SBR/can question

[Rookie]

I've seen the statement about not going under 10.5 inches because of warranty issues, but a UMP has an eight inch barrel.

I MIGHT answer my own question...

Are you referring to shorter than 10.5 for rifle rounds versus pistol rounds. Why does it make a difference?

What is EBR?

 

[shooter521]

Are you referring to shorter than 10.5 for rifle rounds versus pistol rounds. Why does it make a difference?

Generally, I've seen this cautionary note in reference to 5.56 carbines specifically.

From the Gemtech website:
Gemtech, and other manufacturers do not recommend the use of barrels shorter than 10.5". There are three primary reasons for this:

Stability: The standard 1:7 twist rate of 5.56mm barrels barely provides one full turn in the rifling before releasing the bullet when using a 7" or 7.5" barrel. This does not impart enough spin on the projectile to properly stabilize it during the critical first few inches of flight as it passes through the suppressor. While the bullet may stabilize downrange suitably to be accurate when shooting unsuppressed, it will not stabilize and will strike baffles when a suppressor is mounted. Some barrels use a 1:8 or 1:9 twist making the problem even worse.

Velocity: The 5.56mm cartridge is also very velocity dependent for stability. Very short barrels, less than 10.5" do not allow sufficient velocity to properly stabilize the round, thereby exacerbating the stability problem described above.

Erosion: The 5.56mm cartridge was designed to burn its powder in a 20" service rifle (M16A1, M16A2). The maximum flame temperature and pressure happen at around 7" from the chamber. Short barrels under 10.5" cause excessive flame temperature and pressure within the entrance chamber of the suppressor. This causes excessive erosion of the blast baffle because hot, high pressure particles of unburnt powder sandblast this baffle. So, provided you are lucky enough to avoid a baffle strike due the above two issues, the suppressor will be worn out in a very short period of time due to erosion.

Although a few inches of barrel doesn't seem like it would make much difference, it really does. The uncorking pressure at the muzzle of a 7" barrel is almost double that of a 10.5" barrel.

What is EBR?

An acronym that many use for "Evil Black Rifle," aka a military-style semi-auto, usually an AR-15.

 

[samot]

im gonna be trying a 8.9 in barrel 1:9 twist on my IGF HK 53 & YHM can .....
Im a little concerned about baffle strikes.... but i have friends that do it all the time& dont have trouble ?? Ill be sure to post the results of my experience. Hopefully YHM will fix my can even if its not covered by warranty if something does happen