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Hi guys
I was really surprised today at the range to get top results with Hodgdon H870 which was always very disappointing velocity wise in my last rifle. However today 61,0 grains and a magnum large rifle primer produced a group just under 1.0" at 100 yards in my 1957 Frankonia Mauser. According to Werner Reb's 1984 reloading manual, (in German), 3,362 fps was predicted and I got 3,231 fps using Norma 71.0 grain .228" bullets.
The fly in the ointment is that H870 seems to have been discontinued and so too are these Norma bullets as components though still loaded in .22 Savage Hi-Power by Norma, I think.
Hodgdon discontinued H-870 quite awhile ago, so any you can find to hide away would be a good plan. As you already know the bullet selection is very restricted unless you can alter some of the others to work. I used H-870 initially to develop loads and always found it accurate but very dirty burning. Since it has gone away I turned to Vihatavuori N-570 with even better results. Nice looking rifle and good shooting too.
Hi Diz
Supposedly if you crimp the vH rounds the H870 shoots a bit more clean and velocity goes up a little too. Hodgdon suggested to me the problem may be that the pressure is too low and hence the dirty burning with this powder. However most of these bullets have no crimping groove or if they do, (i.e. Hornady), it is for the .22 Savage. So they look a bit short made up.
A German reloading catalogue offers a Lee Factory Crimp die in this calibre. I got one by sending a case and loaded bullet, (the case had to be drilled out from both sides to show it was empty), to Lee who custom made one for me. Perhaps this crimper not the most useful tool I own, but it doesn't take up much room, so what the heck. I think you can put a cannelure on a bullet with special tools. Could be an option. Perhaps too just find a solvent that works better, if there is one. I do have a couple of tins of H870. I just spoke to the Hodgdon importer yesterday at his Shotexpo stand. Doesn't sound like he has any old stock of this powder or .228" Norma bullets.
Vihatavuori is a useful powder, for instance in my 7x66 SEvH is right on the money in terms of ft./p/s. and accurate too, (5 shots all touching). But I haven't come across N-570 or data yet.
I have used the Lee Factory Crimp dies on others but never gave thought about the vH. I agree that with the very slow powders, anything you can do to retard the bullet helps to get the heat and pressure up. I have tried some of the designer bore cleaners but usually go back to Hoppe's Bench Rest or J&B Bore Cleaner for jacket fouling. I ruined a perfect barrel once with one of the hot rod bore cleaners and have shied away since.
I had found a few cans of H-870 at the local gun shows but that has dried up too. What bullet are you thinking for your 7x66SEvH, I could run a few numbers for you. Here's one using N-570 with a 170 grain Norma Oryx in a 24" barrel:
N-570 = 82.2grains
Fill = 100%
Pmax = 60673 psi
Vel = 3085 fps
Burn = 98.1%
Eff = 23.2%
All a calculation of course. This powder might be slightly slow in this cartridge but the numbers don't look bad at all.
Here's my source, (below). The table is the thing to check out. I use a 160 Nosler partition and Vihatavuori N160. Norbert Klups got 3,050 fps. I got 2,993 fps but my chrony screen was about 5" further back than his! 4 of my bullets clustered in 5/16" centre to centre. That makes it the most accurate rifle I own, (a Mauser 66).
I haven't done much more work with this rifle as, I've already found the ideal load I think. Also the cases are a bit odd. They have thin necks. This means that the RCBS FL sizing die will not squash them down enough to hold a standard .284" 7mm bullet. It's not the dies fault. If I put in 7x64 cases, it does what it should. The way I could get around this is to source more cases, but it is not easy importing them in this part of the world.
What I have done in the past is to use thin-strong Mylar tape. For instance, if I accidentally put one of my Hornady Over All Length cases in with a batch of the same calibre and size it, (it is meant to have a sliding fit with the bullet when used), I can slip a bit of Mylar inside the neck and stretch it back using just the sizing button set low in the die. It might be that I can also use the Mylar on the outside of the 7x66 SEvH case necks to correct the thin neck issue and keep using them. But I would need to get it to stay on while the case neck was sized and then come off afterwards. A bit fiddly.
