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Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 8:53 pm
by lapua338
Stuart,
I was explaining to ovenpaa on another thread that I don't have access to a chrony to measure my MV. According to the Vihtavouri Reloading Guide the MV is somewhere between 2215-2551fps. I've used 42.3grs of N140. The starting load and maximum load are 37.6 and 43.7grs respectively as per the reloading data (test barrel 24" with a 1:12 twist). My CZ550 has a 25.6" barrel with a 1:12 twist so I've been making the assumption for calculating my bullet drop that the MV is approaching the maximum velocity... say around 2400-2450fps? Is this a reasonable assumption to make?
Greg
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 9:37 pm
by Ovenpaa
Greg, what weight bullet are you shooting or did I miss that?
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 9:48 pm
by lapua338
Ovenpaa,
185gr LAPUA D46's
Greg
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 9:59 pm
by Ovenpaa
A useful rule of thumb with published data is add 25/30fps per inch over 24" so add 50/60fps for a 26" barrel. I would be inclined to change powder, go to around 45 grains of N540 or even 47.5 grains of N550 which should get you to 2750 at a push. Start a bit lower and work up in .3 grain increments.
I have quick load here, if you can give me your OAL I can crunch the numbers with N140 for you. QL is obviously not the same as shooting in the field but it can be surprisingly accurate.
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 10:22 pm
by lapua338
Thanks ovenpaa,
That would be really useful. My cartridge OAL is 2.795"
Greg
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 10:46 pm
by Christel
Ok if I mail it to you? It is a text document.
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 10:51 pm
by Ovenpaa
Argghhh! That is what comes of using someone else's laptop.
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 10:52 pm
by lapua338
Hi christel,
Yeah, that would be great.
Many thanks,
Greg
Re: F Class / F/TR training weekend
Posted: Sat Jan 01, 2011 11:00 pm
by Ovenpaa
I have mailed you the load data for N140/N540/N550 at 60C. QL is nothing more than an indication but it seems to be very close most of the time. shout if you need any more information
Re: F Class / F/TR training weekend
Posted: Sun Jan 02, 2011 1:38 am
by sanselm
Greg,
You wouldn't be too far out with your assumptions, at the end of the day all you would need is a single range visit at about 600 ids to verify your actual elevation and you would be able to work it out from there. As Dave says I would be inclined to look at 550, I used around the 47, 48 gr mark when shooting 185's at 2750 and that shot really well. Your rifle etc certainly won't hinder you if you can get 185's working, Ramon Fito from Spain nearly took a league win last year at Blair Atholl shooting his short barrelled TRG and 185gr Bergers.
I am involved in running the F Class course at Bisley with a few others like Vince so we hope to see you there.
Stuart