Velocity Question - Virgin VS 1X Fired

[LoanHarvey]

Hello,
My buddy and I are in disagreement and I need your input to clear this up please.
Assuming we are dealing with the exact same load parameters, would a virgin fired case or a 1X fired & full length resized case generally have more velocity? Again, same seating depth, powder charge, etc.
Thank you for your input.

 

[dmoran]

Typically, I see slightly more velocity from a formed case that matches the chamber then a new case (or a case that needs to stretch a ways). The variance being from the pressure robbed to iron the smaller dimensional case to the chamber walls then a case that has been formed to a closer match up to the chamber.
Just my 2-cents
Donovan

 

[Schism]

Typically, I see slightly more velocity from a formed case that matches the chamber then a new case (or a case that needs to stretch a ways).

This matches my chrono results as well.

 

[RonAKA]

Hello,
My buddy and I are in disagreement and I need your input to clear this up please.
Assuming we are dealing with the exact same load parameters, would a virgin fired case or a 1X fired & full length resized case generally have more velocity? Again, same seating depth, powder charge, etc.
Thank you for your input.

If the full length resizing returns the case dimensions to the new unfired virgin dimensions, then there should be no significant difference in velocity, attributable to the caze.

 

[AndyA]

on my 7mm rem mag once fired brass shot slightly lower than virgin brass at 400 yds with same charge and same seating depth. probably due to increased chamber volume. difference was maybe 2"

 

[jimbires]

I see more velocity from a formed case too .

 

[/VH]

I think I'd be a little suspicious of whoever I got those "virgin fired" cases from.

 

[MagnumManiac]

I concur, my chrony shows a slight increase in fireformed cases over virgin in most instances, except my 222 Rem, which shows no difference at all.
I find the biggest increase in belted mags, the shoulder blowing forward .020" is the culprit.

Cheers.

 

[Ned Ludd]

For the vast majority of users that set their resizing dies properly, FL resizing comes nowhere near bringing brass back to unfired/virgin dimensions. In my hands for .223 and .308 loads, fired/prepped brass typically gives 5-10 fps greater velocity than does virgin/prepped brass. Not surprisingly, case volume for fired/prepped brass usually falls about halfway in between that of unfired virgin brass and fired [unprepped] brass. As Donovan pointed out, I've always figured a very small net amount of the total energy of combustion went toward expanding the case to fit the chamber, thereby decreasing velocity.

 

[rardoin]

I think I'd be a little suspicious of whoever I got those "virgin fired" cases from.

I suspect my first girlfriend was one of those...despite her claims to the opposite.

 

[LoanHarvey]

You guys are great, thank you!