The 6UM

[khuber84]

6mm is like a disease

F yes it is

 

[Ryan Avery]

I just talked to ADG, and they will make more 6UM brass in early July.

6UM AMMO AND BRASS - Unknown Munitions

All products and prices below are for 50 rounds. All products use new 6UM head stamped ADG brass and premium powders and bullets. Your choice of bullet in loaded ammo including the 115 DTAC Nosering, 108 ELD-M’s, and more. Fire formed brass is processed and ready to load. 6UM-30 New ADG Brass as...

www.unknownmunitions.com

 

[TradLife406]

So besides supporting Roksliders, why the 6 UM vs a 6 Sherman variant? 6 max already has a 40 degree shoulder. The SST seems to come close as well.


Sent from my iPhone using Tapatalk

 

[wysongdog]

So besides supporting Roksliders, why the 6 UM vs a 6 Sherman variant? 6 max already has a 40 degree shoulder. The SST seems to come close as well.


Sent from my iPhone using Tapatalk

For me it’s the head stamped adg brass.

 

[IrkedCitizen]

For me it’s the head stamped adg brass.

Sherman cartridges have headstamped ADG brass too. They require being necked up or down to caliber though. You can only buy it from him and the same goes for dies and reamers.

 

[wind gypsy]

So besides supporting Roksliders, why the 6 UM vs a 6 Sherman variant? 6 max already has a 40 degree shoulder. The SST seems to come close as well.

Who’s koolaid you wanna sip?

 

[6.5x284]

So besides supporting Roksliders, why the 6 UM vs a 6 Sherman variant? 6 max already has a 40 degree shoulder. The SST seems to come close as well.


Sent from my iPhone using Tapatalk

I went with whatever platform I could get all my components in stock at once when I built a fast 6mm. Went with a 6SST since smith didn’t have a 6 Max reamer. Been an easy button for sure. I’d run whatever I could get 200 brass and dies for the quickest in a reamer my smith had on hand. They are all easy to load and deadly for a long ways out. UM is more readily available component wise then when I made mine and I’ve seen a few smiths with UM listed in their chamber list.


Sent from my iPhone using Tapatalk

 

[TradLife406]

I went with whatever platform I could get all my components in stock at once when I built a fast 6mm. Went with a 6SST since smith didn’t have a 6 Max reamer. Been an easy button for sure. I’d run whatever I could get 200 brass of the quickest in a reamer my smith had on hand. They are all easy to load and deadly for a long ways out.


Sent from my iPhone using Tapatalk

That's why I'm wondering. When I built the gun out as a 6.5 PRC I almost went 6.5 SST so I already have some brass.
Head stamped 6 UM Brass is only good if it's available but sizing down 6.5 saum adg brass ain't a big deal.


Sent from my iPhone using Tapatalk

 

[B23]

I'd like to see a pic of a piece of 6UM brass next to a 6.8 Western because they have to be very close to one another.

 

[RWT]

What does a 6 UM get me over a 6 PRC that doesn’t require fire forming? Is the 6PRC an easier build since it is a neck down and maybe trim of readily available brass?

Or did I just ask the A question of the day?

 

[PathFinder]

What does a 6 UM get me over a 6 PRC that doesn’t require fire forming? Is the 6PRC an easier build since it is a neck down and maybe trim of readily available brass?

Or did I just ask the A question of the day?

~150 fps or so. 6 UM is right on the max for case capacity in a 6mm bore, which means going bigger (WSM, 6-7PRC) gives rapidly diminishing returns. If you want an all out hotrod 6mm, the 6UM-40 is it. Yes, the 6 PRC is an easier build. Right now that mostly means that dies are easier to get, it also has a little easier brass availability.
Fire forming is literally the easiest part of brass prep if you do it without projectiles.

 

[huntnful]

What does a 6 UM get me over a 6 PRC that doesn’t require fire forming? Is the 6PRC an easier build since it is a neck down and maybe trim of readily available brass?

Or did I just ask the A question of the day?

It gets you about 200fps more with 5 more grains of N570.

