WTF Happened

This might go long on my end so I'll say sorry up front,
I have been shooting my PTA 243 match barreled CBI using winchester brass, 34.6 grns. of IMR 4895, 105gr. Burger hybrid/target bullets into 0.163-0.167 5 shot groups most of last year. When shooting score comps. I was staying in the high 230's or low 240's not the best but getting better every time out.
Now over the winter I got to thinking(my biggest downfall) why not try Lapoua brass for the consitentcy. Well I loaded them up same way, same lot of bullets and same seating depth (2.862) then went to the range. Wow what a disappointment it was at best a 1.5" 5 shot group, there would be some with 2-3 in same hole and the others way right or left no pattern there.
Now keep in mind all of these were prepped the same FL sized, champhered & deburred Length checked and adjusted where needed all loaded exactly the same as the winchester. Just didn't shoot worth a ****. I would have thought at $1.00 a case or in my case $100+ shipping I would have gotten better results or at least close to the same. What do you all think, start load work up all over,try adjusting seating depth or ???. Please no "send them to me I'll make them work, I've been at this a long time just drawing an old timers blank at the moment.
Oh almost forgot this barrel is an 8twist and the load chronos at 2850 right in the ball park berger told me to go for for short range BR.
Thanks

Same powder lot? Same bullet Lot?
I think you will have to tweak the load a bit
I have seen it with different brass before
Oh what fun
Jack

Different brass, different volume, different pressures...

Check your neck tension, the neck thickness may be different and that can cause hell. Also measure case capacity and compare also. I have gotten to the point where I am only buying Lapua brass with the exception of some LC long range for the 308.

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Different brass, different volume, different pressures

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Go back with the exact original load using Winchester brass and see if the rifle shoots them as before. If it does, you can probably assume that the Lapua brass is the problem.

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Originally Posted by BoilerUP

Different brass, different volume, different pressures...

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^^^^this is the problem froggy....take a piece of the win brass size it,trim it and take a piece of lapua size it,trim it and weigh both with H2O...ill bet the lapua has less case capacity and is creating more pressure and your barrel is out of its comfort zone...or drop your charges by .2 to .5g at a time and shoot groups and i bet you find your sweet spot again.

just an FYI...260rem brass has a H2O capacity of about 57g...260 lapua brass has a case capacity of about 53g.

Do you full length size the Win brass each time or just neck size ? If just neck sizing your Lapua is getting fire formed and will fit your chamber better next time. Do one or the other.
My Win brass necks thickness are from 0.012" to 0.015" so I turn them to 0.0125" then use an 0.266" bushing giving me 0.002" neck tension.
My Lapua is a pretty consistent 0.015 neck thickness so I just clean them up a little and use a 0.271" bushing. This is AFTER I have fired these cases in that chamber once. I'm not sure how much tension you use but it probably be different between the two brands. As will the fill ratio of the case.
I have also noticed a difference in the feel of different batches of Win brass when turning, some feel harder so I anneal the Win first. I know the Lapuas have had this done already.
Good luck and keep us posted

I'm just wondering why you would shoot 105 gr. bullet for short range.....:confused:

Different brass equates to a new load work up.

Fred to answer your question both ranges I shoot at are pretty much set in a bowl. On one there is 200'-300' or more rock ledges on the side and in back, on the other the rear of the range is over 500 feet high and the range it self sits on the flats (at one time it was all farm country), most times the wind is never going in the same direction at any one time and both always seem to have wind , never a calm day. So after some searching I decided to go heavy to fight off some of my own wind reading defects and try an push heavier to help fight off the wind, also recommended by Berger.
I am going to grab the Magneto speed this week end and see what I am getting from the Lapua. I know the Win brass combo gives me 2839-2855 with the majority of shots being 2851 fps. I had one target in the truck that had 10 shots @100 under a nickel and another with 8 under a dime but I'll be darned if I can find them to show you.
I guess I will need to start over or just stick with the Win. brass for now

Wedgy go back and reread the original post and you will find the answer.

I ran into much the same problem last fall. After a 30 year hiatus I thought it was about time to revisit the 25-06 for deer season. I had all the parts, a new Steve 200 takeoff barrel , 100 sticks of new Rem brass and bullets ,100s to 120s. Digging through my old notes to see what worked well in the past I loaded a few sticks w/R22 with 100BTs, 117 Sierras' and the old 120 Nosler Soild Base. Nuth'n to write home about, 1.5-2" groups.

Then I had a brain fart. I grabbed 10 Winchester once fired '06s. prep'm them and back to the range. The first three shot group(R22-100 Nosler SB) went into the high 2s", the five shot into the high 3s. Figuring case capacity was the snafu I tired tweaking the charge using the Rem brass without much if any improvement. I even tried annealing and cleaning up the necks with no luck. Since time was getting short I prep'd 20 sticks of the Win '06, loading them, sighted in and went hunt'n. My oldest grandson dropped a basket six with it @ roughly 150 the second day of the season.

Why the Rem brass shot like ..... I have no clue.

Bill