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Double Rifles, Single Shots & Combinations >> Double Rifles

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ruffcountry
.300 member

Reged: 06/01/09
Posts: 210
Loc: usa

3/4 rule
#245648 - 14/04/14 03:25 AM

the 3/4 rule was mentioned in another post and not wanting to hi jack anyones thread I am starting a new one for further discussion . I had not heard of this "rule" and found it interesting . have many heard of or found evidence that it works , often , sometimes , rarely ? what say you ?

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Double Rifle Shooters Society

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Huvius
.416 member

Reged: 04/11/07
Posts: 3554
Loc: Colorado

Re: 3/4 rule [Re: ruffcountry]
#245663 - 14/04/14 07:24 AM

I think that it is a generalized starting point for a 75% bullet weight with the same powder charge.
I suspect it will work well in some rifles and maybe not in others but I don't know if tweaking the charge is expected.
I have read of it working quite well but have yet to try it myself.

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He who lives in the past is doomed to enjoy it.

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bonanza
.400 member

Reged: 17/05/04
Posts: 2335
Loc: South Carolina

Re: 3/4 rule [Re: Huvius]
#245673 - 14/04/14 11:20 AM

Yes, you can get a double rifle to regulate with a lighter projectile within a minute of grapefruit by tweaking the charge.

Basically:

.577 --> 650
.500 --> 440
.470 --> 375 (cast bullets for .475 Linebaugh)
.450 --> 350
.400 --> 300
.375 --> 235
.350 --> 200

These have work fine for me in each of the calibers in a double rifle.

B.

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"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

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ruffcountry
.300 member

Reged: 06/01/09
Posts: 210
Loc: usa

Re: 3/4 rule [Re: bonanza]
#245680 - 14/04/14 02:33 PM

are those calibers or weights or both ? please pardon my denseness

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AkMike
.416 member

Reged: 19/11/05
Posts: 2576
Loc: Anchorage, Alaska

Re: 3/4 rule [Re: ruffcountry]
#245688 - 14/04/14 06:48 PM

Just use a bullet that's about 75% of the regulated bullet weight and the regular powder charge. For one of my 450 NE's they're set with 480 grn bullets. But 500's work fine also. 75% of 500 is 350grn which works out just fine. You can fine tune from there to suit your rifles needs.
Cal Pappas has used 75% of the powder with a full weight bullet.
I haven't tried that combo yet.

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"When you see that in order to produce, you need to obtain permission from men who produce nothing; when you see that money is flowing to those who deal not in goods, but in favors; you may know that your society is doomed." Ayn Rand

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hoosier
.224 member

Reged: 11/07/11
Posts: 32
Loc: Indiana,USA

Re: 3/4 rule [Re: AkMike]
#245693 - 14/04/14 09:31 PM

I have used this method in my Pedersoli 45-70 with 300 and 425 grain bullets with enough accuacy to hunt with at reasonable ranges. The powder charge has to be tweaked some for good results. Noticed that the lighter bullets need to run just a little slower than the heavier ones in my rifle to regulate.

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BigMike

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bonanza
.400 member

Reged: 17/05/04
Posts: 2335
Loc: South Carolina

Re: 3/4 rule [Re: ruffcountry]
#245695 - 14/04/14 10:47 PM

Caliber on the left and lighter projectile weight on the right

--------------------

"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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DUGABOY1
.400 member

Reged: 02/02/03
Posts: 1340
Loc: TEXAS USA

Re: 3/4 rule [Re: ruffcountry]
#247212 - 09/05/14 08:33 AM

Quote:

the 3/4 rule was mentioned in another post and not wanting to hi jack anyones thread I am starting a new one for further discussion . I had not heard of this "rule" and found it interesting . have many heard of or found evidence that it works , often , sometimes , rarely ? what say you ?

Ruffcountry, The 75% rule has always worked pretty well for me! The thing is you can't always find a bullet that is a true 75% of the normal bullet in every chambering. With that in mind you get as close as you can, and tweak the load a tiny bit one way or the other till you hit the sweet spot.

As we all know some double rifles have to be petted a little to get their attention!

Edited by DUGABOY1 (09/05/14 08:39 AM)

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mauserand9mm
.400 member

Reged: 03/09/09
Posts: 1039
Loc: Queensland, Australia

Re: 3/4 rule [Re: DUGABOY1]
#247224 - 09/05/14 10:46 AM

Works in my Merkel 500NE double. Same load for 450gn as 570gn (106gn AR2209). I could use these loads interchangeably too - same POI and regulation.

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