7 Degree Leade?

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ian45662
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Re: 7 Degree Leade?

Post by ian45662 » Wed Apr 14, 2021 11:46 am

So a chamber with no freebore like in my HW and CPA essentially just have a transition? No Lead so to speak?

TexasMac
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Re: 7 Degree Leade?

Post by TexasMac » Wed Apr 14, 2021 1:41 pm

ian45662 wrote:
Wed Apr 14, 2021 11:46 am
So a chamber with no freebore like in my HW and CPA essentially just have a transition? No Lead so to speak?
That's essentially correct but in your case you could also refer to the step as a leade since the transition step & leade are one in the same as long as you & the reader understand the difference. I intended the clarification mainly for those with rifles that have freebore & may be confused.

Wayne
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ian45662
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Re: 7 Degree Leade?

Post by ian45662 » Wed Apr 14, 2021 1:51 pm

Gotcha

TexasMac
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Re: 7 Degree Leade?

Post by TexasMac » Wed Apr 14, 2021 2:23 pm

Here’s an illustration of the chamber & throat of the Browning .40-65 & .45-90, both of which have extended freebore. The D dimension is the transition step, the F dimension is the freebore & the leade is dimension G. C is the angle that this thread refers to. BTW, since the freebore diameter is slightly larger than the groove diameter in these rifles there is also a freebore-to-leade transition section labeled as FT. Also, for clarity, the riflings are illustrated with no twist.

Wayne

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Kurt
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Re: 7 Degree Leade?

Post by Kurt » Wed Apr 14, 2021 2:26 pm

If you look at the fifth chamber cast from the top, that is a cast of a .40-65 Browning BPCR that had a bad throat that nee3ded to be cleaned out so it would shoot decent. I made a chamber cast and sent it to Manson to make a throating reamer and he measured it and told me that it would take a 4º-2º-30' compound to clean that chamber throat out. That is from the chamber wall to the bottom of the groove or top of the lands. He said that will make a very long lead angle of .4085" to get it where it should be to fix this problem. And throating that bad chamber made that rifle a very good shooter despite that long funnel throat.
Now he called this compound transition a lead angle and I would call it the same because there is no cylinder freebore from the 45 transition to the freebore that leads to the lead of the lands.
I just call it a funnel throat. ::D
The bottom chamber cast is from my .40-65 tight chambered 5º-2º30' throat.
But all those transitions are from the chamber wall to the lands. Even the original sharps cast is this way.
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semtav
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Re: 7 Degree Leade?

Post by semtav » Wed Apr 14, 2021 3:02 pm

I know if a good originally chambered specimen showed up I 'd have to buy it to see what they were all about.
But I don't know about rechambering one to that.
I think What Dave's salesperson said the other day might ring true about chambers too.
When I called to return a DD mould that didn't have the right length Major diameter, i mentioned they might just bore it out.
He said " Dave didn't get to be an 8 time national Champion by rechucking moulds " !!
Might be true with chambers too. Do it once and leave it alone !!

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Distant Thunder
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Re: 7 Degree Leade?

Post by Distant Thunder » Wed Apr 14, 2021 3:56 pm

Since the 7 degree angle starts from the neck outside diameter and to some point at or near groove diameter and then changes to a leade angle of whatever degrees it might be you have a gap in front of the case mouth that starts at roughly .481" to .482" diameter and tapers at 7 degrees to the groove diameter of .458". The length of that 7 degrees is somewhere around .090" to .100" long and is just an oversize tapered freebore. Why on earth would I want a gap .481" diameter in front of my chamber? It's similar to the forcing cone in a revolver which is there so bullets don't shave lead as they move from the cylinder and into the barrel should there be any misalignment between the cylinder and barrel.

I understand how the 7 degrees works I just don't understand putting an oversize funnel in front of my chamber is the best solution to having brass that is too short! Just make your brass the right length and lead and paper rings are not a problem. The 7 degree fixes a problem that shouldn't be there in the first place!
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Re: 7 Degree Leade?

Post by mdeland » Wed Apr 14, 2021 4:04 pm

Is the seven degrees the acute or included angle ?

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Re: 7 Degree Leade?

