Going up or down?

ARlife4me

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Apr 18, 2018
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Looking across different calibers (not particularly cartridges) with the same bullet weight (or within 2grs) has got me thinking "I could go with 30cal 168 or 28cal of the same weight"? While the less caliber usually has the higher bc for the advantage what makes you decide on what to choose if you don't have back to back calibers? I've skipped the 25 and 28cals only because of the next 1 up covers the same weight and/or the next 1 down does also. I can shoot 168's in my 30cal, so why would I want a 28cal? I am limiting myself to 2.830" due to using AR's. What drives your decisions for SA's and non-magnums?
 
Probably not going to be able to use the big 7s in a AR setup. The 180 class 7mm has super high BCs and are great for long range. Most of the 160s are way higher than 30s. You are Restricting yourself just by using ARs
 
Probably not going to be able to use the big 7s in a AR setup. The 180 class 7mm has super high BCs and are great for long range. Most of the 160s are way higher than 30s. You are Restricting yourself just by using ARs
I know there is limitations in Ar's, but the 284win can give me a 2.830". I'm not doing any SA's in BA guns, only lam's.
 
BC and maybe velocity is why I would consider a smaller bore, velocity is a maybe though depending on your use but in general a larger bore will propel the same weight bullet faster than a smaller bore. I think you can drive a 150 faster in a 308 than you can a 150 in a 7-08 but if we are using similar style bullets the 7mm will pass the 30 cal at some distance in velocity and retained energy. The question becomes does it matter to you? The AR platform being mag length restricted and semi-auto is another whole set of limitations though.
 
I like that you're beginning with bullets. Everything does begin and end with a bullet.
But that also makes it hard for us to help you work through the entire loop.

And I'll pile on another consideration: barrel life
For an appropriate capacity to drive a given bullet weight to equal result of another, the smaller bore usually has lower barrel life (depending on powder). With your system being an AR, then maybe barrel life matters.
 
Just collecting thoughts on what other people would do? I've reloaded for 38 years and understand a lot on powder choice in AR's. Barrel life would last longer that what I could shoot. 1 reason being I have many in the same cartridge spread out over 5 or more per AR's. I have 6 kids that could shorten barrel life though? Not just powder choice on barrel life, but bearing surface. Most likely throat will be gone before bore. I wouldn't mind having a 27-08 to fill the void, but then again I don't have a 28cal either. I'll run heavier bullets in the 260rem (125-144gr) and in 6.5creed a little lighter ones (100-135gr). 1 day I might get a 28cal for an AR10 (7-08 or 284win), unless I get a necked down 308win for another void?
 
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