Home Forums Hunting & Shooting Ask The Gunwriters Why do the 6.5x55 rifles react so poorly to cast boolits at 1900-2000 fps?

I have had very good success in casting boolits for several different rifle calibers and pushing them to between 1900 and 2000 fps. These are usually a bit oversized, sport a gas check, consist of wheel weights with some tin added and have Lee Liquid Alox for lube. I have several different rifles that will shoot 2" groups with such - usually 2-3" at 100 yards for 5 shot groups. 30 caliber, 8mm, 40 caliber, 45, 50...

But the 6.5x55 has thus far eluded me for velocities past about 1600 fps. I have a good 150 grain mold and size the boolits to .266" which is supposed to help... the boolits are concentric - nothing wrong with them.

I guess that it's the twist rate but it just doesn't make sense to me. And I've tried different alloys and such with no joy. Others also report difficulty with this.

So the question is why? What about this caliber makes it so difficult to get an accurate cast boolit load?

Its a mystery that I have yet to hear a good explanation for.

I have no idea other than that they are offended by the spelling.

Are they round nose bullets?

Rough bore?

JEff

They were designed for 156g+ jacketed bullets. Long and heavy for caliber. Perhaps a bit harder lead bullet would work better. It does depend on the bore. My Sako loved to foul, but was still accurate. Cleaning was a chore to say the least.

Lots of info on the castboolit site:
http://castboolits.gunloads.com/index.php

Fast twist and over sized chamber in the neck area are the main culprits.....
Lots of info at the castboolit site on the 6.5X55..
Some are claiming 2300+fps..
99.95% don't get much past than were you are..

Latest:
http://castboolits.gunloads.com/showthread.php?p=1306288#post1306288

I don't bother with cast in the 6.5X55 myself..

Small bores are always more difficult as any variation is magnified as a % of imperfection.
1900-2000 is the top edge for the metal you are using.
Lee liquid is a good lube, but if you invested in a SAECO lube sizer with SPG lube you'ld be way ahead.

Buy some good Lyman mix bullet metal rather than WWs with a bit on tin.
Many times small bores like 100% linotype metal.

You need to know the twist, need to slug your bore, is it a top quality mold? Have you segregated your bullets by weight ?

Suggest you may wish to avail yourself of the ton of experts at www.castboolits.com

Back in my "ute" I cast for small bores down to .224. Now I don't bother with anything less than 30 calibers and the vast majority run from 35 to 61 caliber.
Much less critical and results are just fine. 5 shots bottom to top with a bone stock Ruger 77 with plain old wheel weights. Segregated +- 2/10th. Chronys at 1600 fps.

The faster twist of the Swede might be hard on cast bullets.

I would think a cast bullet in the Swede ought to be up around 170 grains or more to work well with the fast twist and long throat.

They are (nominally) designed around 156-160 grain jacketed. A cast bullet would need to have more weight to get to the appropriate length.

I'm a member on castboolits and have explored this there. There are members there that claim to have solved the problem but they don't share the information. At least not that I know of.

I just thought I'd throw this out here and see what information came back.

My mold is a 150 grain = it's packed up right now and I can't remember the brand - I think it's RCBS but I might be wrong - there aren't very many heavier .264" molds. And I haven't seen any heavier other than custom molds. This one that I have is a gas check design - roundnose. I sized mine in a custom .266" Lee size/lube kit - I have an RCBS luber sizer but I've gone to Lee's bottom-push sizers for all of my calibers now.

I have heard that Arisaka and Carcano 6.5mm rifles give
the same results with cast bullets.

Same results as in .... ?

Same results as the 6.5 Swede or same as jacketed bullets?

What kind of mold?

Are you getting any leading at the muzzle?

As twist gets steeper, the bullets shape and hardness effects accuracy from the side load imparted on the bullet; gas checks keep it "in check", but it starts at the nose of the bullet on down. Notice the production mold looks the same for most all cartridges, calibers.

I've never ran cast in a 6.5, but have done 22 1-9's and pushed them to over 3,000 fps, but that generally will not happen with a production mold.

Another way to get around fast twists is to use fillers and/or really slow powders; they just pamper the steering base more and move obturation back, both of which can make less stress imparted to the "side load" and the delicate bullet as whole.

This is all assuming the bullets fit close to the throat diameter and groove.

I get fine accuracy and all is well for 1500-1600 fps. It's when I push them to my desired 1900-2000 fps that I get problems - not so much leading as just really poor accuracy.

Powders?

Average or poor accuraccy with cast bullets.

I did not see the OP's twist rate.

If you are anywhere over 1 in 8 it won't work. The heaviest you can really go with great accuracy, my experience, is 130's from a 1 in 9. I believe the original Mausers were 1 in 8.56 to shoot 160 grainers. Don't know about the velocity.

But the BC of a 150 or 160 makes it a cruise missle. Should be pretty predictable at long range.

HawkI - I am presently sitting in Cedar Rapids (My daughter is in post-grad at Iowa) Her mother and I are also Hawkeye

I tried several different powders... with same results.

I increase the diamter as suggested - didn't help.

Coltdriver, the twist is standard military swede twist - (metric) haven't tried these in my Win Classic Featherweight... and I don't know the twist rate of it.

What's weird to me is that the rifles were originally set-up to stabalize 160 grain round nosed bullets going around 2400 fps IIRC. You'd think they'd be fine with 150 grain boolits at 1950...

OSOK,

What style of bullets are you trying? Are they bore-riders up front with a short bearing surface in the rear? If so, switch to a full-diameter design that graves in the rifling sooner. Also try seating them out to touch the rifling, or as far out as possible. Too much jump to the rifling leade, and/or a short bearing surface on the bullet, can cause the bullet to skid through the rifling instead of taking hold of it and spinning the bullet properly. Also try harder alloy (e.g. linotype) as has been suggested. You might also try a gas check bullet instead of plain base. There is no end of things to try as long as you have money to spend. It might be best to obtain small quantities of commercial-cast bullets to try and find a design that works before buying a mould. Please keep us informed as I'm sure many here are interested in the results, including me. Thanks.

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