The 6UM

PathFinder said:
Got my 24" Bartlein 7.5tw 5R back from UM on Saturday. It's looking really promising with N570, charge workup was under 1 MOA for 5 shots. I'll update the reloading thread with data this week once I finish workup. There will probably be a "cruise control" load with H1000 and a fairly near max load with N570 that's over 3400 well before the barrel is broken in. Looks like the 24" is running 50-75 fps faster than the 22" +P barrel did.
Click to expand...
Why the new barrel? Just wanting another or was the Osprey giving you trouble?
 
Tullis94 said:
Why the new barrel? Just wanting another or was the Osprey giving you trouble?
Click to expand...
Something happened with the Osprey...I'm pretty sure it was my fault.
It shot well out of the gate. I did a bare minimum load development because UM fire formed 50 brass for me and I didn't have my dies yet. So I only had 50 brass to develop a load, verify drops, and hunt for a month. At the end of that month I shot a few more of those and some standard fire form loads on paper. It was still shooting well. 3/4 MOA with N570/DTACS and 1 MOA with fire form loads (55 7828 SSC and 105 Hybrids).
Next I fire formed 100 brass with Titegroup and no projectile or filler. At that point I started full load development and it never shot better than 1.5 MOA after. UM borescoped the barrel and it was fire cracked 4" down the throat at 196 rounds + 100 fireformed without projectiles. The throat was more worn than Ryan's at 700 rounds.

It's one of two things; either the fire forming without bullets killed the throat or the Osprey blank couldn't handle the hotrod cartridge. PVA said that fire forming that way is like sandblasting at over 4k fps, and I think they're probably correct. That's exactly when the accuracy went to hell. Ryan's barrel lasted as long as was predicted so I think my barrel was definitely an anomaly. I'm sure there will be more PVA barrels out in the wild, they have a reamer available for prefits now. My guess is that they'll be just fine with normal use.

Long story short, I'd recommend fire forming with cheap 100 gr soft points and 55 grains of 7828 SSC. Unless you have a fire forming barrel like I now do, in which case the Titegroup method is very quick and economical. I've updated the reloading thread with that information. For anyone dedicated to using the 6 UM for a while I'd recommend finding a shot out 6mm blank to use as a fire form barrel. They should be plentiful with all of the match 6mms out there today and will allow you to fire form as many brass as you want without it eating up barrel life.

Whether or not a +P is a good idea remains to be seen. It definitely allowed higher powder charges and lower peak pressures.

UM was great to deal with through all of the issues I made for myself. Very responsive and right on top of things, Blaine made sure everything got figured out ASAP. PVA was responsive and helpful as well.
 
PathFinder said:
Something happened with the Osprey...I'm pretty sure it was my fault.
It shot well out of the gate. I did a bare minimum load development because UM fire formed 50 brass for me and I didn't have my dies yet. So I only had 50 brass to develop a load, verify drops, and hunt for a month. At the end of that month I shot a few more of those and some standard fire form loads on paper. It was still shooting well. 3/4 MOA with N570/DTACS and 1 MOA with fire form loads (55 7828 SSC and 105 Hybrids).
Next I fire formed 100 brass with Titegroup and no projectile or filler. At that point I started full load development and it never shot better than 1.5 MOA after. UM borescoped the barrel and it was fire cracked 4" down the throat at 196 rounds + 100 fireformed without projectiles. The throat was more worn than Ryan's at 700 rounds.

It's one of two things; either the fire forming without bullets killed the throat or the Osprey blank couldn't handle the hotrod cartridge. PVA said that fire forming that way is like sandblasting at over 4k fps, and I think they're probably correct. That's exactly when the accuracy went to hell. Ryan's barrel lasted as long as was predicted so I think my barrel was definitely an anomaly. I'm sure there will be more PVA barrels out in the wild, they have a reamer available for prefits now. My guess is that they'll be just fine with normal use.

Long story short, I'd recommend fire forming with cheap 100 gr soft points and 55 grains of 7828 SSC. Unless you have a fire forming barrel like I now do, in which case the Titegroup method is very quick and economical. I've updated the reloading thread with that information. For anyone dedicated to using the 6 UM for a while I'd recommend finding a shot out 6mm blank to use as a fire form barrel. They should be plentiful with all of the match 6mms out there today and will allow you to fire form as many brass as you want without it eating up barrel life.

