Sig

[USCGME2]

Anybody have or seen the Sig P556-S-PSB? Saw one online and they hail it as a pistol so it doesnt need a stamp? How can that be if it has the "brace" on it? Looks super awesome cool though.

summitgunbroker.com/p556-psb.html

[kutkota]

I've seen similar. Think it's all about the writing of law or more importantly the wording.

[Cwi555]

Feb 11, 2014 14:37:29 GMT -7 USCGME2 said:

Anybody have or seen the Sig P556-S-PSB? Saw one online and they hail it as a pistol so it doesnt need a stamp? How can that be if it has the "brace" on it? Looks super awesome cool though.

summitgunbroker.com/p556-psb.html

I've seen it, but have never been a fan of short barreled 5.56 weapons given the round needs velocity for effectiveness. There are some accurate 1680 loads (and other powders) specifically designed to burn faster/accelerate faster, but they are not standardized. 16" barrel is the minimum length in my opinion.

That aside, that particular design is approved (for now) by the ATF. That does not mean local LEO, ATF agents, FBI, etc will know this. By the time it is discovered it was legal, they could have already had you arrested, raided your home, and in short ruined your life. Post event vindication is cold comfort in my eyes.

[USCGME2]

Do most of those 5.56 "pistols" have have velocity issues? Does that cause them to misfeed or does it become an accuracy issue?

[Cwi555]

Feb 11, 2014 15:24:57 GMT -7 USCGME2 said:

Do most of those 5.56 "pistols" have have velocity issues? Does that cause them to misfeed or does it become an accuracy issue?

Depends on the design. Piston designs usually work well for cycling. The direct gas impingement design (read gas tube), can be controlled by keeping the barrels gas port the right diameter, but it doesn't do anything for the burn rate of the powder. In effect, your catching the gas expansion much earlier than you would for the longer length barrel. For that gas system, there will be an inherent increase in carbon build up as the gas that hits the rings is hotter, and at higher pressure.

For velocity, the difference between a 10" barrel and a 16" barrel is approximately 300-375 FPS loss for the shorter barrel and approximately 240-290 ft/lbs energy depending on the particulars. Checking ballistics, it's like starting the round 125-175 yards down range.

Long range accuracy has always suffered in my opinion and experience.

[USCGME2]

Thanks for the input, it makes a lot of sense. I guess then this type of rifle is an up close and personal weapon or for dynamic entries. Kinda limits its uses for my purpose. Again, thanks for the low down.