan Avery any update on what the final dimensions of the brass coming from ADG, I heard that it it was still going to be a neck down and fireform operation. Essentially 6.5 Saum headstamped 6UM.

 

[Ryan Avery]

The last word from ADG was 6mm necks, but it will need Fireforming. But that is not solid.

October timeframe.

 

[Tx_300wsm]

Well, my barrel just showed up! Is there any update on when dies will ship?

 

[sturner88]

Trying to understand the gains here, maybe someone can explain this to me like i’m 5.

Background—i’ve already been convinced from this forum and my real world experiences that 77tmk 223 and heavier 22cm is absolutely lethal on medium game but I do keep a larger rifle for specific hunts where i’m required to use one.

I have an accurate and to-date reliable 6.5prc shooting 147eldm at 2900fps. Are there truly nominal gains switching to a 6um?

From an outsiders perspective I would be switching to a cartridge I have to fireform, giving up a ~.700bc for a .535bc, recoil seems to be close to a wash, would gain just a bit in flatness of trajectory but within 500 yards… I really don’t see the benefits?

For the time and money it would take to source a rifle and build ammo, I could just practice an absolute boatload with my 6.5 PRC. What am I missing?

 

[Axlrod]

Trying to understand the gains here, maybe someone can explain this to me like i’m 5.

Background—i’ve already been convinced from this forum and my real world experiences that 77tmk 223 and heavier 22cm is absolutely lethal on medium game but I do keep a larger rifle for specific hunts where i’m required to use one.

I have an accurate and to-date reliable 6.5prc shooting 147eldm at 2900fps. Are there truly nominal gains switching to a 6um?

From an outsiders perspective I would be switching to a cartridge I have to fireform, giving up a ~.700bc for a .535bc, recoil seems to be close to a wash, would gain just a bit in flatness of trajectory but within 500 yards… I really don’t see the benefits?

For the time and money it would take to source a rifle and build ammo, I could just practice an absolute boatload with my 6.5 PRC. What am I missing?

Some of it depends on how far your max range is.
On the fire forming issue, in my experience all new brass benefits from fire forming, no matter the cartridge. And all new barrels speed up a bit in the first 100-150 rounds. Fire forming also provides time to find "pressure" or max loads with different bullet/powder combos and gives you trigger time on a new rifle. So if fire forming is too much effort, the best thing to do is shoot factory chamberings with factory ammo.

 

[atmat]

Some of it depends on how far your max range is.
On the fire forming issue, in my experience all new brass benefits from fire forming, no matter the cartridge. And all new barrels speed up a bit in the first 100-150 rounds. Fire forming also provides time to find "pressure" or max loads with different bullet/powder combos and gives you trigger time on a new rifle. So if fire forming is too much effort, the best thing to do is shoot factory chamberings with factory ammo.

You fireform standard cartridges?

 

[mullmann]

You fireform standard cartridges?

Every piece of brass forms to the chamber. That’s why you typically don’t need to bump shoulders back right away. I have had new pieces of brass in a box that had to be sized before firing due to not fitting in the chamber and others in the box got two firings before needing shoulder bump.

 

[Axlrod]

You fireform standard cartridges?

Well everyone does, they may not call it that. Fire forming is just the process of firing new brass in your chamber. After several firings the brass is a little bit larger than your chamber, so the shoulder needs setting back

 

[sturner88]

Some of it depends on how far your max range is.
On the fire forming issue, in my experience all new brass benefits from fire forming, no matter the cartridge. And all new barrels speed up a bit in the first 100-150 rounds. Fire forming also provides time to find "pressure" or max loads with different bullet/powder combos and gives you trigger time on a new rifle. So if fire forming is too much effort, the best thing to do is shoot factory chamberings with factory ammo.

i’m all for finding any “edge” I can get via different cartridges, equipment etc. But it seems like a lot of work for marginal gains when better gains could be made by more practice time. Then again, the 6um may be targeted more towards a range I currently have no business shooting at or a crowd that is significantly better calling wind/executing field shots than I am.