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-   -   Lets discuss "Accuracy" (http://www.professionalsoldiers.com/forums/showthread.php?t=48987)

Rob_Frey 07-06-2015 17:39

Quote:

Originally Posted by PRB (Post 587025)
I like a swamped barrel with round rifling and a relieved crown for easy loading.

Whitworth?

jw74 07-08-2015 10:20

Quote:

Originally Posted by Guymullins (Post 587042)
I was looking at a Rigby .416 a couple of days ago. The new Rigby company is back in England, making handmade rifles which are based on the original Rigby's of old.

They are crazy expensive

it was marked as shot over 65 yds and the group was well over three inches. This put me off the rifle and the company completely as I consider that unacceptable accuracy for any rifle, apart maybe for a double, but even then, I would be disappointed. My Remington .375 will shoot to a half inch over that distance and I question a manufacturer who would proudly include a target showing that kind of accuracy for a very expensive gun. The old Ruger .416 Rigby I have shot with in the distant past would beat that hands down and cost one tenth the price.

I'm guessing that they are touting the handmade 'old-world' aspect of the rifle and holding the current desire for ultra-accuracy in disdain and perhaps unneccesary when their rifle is meant for something cape buffalo-sized at 30 yds.
I'm with you though. If all I wanted was an old, heavy, inaccurate rifle I wouldn't compund the problems by emptying my bank account also.

Was the target you saw shot off hand?

Guymullins 07-08-2015 14:14

Quote:

Originally Posted by jw74 (Post 587221)
I'm guessing that they are touting the handmade 'old-world' aspect of the rifle and holding the current desire for ultra-accuracy in disdain and perhaps unneccesary when their rifle is meant for something cape buffalo-sized at 30 yds.
I'm with you though. If all I wanted was an old, heavy, inaccurate rifle I wouldn't compund the problems by emptying my bank account also.

Was the target you saw shot off hand?

That information was not available, but why would a manufacturer even include a target if it were shot offhand with iron sights? Mind you, iron sights at 65yds should still give better accuracy than that.

HOLLiS 07-08-2015 17:03

Quote:

Originally Posted by Guymullins (Post 587042)
I was looking at a Rigby .416 a couple of days ago. The new Rigby company is back in England, making handmade rifles which are based on the original Rigby's of old.

They are crazy expensive, although not in the Holland&Holland league, but I always fancied one as it is a caliber I greatly respect, and getting it in a Rigby is the cherry on top.

With the rifle, came a sample target and I was shocked to see that it was marked as shot over 65 yds and the group was well over three inches. This put me off the rifle and the company completely as I consider that unacceptable accuracy for any rifle, apart maybe for a double, but even then, I would be disappointed. My Remington .375 will shoot to a half inch over that distance and I question a manufacturer who would proudly include a target showing that kind of accuracy for a very expensive gun. The old Ruger .416 Rigby I have shot with in the distant past would beat that hands down and cost one tenth the price.


Accuracy is related to the need. As JW pointed out 3 In group at 65 yards is good medicine for cape buffalo.



BTW before I forget.

LR9147, thank you for your contributions to this thread.

longrange1947 07-09-2015 09:20

That Rigby was an "Elephant Gun" with tremendous pressures that required a large free bore. That is what effects the accuracy and as Holli stated, at less than 100 yards at a Cape Buff, Hippo, or an Elephant you have the accuracy needed and the the power required to save your butt. Weatherby has the same accuracy in their large bore weapons and again due to free bore due to the pressures.

Hollis, my pleasure. At you guys service when I can help.

Guymullins 07-09-2015 15:17

[QUOTE=longrange1947;587309]That Rigby was an "Elephant Gun" with tremendous pressures that required a large free bore. That is what effects the accuracy and as Holli stated, at less than 100 yards at a Cape Buff, Hippo, or an Elephant you have the accuracy needed and the the power required to save your butt. Weatherby has the same accuracy in their large bore weapons and again due to free bore due to the pressures.



The .416 Rigby is designed to quite low pressures. 47 000psi compared to the .375 H&H at 62 000 psi. The .416 Weatherby is 63 000psi.
So I don't think chamber pressures can really be blamed for the poor accuracy of the Rigby rifle. The CZ 500 made for the .416 Rigby round, which costs a fraction of the Rigby rifle, shoots a standard 1.5 inch group at 100yds and often much better than that. The CZ is very popular here in Africa as it is great value for money and makes a good workhorse.

