extreme deviation

[runfiverun]

o.k. i have taken a rcbs 180 gr spire pt mold and opened up
the back .475 of it to take .312 diam copper tubing.

i then cast through the "jacket" and end up with a boo/ulit
weighing about 185-6 gr.

these shoot pretty well in the 7.7 and 7.65 arg

however i am having velocity variations of 150 fps, i am getting near
1800 fps.
my load is 33.5 gr imr 4895
i have tried federal 210's and win lr.
i tried taking the powder up a grain and a half but same results
do not have any pressure signs .

just cannot get this load to settle down.

aaaugh :???:

[HeavyMetal]

Have you recovered any bullets?

From the description it sounds like the base of the bullet is lead poured through a copper "tube" and the rest of the bullet is exposed lead again.

If this is the case I think you need to come up with a way to "capture" a few fired bullets in a manner that will not deform them.

My suspisions are that the inner casting, not having anything to secure it to the cooper tube, is "slipping" when fired.

This was an issue with the old Half Jacket bullets made in the 50's and 60's. They'd shed a jacket in low pressure loads and leave it stuck in the barrel.

In this case I don't think the copper and lead are coming apart just the lead core slideing up the cooper tube, making the case bigger, thus lowering veloicity and creating the veloicty variation.

The fact that an increase in powder did not net you an increase in velocity kinda confirms the idea but again get some recovered bullets and see whats going on.

Now on to idea 2. If this is whats happening a tool to put a cannalure on the cooper tube to crimp the lead core in place my solve the problem.

Do you know anyone with a Corbin cannaluring tool? This is designed for jacketed bullets but can be used on copper, lead, or brass case's and I think( if I'm going in the right direction) this might cure the issue.

What are your thoughts on my idea?

[Bret4207]

With copper tubing you could take a tubing cutter and dull the cutting wheel. Then run it to a certain depth and it'll leave a "cannalure". Not as fancy as the Corbin, but it'll work for experimental work.

[runfiverun]

i do not think the tube is slipping
as i have about 10 thousands of lead exposed at the rear of the tubing
i was worried about the separation in the bbl.
the false cannelure is a good idea though, as when these hit hard dirt i have
recovered a few of the jackets,as i get core separation upon impact, and mushrooming
about 1/4 of the way down the jacket.

i am trying to get the shot to shot variation lower as i get vertical
stringing on the target, would have one hole here except for the vertical.

[HeavyMetal]

Vertical "stringing" as well as the shot to shot difference in velocity still hint at a core shift in your bullet.

If this load performs with commercial bullets, with no other changes in the rifle or load, I still think you need to play with some type of crimp on the core.

The current bullet sure seems to be "trying" but .010 of an inch of lead acting as "cork" on the base of the jacket core isn't enough. I can peel .010 of lead with my fingernail! Add
35,000 psi to that and your "cork" ain't squat. I do suspect that bit of "cork" is the only reason you haven't had a seperation in the barrel.

The tubing cutter Idea, posted by Brett 4207, is a good thought but it needs to be applied to the center of your finished bullet! The revised idea is to act as a cannalure Just putting enough pressure to create a grouve in the jacket! This should compress into the lead core and, in addition to your .010 base "cork", might just cure the problem.

Hope were helpin'

[runfiverun]

o.k.
i think i will try to put a cannelure maybe two on the boolit jacket.

and try to push it a bit harder, was wondering if i was just not pushing the bullit
all the way down the bbl?
thats why i tried it in the 7.7 it has a 4" longer bbl when the velocity stayed the same
and the variations stayed the same i thought maybe the load had a problem?

i really don't want to push these past 2000fps as i want to use them for brush hunting
on deer,coyotes, and just shooting rocks, for my girls.

but they expect better loads from me no matter what i cook up.

[Junior1942]

You're flirting with a disaster, IMHO. If one of those "jackets" sticks in the bore after the lead core shoots out of it, and you fire another round. . . . .

[HeavyMetal]

The fact that you even switched rifles and the problem stayed consistant makes my head swell with the thought I might be right.

Let us know if our "ideas" work out for you.

[garandsrus]

You're flirting with a disaster, IMHO. If one of those "jackets" sticks in the bore after the lead core shoots out of it, and you fire another round. . . . .

I agree with Junior... Most things I have read say that you can have an exposed lead tip or bullet base, but not both!

