.257 Roberts for Bighorn Sheep Hunting? Best Ammo (Round, Load, Cartridge) for a Successful Bighorn Sheep Hunt
- Hunting Calibers
- 04 Apr, 2020
Is the .257 Roberts a viable caliber/load/round/cartridge for bighorn sheep hunting? The accurate answer is “it depends”. However, the goal of this article is simply to address the question of whether the .257 Roberts is within the ideal range of suitable calibers to harvest bighorn sheep.
As with anything, the devil is in the details. To answer the question completely, we would need to evaluate the downrange distance to the bighorn sheep, the bullet type, the grain weight of the bullet, the physical condition of the firearm, the size of the bighorn sheep in question, the shot placement, the local wind conditions, the expected accuracy of the shooter, the ethics of the ideal maximum number of shots – the list goes on.
What we can do is provide a framework to understand what average conditions might look like, and whether those are reasonably viable for a shot from the average shooter to harvest a bighorn sheep in the fewest number of shots possible, i.e., ethically.
Let’s dive right in. In the question of “Is the .257 Roberts within the ideal range of suitable calibers for bighorn sheep hunting?” our answer is:
Yes, the .257 Roberts is A GOOD CHOICE for bighorn sheep hunting, under average conditions, from a mid-range distance, with a medium grain expanding bullet, and with correct shot placement.
Let’s look at those assumptions a bit closer in the following table.
|Animal Species||Bighorn Sheep|
|Muzzle Energy||2040 foot-pounds|
|Animal Weight||220 lbs|
|Shot Distance||150 yards|
What is the average muzzle energy for a .257 Roberts? In this case, we have assumed the average muzzle energy for a .257 Roberts round is approximately 2040 foot-pounds.
What is the average weight of an adult male bighorn sheep? Here we have leaned conservative by taking the average weight of a male individual of the species, since females generally weigh less and require less stopping power. In this case, the average weight of an adult male bighorn sheep is approximately 220 lbs.
What is the distance this species is typically hunted from? Distance, of course, plays an important role in the viability of a given caliber in bighorn sheep hunting. The kinetic energy of the projectile drops dramatically the further downrange it travels primarily due to energy lost in the form of heat generated by friction against the air itself. This phenonemon is known as drag or air resistance. Thus, a caliber that is effective from 50 yards may not have enough stopping power from 200 yards. With that said, we have assumed the average hunting distance for bighorn sheep to be approximately 150 yards.
What about the other assumptions? We have three other primary assumptions being made here. First, the average bullet weight is encapsulated in the average muzzle energy for the .257 Roberts. The second important assumption is ‘slightly-suboptimal’ to ‘optimal’ shot placement. That is to say, we assume the bighorn sheep being harvested is shot directly or nearly directly in the vitals (heart and/or lungs). The third assumption is that a projectile with appropriate terminal ballistics is being used, which for hunting usually means an expanding bullet.
A common thread you may encounter in online forums is anecdote after anecdote of large animals being brought down by small caliber bullets, or small animals surviving large caliber bullets. Of course those stories exist, and they are not disputed here. A 22LR cartridge can fell a bull elephant under the right conditions, and a newborn squirrel can survive a 50 BMG round under other specific conditions.
Again, the goal of this article is simply to address the question of whether .257 Roberts is within the ideal range of suitable calibers to harvest bighorn sheep - and to this question, the response again is yes, the .257 Roberts is A GOOD CHOICE for bighorn sheep hunting.
This article does not serve as the final say, but simply as a starting point for beginner hunters, as well as a venue for further discussion. Please feel free to agree, disagree, and share stories from your own experience in the comments section below.
Disclaimer: the information above is purely for illustrative purposes and should not be taken as permission to use a particular caliber, a statement of the legality or safety of using certain calibers, or legal advice in any way. You must read and understand your own local laws before hunting bighorn sheep to know whether your caliber of choice is a legal option.
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