Necked-down .308s and barrel length?

[ArmedBear]

It's axiomatic that .308 works better than .30-06 in a 20" barrel, whereas the .30-06 really likes full-length barrels to get up to speed. That makes sense, I think, since the shorter .30 cal cartridge uses less powder, but hotter powder.

What about when you neck it down?

How does a .243, .260 or 7mm-08 work in a 20" barrel, or shorter?

 

[interlock]

.308 based rounds

IN MY EXPERIENCE.

I have found that if you want to shoot a midle wieght bullet in them then a shorter barrel is fine ie 80 gr in .243 or 130 gr in 7mm08 because you can use a fast burning powder. if you want a heavier bullet ie 100 gr in 243 or 150+ in 7mm08 then you need a slower burning powder to get the best performance. if that is the case then a longer barrel is better

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[tango2echo]

Ditto.....