Whether or not a +P is a good idea remains to be seen. It definitely allowed higher powder charges and lower peak pressures.

UM was great to deal with through all of the issues I made for myself. Very responsive and right on top of things, Blaine made sure everything got figured out ASAP. PVA was responsive and helpful as well.
Click to expand...
Do you have a barreled action just to fire form? Or do you take the barrel on/off from your action?
Thanks
H
 
PathFinder said:
Something happened with the Osprey...I'm pretty sure it was my fault.
It shot well out of the gate. I did a bare minimum load development because UM fire formed 50 brass for me and I didn't have my dies yet. So I only had 50 brass to develop a load, verify drops, and hunt for a month. At the end of that month I shot a few more of those and some standard fire form loads on paper. It was still shooting well. 3/4 MOA with N570/DTACS and 1 MOA with fire form loads (55 7828 SSC and 105 Hybrids).
Next I fire formed 100 brass with Titegroup and no projectile or filler. At that point I started full load development and it never shot better than 1.5 MOA after. UM borescoped the barrel and it was fire cracked 4" down the throat at 196 rounds + 100 fireformed without projectiles. The throat was more worn than Ryan's at 700 rounds.

It's one of two things; either the fire forming without bullets killed the throat or the Osprey blank couldn't handle the hotrod cartridge. PVA said that fire forming that way is like sandblasting at over 4k fps, and I think they're probably correct. That's exactly when the accuracy went to hell. Ryan's barrel lasted as long as was predicted so I think my barrel was definitely an anomaly. I'm sure there will be more PVA barrels out in the wild, they have a reamer available for prefits now. My guess is that they'll be just fine with normal use.

Long story short, I'd recommend fire forming with cheap 100 gr soft points and 55 grains of 7828 SSC. Unless you have a fire forming barrel like I now do, in which case the Titegroup method is very quick and economical. I've updated the reloading thread with that information. For anyone dedicated to using the 6 UM for a while I'd recommend finding a shot out 6mm blank to use as a fire form barrel. They should be plentiful with all of the match 6mms out there today and will allow you to fire form as many brass as you want without it eating up barrel life.

Whether or not a +P is a good idea remains to be seen. It definitely allowed higher powder charges and lower peak pressures.

UM was great to deal with through all of the issues I made for myself. Very responsive and right on top of things, Blaine made sure everything got figured out ASAP. PVA was responsive and helpful as well.
Click to expand...

Your barrel was rough, and it looked like peeling paint four inches down the barrel. Can wait to see how your new barrel does!

I finally gave the original 6UM to UM for a dedicated FF barrel. It had 720 rounds on it and still was shooting well, but they were in desperate need of it. Many of them are being built right now at UM and other gunsmiths. Awesome stuff. I should have my short barrel 6UM up and running within two weeks. Kurt from Stone Glacier just had one built at UM. Form is having one built soon. If you are reading this, you need one too. :) Head-stamped brass is the goal!!
 
Ryan Avery said:
Your barrel was rough, and it looked like peeling paint four inches down the barrel. Can wait to see how your new barrel does!

I finally gave the original 6UM to UM for a dedicated FF barrel. It had 720 rounds on it and still was shooting well, but they were in desperate need of it. Many of them are being built right now at UM and other gunsmiths. Awesome stuff. I should have my short barrel 6UM up and running within two weeks. Kurt from Stone Glacier just had one built at UM. Form is having one built soon. If you are reading this, you need one too. :) Head-stamped brass is the goal!!
Click to expand...
Head stamped brass would be a game changer.
 
Ryan Avery said:
Your barrel was rough, and it looked like peeling paint four inches down the barrel. Can wait to see how your new barrel does!

I finally gave the original 6UM to UM for a dedicated FF barrel. It had 720 rounds on it and still was shooting well, but they were in desperate need of it. Many of them are being built right now at UM and other gunsmiths. Awesome stuff. I should have my short barrel 6UM up and running within two weeks. Kurt from Stone Glacier just had one built at UM. Form is having one built soon. If you are reading this, you need one too. :) Head-stamped brass is the goal!!
Click to expand...

