Some progress with my 6x45

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  • Last Post 01 June 2015
mtngun posted this 31 May 2015

My 6x45 Contender project had been giving me a hard time, shooting patterns rather than groups, but I'm finally making a little progress.  Best results so far have been with slow powders, light bullets, and Ardito-style sizing and loading so that only the gas check is inside the neck.

27 1/2” Shilen barrel blank, 1-10 twist.  Oven treated wheelweight, Rooster HVR lube.

The bullet drops out as a one-diameter bullet, but is then sized in a nose die that closely matches the throat and bore.   By adjusting the sizing depth, I can arrange for it to be just off the rifling when seated with only the gas check in the neck.  Next best thing to breach loading.  I'm grateful to the CBA for teaching me this stuff. :^:

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mtngun posted this 31 May 2015

Forgot to mention that it currently has 100+ rounds through it at 2500+ fps since the last time I ran a wet patch through the barrel, and it's as clean as a whistle.

It used to start fouling around 2600 fps, but then I put 10 firelapping rounds through it and it now seems to run clean up to 2700 fps, though whether I can get it to group at 2700 fps is another story. :D   

I haven't attempted anything faster than 2700, my personal goal is to start out at 2500 and then try to work my way up to 2700.   No practical reason for shooting cast in a 6x45 at high velocity, it's just a game I like to play to force myself to step outside the comfort zone, try different things, and hopefully learn something. 

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Ken Campbell Iowa posted this 31 May 2015

i like that bullet design ... good to see 6mm shooters also ...if i ever get my incredibly highly accurate 6mm super rook together i want to see just the least angle nose cone i can use before it goes bad at 50 and 100 yards .

short bullets ?? heresy !!!

ken

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JSH posted this 31 May 2015

A favorite cartridge of mine, only I used FLGC's. H335 and almost any bullet from70-80 grains.

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mtngun posted this 31 May 2015

Today I tried increasing the powder charge.  Believe it or not, it's tougher to get good accuracy as the velocity increases ! ;)

I ran out of bullets so that's as far as I got.    It remains to be seen if I can tune the load to improve accuracy at 2700 fps.

As usual, the barrel was still clean at the end of the session other than a little powder residue, so I didn't bother cleaning it.

To lend an air of expertise to my efforts, as Joe Brennan might say , I went to the trouble to calculate the mean radius and the radial standard deviation.  ;)   No matter how you measure it, there's room for improvement. 

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Ken Campbell Iowa posted this 01 June 2015

i would like to see what about 3.5 gr. unique would do for that bullet ... making sure each shot you don't get one stuck in the barrel, of course .

dang i gotta get my rig together .

ken

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John Alexander posted this 01 June 2015

I know that you are interested in a high velocity load but if you decide to explore the other end of the velocity and powder burn range as Ken suggested I think you will have better luck with soft maybe very soft bullets.  TiteGroup burns cleans for such things -- if you can get it but BE and 700X also work as would other fast burners.

With everything else equal, which never happens, your ten inch twist can of course handle longer bullets which would be easier to get accuracy with -- but not high velocity.  I know I'm not telling you anything new but just rambling. John

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mtngun posted this 01 June 2015

I've tried up to 88 grain bullets in this barrel -- mostly at 2500 fps, of course. They did poorly, I'm guessing because they generated more pressure.

When I first started playing with cast bullets in rifles, I worked up reduced loads just because everyone else was doing it. For a while I carried those reduced loads on big game hunts, to use for the occasional forest grouse, and my ex liked to use them for rockchucks. However, the reduced load had a different POI than the big game load, and switching backing and forth between cast and jacketed could cause the first shot to go awry due to the different barrel condition, so I finally decided that it made more sense to pack a 22LR pistol for forest grouse.

So my reduced rifle loads sat on the shelf and never got used. I finally lost interest in them altogether. But that's just me, and obviously many casters enjoy plinking with low velocity loads.

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mtngun posted this 01 June 2015

BTW, back when I messed around with reduced rifle loads, I did experiment with different alloys.

A 1450 fps pet load for a 7TC and later for a 7-30 Waters did best with 40%lino/60%wheelweight. If I tried to use a softer alloy, it was impossible to size the long, skinny 170 grain bore rider in the lubrisizer (push-thru's weren't well known back then) without bumping up the nose. When I tried heat treating the bullet in wheelweight, I encountered banana-shaped bullets. Maybe I was getting them a little too hot, I don't remember, but anyway I gave up on heat treating those long skinny bullets.

My ex's 308 rockchuck load did very well with heat treated WW, but that was the Lyman 130 grain spitzer intended for the 30 carbine. It was short and stubby and did not have a bore rider, so I didn't have to worry about it bumping up in the lubrisizer or becoming banana shaped. I didn't have a chronograph in those days but it used a moderate load of RL7 that should have generated 1600 - 1700 fps.   I sized it 0.312” to match the Ruger's sloppy chamber.

My guess is that the folks who are reporting better results with soft alloys are shooting undersize bullets, or shooting bore riders that benefit from the nose bumping up. But I try to keep an open mind. Every time I think I have cast bullets figured out, I encounter a gun that doesn't work the way my theory said it should and I am forced to rethink my theory. :D

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John Alexander posted this 01 June 2015

When I lived and hunted in Alaska and when a Spruce Grouse (they called them fool hens there) showed up I used to shoot them with full charge loads in my 270.  Of course the blast got through to even those low IQ birds and you only got one per flock instead of perhaps more with a rimfire.

My main interest in cast bullets is just to see if I can get the bullet holes to appear close to where the cross hairs were so fast or slow makes little difference to me -- whatever works.

John

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