Kiwi-bloke,
You should be able to get .404 Jeffery cases "Down Under", and you should be able to make 7x66 cases from them, but the rim will have to be turned to size. The result should be cases with thick necks. Then you could thin the necks to the thickness you need.
Mike
To be honest I have never had a problem with thin case necks, it is usually the other way and they are thick. I think your Mylar tape idea will work and i would like to hear about it. If you are getting performance like that than don't fix what isn't broken. Of course I did go to the site and looked at the data and then confirmed that Vihtavuori is indeed a subsidiary of Kemira of Finland so the names are different but powders are the same in this case. I plugged in the 160 Nosler Partition and the N-160 load at 67.5 grains. I had to change the OAL to that from the data and it is a bit longer than the program wanted. That gives the case some added volume and lowers the pressure but on the other side it moves the bullet closer to the rifling and increases the shot start pressure. A trade off at best. Here's what came out and it's a bit slower than I expected:
N-160 = 67.5 grains
Fill = 89.7%
Pmax = 49898 psi
Vel = 2804 fps
Burn = 98.3%
Eff = 23.9%
Then I cranked up the loading to get the velocity:
N-160 = 73.0 grains
Fill = 97.0%
Pmax = 62385 psi
Vel = 3013 fps
Burn = 99.7%
Eff = 25.5 %
I am not sure why the velocity comes out slow from his data and your results but there are a lot of variables unaccounted for, like maybe the barrel was longer than 24". That's why I like to have something real for comparison. It's a heck of a cartridge and there is a belted version that is even bigger. Far ahead of it's time I think.
Replying to Diz about your post of 02/14/2018, (but it will be of general interest to all):
You predicted 49.7g (max) of IMR 4350 with a 70g Hornady bullet in the 5,6x61 SEvH for 3,400 fps. I looked through my loading book and found I'd previously loaded 49.0g IMR 4350 with a 71g Norma bullet, (and mag primer). This produced 3,389 fps at 10 feet, Std. dev. = 14 for 10 rounds. Bolt lift was moderate. Primer cratering not noted. Bullet was loaded to 1 diameter deep and adjusted to 1 thou run-out with a Hornady tool. Accuracy was 4 in 15/16" centre to centre at 100 yards.
So your prediction was very close. Are you using Load From a Disk?
Kiwi_bloke, I thank you very much for posting that info because I really like having solid feed back on these calculations. I am running Quick Load V 3.9 that comes with a ballistics program called Quick Target. I think this is the fourth version that I have purchased and it does work very well but as you must know you need to use your head along with it. The people that wrote the program will deny that it is for load development but I think that is strictly for liability reasons. Once again thanks very much and best of luck in the future. Diz
Hi Everyone,
I was lucky enough to meet Diz this past weekend, as he has been on this site, he was generous with his time and knowledge.
It was an honor to meet and spend the afternoon with him. He is both a Gentleman and a warrior.
Jeff
Devo, I appreciate the kind words and we did have a great afternoon discussing guns, shooting and reloading. I was particularly interested in seeing his rifle since we both have Chris. Triebel’s in 5.6 vH. I am not ashamed to say that his is nicer than mine with some very nice figure in the wood and a full-length stock. His also has a very elegant cartridge trap in the butt and a horn trigger guard that I have been lusting for. The interesting part is that the metal work is very nearly the same with engraving, color hardening and features and in this area, they are very similar. But his has a quick detachable side mount for the scope while mine is on top. The side mount is rather interesting with the way it goes together and looks very strong and reliable.
I am glad to have the opportunity to meet "Devo" as he is a serious collector and shooter and nice to have someone close that appreciates the finer guns. I am looking forward to doing it again.
Thanks, Diz
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