Headstamped fully formed brass or headstamped saum brass like the Sherman’s?


Sent from my iPhone using Tapatalk
 
PathFinder said:
Something happened with the Osprey...I'm pretty sure it was my fault.
It shot well out of the gate. I did a bare minimum load development because UM fire formed 50 brass for me and I didn't have my dies yet. So I only had 50 brass to develop a load, verify drops, and hunt for a month. At the end of that month I shot a few more of those and some standard fire form loads on paper. It was still shooting well. 3/4 MOA with N570/DTACS and 1 MOA with fire form loads (55 7828 SSC and 105 Hybrids).
Next I fire formed 100 brass with Titegroup and no projectile or filler. At that point I started full load development and it never shot better than 1.5 MOA after. UM borescoped the barrel and it was fire cracked 4" down the throat at 196 rounds + 100 fireformed without projectiles. The throat was more worn than Ryan's at 700 rounds.

It's one of two things; either the fire forming without bullets killed the throat or the Osprey blank couldn't handle the hotrod cartridge. PVA said that fire forming that way is like sandblasting at over 4k fps, and I think they're probably correct. That's exactly when the accuracy went to hell. Ryan's barrel lasted as long as was predicted so I think my barrel was definitely an anomaly. I'm sure there will be more PVA barrels out in the wild, they have a reamer available for prefits now. My guess is that they'll be just fine with normal use.

Long story short, I'd recommend fire forming with cheap 100 gr soft points and 55 grains of 7828 SSC. Unless you have a fire forming barrel like I now do, in which case the Titegroup method is very quick and economical. I've updated the reloading thread with that information. For anyone dedicated to using the 6 UM for a while I'd recommend finding a shot out 6mm blank to use as a fire form barrel. They should be plentiful with all of the match 6mms out there today and will allow you to fire form as many brass as you want without it eating up barrel life.

Whether or not a +P is a good idea remains to be seen. It definitely allowed higher powder charges and lower peak pressures.

UM was great to deal with through all of the issues I made for myself. Very responsive and right on top of things, Blaine made sure everything got figured out ASAP. PVA was responsive and helpful as well.
Click to expand...

Not trying to say anything negative at all, but is fireforming without projectiles a thing? It just seems like the results you received would be the norm in this situation? I don’t know anything about reloading or fire forming. Just curious


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silasbowhunter said:
Not trying to say anything negative at all, but is fireforming without projectiles a thing? It just seems like the results you received would be the norm in this situation? I don’t know anything about reloading or fire forming. Just curious


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Click to expand...
It is. I've read of a lot of people using stuff like cream of wheat, wax, etc to create a little pressure to form the case when you fire. I've never read of negative results like PF had.
 
silasbowhunter said:
Not trying to say anything negative at all, but is fireforming without projectiles a thing? It just seems like the results you received would be the norm in this situation? I don’t know anything about reloading or fire forming. Just curious


Sent from my iPhone using Tapatalk
Click to expand...
It is. Most people add some kind of filler or plug. The filler can create some serious fouling and that's what I was trying to avoid. Whether it's easier or harder on barrels is highly debated and never supported with any kind of data.
I wish I would have scoped mine before and after fire forming.

Sent from my Pixel 6 using Tapatalk
 
PathFinder said:
It is. Most people add some kind of filler or plug. The filler can create some serious fouling and that's what I was trying to avoid. Whether it's easier or harder on barrels is highly debated and never supported with any kind of data.
I wish I would have scoped mine before and after fire forming.

Sent from my Pixel 6 using Tapatalk
Click to expand...
Did you use anything as a filler? Or just dump powder and shoot vertical?
 
Just dumped powder and shot vertical. Worked up until I got a fully formed case aside from the shoulders not being completely sharp at 20 grains.
Also lubed the cases so they stretched uniformly. The whole detailed procedure is in the reloading thread.

