45-70 vs 308Win Loudness

[Jackal1]

How does the acoustic sound pressure level (loudness) compare between 308Win and the 45-70's 3-power levels (Trapdoor, Lever Action, Ruger Only)?

I am familiar with the sound from a 16" 308Win and am fine with it (w/hearing protection), but was surprised when an acquaintance said their 45-70 is significantly louder than 308Win. I understand the 45-70 is a lower-pressure cartridge but perhaps the amount of powder is a factor?? I have a hard time seeing how 45-70 is louder but would love to hear your experiences!


Required Disclaimer:
Yes, I understand earmuffs are required for either cartridge. I submit this question because for some 'quieter' cartridges I am comfortable with wearing a single layer if protection (muffs or plugs), while for some 'louder' cartridges I double up (muffs + plugs). And.. frankly I thought 45-70 would be acoustically tame compared to the higher pressure rifle cartridges!

 

[.455_Hunter]

A Trapdoor Springfield rifle firing .45-70 genuine black powder ammo is more of a "boom" and not a sharp ear piercing bang like the .308.

 

[Archie]

Smaller bore rifles seem to be higher pitched in report than larger bore rifles. I think due to that, smaller bore rifles are more obnoxious in report. Not sure if that actually affects decibel level of report, but I do remember the M79 grenade launcher to be much more 'friendly' than the M16 rifle. Since RELACT I find that shotguns are gentler on my ears than rifles.
Considering the M79 launcher and shotguns in general generate less pressure, this may be an 'apples to oranges' comparison.
I openly admit to never having conducted a detailed study of the matter.

 

[CoalTrain49]

From what I've seen 45-70 isn't as loud as a .308 but when you get around 160 decibels, which both are, it doesn't make a lot of difference.

 

[jmr40]

45-70 loads are all over the place. Barrels run from 16" to 28" depending on the rifle. You'll see a wide range of noise levels. And it will always be louder for bystanders than the guy pulling the trigger.

308 loads can vary some, but generally speaking not all that much unless you get into some powder puff hand loads. And most barrels will be 20-22" in length so the noise levels should be pretty consistent. But a 16" barreled 308 is going to be pretty loud.

IME once you reach a certain level my ears can't really tell the difference.

 

[HowieG]

Generally speaking, a 308 holds as much, or more, powder grain wise as a 45-70. The 308 pressures are much higher and the gas velocity is higher in consequence. Plus the bullet is travelling at a much higher veloctiy out of the a 308, so you get a much sharper sonic crack. I would equate the noise of each as sort of a snare drum versus a bass drum sort of thing. Big hole in the barrel and lower velocity versus small hole and high velocity. I would expect your hearing loss to be in a different frequency range with each.

As always, the shorter the barrel, the closer the blast is to your ears. I am not even willing to subject myself to an M1A Socom 16 without protection. I imagine I could probably cope with a Trapdoor Carbine firing 45/55 carbine black powder loads. The carbine has a 22 inch barrel, the BP blast is low velocity, and the 405 grain lead bullet is barely supersonic when it leaves the muzzle.

 

[Varminterror]

308win is typically about the same volume of ejecta, flying faster, and exiting the muzzle at higher pressure = far more acoustic energy.

 

[highlander 5]

One day I was at the pistol range which is next to the rifle range,as I was shooting my pistol I heard the weird "boom" then a crack.
Being nosy I went over

to see what was making that strange sound,turned out to be one of the regulars firing a Shiloh Sharps in 45/70. The boom was the black powder going off and the crack was the bullet breaking the sound barrier. There was a second between the boom and the crack of the bullet very hard to explain you had to be there to hear.

 

[trekker73]

I think a 308 with 16" barrel would be louder than a lot of regular length barrel 45-70 loads

 

[someguy2800]

308 is always loud. 45/70 varies a lot with barrel length and muzzle pressure. The trail boss load I shoot in mine is almost safe to shoot without hearing protection (not that I’m recommending it). Obviously full house loads with higher muzzle pressure will be louder, but I don’t think you’ll ever find a comparable apple to apple where a 45/70 is louder than a 308 unless you compare a 28” 308 to a 45/70 pistol or something silly like that.

 

[.308 Norma]

Never mind.

 

[westernrover]

The difference is going to be a result of the muzzle pressure, and the muzzle pressure is highly dependent on the barrel length. While the Trapdoor load's MAP is lower and you would generally expect a low muzzle pressure from it, that would not be true in the case of a short Mare's leg or other unusually short barrel. Using a slow powder will also raise muzzle pressure. Comparing Ruger-only loads and 308, the MAP of 308 is still about 10kpsi above the highest Ruger-only load's I've seen (is there even a standard?), so barrel length and powder will still make the difference. The 308 can be loaded to a lower pressure or it could be loaded with a faster powder and then muzzle pressure could be quite low, especially with a long barrel.

 

[HowieG]

The difference is going to be a result of the muzzle pressure, and the muzzle pressure is highly dependent on the barrel length. While the Trapdoor load's MAP is lower and you would generally expect a low muzzle pressure from it, that would not be true in the case of a short Mare's leg or other unusually short barrel. Using a slow powder will also raise muzzle pressure. Comparing Ruger-only loads and 308, the MAP of 308 is still about 10kpsi above the highest Ruger-only load's I've seen (is there even a standard?), so barrel length and powder will still make the difference. The 308 can be loaded to a lower pressure or it could be loaded with a faster powder and then muzzle pressure could be quite low, especially with a long barrel.

The SAAMI standard for 45/70 is real low. Max loads in Lyman 50th for the Trapdoor are 18,000 PSI. Loads for the Winchester 1886 jump up to around 26,000 PSI according to the same Lyman 50th. The max pressure for a Ruger #1 is around 38,000 PSI. The max pressure for the 308 Winchester is north of 60,000 PSI.

 

[westernrover]

Yes, but with a slow powder in the 45/70 and a 12" barrel Mare's Leg, even at SAAMI MAP, 6000 psi of muzzle pressure could be seen. With the 308, a fast powder, and a 26" barrel, the muzzle pressure could be the same ~6000 psi. With 45/70 loads that have a higher MAP, things like the powder and especially the barrel length will make the difference. Without a doubt, the 308 can be made louder than 45/70 at any MAP that's been published. With the shortest barrel and slowest powder, a 308 loaded to the MAP limit will be the loudest.