Questions on 303 Reloads

I have quite a few years experience loading various pistol calbres and a few years experience loading .303 and 6.5 x 55 Swedish. However I'd like to check some points and ask a few questions:-
1) Does anyone make a good copy of the Mk VII flat bottomed military bullet?
2) If so any ideas where I can get some in the U.K.?

At the moment I'm experimenting with Vithavouri 140 loads behind a 180 gr Sellier & Bellot bullet.

The standard load that people use seems to be 41 grns. At present I'm getting qite good results with 39 grns but lack range time to try a lot of loads in between.

Can you confirm if I am right when I say that an increased powder charge will result in a flatter trajectory?

Will an increased powder charge print higher on the target at say 200 yards / 400 yards / 600 yards?

The Rifles I'm using are a No4 Long Branch an SMLE III* and a Long Lee.

Any help / discussion / ideas / theories are welome as are pet loads (I do know enough to start recommended loads 10% and work up!)

Thanks

If you have not already got it, get the Vihtavuori Reloading Manual.
For N140 and a 180 gn bullet, this give a load varying from 36.0 gn (min) to 39.7gn (max) for a 180gn spitzer - i.e. the pointy flat-base bullet form that goes so well in Enfields - and in most other old service rifle, in my experience.
So your 39 gn is fine, but 41 gn is definitely over the top for N140 according to the manual. You can go up to 41.7 with N540.

Up to now I have found the data in the Vihtavuori manual to be reliable, and see no reason to go above their recommended maximum load.
They do, however, go up to 41.7gn with N140 for the 174gn HPBT.

Why the big difference in max. load for only 6gn difference in bullet mass?

I think the reason is not the 6gn, but the difference between a boattail and a flat-base. The boat tail starts to come free of the neck much earlier than a flat-base, and one imagines that this reduces the peak pressure, compared with a flat-base of the same weight, seating depth etc.

I would respect the max. loads given in the Vihtavuori manual. And within the given range, pick the load that gives the best accuracy, not maximum velocity. That may, of course, be the max. load - but not always!

Thanks Patrick, we had originaly been using Reloader 15 before switching to VIT 140. The Sellier and Bellot bullets are boattail. I have checked the manual and do not exceed max loads, nor do I chase velocity at the expense of accuracy. I had hoped to hear from others re their loads as I do not have the range time to experiment from 36grns to 39.7 but it looks as though I'll just have to be patient.

As to part 2 of your original post; In another thread I had asked basically the same question and was recommended the Woodleigh bullet. 174 Gr, flat based, but not quite a spire point. Not too hard to find them online. Made in Aussi land, but sold elsewhere. Midway carries them in the U.S. The No 1 Mk III will probably require the flat base more than the #4. There is also a round nosed, flat base 174 grain made by Hornady I think.

Good shooting