If you're loading to similar velocities it's probably a powder solution that will increase or limit potential Dbs. Long burn powder can still make it out of the suppressor and burn increasing sound. If you have a couple powder selections I'd load to spec to same velocities with different powder and see what you get.

 

that would be odd, my handloads are a fast powder, n550 for 130gr monolithics. Factory ammo for 6.5x55 has a better casefill as is typical of thos cartridge at least here in Nordic countries, it assumes a 29" barrel. Velocities arent worlds apart but handloads are faster, 780m/s for both factory loads vs about 830m/s for my handload.

Il load them to the same velocity tho, see what happens. I do suspect something else might play a role. Tip profile maybe? the quitest round is a FMJ, its actually pleasant to shoot without hearing protection out in the field. On the loudest end my handload wich is a brass hollowpoint

 

Your twist rate is more than adequate to stabilize any useful hunting bullet you choose, so I don't know why you say you are "somewhat limited". Drop the "monolithic" plan if your twist doesn't meet the makers requirements. Going with the fastest burning powder listed in your reloading manual will help reduced noise & going with a heavy bullet will help with energy requirements. I use a 155 grain Lapua Mega Bullet in my 6.5 Creedmoor & handload it to match Lapua 6.5x55 Swede factory ammo velocity, which is 2550 fps.

 

Limited, the same way my 308 is Limited. No subsonic or close to subsonic super heavy bullets.
And compared to the m96 its sligtly limited.

 

The sound difference comes from both bullet design and powder burn characteristics. Jacketed bullets like the S&B FMJ create less turbulence behind the bullet compared to monolithic or half-jacket designs, resulting in less noise.

 

A lot of what you’re hearing is down to the powder burn profile and bullet base shape. Faster powders that complete most of their burn inside the barrel usually make for a softer report through a can, while slower powders still burning when they hit the baffles add extra crack.

 

The slower burning or higher energy the powder, all else being equal, the more of it is used to reach a given peak pressure. More powder or energy content makes more gas (the reason slow and high energy powder gives you higher velocity for the same peak pressure value), so a bigger muzzle blast results both from the greater quantity of gas being expelled and from the greater bullet velocity putting more power into shockwave formation. Instead of N550, try working a load up with N140 for comparison. You lose some velocity, but that's just a good challenge to practice stalking your game to get a little closer.

 

would a faster powder for the same bullet do it or is there something to gain from also increasing bullet weight (lower total velocity).

Iam not entirely clear on what contributes to the noise, does bullet speed matter mutch once its already supsonic? for instance 2600fps vs 2800fps

from what i can tell the velocity difference makes little practical difference at my ranges with this cartridge. With the same point of aim it would be low lung rather than smack in the center of chest. I dont usually shoot mutch past 200m on deer sized game. I dont have a dog after all. Seeing a roe deer bolt lile a bat out of Hades 200m away already gives me the nervous sweats.

 

Velocity affects how sharp and loud the shockwave is, but unless you are in a place with a strong echo, the shooter isn't going to experience much difference from it. Mostly, this will affect people to the side of the trajectory, so it affects noise pollution.

For powder speed, at any given peak pressure value, faster powders produce lower muzzle pressure, providing less gas to expand into the can. Using the faster powder with a heavier bullet will produce even less gas, as you can't use as big a charge with a heavier bullet. So it should be even more quiet.

 

hmm, so what about caliber? for instance 223 vs 30-06. both shot at around the same velocity with relatively equivalent powder and pressure. Just trying to understand how it all works

 

The 30-06 burns more powder to get its heavier bullet up to matching velocity. Also, for a same-length barrel, it will have a smaller expansion ratio, so the muzzle pressure will be higher. Thus, it has an inherently larger volume of gas at higher pressure, creating the muzzle blast. It would take a suppressor with more volume to bring the sound of that extra gas down the same number of decibels as the 223 would require.