With the pressures generated when firing a shell, I wouldn't think that a canellure would be enough to guarantee that the lead sausage won't squeeze out of the copper bun.

John

[Molly]

You're paddling in strange waters, but you might try a _thin_ smear of flux inside the jacket, and casting mighty hot.

Just out of curiosity, why are you casting jacketed bullets instead of swaging them?

Molly

[runfiverun]

cause i have casting equipment.
have been out of work for a few months, and this mold was not any good.
and i think swaging equipment is really expensive, at least corbins stuff is...
if there is a company selling less expensive swaging stuff i would be interested..

[runfiverun]

going to try new tact here
opened up the front of the mold to 312 also
so it fills the bbl and seat to the lands.
as the 4895 only fills about 60% of the case i think i may try a slower powder
also, if i can keep velocities below 2000 fps, i think i may try a filler here
to keep the boolit moving.

any ideas?

[Larry Gibson]

going to try new tact here
opened up the front of the mold to 312 also
so it fills the bbl and seat to the lands.
as the 4895 only fills about 60% of the case i think i may try a slower powder
also, if i can keep velocities below 2000 fps, i think i may try a filler here
to keep the boolit moving.

any ideas?

Before you switch from the 4895 try a 1/2 - 1 gr filler of dacron over the powder. That almost always reduces ES with 50-70% loads of 4895. I would also be leary of the core slipping. If you can pick up an old tube cutter it can be dulled and then used to press a canelure into the tube. The solder flux inside the tube is also a good idea.

Larry Gibson

[Molly]

... i think i may try a filler here to keep the boolit moving. any ideas?

Yeah. COW (Cream of Wheat) forms a really solid wad behind the bullet when it is fired. This plug might be good insurance against shedding the jacket. Or, if you manage to find one (a stuck / shed jacket) in the bore, a blank with COW _might_ be able to take it out. I don't THINK it would cause bulging, since there's no solid obstruction in a case like that, but it's your gun: You decide.

Molly

[runfiverun]

when the wind gets below 25 mph iwill try new load
33.2 gr i-4895, with dryer lint over the powder, and light lee crimp.
only lee crimp die i have.

made 50 new pieces of brass today as the other brass had been shot quite a bit.

i am dedicating a 7.65 that has been cut down, think i gave about 40.00 for this
about 10 yrs ago.
has a nice bbl with excellent rifling and measures out just a hair over 311.
and it has a pretty tight chamber. [ the lee sizer wouldn't make brass short enough,
had to use my rcbs to finish sizing the brass]

[Larry Gibson]

runfiverun

Many of the Lee dies are made for the 7.65 Belgian/Argentine. While many claim the two are interchamgeable and the same cartridge I do believe they are. Numerous Belgian chambers I have measured are .010" longer in headspace than most all Argentine chambers. Also the groove depth on most Belgians\ barrels is .314-.316 where as most Argentines, particularly the M91s are .311-.312. I most often removed .01" from the bottom of those Lee dies (it is reputed the 7.65 dies from Lee the last couple years have this corrected?) and they then work fine. Since you've the RCBS die you're good to go, just thought I'd mention it is all.

Are you able to crimp the front of the tube into the core with the Lee FCD? Should be a way to make that happen.

Larry Gibson.

[Ricochet]

A Lee Factory Crimp Die is a handy and inexpensive way to apply a cannelure. Try one for a 7mm cartridge and hold the boolit in the top of the die to the proper depth as you force it down on a shellholder. Or just use a proper one for your cartridge to apply a very deep case mouth crimp that will make its own cannelure in the boolit jacket.

[runfiverun]

that is a good idea i tried it with tha 7.65 there wasnt enough.
next time i get to town i will try to find a 7mm squeeze die

larry, i keep this die as it fits my girls rifle perfectly,except
it works the necks down enough to hold a 308. this and the 223 die that would
keep every piece of brass i put in it. are the reason i am not a lee fan.

[runfiverun]

wooo-hooo
well that load is sure nice
thanks y'alll
i could tell the difference in the brass l.c. tw and sl all military 06 once fired
it did not care for the l-city, as i only have a few of these, no biggie

the velocity at 8' was 1950
and the ev was 24 and mv was70
nice 2" group about 2 1/2 low at 100 with no vertical stringing

i need to open the rear sight a bit on this rifle
will try the fed 210 again. and try to capture some boolits
maybe mix ww and lead to soften these up