6mm 115 vs .257 133, mountain rifle

ORfish

Lil-Rokslider
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I am looking at building a fast-twist gun to shoot the 115 6mm bullet or the 133 .257. Both are the best B.C. hunting bullets I can find in those sizes. My needs are hunting based, and will be shot with suppressor on backpack hunts (so 7 1/2 lbs with scope). Target animals are antelope, mulies, blacktail, caribou, and Coues. I have elk guns already. The reason for the high BC bullets are the high and unpredictable winds. Hunting ranges 300-500 yards, although will practice shots out to 1000. Will be reloading. Soooo, what I was interested in was an options on maxing out the 6mm or .257 and which would be the better long range hunter. I keep going back and forth and not making progress. Of course after I choose the bullet, then the caliber discussion follows (6mm Creedmoor, 240 Weatherby, 25-06, 25 Creedmoor, .257 Weatherby etc...)
 

hereinaz

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25 Sherman Short Tactical shooting the 131 or 133. Cut the barrel to 22 and go to town.

End of story.

Runs in a short action, up to 3200 fps. Matches big 7 and 300 magnum in drop.
 

hereinaz

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I am sorta like you. I have a 7SS for elk. I built a 6 BRA for the animals you named at intermediate distances.

But for wind, the 131 or 133 crush it. As soon as my reamer comes in for the 25 sst, there are four of us building them on Proof barrels. The Sherman cartridges are just flat efficient and accurate. Super easy to load for and exceptionally low ES.

I can get you a Proof CF barrel for it at a nice discount and my smith cuts a mean chamber. PM if you want to talk more.

I have run the 6 creed and 115s, and they hammer as well. But the extra weight is what you want for wind, plus the SST can flat spit them out. I would still do a 25 creed over the 6 creed for wind.
 
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I feel like hereinaz is right about the 25 Sherman. With the 133’s I think the 25-06 will lose too much velocity to do it justice. 257 wby is gonna get to be way too long with a suppressor since 26” is pretty much the standard.
 

hereinaz

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I feel like hereinaz is right about the 25 Sherman. With the 133’s I think the 25-06 will lose too much velocity to do it justice. 257 wby is gonna get to be way too long with a suppressor since 26” is pretty much the standard.
You are right about length. Barrels with the Sherman cartridges can be run down to 22 inches and you don't lose much. They are efficient powder burners. My 7ss uses 7.5 grains less H1000 to run a 180 vld at the same speed as my 7 rem mag, that's more than 10% with the 68.5 grain load of my Rem Mag. That efficiency leads to better burns and shorter burns, producing consistent groups and low ES.

I can't see any reason that by cartridge specs alone you would want to choose a long action over a Sherman short action.

I ran my 7ss at 26", but my next one will be 22" based on what others have done. I will only loose maybe 80 fps with a 22" and can.
 
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I would consider if you are willing to use a muzzle brake or not, and if you want to be able to spot impacts. I have a fast twist 25-06 with no brake that weighs about 10 pounds scoped. I can usually spot impacts beyond 500 yards but it’s not that easy. Anything more would be too much recoil for me. My next build will be a 25creedmoor for this reason. I don’t want to shoot with a brake and I don’t like recoil. This 25-06 is also not as accurate as I hoped so I’m working on burning it up ASAP 🔥
 

hereinaz

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I would consider if you are willing to use a muzzle brake or not, and if you want to be able to spot impacts. I have a fast twist 25-06 with no brake that weighs about 10 pounds scoped. I can usually spot impacts beyond 500 yards but it’s not that easy. Anything more would be too much recoil for me. My next build will be a 25creedmoor for this reason. I don’t want to shoot with a brake and I don’t like recoil. This 25-06 is also not as accurate as I hoped so I’m working on burning it up ASAP 🔥
He's gonna use a suppressor, so recoil from a 25 is a non issue. I have a suppressor on my 7 SS that is sub 12 pounds loaded and ready to roll, and I can spot shots easily from prone and my favorite tripod positions.

My recommendation to you is to sell the 25-06 while it has life and get that 25 creedmoor now.
 
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He's gonna use a suppressor, so recoil from a 25 is a non issue. I have a suppressor on my 7 SS that is sub 12 pounds loaded and ready to roll, and I can spot shots easily from prone and my favorite tripod positions.

My recommendation to you is to sell the 25-06 while it has life and get that 25 creedmoor now.
I’ve actually got a 25creed prefit ordered. Just a matter of when it gets here and if I try to get it swapped before this season or not..
 
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