6.5 acuracy and and mould

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Joined: Thu Dec 29, 2011 6:28 am

6.5 acuracy and and mould

Post by wheelerdan » Thu Dec 29, 2011 7:21 am

My end question is what kind of mould to buy,..... but before I ask it let me explain.

For background I am an experienced reloader, caster, gun nut and shootist. I have worked with standard cartidges wildcats, rifles, revolvers, auto loaders, the gammit. I have succesfully loaded and used cast bullets from several manufacturers and have had good results with everthing, except the example below.

The problem is with a 6.5x55 Ackley improved rifle built on a Montana 1999 action and barrel. The problem I describe has been consistent before and after the AI chambering. The rifle was I ordered it with a 1 in 7.5 twist and a throat to fit a dummy 6.5x55 dummy round with a Hornady 160 RN bullet in it. The AI change was done because the rifle had a problem with round popping out of the magazine. The AI fixed the problem and increased performance a full 10% (which is fun but irrelevant). The file shoots 140 grain and 160 Hornbady bullets to 3/4 " @ 100 yards, with a preference for the 160 grain round nose. The bore measure .2635. The chamber .2645.

BTW if you have not tried this wildcast, it is amazing. The 140 grain HOR bullets easily achieves 3000 FPS in this 24" barrel.

I had LBT make me a 160 grain mould to mirror the HOR 160 from the same dummy round the gun was made from. The goal being to shoot the same kind of load as jacketed, a lot, cheaply. It is gas checked bullet design. Lube is LBT Blue. They cast from the mould @ .267. They are very difficult to cast, perfectly, unless the mold is "HOT". At temps where anything else casts find, these .267 are apt to wrinkle unless the mould is heated in the melt briefly before each cast. The alloy is 7 parts monotype and 3 parts pure lead. I casts to about 17-18 BHN when dropped from the mould into water.

I heat the melt in a big on a burner then transfer into a Lee bottom pour pot for casting. Sprues and such go back into the bulk pot. I I have a Star lubrisizer and resize the bullets to .264. The lube is LBT blue, Hornady .264gas checks.

I have tried loads from about 1300 FPS to 2100 FPS, using IMR 7625 powders to 4198, 3031, 4895, 4350. The best I have been able to shoot is about 2" @ 50 yards. Most of the tests are more of a pattern than a group. Very disappointing. The bests speed range where the 2" group occured appears about 1750 FPS ( I use a chrony). Loads too much either side become patterns, instead of groups.

I am very bamboozled.

I really do want to find a mould which will meet my goal, but I don't know where to look for the problem. Aside from adjusting powder, filler materials, slugging the bore, fire lapping the bore, cleaning the bore, weighing and sorting bullets, how else might I proceed to solve this dilemma and what mould should I buy?

BTW, I realize one of your goals is to shoot more, so I'd be hpy to help you with that by sending this thing to you to try :lol:

Thanks a bunch.


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Re: 6.5 acuracy and and mould

Post by mtngun » Thu Dec 29, 2011 9:02 am

Well, you would need to know more about your throat. Shape, length. And what shape and length of protruding nose will or will not cycle through the action. A chamber impression would be a good place to start, if you haven't already made one.

In general, copying a jacketed bullet design is not a good idea. Cast bullets play by different rules, and have their own design requirements. Sometimes it is necessary to experiment with several different cast designs before you find one that will feed reliably through a bolt action. And sometimes the design that will feed, won't shoot, and the design that will shoot, won't feed. Sad but true.

I'm not a 6.5 shooter myself, but have heard it has some special challenges because of the long, skinny bullets and fast twist. The skinny bullets are easily bent by acceleration forces, end up being banana shaped, and won't shoot worth a hoot.

Dropping a hot 6.5 bullet into water can also bend the bullet. You may not notice it with the naked eye, but it could be there. I prefer to drop onto a folded towel. And even there, it would still be easy to bend a 6.5.

The longest 6.5 I could cut would be about 140 grains. Veral is one of the few who would be able to cut 160 grainers. They are very, very difficult to lathe bore.

I don't recommend firelapping unless you have a throatless rifle. Firelapping tends to wallow out the throat, and many chamberings have a sloppy throat to begin with.

Your difficulty casting the 6.5 is not surprising. Veral's blocks were designed for 44 - 45 caliber bullets. They would run way too cool with a 6.5. Plus, long skinny bullets are always more difficult to fill out under the best of circumstances. It is difficult to avoid wrinkles and voids at the nose.

Thanks for your question. I don't know the answers, but it's interesting to think about the possibilities.

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