Undersized .45-70?

[JSnover]

Slugged my bore the other day and measured .452, and .455" It's noticeably tighter just ahead of the chamber, even when driving the slug from the muzzle. I plan to slug it again, this time putting one though the breech end, stopping just ahead of the chamber and another thru the muzzle so I can see just what's what. In the meantime, is it common for bore/groove diameters to be that far under the nominal spec? The rifle is a new Buffalo Classic. Should I start looking for molds and sizing dies that will produce .456 or .457" boolits?

[leftiye]

Nope, Industry standard is .450 bore, and .458 groove. Yep, NEF seems to use Marlin's reject barrels, and that's somewhat common for them. They'll tell you it's "within specs." What unadulterated bool stuffin'. Let us know if those .0015" deep grooves stabilize anything! BTW, NEF 45-70 chambers often do not have any freebore, nor leade, FWIW.

[trk]

...
BTW, NEF 45-70 chambers often do not have any freebore, nor leade, FWIW.

That's MUCH better than the NEF's (.357 Mag. in particular) that have 3/4" gap between the end of the casing and the start of the rifling!

[JSnover]

All righty then. Looks like I'll stick with the "big" boolits to make up for the grooves that aren't quite there.

Thanks!

[76 WARLOCK]

Has anyone here ever used a throater to open up a rifle like mentioned above? I have a Browning with no throat and bought a throater reamer from Brownells but have been afraid to try it.

[JSnover]

I work in a machine shop and I know of the procedure but I've never done it and wouldn't try to explain it. Too many things could go wrong. A good machinist could handle it but make sure he understands the purpose and function of the tool.
Better yet, find a gunsmith. Midway offers a locator service. Type in your location and choose the type work you need done.

http://gunsmithlocator.com

[Leftoverdj]

I had a throater and used it to put a gentle leade in a Handi. The abrupt throats are standard to the .45-70 and not just with NEF. I got a very slight accuracy improvement at the cost of having to seat bullets out 1/8" or so. It would have to be a very short constriction to be removed by a throater.

I have never seen any evidence at all that NEF uses reject Marlin barrels, and am inclined to discount that as pure urban legend. The shallow grooves that NEF uses are entirely adequate with smokeless loads.

It's the constriction that's being measured, not the groove diameter. Worry about that before you worry about bullet diameter. NEF should make good on a bore constriction where they would be unconcerned about a barrel within tolerances.

[drinks]

JS, your barrel is out of spec.
I called the factory about my .44 Mag. barrel and was told if a barrel is within + - .002, it was in spec., my was just at the top end, .431.
The spec. for .45-70 is .450 - .458, my .Handi .45- 70 is .450 x .4565, just at the bottom of spec.
I get good accuracy with most bullets, try yours and stick to gas check bullets, the gas check seems to act as a wrench and get a good grip.
The Lee 405gr hollow base works good in my gun, too, even with straight wws, no soft alloy needed.

[JSnover]

Thanks, drinks.
I've got a 459400 hollow base mold, plan to cast a few up and see what happens this weekend.

[KCSO]

I have used a long leade throater to make p/p chambers in a couple of guns. It also helps with some of the single shots with no leade. Such a throater made the rounds of the Shooters site a few years ago.
Now if there is a constriction ahead of the chamber the rifle just won't shoot cast well, you can't squeeze the bullet down and then have it slug back up. It sounds to me like the blank was installed backwards, an unfortunatly common practice.

[leftiye]

trk, Get a 35 caliber neck reamer and turn that into a 357 maximum. Or.....

Don't care what NEF says, plus/minus 002" tolerance is criminal (also sloppy). Since when are their "specs" a substitute for industry standards? When the bore is +.002", and the groove is - .002" that's what's called a mess. Can't even imagine how they can conscience selling those barrels. Ought to fire those sloppy workers or train them.

I have acquired a .45 caliber throater, but have not used it yet. Also, my chamber is .008" larger than cartridge size in the chamber neck area, that might also be standard for an 1873 rifle, but ain't much good anyway! Thought of puttin my 45-100 reamer in there.

[lovedogs]

I was surprised to hear of this. My wife and I both have BC's and both are right on spec. They are smooth and straight all the way. And both shoot fantasically! If I were you I'd send it back to the factory. And in a few days I'd call them up and talk to them. I've done this on other guns. Sometimes they try the old "it's within specs" thing. I refuse to listen to that and tell them if they won't fix it right then don't bother to return it to me, I'll buy another brand. Every time I've done this I've gotten a new bbl. and the guns have been real shooters afterwards.

[calsite]

would bore lapping help with the restriction at all.

[JSnover]

I've considered reaming but the rifle hasn't been fired enough to know what's really going on. After I get some real-life range results I'll figure what (if anything) to do next.