December $487 prefit group buy, several barrels are a go

[Speaks]

Hey guys looking for some advice here. I keep toying with ordering a 6UM 40.

Two questions -

1 - Assume since its only offered in 20 that gives meaningful performance gains over something like at 18?

2 - If I have a 6CM and a 6.5 PRC is there a real meaningful gain to be had here? I would either be barreling the PRC or I do have another action I could use but UM seems like a pretty direct replacement for it. It looks like some small performance gain and a small improvement in recoil but not a game changer on either. Trade off is loosing access to decent factory ammo, the 147 eldm factory loads are pretty good through my PRC.

I keep debating going down that rabbit hole vs just getting an extra barrel and ammo for the 6CM and shooting the shit out of it (and yes I have a 223 trainer).

 

[hereinaz]

Hey guys looking for some advice here. I keep toying with ordering a 6UM 40.

Two questions -

1 - Assume since its only offered in 20 that gives meaningful performance gains over something like at 18?

2 - If I have a 6CM and a 6.5 PRC is there a real meaningful gain to be had here? I would either be barreling the PRC or I do have another action I could use but UM seems like a pretty direct replacement for it. It looks like some small performance gain and a small improvement in recoil but not a game changer on either. Trade off is loosing access to decent factory ammo, the 147 eldm factory loads are pretty good through my PRC.

I keep debating going down that rabbit hole vs just getting an extra barrel and ammo for the 6CM and shooting the shit out of it (and yes I have a 223 trainer).

If you keep the 6.5 barrel, it’s always an option.

How big the differences are, always depends on how you weigh the factors. Changing all the time isn’t good.

Shooting practice always trumps the gains by the marginal improvements in performance. You would become a better rifleman only with rounds down range. I say shooting out a barrel will do more than switching what you have.

 

[TheViking]

Hey guys looking for some advice here. I keep toying with ordering a 6UM 40.

Two questions -

1 - Assume since its only offered in 20 that gives meaningful performance gains over something like at 18?

2 - If I have a 6CM and a 6.5 PRC is there a real meaningful gain to be had here? I would either be barreling the PRC or I do have another action I could use but UM seems like a pretty direct replacement for it. It looks like some small performance gain and a small improvement in recoil but not a game changer on either. Trade off is loosing access to decent factory ammo, the 147 eldm factory loads are pretty good through my PRC.

I keep debating going down that rabbit hole vs just getting an extra barrel and ammo for the 6CM and shooting the shit out of it (and yes I have a 223 trainer).

You have to do some math and figure all this out. On average you lose 25-30fps per inch of barrel. Take your approximate velocity, use box if you’re shooting factory. Then subtract 25-30fps per inch from 24” (typical test barrel length). Find the BC (ballistic coefficient) of the specific bullet you’re using. Use a ballistic calculator with environmental (elevation, temp, etc). Keep your bullet above 1800fps at impact, I personally do 2000.

6.5 PRC will give you +/- 200fps over 6.5 CM, which will you give you about 200 more yards of range.

 

[JoeK]

If you keep the 6.5 barrel, it’s always an option.

How big the differences are, always depends on how you weigh the factors. Changing all the time isn’t good.

Shooting practice always trumps the gains by the marginal improvements in performance. You would become a better rifleman only with rounds down range. I say shooting out a barrel will do more than switching what you have.

Very well put ^

 

[walk2112]

I thought the tikka COAL limitations would prevent the 257 w/heavy high BC bullets? Or just if need the UM bottom metal and magazine to work? I also thought I read that it would require milling a groove in the feedramp /receiver…?

Yep, would want one of the longer magazine options from the aftermarket to really seat the bullets where they oughta be.
I don’t know about milling a groove receiver, thought that was for other actions, but could be wrong as I haven’t tried one.

 

[Speaks]

If you keep the 6.5 barrel, it’s always an option.

How big the differences are, always depends on how you weigh the factors. Changing all the time isn’t good.

Shooting practice always trumps the gains by the marginal improvements in performance. You would become a better rifleman only with rounds down range. I say shooting out a barrel will do more than switching what you have.

Thanks I think your right. The shiny new better thing is always tempting.

Will just shoot the 223 and the new 22CM and 6CM barrels a bunch and if I get to where I actually need more than that to kill actual animals will consider whether to keep the PRC or swap it to a UM.

 

[AZ_Hunter]

Would anyone else be interested in either a 6-284 or 6mm Rem AI? Something to maximize a 6mm with a std bolt face.