Two girls with nice can

[Dustbuster]

[TNMTBik3r]

Nice looking builds. What rail is on the top build? I like the vent design.

[Dustbuster]

Samson 7.5 and a JP bolt I bought from you! Edited December 26, 2014 by Dustbuster

[Dolomite_supafly]

I need to get the buffer out to you. Keep forgetting it.

[Dustbuster]

Yes sir ! Gotta get that 3 gun rifle ready!!!!

[A.J. Holst]

Oh, those kind of girls...

[Fourtyfive]

Is it just my Huntertown Arms suppressor that says not to shoot on a barrel less than 11.5 " ?

I see Gem Tech says 10.3" I guess it just varies by can thickness ?

Blast chamber size ?


Found this :

Gemtech, and other manufacturers do not recommend the use of barrels shorter than 10.3" (USGI Mk18). Damage to 5.56mm suppressors used on barrels shorter than 10.3" with 5.56mm cartridges is not covered under warranty. 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 10.3" do not allow sufficient velocity to properly stabilize the round, thereby exacerbating the stability problem described above.


Barrel Length Studies in the 5.56mm NATO Weapons; P. Dater, M.D.; J. Wong

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 10.3" 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.

Pressure: As the barrel length is reduced, the pressure within the suppressor increases. A 10.3" barrel is the minimum barrel length that we require to maintain an adequate safety factor and prevent any damage to the suppressor or injury to the user.

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 70% higher than that of a 10.3" barrel. Edited December 27, 2014 by Fourtyfive

[Dustbuster]

 AAC 762 6 SDN,shown above, works great w gas cranked down through adj block, but I get what you're saying...makes sense

used this same can to run 1000 rounds of 7.62 x 39 through a test, rifle no wear, lots of soot and heat. 

[MacGyver]

5.56 and 300 Blackout are way different animals when it comes to barrel length needed to fully consume powder.  Like was mentioned above, 5.56 is going to have a lot of powder still being consumed as it exits a short barrel.  300 Blackout was designed for full consumption in 8.5" barrels.  As such, erosion is going to be much higher in a 5.56 with a short barrel than it is in a 300 blackout.  The 338 Spectre can use short barrels effectively, too.

[Fourtyfive]

Are the girls in the pic 300 BLK ?

[SingleStack]

I think the title  Two girls one can 

would have been funner :rofl:

[ProfEngr]

Fortyfive,

 

Any data for the 5.7? I have a 12" barrel, 1:8.5, that deposits small flecks of copper-ish material in the first chamber. Hollowpoints. AAC says the 5.7 works fine with the M4-2000 (or any other 5.56 for that matter).

[Fourtyfive]

Fortyfive,
 
Any data for the 5.7? I have a 12" barrel, 1:8.5, that deposits small flecks of copper-ish material in the first chamber. Hollowpoints. AAC says the 5.7 works fine with the M4-2000 (or any other 5.56 for that matter).

That info came from the Gemtech website , consult Dolomite here on the forum would be my suggestion. I am no expert in this field ....

[Dustbuster]

both are 556's they cycle fine,I just shoot em and clean em when needed.

[Dolomite_supafly]

That info came from the Gemtech website , consult Dolomite here on the forum would be my suggestion. I am no expert in this field ....

 

I am clueless about the 5.7.

[Fourtyfive]

Fortyfive,

Any data for the 5.7? I have a 12" barrel, 1:8.5, that deposits small flecks of copper-ish material in the first chamber. Hollowpoints. AAC says the 5.7 works fine with the M4-2000 (or any other 5.56 for that matter).

I'm not sure what kind of data you looking for but the Kestrel 5.56 I have is rated for the 5.7 but mentions nothing specific to it's minimum barrel length in that caliber ; it's a cover all min. barrel length. http://www.huntertownarms.com/k556.php Edited January 9, 2015 by Fourtyfive

[wolverine]

Now this is a nice can

 

http://2.bp.blogspot.com/-oeqJj3cRuAQ/ULQFRIRQqsI/AAAAAAAAk5U/jJGVNv9M9nQ/s640/gunzzzs.gif

Edited February 8, 2015 by wolverine