 

[HighUintas]

Someone running the numbers on WEZ for hit probability between 6cm, 6prc, and 6um really helped me decide that I'm sticking with 243win or 6cm

 

[BBob]

I'd like to see a pic of a piece of 6UM brass next to a 6.8 Western because they have to be very close to one another.

Nearly identical in case capacity. There are at least a couple working on a 6 Western at the moment. A potential downside to starting with the 6.8 is fairly thick neck walls when sizing down.

 

[Axlrod]

What does a 6 UM get me over a 6 PRC that doesn’t require fire forming? Is the 6PRC an easier build since it is a neck down and maybe trim of readily available brass?

Or did I just ask the A question of the day?

Fire forming is just firing new brass in your gun the first time. It gives you a chance to:
Expand your brass to your chamber
See where you reach pressure with different loads
Allows your new barrel to break in & "speed up"
Gives you valuable trigger time behind your gun.

"Practice is a waste of time" said no intelligent person ever

 

[ThunderMug]

I’m a newb with the 6UM, but I hit pressure earlier than I expected and I’m pretty sure it was from a carbon ring. I scrubbed the chamber/throat with iosso bore cleaner and was able to work back up. I think my final load is going to be 68 grains of 570 with the dtacs, and that got me close to 3200 with an 18” barrel.

How far are you loading off the lands?

.006 off the lands. I am shocked that I am not able to get more velocity.
I just got done scrubbing my barrel after fire forming 110 pieces of brass. So I ASSume I don't have a carbon ring.

I am really surprised that I can't get better velocity.

 

[PathFinder]

.006 off the lands. I am shocked that I am not able to get more velocity.
I just got done scrubbing my barrel after fire forming 110 pieces of brass. So I ASSume I don't have a carbon ring.

I am really surprised that I can't get better velocity.

Is that supposed to be .006 off the lands or .060?

Sent from my Pixel 6 using Tapatalk

 

[ThunderMug]

HELP! I am lost...

I am not getting anywhere near the velocity that everyone else seems to be getting.

I built a 16" barrel and a 20" barrel 6UM

BOTH:
-6UM-40 degree.
-Bartlien barrels.
-Defiance actions.
-115 DTACs.
-215Ms.
-ADG 6UM brass.

I fire-formed 110 pieces of brass in each. Scrubbed the barrels with Witches Brew before I started working up a load for each rifle.
Bumped shoulder .0005 (I would have done more, but my mild fire form load was 57gr of H1000)
Neck tension .002
2.910 OAL.

I am getting around 2,960 FPS out of the 16" barrel with 65gr of N570 with very stiff bolt lift.

I am getting around 3,150 FPS out of the 20" barrel with 65gr of N570 with very stiff bolt lift.

I am getting heavy bolt lift starting at 63gr with light ejector marks on both rifles.

Everyone else seems to be getting wayyyyyy more velocity.

WTF?

 

[IrkedCitizen]

Are your DTACs coated?

 

[Montucky]

HELP! I am lost...

I am not getting anywhere near the velocity that everyone else seems to be getting.

I built a 16" barrel and a 20" barrel 6UM

BOTH:
-6UM-40 degree.
-Bartlien barrels.
-Defiance actions.
-115 DTACs.
-215Ms.
-ADG 6UM brass.

I fire-formed 110 pieces of brass in each. Scrubbed the barrels with Witches Brew before I started working up a load for each rifle.
Bumped shoulder .0005 (I would have done more, but my mild fire form load was 57gr of H1000)
Neck tension .002
2.910 OAL.

I am getting around 2,960 FPS out of the 16" barrel with 65gr of N570 with very stiff bolt lift.

I am getting around 3,150 FPS out of the 20" barrel with 65gr of N570 with very stiff bolt lift.

I am getting heavy bolt lift starting at 63gr with light ejector marks on both rifles.

Everyone else seems to be getting wayyyyyy more velocity.

WTF?

View attachment 883421

Did UM build these shortiies…..or did you diy…? I’m just curious….