LC cases verses FC and others

[StockDog]

I have lots of LC 308 cases that I have been loading for my AR10 and 5R. (different loads for each rifle)

I estimated about 2 grains lower than standard for max loads per my manuals. I have switched to loading all LC cases and am trying to find a good rule-of-thumb for working up loads.

How much difference do you guys figure on loads? Am I over or under estimating?

 

[wfjames22]

Re: LC cases verses FC and others

Work up until you see signs of over pressure, then back off. Max loads in any manual are only max loads for what they shot the loads in. No substitute for working the loads up in each of your rifles and determining the max load for those particular components in that particular rifle.

Another way is to use a chronograph. If your velocities are extremely high, with questionable pressure signs-you are there.

 

[Tangodown911]

Re: LC cases verses FC and others

Weigh the brass. Lc is heavier which means less powder cap. IE. Win and Hornady are both lighter than fc/lc.

 

[Grump]

Re: LC cases verses FC and others

This is as stinking idiotic as the legendary three-day or whatever argument in ancient Greece about how many teeth there are in a horse's head.

No one would go out in the street and look for themselves.

MEASURE YOUR OWN FIRED CASES!!!!

Empty and full of water. My last round of logging info showed that two lots of brass, fully four grains apart in empty weight, had only inconsequential differences in interior volume.

My current FC cases are virtually identical to older LC and FA 7.62mm brass. But I also found that an older batch is NOT and do follow the now-outdated shooter urban legend of being "lighter" than LC.

My brass:


Case Full Dry Capacity
FA 63M 239.52 183.52 56.00
LC 86M 239.58 183.58 56.00 (yes, identical. A prior pair of batches ALSO came out the same, at 56.2 or so)
New FC 235.69 179.75 55.94
Lapua 234.60 178.12 56.48
Old FC 220.44 162.71 57.73
Hornady 219.95 162.12 57.83

 

[Jumper]

Re: LC cases verses FC and others

I've got a batch of LC Match 94 .308 brass that I've been loading for my AR10-T. I know this; I cannot get close to listed max loads in the LC brass before my primers flatten and recoil seems more than normal. My still developing rule of thumb is 2gr less than max for faster powders, and 1gr less than max for powders like IMR 4064.

 

[desertHK]

Re: LC cases verses FC and others

I use LC 01 brass with IMR 4064 in my POF 308 rifle. Those brass can definitely take the abuse from a gas run. Case is a bit less compared to WCC, or Lapua (although not that much less). I was able to get to 43.8 grains of IMR4064 for my 175 SMK pill (Max for Lyman is 44 grains and 45 for Hodgdon manual).

 

[Grump]

Re: LC cases verses FC and others

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DesertHK</div><div class="ubbcode-body">I use LC 01 brass with IMR 4064 in my POF 308 rifle. Those brass can definitely take the abuse from a gas run. Case is a bit less compared to WCC, or Lapua (although not that much less). I was able to get to 43.8 grains of IMR4064 for my 175 SMK pill (Max for Lyman is 44 grains and 45 for Hodgdon manual). </div></div>

Last go-round, my rifle's limit was 43.0 gr 4064 under the Sierra 175 MK. Fudging QuickLOAD's burn rate to match recorded velocities (it got me to 2625 or so out of a 22-inch barrel) showed it was absolute max chamber pressure per the specs.

That's with newer FC brass. Lost some from the testing, too thin ahead of the web from being over-sized.

 

[raptor99]

Re: LC cases verses FC and others

I agree with Grump. I have some "92" LC match brass and it has nearly the same identical case cap. as the FC match brass I was shooting in my AR10.

You can not go by weight alone. My Lapua brass has nearly a full grain of powder "Less" cap. than the Winchester brass I use in my 260. Some of my Winchester brass is nearly 10grs ligher or heavier than the last batch of Winchester brass I bought.