loading 308 win, going from win brass to lapua brass

[brian923]

well, i was finally able to splurg and get some lapua brass.. ive been dreaming of using some, to see if it will shoot better in my savage 308. i am currently shooting, 44.5 grains varget, 168 grain horn. a-max, in Winchester brass with a rem benchrest primer. (i believe 9 1/2?) i am not sure of the velocity, as i do not have a crony yet, and i dont know which ballistics program is capable of calculating velocitys (i think its quick load?) the rifle is a savage 10, in a mcmillian stock with a 26" long barrel, which i believe to be a 1-10 twist. its the factory barrel. i am able to shoot a 3/4" 10 shoot group at 100 yards. im not complaining... just trying to see what lapua brass is all about.

my question is, do i have to change anything with my current load with Winchester brass, to use in the lapua brass? i also picked up some federal 210m primers just to try out. do you think that these would be better or worse than the rem 9 1/2 benchrest primers? thanks for all your help, brian.

 

[nosualc]

Yes, you have to work on your load again as you are changing components (brass or primers). For safety, standard advice is to reduce your powder charge and work up, backing off if you see pressure signs.

-nosualc

 

[Bob3700]

I will tell you that the Win 308 brass that I have (currently purchased lot) weights around 157-158 gr each. The Lapua brass that I have weights in the 174 gr range. So there is a significant difference in the wt. of the brass. Less internal volume for the Lapua.

If you scout around, there is a formula to figure the powder charge vs difference in case wt. Can't remember it right now.

You would be wise to back off your Win load at least 1-1.5 grs and work back up. The Fed 210M should be a better primer than the Rem 9 1/2. They are milder and over a chrono would give better numbers.

Have fun and be safe.

Bob

 

[tiny68]

I did this exact thing 5-6 years back. Bob and others are on with reducing 1.5 grs and start working up new load. I went from 45.0 gr of Varget with the 168 SMK in Winny brass to 44.2 in the Lapua brass.

Luck, Tim

 

[bugman]

+1 to what Bob said. Every .308 Win case that I have ever used (this was some years back) had more internal case capacity than .308 Lapua cases. Note...I am referring to the large primer .308 Lapua, not the "new" small primer .308 Palma cases. At any rate, back down on the charge weight and safely test. A chronograph would probably help.

Primers? That will depend on a lot of factors, probably more on your powder choice than anything else. No easy answer. You will just have to test, after everything else is determined.

Jack

 

[brian923]

thanks guys, for the quick responses. i figured i would have to kinda "start over" but im sure ill be able to find the sweet spot pretty quickly.

i was looking at my varget supply, and im running kinda low. i was wondering if you guys had any suggestons as to if i should try a different powder, or stick with varget... what do you use/recommend??? i work dangerously close to cabelas, so i should be able to get a lot of different types of powder. ive been reading on the 8208, rl 15 and 4064... these seem like some good choices, im just looking to see if anyone else has any more opinions on this. thanks guys, brian

 

[nosualc]

Varget is very popular for the .308, and has excellent temperature stability. It has the disadvantage of being in seemingly constant short supply, and having significant lot to lot inconsistency. Guys tend to work around this by buying 8lb containers (maybe more than one).

If Varget is working well for you, and you can find it, buy enough to last yourself a year or two with the same lot #, and move on to other things.

Otherwise, the other powders you list (and others) are fine choices. The .308 isn't that picky.

If you haven't already, read this:http://www.accurateshooter.com/cartridge-guides/308win/

-nosualc

 

[Bob3700]

I shoot Varget exclusively in my Palma rifle. For the most part that means I am shooting 155 gr bullets and rarely go heavier.

RL15 works well but I consider it a powder that generates a lot of carbon fouling.

IMR4064 is great but really doesn't give good groups until you are in the higher pressure loads.

The advice on purchasing an 8# keg is excellent. That way you don't have to worry about power variations for quite some time. Buy as much as you can afford and they go shoot.

Bob

 

[signut]

Only thing I would add is if you are using a neck bushing die you will need a different bushing for the Lapua brass to keep the same neck tension. The Winchester brass and Lapua brass are of different neck wall thickness at least in all that I have used.

 

[1shot]

If all the good information already supplied wasn't enough to give you a headache, also realize that W-W brass isn't nearly as tough as Lapua. I've had loads that even reduced for Winchester brass would expand the primers to when they ejected, I'm not sure which left the loading port first, the case or the primer! Another powder to try is IMR-4895. My Palma rifle has shot 180-185 gr. bullets at some very respectful velocities and held well under MOA at 1,000 yds.
I hope this helps,
Lloyd

 

[Jet]

Like stated above reduce your loads by 1.5 maybe even 2 grains then work up. Lap brass is great but it's added wall thickness could spike your pressure if you went with your standard WW brass load.

I get very good results with Varget, 4064 and RL15.

Good luck

Jet

 

[Laurie]

Brian,

in my rifle (yours will be different), the 'water overflow capacity' of fireformed cases is

56.1gn Lapua
57.0gn Winchester

showing the different capacities. These measurements are obtained by taking a fired, unsized case with spent primer still in situ and weighing it twice - empty and with water level with the case-mouth, the difference being the capacity in grains of water which is easily converted to C.C.s.

This plus bullet model plus COAL gives the combustion chamber volume of that brass in my chamber only (a 'tight' one cut with a 'minimum SAAMI chamber' reamer).

Run your load of 44.5gn VarGet through QuickLOAD and assuming COAL is 2.900-inches, you get:

Win brass
Usable case capacity (full capacity less the volume taken up by the shank and tail section of the seated bullet): 3.261 cm cubed.

99% fill-ratio
52,623 psi estimated PMax (v 60,191 psi MAP allowed by SAAMI)
2,721 fps estimated MV


Lapua brass
Usable case capacity (full capacity less the volume taken up by the shank and tail section of the seated bullet): 3.203 cm cubed.

101% fill-ratio (light compression)
54,601 psi estimated PMax (v 60,191 psi MAP allowed by SAAMI)
2,760 fps estimated MV

QuickLOAD is a very useful and sometimes, but not always, very accurate predictor of pressures and MVs and the above data refers solely to my manufacturing lots of brass fireformed in my rifle's chamber, but gives a guide as to the difference in likely pressures generated by this change of make of case.

Personally, I'd always drop 1-1.5gn and work back up in such a scenario. If you change to Fed 210M primers, do this at the same time as changing primer models can also affect pressures. Whether that change would make a noticeable difference to groups is debatable, but certainly won't do any harm as the F210M is probably the number-one choice amongst precision minded long-range 308 Win shooters.

Apart from likely pressure changes, you'd want to re-tune the load to get a new 'sweet spot' which will likely be at a slightly different charge weight from that in the Winchester brass.

Hope this helps you a little!

 

[brian923]

thank you all so much for all your help. i really appreciate it. have a great new years and ill keep ya posted as to how my shooting goes. theres still a couple more days of deer season to go, but after that, ill get back out and do some load testing. its soposed to get downright cold though, so we'll have to see how the weather acts to see if i can get out there. hopefully using varget with its temp insensibility will help with working up loads in the winter.

 

[XTR]

If you're changing brass and looking for target accuracy then you're going to want to do another OCW workup anyway. Load down to 43.* and work your way up to about 44.5 and see where the node falls. That's where you want to be.