Thread: Seriously underrated 6.5x47 Lapua

Originally Posted by Tussock

As in I don't thing there is a round that boots less for the ammont of downrange oomph.

Of course not, recoil is a linear relationship with muzzle energy.
If you want more oomph down range you will inevitably get more recoil.

Whether the 6.5x47 hits the sweet spot between the two is down to personal preference.

Originally Posted by Beetroot

Of course not, recoil is a linear relationship with muzzle energy.
If you want more oomph down range you will inevitably get more recoil.

Whether the 6.5x47 hits the sweet spot between the two is down to personal preference.

Recoil is quoted as a linear relationship to muzzle energy, but muzzle energy is divided between the projectile and the venting gas. The projectile and the venting gas have a different effect on felt recoil. Recoil is an equation with muzzle energy in it. Felt recoil is what transfers to the shoulder.

Take a rifle and shoot it with a 26" barrel and then shoot it with a 10" barrel. Minus the difference in friction down the barrel, the muzzle energy is the same. See if they both feel the same to shoot. At 26" the energy is in the projectiles motion, and at 16" the gas discharge. At 16" some of the energy is probably in a huge fire ball of un-burned powder. Try a muzzle brake. The muzzle brake does not direct the projectile out sideways.

A linear relationship between felt recoil and muzzle energy is an oversimplification. It comes down to efficiency. How much from the energy from the powder (the only source) can be transferred to the projectile. I personally think the projectile moves the gun very little compared to the high pressure gas at the muzzle and the diameter of the hole the gas vents out of. I think nothing makes more efficient use of the powder in a 20" barrel (or there abouts) than a 6.5x47L. I think Lapua planned that. It is not a consideration in most rounds.

Be curious to know how many people have actually shot 6.5x47

Originally Posted by Tussock

Recoil is quoted as a linear relationship to muzzle energy, but muzzle energy is divided between the projectile and the venting gas. The projectile and the venting gas have a different effect on felt recoil. Recoil is an equation with muzzle energy in it. Felt recoil is what transfers to the shoulder.

Take a rifle and shoot it with a 26" barrel and then shoot it with a 10" barrel. Minus the difference in friction down the barrel, the muzzle energy is the same. See if they both feel the same to shoot. At 26" the energy is in the projectiles motion, and at 16" the gas discharge. At 16" some of the energy is probably in a huge fire ball of un-burned powder. Try a muzzle brake. The muzzle brake does not direct the projectile out sideways.

A linear relationship between felt recoil and muzzle energy is an oversimplification. It comes down to efficiency. How much from the energy from the powder (the only source) can be transferred to the projectile. I personally think the projectile moves the gun very little compared to the high pressure gas at the muzzle and the diameter of the hole the gas vents out of. I think nothing makes more efficient use of the powder in a 20" barrel (or there abouts) than a 6.5x47L. I think Lapua planned that. It is not a consideration in most rounds.

Be curious to know how many people have actually shot 6.5x47

Regarding recoil, can anyone answer the following question and not just guess or speculate on the answer: If two rifles of identical weight and effective barrel length ahead of the chamber, one a 6.5 06 and the other a 6.5 saum are loaded with identical powder charges and projectiles the 6.5 saum will achieve a higher muzzle velocity. Q Is there any difference in recoil ??

Originally Posted by Moa Hunter

Regarding recoil, can anyone answer the following question and not just guess or speculate on the answer: If two rifles of identical weight and effective barrel length ahead of the chamber, one a 6.5 06 and the other a 6.5 saum are loaded with identical powder charges and projectiles the 6.5 saum will achieve a higher muzzle velocity. Q Is there any difference in recoil ??

Purely in terms of practical physics, as I think gas discharge creates more thrust into your shoulder (by working exactly like a thruster) then the saum would have to have less recoil, as in order to get higher velocity, all else being equal, it needs to make better use of the powder charge.

In other words, more efficiency means more energy transferred to the motion of projectile and less to the rifle.

Originally Posted by Tussock

Purely in terms of practical physics, as I think gas discharge creates more thrust into your shoulder (by working exactly like a thruster) then the saum would have to have less recoil, as in order to get higher velocity, all else being equal, it needs to make better use of the powder charge.

In other words, more efficiency means more energy transferred to the motion of projectile and less to the rifle.

I am no expert on this subject and that is why I asked the question. I think that your answer is probably very close to the truth Tussock. Some formula would suggest that we divide the foot pounds of projectile energy into the weight of the stock to get recoil energy, this would suggest that blanks create no recoil, which is not true. Other formula take the weight of the propellant and divide that into rifle weight.
What happens to recoil if we fire two bullets from a 308, one at 130 gr and one at 150gr both with the same 40 gr charge of 2209 - is there a difference in recoil ???