40/85 ballard project.

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bruce m
Posts: 3350
Joined: Tue Aug 04, 2009 5:25 am
Location: australia

40/85 ballard project.

Post by bruce m »

the 40/72 has served well as a long range cartridge using a 13 twist, and pp bullets which allows use of over 80 gns of powder.
having shot out the barrel, a new one is on the way.
this invites opportunities.
the 40/72 would give slippery 440 gn bullets 1300 fps, but the odg long range rifles would probably have been doing closer to 1400.
my chamber was for groove diameter bullets, and a dual diameter bullet solved that problem, the big diameter being finger seated in fired cases and the small diameter pushed up the bore in the traditional manner.
the 9.3x74 rimmed cartridge has similar base dimensions to both the 40/72 and the 40/85 ballard, and necked up to 40 cal, similar length to the 40/85.
more powder capacity and more velocity.
a chamber cast from an original remington 40/2.5" showed a transition angle lower than my 7 degree reamer - perhaps 4 or 5 degrees.
time to order a reamer, which in this case will be for bore diameter bullets exclusively.
i would like to finger seat bore diameter bullets in fired cases with just a little friction to make handling ammo easy under pressure.
given that cases have some springback, possibly 0.001", the neck diameter of the chamber will need to be that measurement more than a loaded round.
am i pushing this too fine. maybe 0.002" larger would be more sensible to allow for unforseens.
keep safe,
bruce.
ventum est amicus meus
SgtDog0311
Posts: 83
Joined: Wed Jun 25, 2014 9:08 am

Re: 40/85 ballard project.

Post by SgtDog0311 »

Bruce, I had a Ballard 40-85 that had a sewer pipe for a bore so I had it relined. I designed a 40-65 reamer to my specs and had Manson cut it trying to do some of the same calculations for a finger seated bullet that would match groove diameter. It was my first attempt at such a thing and I got lucky. I think I eventually decided my springback amounted to more like .001 but I'll dig some out and check them against the reamer diagram and report back.

The old Ballard started out looking like this and I called it my Reservation Rifle. I got another old original stock to replace it with but I sorta like that old Pacific and still have the original stock. If I had it to do over I would have bought a new barrel but that's another story in itself. It shoots pretty good as is though. Shot it in my last couple BPCR matches and at the Quigley this last year.
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SgtDog0311
Posts: 83
Joined: Wed Jun 25, 2014 9:08 am

Re: 40/85 ballard project.

Post by SgtDog0311 »

Well, just checked the reamer diagram and the neck is .4315. Checking a couple cases I find them to be perhaps .0015 under that if you roll a case and average measurements. Now my cases are reformed 45-70 annealed Starline and turned to .009 wall thickness. I measured at the case mouth. My slip fit might be called lose since I don't have compressed air pushing them back up so I taper crimp after seating for handling purposes. Hope that all makes sense.
bruce m
Posts: 3350
Joined: Tue Aug 04, 2009 5:25 am
Location: australia

Re: 40/85 ballard project.

Post by bruce m »

yes the ballard pacific!.
very few and far between here in oz, and probably as good a hunting bpcr as you can get.
someone making a good quality replica would deserve to succeed.
keep safe,
bruce.
ventum est amicus meus
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