Post by TexasMac » Wed Apr 14, 2021 4:39 pm

Jim,

I have no idea where your comment about short brass originated or where you got the .481” dimension but if you’re referring to Kurt’s comments I can understand why he cut the long throat in the Browning. If one adds up the throat dimensions of the typical Browning .40-65 it totals approximately 0.356”. Toss in a bit for a slight non-concentric chamber which is present in some of the rifles & 0.4085” makes sense since Kurt obviously wanted one continuous 7 degree transition from the case mouth to the top of the lands.

Wayne
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Re: 7 Degree Leade?

Post by Kurt » Wed Apr 14, 2021 5:13 pm

Jim,

My chamber reamers with the tapered throat are a PP bullet bore diameter only, a GG will not fit in a unsized fired case with only at the most .002" per side, 4 thousands inside case diameter over bore diameter, very tight. That is even tighter than a lot of standard GG chambers are.

Those two targets are some test loads working on loads for the .40-65 and I have several targets like those shot at 200 yards.
Can I do this every time I take the rifle out.....no I cant, I don't think anyone can.....but the rifle is capable of that kind of accuracy.
I have standard GG chambers I took out that 45º transition and they shoot very good also.
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Re: 7 Degree Leade?

Post by Kenny Wasserburger » Wed Apr 14, 2021 7:05 pm

There is a simple solution to all of this:


Buy a standard Shiloh Chamber, patch to bore as snug a bullet and paper allow, or a dual diameter bullet made to fit your Shiloh. It works perfectly.

The proof in patching to bore or just a grease groove, has won 5 of My Six National Scope Titles with a standard chamber.

My Hell Bitch 45-110 won a Creedmoor Scope championship in 2006 with a Grease Groove bullet, same chamber same rifle won again in 2013 Creedmoor Scope championship.


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Glen Ring
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Re: 7 Degree Leade?

Post by Glen Ring » Wed Apr 14, 2021 7:54 pm

Thanks for the explanation Wayne. That helps a bunch.
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Re: 7 Degree Leade?

Post by bruce m » Wed Apr 14, 2021 8:11 pm

i have had what looks like thin wire pieces of lead (hair thickness)with greasers, and thin paper rings in 45/2.4 and 40/72 with 45 degree transitions.
converting the 40/72 to 7 degrees made that go away.
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Distant Thunder
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Re: 7 Degree Leade?

Post by Distant Thunder » Wed Apr 14, 2021 8:31 pm

Wayne,

The .481 is a tight .45 caliber chamber at the case mouth, most are probably looser. So whatever your brass length is with the 7 degree the chamber immediately in front of you case is .011" larger per side than the case ID (bullet), .011 x 2 = .022 and .459 (case ID) + .022 = .481. This is of course for .45 caliber and other calibers will be different. A .44 caliber will be .471 just in front of the case. A .40 caliber will be .431 in front of the case. This assumes tight chambers, some chambers will be even a few thousandths bigger. Why on earth would it be good to run a .409 bullet through a funnel that is .431 diameter right in front of your brass? How does that work? The bullet has to bump up to try and fill that .431" diameter, right?

My point being that any bullet, paper patch or grease groove, will have to bump up into this funnel and then be squeezed down by the 7 degree angle as it moves forward and eventually be squeezed down to the bore and groove diameters. And that's the part I think is perhaps not the best.

I most often hear that the 7 degree prevents paper rings and it does, but paper rings occur because the brass used in the standard chamber is to short and the bullet upsets into the gap at the end of the chamber between the short brass and the 45 degree chamber stop. I just question the idea of opening this area at the end of the chamber up into a funnel shape that is .022" bigger at the end of the brass than the bullet. The 7 degree is gentle enough to iron out the bulge in the bullet after it upsets, but you're moving a lot of lead around just to make up for short brass problems. That's not ideal.

Get the brass the correct length for the standard chamber so there is not a big gap and you won't get paper rings. Or you can just cut a funnel in the chamber and that works too I guess.

I shoot standard chambers because they are so very accurate with properly prepared paper patch ammo.
Jim Kluskens
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Re: 7 Degree Leade?

Post by mdeland » Wed Apr 14, 2021 9:24 pm

So is this taper 3.5 degrees per side (acute) for a total of 7 (included) or is it 7 degrees per side(acute) for a total of 14 (included)?

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