How Bullet Weight Affects Speed And Recoil

[Mark37082]

The testing equipment used by MDT is impressive. I always appreciate the efforts to help us understand the effects of changing variables in loading and shooting. The sharpness of recoil for lack of better term is real in relation to how it feels to the shooter. I call it the pain factor. Understanding this is a bit above my pay grade, but my common sense tells me trying to stop a faster moving lighter object vs a slower heavier object increases the pain factor.

 

[3chester]

Those Savage boys,up in Utica, NY, made over 1,000,000 Model 99's, from the 1920's to 1980's. One of the most common cartridges 99's were chambered for was 300 Savage. So a 1920's era 300 Savage, energy wise, almost a ballistic twin to the 6.5 Creedmoor, as both will shoot a 150 grain bullet at 2,800fps. They made quite a few those 99's with steel butt plates. Double Tin Filson or a wool Mackinaw hunting jacket, could be counted on to soak up any recoil in the Whitetail woods, back then.

 

[PApa Black]

Great experiment!

 

[baldhunter]

The type of powder used has a big affect on recoil.That is probably one reason why the 120gr factory load with less velocity than the 130gr had more recoil.I found that out many years ago when I got my chronograph.I was loading H-870 and IMR 4350 in my 7mag.The H-870 had way more noticeable recoil than the IMR 4350 load,but the IMR 4350 load had over 100fps more velocity.I tried Magpro in my 300WSM.I wasn't even close to max and the recoil was horrible.Velocity was not that great either.I've used Magpro in other cartridges and it worked great and I never noticed the recoil being that offensive like I did with it in the 300WSM.I have also noticed in some rifles an increase in bullet weight is more noticeable than others using the same cartridges in both.So many variables in recoil.

 

[khmplus]

Recoil energy should be approximately equal to the energy used in accelerating the bullet. If the powder charge is the same in each case, the energy stored should be the same also. A heavier bullet spends more time in the barrel, so perhaps the powder is more completely burned by the time the bullet exits the barrel, so more energy has been expended. If you calculate the mass times velocity squared for each of the hand loads, the bullet energy increases slightly as the bullet weight increases. A faster burning powder for lower bullet weights would probably even things out.

 

[C-130 Dude]

While I can accept that basically having a max charge with the heaviest bullet and then reducing bullet weight with the same charge will result in their findings, I believe those differences would be reduced given equal loading pressure loadings.

I appreciate as Feenix does, the effort they put into testing and the related expenses.

What caught me by surprise was that the factory loaded 120 grain had more measured recoil than the 130 grain bullet, even though the 130 grain was almost 125 fps faster. Wonder if is related to burn rate?

Hhmmm, I think more testing is in order.

Powder and primer choice will skew the results. That's why they eliminated it.

 

[Tiny Tim]

Understanding this is a bit above my pay grade, but my common sense tells me trying to stop a faster moving lighter object vs a slower heavier object increases the pain factor.

All things gave a point of diminishing returns. A 124 grain HH in a 300 RUM @4000+ fps is a *****-cat with sharp claws.

 

[Tiny Tim]

Powder and primer choice will skew the results. That's why they eliminated it.

Agreed, but they could have loaded to similar pressures with different bullets.

 

[doug2080]

Disappointing that they did this with a weakmoore. Been interesting to see what the results would be with a magnum instead of the bud light of the rifle world.

 

[3chester]

Like that machine , it could probably measure a gnat fart. If ya notice 6.5 Creedmoor, level of recoil, is a problem, maybe try a heavier blend of cotton on a guy's T-shirt picks.

 

[C-130 Dude]

Agreed, but they could have loaded to similar pressures with different bullets.

I may have missed this, but did the guy say they were loading to max Sammi charge? I don't know what the individual charge weights were. Be interested to know. ???

 

[FEENIX]

I may have missed this, but did the guy say they were loading to max Sammi charge? I don't know what the individual charge weights were. Be interested to know. ???

The handloads all have the same load charge; he mentioned it with the 143 test load.

 

[akmtnhnt]

A significant factor, but usually less considered, is cartridge efficiency.
Unburned powder, formed as a slug (with it's mass) traveling with/against the bullet, adding to bullet weight in the bore.

There is potential for less efficient burn with this testing.

Even if all the powder burns, the more of it, the more recoil. People think you're only accelerating the bullet, and equal and opposite of that, but you're also accelerating the powder, or the gas it becomes after it's burned and all it's mass.
If you take the same bullet and two different powders, one that requires 5 more grains to get the same velocity, the one that requires 5 more grains of powder will recoil more. Same bullet, same velocity.
You'll also see this with different cartridges shooting the same bullet. If you take a 308win and a 300wm in rifles of the exact same weight, load them both with a 180gr bullet and load them both with the same powder to get both to 2600fps. The 300wm will recoil more because it has so much more capacity in the cartridge it will require a good bit more powder to create the pressure required to get the 180 up to 2600.

 

[Mikecr]

I think if you used the right powder (not the same powder) for different bullet weights, to get same load pressure, the recoil differences would follow bullet weight more closely.
I also think that increasing shoulder angle, and again comparing with appropriate loads for same pressure, both would exhibit lower recoil.
Both situations would reduce the amount & duration of unburned powder in the bore.

Then you have barrels which are obviously too short to burn the charge INSIDE the bore, increasing muzzle pressure.
Big fireball and never really fun to shoot..