Lapua vs Federal brass

[tcoz]

I recently bought some 3-4 times fired Lapua 308 brass to use for the first time in my Savage Model 10. Today's range trip included about half of the rounds loaded in them and the other half in some once fired Federal cases. Brass prep was identical and load and bullet were the same. 168gr A-Max over 42gr IMR4064. I was expecting them to shoot the same but I was somewhat surprised in that I was maintaining 0.5 to 1 MOA groups with the Lapua rounds and 1 to 1-3/4 MOA groups with the Federal rounds. Each group was five rounds and I shot four groups with each.

Are results like this to be expected? Frankly, I was just expecting to get longer case life, not necessarily better accuracy.

 

[RPRNY]

Well, you picked a good load. That helps. It's a keeper in the Lapua brass.

Different brass, different powder capacity one might expect. Weigh 5 Federal and 5 Lapua to get average weigt. Or weigh each filled to covexity with water and see difference. My WAG - that's an industry acronym - is that the Lapua is thicker with slightly less capacity giving slightly higher pressure. Free, and worth every penny of it!

Load another group and try 42.5 grs and 43 grs in the Federal. Please do report back. Enquiring minds want to know...

 

[tcoz]

That's a good idea RPRNY. First I'll weigh each of the fired cases from today and see if there's enough difference to possibly account for it.
Next range trip should be Thursday.....predicted high temp of 97 but I'm going to be out there by 7am.

 

[joneb]

I find that maybe about 60% of Federal cases are worth reloading, the other 40% have inconsistent case wall thicknesses.
Of the ones I do reload I need to sort them by weight.

 

[tcoz]

Different brass, different powder capacity one might expect. Weigh 5 Federal and 5 Lapua to get average weigt. Or weigh each filled to covexity with water and see difference. My WAG - that's an industry acronym - is that the Lapua is thicker with slightly less capacity giving slightly higher pressure. Free, and worth every penny of it!

These are the results I got after weighing ten fired cases of each.
Federal (not Match): Ave-181.3gr, SD-0.503, Range-2.9gr
Lapua: Ave-177.7gr, SD-0.202, Range-1.4gr
There wasn't as much of a difference as I expected and just as unexpected was the fact that the Federal cases were heavier therefore smaller inside volume therefore slightly higher pressure than the Lapua cases.

I find that maybe about 60% of Federal cases are worth reloading, the other 40% have inconsistent case wall thicknesses.
Of the ones I do reload I need to sort them by weight.

Would the results of weighing the cases that I gave above qualify the Federal cases as being inconsistent enough to make them not worth reloading? It doesn't seem like it to me but I'm new to loading for the utmost accuracy.
Another question joneb is what does everybody do with cases after they're sorted by weight (volume)? How does it affect the way you reload them? I've wondered about this for quite a while and this seems like a good time to ask.

 

[jmr40]

Federal cases have less volume than most any other. I've developed some good loads in Federal brass, but to get the same velocity it requires a little less powder. It'd be interesting to see what type of speeds you were getting. I'm betting that the loads in Federal cases were noticeably faster. If you work up loads in the Federal cases that get the same speed as the ones in other brass I bet you start seeing similar accuracy.

 

[Demi-human]

I contest that the one half less spread in wieght of the Lapua brass is the larger factor. Faster or slower, when the velocities are closely grouped, will so the group on target. Yes Lapua is worth it. Especially after the life cycle is factored. I wiegh my dry Lapua into groups of a half grain, as it is easier than wieghing them with alcohol for capacity. Shoot well Thursday.

 

[someguy2800]

I bet the lapua brass also has the flash holes debured and may have .060" flash holes as well.

 

[joneb]

"There wasn't as much of a difference as I expected and just as unexpected was the fact that the Federal cases were heavier therefore smaller inside volume therefore slightly higher pressure than the Lapua cases."

Not sure if the alloy of the brass would make a difference?

The variation of wall thickness of Federal 308 Win brass caused concentricity issues, this variation that is easily measured at the case mouth runs the length of the case.
I have been happy with Nosler brass it's cheaper than Lapua, I bought a 100 of the Nosler factory seconds which had minor blemishes.

 

[ants]

I bet the lapua brass also has the flash holes debured and may have .060" flash holes as well.

My brain was thinking flash holes, and case capacity, and square & concentric at the base.

Most of my rifles are just ordinary, but the really good one has the bolt face squared to the bore. When the brass is also square, things work MUCH better. A little known variable but critical nevertheless.

 

[USSR]

Now you know why, almost to a man, the guys on the firing line for 1,000 yard F Class Competition used Lapua brass.

Don

 

[tcoz]

I'm finding that out Don. It looks like there's more to it than just increased case life.