1st 223 Chrono test

[hdwhit]

You don't mention barrel length.

Assuming the now nearly ubiquitous 16 inch barrel, 2700 fps with 62 grain bullets is about what I would expect.

What's the problem?

 

[kmw1954]

You don't mention barrel length.

Assuming the now nearly ubiquitous 16 inch barrel, 2700 fps with 62 grain bullets is about what I would expect.

What's the problem?

Post 43 and 55! No problem!!

 

[SSN Vet]

When I started loading cast, I had both a Savage 99 in .308, and a Marlin 336 in .30-30, both used the same bullets... a 173grn FP. I loaded up test loads in both cartridges with the same loading data... everything the same except, of course, the cartridge case. 28grn IMR3031 in the .30-30 case gave me 2000fps out of the Marlin, but only 1775fps out of the .308 Savage.

I would attribute this to two things.

1.) the Marlin 336 has micro-groove rifling which cuts the bullet less and offers less resistance

2.)The H20 capacity of the 30-30 Win: 45.0, while the 308 Win: 53.0 .... so smaller case would yield a higher pressure.

Higher pressure with less resistance = higher velocity

 

[Charlie98]

I'm not sure why I was surprised... I've known since I started loading .308/7.62mm for my M1a that there is a significant difference between commercial .308 brass, and military 7.62mm brass, enough that you can easily go over pressure just by switching from commercial to military with an established load.

Quoting meself... as I mentioned, I was initially surprised at the differences... but not once I thought about it.