25 Creedmoor

Lance, looks like you have a winner there. Would you mind walking me through the thought process of using SRP vs LRP as well as necking up from 6mm vs necking down from 6.5mm? Prior to reading your post here, if I had built a 25 CM last month I would have necked down 6.5 LRP brass with my only reasoning being that .264 to .257 is a smaller gap than .243 to .257 and I have more LRP's than SRP's. I will admit I'm completely ignorant to the pros & cons of using SRP vs LRP other than I assume LR is hotter. Same thing with necking up or down, ignorance. If I had to venture a guess the primers would relate to es/sd consistency and necking up with mandrel results in less time spent on brass prep. Perhaps it's just what you had available. Just trying to learn something new.
I went SRP because, I have about 7k Fed GM205M, CCI BR4, and CCI 450, and only had my 6CM using Lapua 6.5CM brass (got them before Lapua made 6CM brass) to use them in. So I literally decided to build a couple SRP rifles since I have so many. Plus, I have 1450ish .257 135 LR Hyb, 1400 133 Elite, and 600+ 131 BJs. So a 25CM was a no brainer.
SRP brass takes warm loads with less primer pocket loosening, as there is more material around the primer pocket, so less stretching. I don't think SRPs are any less hot than LRPs. Especially if you get up into the 450s. ES/SD can be in the single digits with either SRP or LRP. Just depends on your loads and how anal you are with assembling them.
I also built a .260AI using Alpha SRP .260 Rem brass to use the SRPs I have on hand. I plan on running it on the warm side, so the pockets should last longer.

As far as necking up vs necking down, either is acceptable. But the reamer I used has a specific neck diameter, and expanding 6CM brass gives slightly thinner neck walls than necking down 6.5CM brass. So I have my desired neck clearance in my chamber. There are two other rifles chambered off this reamer. One buy used Lapua 6CM brass with no need to turn necks. The other guy used Lapua 6.5CM brass necked down, and needed to just skim his necks. Since I HATE turning necks, 6CM brass was my choice.
 
I went SRP because, I have about 7k Fed GM205M, CCI BR4, and CCI 450, and only had my 6CM using Lapua 6.5CM brass (got them before Lapua made 6CM brass) to use them in. So I literally decided to build a couple SRP rifles since I have so many. Plus, I have 1450ish .257 135 LR Hyb, 1400 133 Elite, and 600+ 131 BJs. So a 25CM was a no brainer.
SRP brass takes warm loads with less primer pocket loosening, as there is more material around the primer pocket, so less stretching. I don't think SRPs are any less hot than LRPs. Especially if you get up into the 450s. ES/SD can be in the single digits with either SRP or LRP. Just depends on your loads and how anal you are with assembling them.
I also built a .260AI using Alpha SRP .260 Rem brass to use the SRPs I have on hand. I plan on running it on the warm side, so the pockets should last longer.

As far as necking up vs necking down, either is acceptable. But the reamer I used has a specific neck diameter, and expanding 6CM brass gives slightly thinner neck walls than necking down 6.5CM brass. So I have my desired neck clearance in my chamber. There are two other rifles chambered off this reamer. One buy used Lapua 6CM brass with no need to turn necks. The other guy used Lapua 6.5CM brass necked down, and needed to just skim his necks. Since I HATE turning necks, 6CM brass was my choice.
Exactly the info I was looking for and makes complete sense. Thank you.
 
Here's my latest idea....

I know where a Rem 700 youth sits thats $375 in 243. I could buy that and screw on a good barrel (open to suggestions) I'd place her in an AG composite stock and hang a trigger tech diamond underneath.
Ideas:
1. Shillen
2. Proof
3. Criterion
4. Krieger
5. Other (you pick)
 
I am thinking I will build my daughter her first hunting rifle in 25 Creedmoor. I think it will do well as a deer and down rifle. I may do a 25sst but I will guess I decide when I order lol.
 
Here's my latest idea....

I know where a Rem 700 youth sits thats $375 in 243. I could buy that and screw on a good barrel (open to suggestions) I'd place her in an AG composite stock and hang a trigger tech diamond underneath.
Ideas:
1. Shillen
2. Proof
3. Criterion
4. Krieger
5. Other (you pick)
My last two barrels have been preferred barrel blanks, I have been very pleased. The 6MM creed I built for a buddy is a heck of a shooter. Maybe give them a look.
 

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As far as SRP or LRP, with this cartridge, SRP is the way you want to go. LRP works, but the primer pockets are very short lived. 25CM is a higher pressure cartridge, than it's siblings in .243 & .264 bore size.

I got in on Alpha's first run of stamped brass, it's super consistent accurate, but not very durable. The Starline SRP 6.5CM necked down, was just as consistent and accurate, while more durable, it just didn't have correct headstamp, so segregating from 6.5CM was very important.

I'm using Peterson SRP stamped brass now "The Good Stuff" and I haven't checked lately but, it was mostly available, so I'v a lot it, even @ $1.04 each, it a great value. (Just checked it's still available, just like the Berger 135LRHT at the local GS)
 

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