7 Rem Ultra Mag & Berger 195

[Cutarm]

Hello forum members. I have a question for anyone that has put together a 7 Rem Ultra Mag.

What's the opinion or recommendation on throating the 7 RUM? Should I stick with the SAAMI spec .400" of freebore? Or can I get away with throating short for the Berger 195? I'm guessing that would be around .200".

Also, can someone explain the difference between "freebore" and "parallel"? Or are they the same thing?

Thank you.

 

[Jeremy338]

Hello forum members. I have a question for anyone that has put together a 7 Rem Ultra Mag.

What's the opinion or recommendation on throating the 7 RUM? Should I stick with the SAAMI spec .400" of freebore? Or can I get away with throating short for the Berger 195? I'm guessing that would be around .200".

Also, can someone explain the difference between "freebore" and "parallel"? Or are they the same thing?

Thank you.

Old post. New member q's on results of the 195 bergers

 

[TwoMore]

I am running A 7mm Ultra Rogue (7mm rum AI) I built just for the 195. I have tested RL 33 and wc 872. I am settling in on the 872 , lil cleaner than the 33, and it is shooting under .250 moa . A week ago I shot it at 420 yards and shot a good .786 group . the 33 I worked up to 96 grains 3281 but I doubt the brass would take to much there, specially in the heat, I settled in at 93 to 94. 93 is 3180, 94 is 3220 the 872 is almost identical just about a grain more to hit the same speed but the 872 seems to not mind the hot temps near as much as I have been shooting in. My chambering is pretty long in the lead with .260 FB and .949 bore rider. so with the freebore and bore rider lead it is 1.209, I jam the lands .005, if I pull off my ES gets a lil squirrely , but right now at 90+ temps it is usually under 20fps, still lookin for single digits lol but it is shootin well. The 33 has seen 12 fps ES but like is said it is pretty dirty, for me anyway.

 

[Jeremy338]

I am running A 7mm Ultra Rogue (7mm rum AI) I built just for the 195. I have tested RL 33 and wc 872. I am settling in on the 872 , lil cleaner than the 33, and it is shooting under .250 moa . A week ago I shot it at 420 yards and shot a good .786 group . the 33 I worked up to 96 grains 3281 but I doubt the brass would take to much there, specially in the heat, I settled in at 93 to 94. 93 is 3180, 94 is 3220 the 872 is almost identical just about a grain more to hit the same speed but the 872 seems to not mind the hot temps near as much as I have been shooting in. My chambering is pretty long in the lead with .260 FB and .949 bore rider. so with the freebore and bore rider lead it is 1.209, I jam the lands .005, if I pull off my ES gets a lil squirrely , but right now at 90+ temps it is usually under 20fps, still lookin for single digits lol but it is shootin well. The 33 has seen 12 fps ES but like is said it is pretty dirty, for me anyway.
I got a 27.5 krieger 8 twist
I'm prob going to settle around 90 gr in the ultra. Oal 3.9. Started at 94. One and done on the brass. Got some bad info. She was running 3200 for the first 100 rounds and then started losing primers every other shot. Looks like the rum isn't going to be much over 3000ish. Shoots in the high 3's but sketchy. Thanks for the info

 

[coj0502]

By any chance did you have a look with a bore scope? I have run into similar issues on a 28 nosler and on a 7 RUM both when using Retumbo, dramatic increase in pressures and high ES after roughly 100-150 rounds. I did not bore scope but did do a deep clean with a carbon remover and copper remover and the problem went away.

 

[Jeremy338]

Haven't scoped it but I think she was a little toasty. 94 is what I was told would be a good load started acting up and put it in the safe. Built the gun when the 195 were released. I'm sure the throat ruffed up and started building pressure. Was hoping to get 3200. That was a pipe dream. Lol. I use kg products the barrel should be stripped. Curious where you ended up load wise/fps powder charge on the rum. Most my rifles were easy to develop a load for. Seems like the 7rum is finicky.

 

[TwoMore]

Haven't scoped it but I think she was a little toasty. 94 is what I was told would be a good load started acting up and put it in the safe. Built the gun when the 195 were released. I'm sure the throat ruffed up and started building pressure. Was hoping to get 3200. That was a pipe dream. Lol. I use kg products the barrel should be stripped. Curious where you ended up load wise/fps powder charge on the rum. Most my rifles were easy to develop a load for. Seems like the 7rum is finicky.

I know I run 94 of retumbo on my sendero 7RUM with a 168 vld and it is a great load, at 3.760 coal and 92 with a 180 I think if I were to try the 195 in that rifle I would start at about 88 because of the long bearing surface and maybe try 90 if everyt thing looked good

 

[coj0502]

Haven't scoped it but I think she was a little toasty. 94 is what I was told would be a good load started acting up and put it in the safe. Built the gun when the 195 were released. I'm sure the throat ruffed up and started building pressure. Was hoping to get 3200. That was a pipe dream. Lol. I use kg products the barrel should be stripped. Curious where you ended up load wise/fps powder charge on the rum. Most my rifles were easy to develop a load for. Seems like the 7rum is finicky.

I never tried the 195's in the RUM the freebore is about half of the SAMMI spec so I stuck with the 180's at 3150 FPS and it only took 79.5gr of Retumbo to get there.

 

[Jeremy338]

When the gun was built there wasn't a lot of data with the 195 re33 combo. Bob beck runs retumbo and gets high fps. Just curious with re 33 if anyone was pressuring up early. Say around 3100ish. My particular gun doesn't shoot retumbo as well

 

[TwoMore]

What brass are you shootin Jeremy? i am asking because i have to reduce 2 to 3 grains with nosler brass

 

[TwoMore]

for me 33 is alot like retumbo in it will get pressure real quik

 

[Jeremy338]

Norma. Always new brass. Lol
One and done. If the primers would hold I would keep it where it's at. Running 215m's. Should I switch to the cci 250's

 

[TwoMore]

215m's are hotter, I shoot 215's and 250's, I think norma makes nosler brass, I may be wrong but like I said with nosler I have to tone down a tad but I still get good velocity even with the bit lighter load with that brassI checked my rem once fired against the nosler once fired and it is 4 grains different , the rem holds more

 

[Jeremy338]

91.6 is where I'm at now. I'll try 89.5 with 250's and work up. Currently running 3150fps. Thanks for the info