Sent from my Pixel 6 using Tapatalk
 
Now that there are a few of these out in the wild has everybody settled on the 115 dtac as “the” bullet for the 6 um or is anyone trying something different
 
Mountainrancher said:
Now that there are a few of these out in the wild has everybody settled on the 115 dtac as “the” bullet for the 6 um or is anyone trying something different
Click to expand...
I have only shot 3 bullets through mine (115 DTAC, 108 ELD M, 105 Hybrid) but I've mulled it over a bunch and that's what I'm sticking to for now. At least until there is a 115+ grain ELD or TMK :)
There are a few considerations:
  • Will they survive launch at a certain twist?
  • Terminal performance at short range where impacts could be over 3K
  • Terminal performance at long range to take full advantage of increased reach
  • How the bullet behaves as the barrel wears
  • Availability
So far as I've reasoned it out the 115 NR DTAC is the only one that handles all points. 108 ELD will survive a 3400+ launch out of a 1:7 twist, so will 105 hybrids. Both shot well at those velocities but were leaving a lot on the table vs the DTAC. The 115 Berger HVLD is intriguing but may as well not exist for its poor availability.
The DTAC should handle high impacts, low impacts, survives launch, is cheap and available, and the RBT should help with performance at high round count. The question with them is whether they should be deep or shallow cut. Ryan and I have both had a few deep cuts go poof en route to the target, but no shallow cuts. Those were both 1:7 twists so hopefully the 1:7.5s don't have that issue. My barrel was in pretty rough shape when I had a few not make it as well. I'm still planning to hunt with deep cuts as they should be better on deer at lower impact velocity. As terminal results roll in this fall we'll learn more about it, but the DTAC has quite the track record so far.
Form suggested the 103 ELD X and 105 HPBT in terms of handling the velocity, but both give up a lot in terms of BC. It will depend on your desired effective range; if staying under 1K the ELD X would probably be great.
Ryan and Form have way more terminal experience with these, but those are the factors I'm considering in staying with the DTACs for now.
 
PathFinder said:
I have only shot 3 bullets through mine (115 DTAC, 108 ELD M, 105 Hybrid) but I've mulled it over a bunch and that's what I'm sticking to for now. At least until there is a 115+ grain ELD or TMK :)
There are a few considerations:
  • Will they survive launch at a certain twist?
  • Terminal performance at short range where impacts could be over 3K
  • Terminal performance at long range to take full advantage of increased reach
  • How the bullet behaves as the barrel wears
  • Availability
So far as I've reasoned it out the 115 NR DTAC is the only one that handles all points. 108 ELD will survive a 3400+ launch out of a 1:7 twist, so will 105 hybrids. Both shot well at those velocities but were leaving a lot on the table vs the DTAC. The 115 Berger HVLD is intriguing but may as well not exist for its poor availability.
The DTAC should handle high impacts, low impacts, survives launch, is cheap and available, and the RBT should help with performance at high round count. The question with them is whether they should be deep or shallow cut. Ryan and I have both had a few deep cuts go poof en route to the target, but no shallow cuts. Those were both 1:7 twists so hopefully the 1:7.5s don't have that issue. My barrel was in pretty rough shape when I had a few not make it as well. I'm still planning to hunt with deep cuts as they should be better on deer at lower impact velocity. As terminal results roll in this fall we'll learn more about it, but the DTAC has quite the track record so far.
Form suggested the 103 ELD X and 105 HPBT in terms of handling the velocity, but both give up a lot in terms of BC. It will depend on your desired effective range; if staying under 1K the ELD X would probably be great.
Ryan and Form have way more terminal experience with these, but those are the factors I'm considering in staying with the DTACs for now.
Click to expand...
Thanks for that info, any opinions i the Berger 115 gr VLD Hunting bullet.
 
PathFinder said:
It is. Most people add some kind of filler or plug. The filler can create some serious fouling and that's what I was trying to avoid. Whether it's easier or harder on barrels is highly debated and never supported with any kind of data.
I wish I would have scoped mine before and after fire forming.

Sent from my Pixel 6 using Tapatalk
Click to expand...

Interesting, thanks for the lesson!


Sent from my iPhone using Tapatalk
 
I have 181(I might be off by a couple, I just counted quickly) 6mm 115 Berger VLD hunting that I have no plans for, if anyone is interested.
 
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