6 UM or 6-7PRC?

[RogerPa]

UM also built my 6-7 PRC, and I love it! It’s running 3250 FPS with 68 gr. of N570, and the 115 gr. DTAC’s. Honestly, it will also shoot the 115 Berger’s at the same speed, and “zero” point of aim change. I lose a little BC with the Berger’s, but that amounts to 1 click (1/4 moa) at 600 yards. I use Peterson brass, and have had zero issues. I do not have to turn necks, I’ve never split a neck, No problems whatsoever! I’m sure there’s a lot of speed sitting there, as the case has plenty of remaining room, but it shoots so darn good in the 3250’s, I hesitate to ask for more.

 

[RogerPa]

To further my earlier reply, I should add the reason I tried the 115 Berger (VLD-Hunt) was related to a comment from Ryan, in which he talked about the DETAC’s being a “very hard”bullet. Killers for sure, but he suggested maybe for antelope & whitetail, they may be a bit too hard(?). My first hunt with this rifle is going to be a Wyoming antelope hunt this fall, with my grandson. We each have a tag, and I’m looking forward to seeing the terminal performance! Maybe we’ll get a chance to test both bullets? I’ll see how that goes.
Related to the photo’s below, #1 is a 3 shot group, fired with the DETAC’s at 600 yards. It’s right at 1 1/2 inches. (Not MOA). #2 is also at 600 yards, and a single shot using the 115 Berger. No scope adjustments were made, other than adding 1 click up for the difference in BC. #3 is just a photo of the UN 6-7PRC on the Rokstok. Not sure if any of this helps, but it fun to converse with someone who’s interested!

 

[Darrindlh]

Would you go 6-7Prc or a straight 6 Prc? If you had to do it again? I am considering one of these two.

Darrin

 

[knorthcutt222]

Would you go 6-7Prc or a straight 6 Prc? If you had to do it again? I am considering one of these two.

Darrin

I haven't had any problems with my 6-7 so far. Just like any wildcat you are kinda guessing.

 

[IrkedCitizen]

With there being 6um headstamped adg brass i don't see a reason to do a 6saum or 6prc. If you dont want to fireform just get the 6UM30° chamber

 

[GoatPackr]

As an owner of a 6-7PRC who plans a couple more 6mm rifles for my wife and kids I will be building 6 UM rifles for them.
Reason I would go 6 UM now is the availability of brass and dies.
I'm undecided on what shoulder I would go with. If I can find a cheap 6mm barrel just for fire forming I'd like to go with the improved shoulder.

 

[RogerPa]

Owning and shooting a 6-7 PRC has been pretty easy, certainly fun, and the terminal performance has been nothing but outstanding! It’s 3 for 3 on game (2 antelope, 1 whitetail) from 145 yards, 270 yards, and 525 yards. At the time we ordered it, there were no factory 6UM cases available, and that made the decision somewhat easier. Sure, it’s overbore, and there’s no doubt more room for powder. But running the 115’s in the 3250’s is easy, forming brass is easy, and it shoots better than I can. I’m not at all unhappy with the choice!

 

[Darrindlh]

Would you say it is possible to neck down 7 prc to 6 mm in two steps? First necking down to 6.5 then second necking down to 6 mm or is more necessary .

Darrin

 

[Schmo]

Would you say it is possible to neck down 7 prc to 6 mm in two steps? First necking down to 6.5 then second necking down to 6 mm or is more necessary .

Darrin

I think you can do it in two steps, but I figure you’d have to neck turn. Someone on here knows the answer.

 

[khuber84]

Would you say it is possible to neck down 7 prc to 6 mm in two steps? First necking down to 6.5 then second necking down to 6 mm or is more necessary .

Darrin

I think you can do it in two steps, but I figure you’d have to neck turn. Someone on here knows the answer.

Method of neck down should have little affect in needing to turn or not.

Going from a 313 neck to a 275 neck is solid shrink. I'd reccomend 3 steps, followed my a mandrel.

Whidden bushings have little to no taper at the base, and will not leave the buge at the base the neck. So id go somewhere around 300, 287 274, finished out with a 2415 mandrel.

Easy way, but some the 25-7prc adg brass from west Texas ordnance, and make it on one pass followed by a mandrel!

 

[Schmo]

I just figured neck turning might be required when sizing down that far

 

[Darrindlh]

Method of neck down should have little affect in needing to turn or not.

Going from a 313 neck to a 275 neck is solid shrink. I'd reccomend 3 steps, followed my a mandrel.

Whidden bushings have little to no taper at the base, and will not leave the buge at the base the neck. So id go somewhere around 300, 287 274, finished out with a 2415 mandrel.

Easy way, but some the 25-7prc adg brass from west Texas ordnance, and make it on one pass followed by a mandrel!

Thank you very much for the help!

Darrin

 

[khuber84]

Thank you very much for the help!

Darrin

No problem!

 

[GoatPackr]

I was able to step it with one step but I also have a wildcat die that has tapered bushings just for doing that.
Fire forming is more important with this one than with the 6 UM and their brass being 6mm you are moving a lot more around with the 7mm PRC.