Extreme accuracy is not needed for the average Buff or elephant hunt, however, many African hunters like to carry one rifle to do everything. Thats why my everyday rifle is a .375 H&H. When going out to shoot an Impala for the pot, one can come across an angry buff or jumbo, so selecting a rifle for a specific hunt is not always the wisest thing to do. Naturally, if you have the money to engage a PH who can carry a big bore, you can then traipse out with your 30-06 without any worries.

longrange1947 07-09-2015 16:44

I stand corrected. Several articles I had read on the old guns grouped the Rigby with the other "Elephant guns", H&H and Weatherby, with higher pressures and reduced accuracy.

I bow to your experience in lieu of my readings. :)

Guymullins 07-10-2015 08:50

Quote:

Originally Posted by longrange1947 (Post 587352)
I stand corrected. Several articles I had read on the old guns grouped the Rigby with the other "Elephant guns", H&H and Weatherby, with higher pressures and reduced accuracy.

I bow to your experience in lieu of my readings. :)

You are right with respect to some of the early Elephant calibers. The old propellants were fine when used in England and America, but when subjected to the extreme temperatures of tropical Africa, they developed very high chamber pressures which in turn split cases or made extraction impossible or difficult. Not something hunters were enamored with when hunting dangerous game. For instance, the .458 Win Mag, based on a straight-sided .375 H&H case got a very bad reputation in Africa because they were downloaded by Winchester to avoid excessive pressures in the tropics and thereby delivered sub-standard performance.
Older bullet performance was also unsatisfactory in some of the first Express and Magnum rounds. Rigby gained a great reputation with its .416 round not only because of its gentle pressures but perhaps more importantly, because its patented bullets had very thick steel walls and tips and a well crimped rear which held the led in place and didn't deform badly when penetrating elephant sculls and buffalo shoulder bones. The bullet paths were straight and went further than other bullets through solid flesh and bone.
The .458 Win Mag's reputation is only now recovering, due to modern powders combined with modern bullets, but various higher performing .458 variants are still very popular such as the .458 Lott and Ackley rounds which attempt to cure the round of its old illnesses.

frostfire 07-25-2015 07:36

Quote:

Originally Posted by longrange1947 (Post 587011)
Hollis, not trans sonic, your bullet is doing what the Brits call sleeping. It is what I was talking about above, if I have read your explanation correctly. The round is under spun to make it more accurate at your desired range. Brit Palma rounds are famous for this. The round is rotating around the flight path but not on the flight path, sort of a wobble. The bullet will slowly come back on flight path as the bullet slows and it becomes more gyroscopically stabilized. If a bullet was to go trans sonic while in that condition, the round would really take off due to the turbulence at trans sonic.

Is this the reason, 147gr coming out of my slow-twist 1:32 KKM barrel resulted in key holing at 25m?
I almost wanted to leave it like that so that tiny 9mm diameter would make elongated holes to reach those x and 10 lines:D

Quote:

Originally Posted by longrange1947 (Post 587011)

On the pressure point, that was for the lighter skinner barrels to prevent barrel whip. That is one of the reasons the SVD has such problems is simple barrel whip, well that and crap QC. The pressure point you can find right at the end of the fore stock in which the barrel rests on that pedestal. The heavier barrels do not have a barrel whip problem so the barrels are free floated. This gives about 17 pounds of up pressure and stabilizes the barrel so the bullet comes out of the barrel at the same point, or there abouts. :D
.

Is this the reason I found my 10.5" short barrell AK yields better accuracy than the standard 16" pencil barrel one? I mean better/closer pressure point to the action without much length left for any vibration?

Master Rick, always good to see you back in your element :)

Leozinho 07-25-2015 20:42

Quote:

Originally Posted by longrange1947 (Post 586971)
An ideally stabilized bullet is under spun at the muzzle, and when it gets to the intended accuracy range is properly spun. The bullet will become over spun at longer ranges.

In most bullet/barrel combinations, this is not an issue, but in some, the bullet "wobbles" around its flight path and the wobble becomes less and less until the bullet settles on that flight path. This causes problems with near range zeros.

The second problem is that the precursory column of air forms a mach disc that can upset some bullets. This requires the bullet to be over spun to maintain accuracy, another problem with transitional ballistics. :munchin

For what it's worth, Bryan Litz and his partner Nick Vitalbo (http://appliedballisticsllc.com/about-us/staff/) have done some tests that don't support the theory of a bullet going to sleep as the reason why group size at longer distances are often better than what would be extrapolated from group sizes at shorter distances.

Litz thinks it's using an effectively smaller aiming point at longer distances that produces better groups at distance. Vitalbo thinks its because it's easier to dial out parrallax at longer distances.


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