577/450 innaccuracy issues

[g3a3a1]

I recently started reloading for the Martini Henry. It is my first BP cartridge that I reload for, to get brass I ordered 20rds of bertram brass loaded ammo from Buffalo Arms, it shot fairly well (4-5 inch groups at 100m) however once I started reloading my own my groups at 100m are closer to 2 foot. I have no idea what I could be doing wrong so I thought I would post my set-up here in hopes that somebody more knowledgeable could point out any errors.

Bertram Brass
Swiss 1.5Fg Powder 85 grains
Cotton ball filler
Orange juice disk
Beeswax grease cookie
orange juice disk
X-ring boolit mould 475grn .470dia (no grease in the grooves)

I measured out all of my powder to exactly 85 grains by weight, I also weight 5 of the bullets and they all dropped right around 472grn and all of the shells are 3.2 inches OAL. I have no idea what I could be doing wrong to get such a variance in POI. At 100m it should be shooting ~17 inches high and I am around 26 inches high, other times it will shoot 14-18 inches too the left, and occasionally it will hit 14 inches above my POA. While there is a chance it could be me, I also let my father shoot the rifle and he was also unable to get any discernible grouping with the rifle.

[john.k]

The cause will be blackpowder fouling.I suggest you reduce the load to about 60 gr,and double the ammount of lube.if the bullet has grooves ,grease them.A simple lube that works is 70/30....b/wax&olive oil.

[skeettx]

Yes, lube the bullets and also take some tubing and blow down the bore between shots to keep
the fowling wetter.
What allow for your cast bullet??? Softer is better.
Mike

[curator]

You have failed to mention if your M/H rifle is a MkII, MkIII of a MkIV as the bore size is larger with a MkIV and a .470 diameter slug may not be large enough. In addition, while 85 grains of modern 1.5FG may be OK pressure wise, the original load was more like 85 grains of Fg, a slightly slower powder.

The best internet source of Martini Henry cartridge reloaing is the British militaria website : https://www.tapatalk.com/groups/brit...8cbe67182d7efa

Check them out for more information. For the record, My Martini-Henry Mk11 and MkIV rifles shoot best with .475 to .480 boolits cast from 1 in 40 lead/tin alloy and lots of bee's wax/lard lube. The M/H rifle is purposely made with a very large and long tapered throat to accommodate black powder fouling.

[john.k]

Its funny you should mention that;.I have shot and collected 476 /400 Lee bullets from all my rifles,and found that no smaller bullet fills the grooves.

[curator]

Its funny you should mention that;.I have shot and collected 476 /400 Lee bullets from all my rifles,and found that no smaller bullet fills the grooves.

My Martinis also shoot the Lee 476/400 RF slug very well. The mould I have drops the slugs at .480 cast from 40/1 alloy. This bullet does not carry enough lube for multiple shots when loaded over real black powder but works OK with B-P equivalent smokeless loads.

[Larry Gibson]

Cotton ball filler
Orange juice disk
Beeswax grease cookie
orange juice disk
X-ring boolit mould 475grn .470dia (no grease in the grooves)

Drop;
Cotton ball filler
Orange juice disk
Beeswax grease cookie
orange juice disk

If a filler is needed use Dacron, it doesn't burn and start fires. Use enough filler so the bullet slightly compresses the powder when seated.

Fill the lube grooves in the bullet with lube. A beeswax/olive oil lube is excellent as john.k mentions. I use it at a 5 parts to 4 parts mix for a softer lube.

Bullet should be cast of 20/1 or 16/1 lead/tin alloy with no antimony present.

[bigbore52]

ditto for Curator....et al, ....

FWIW - I had similar accuracy issues many years back until I slugged it and then selected a pill that was slightly over bore and used an alloy mix of 20:1 Pb:Sn - nothing harder but it can be softer ....prefer that brew as I also use it in my other BP rifles ........

Tried a few commercial 458 up to 460 moulds including Lee and RCBS etc and no real joy with any so eventually bought one from David at CBE which drops a .468" RN loosely based on the Postell shape - but not as sharp nosed...I believe he still offers them off the shelf....he also included bottom dies and top punch for the Lyman 4500 lube/Sizer to squeeze it down to the desired diameter - after changing to that pill mine shoots much better - regards powder and how you stuff the case is all pretty academic provided you don't overload it or leave air spaces. I settled on 87gns of Swiss 1.5.....its a mild load and easily handled in most rifles.....

I would suggest, if you can; use genuine felt wads (or similar medium density) on top of the powder calculated to sit to the bottom of the seated pill under slight pressure - if you look into the charged case you can see where the level of powder comes to on the shoulder or thereabouts...I stuff a wad in using a wooden dowel - the wad comes up into the neck and retains its position and is slightly compressed when the pill is seated ......in my case I think they measure about 8mm thick off hand but would have to check, not sure now so don't quote that - easy enough to measure your own as depends on what powder you use and how much......but remember no gap.

I apply an ever so slight roll crimp to the case as I originally flare it to seat the pill....the less flaring and crimp pressure the longer the case life but it's a trade off which you will need to sort out best suits your loads.

There's no need for cardboard spacer wads or lube cookies if your pill is separately lubed as mine are and the lube will not get to the powder through the felt....I've tried a variety of lubes but IMHO, didn't make much difference in my accuracy as much as pill size does .....

I have tried various primers over the journey but settled on using magnum primers for all my BP loads but the MH wasn't fussed using Bertram brass and WLR primers but a word of advice after you let them off which you may already know.....immediately de-prime and rinse them in a brew on 50/50 vinegar and warm water, let them dry and then rinse in warm water to wash out any residual vinegar again allowing them to dry before you clean them - I use the Lee universal de-primer die first up and then clean that as well...by using the vinegar (mild acetic acid) ...neutralises any residual oxides from the burnt and un-burnt powder and will extend your case life considerably......I am onto my 15th reload for some 577/450 Bertram brass - only done a few length trims...in fact the only ones that haven't survive are those I got careless in resizing or loading oopsies...no split necks or pressure weakness signs at all

If you stick to the basics as sure you will, and match your pill diameter slightly larger than your bore then your accuracy should improve - that should be your first of many enjoyable steps in using this fine rifle.

Good luck.......Lee