I just purchased the Larue 18 inch Grendel upper. I already own a 14.5 inch pin and weld 6.5 upper made by sabré. I don't believe there is much resale on the sabré so I'm thinking of cutting it down as short as reasonable and using it for plinking/hogs. I will suppress eventually. I know people are having great success w 12 inch barrels but can I go all the way to 10 without sacrificing too much or damaging suppressors?

I've read about quite a few people going as short as 10.5" with no issues.  Since it's a low pressure round, 10.5" shouldn't cause excessive wear on a suppressor, but I have a feeling most of that will be dependent on the manufacturer of the can.  

If I wasn't in CA, a 12" Grendel with can would probably be my first "freedom" purchase.

11" with Griffin Recce 7

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Thanks for the quick replies. I like the look of the 11 with the front sight post since that will be my configuration.

I noticed that AA just went from 10.5" to 11" uppers for their SBR/Pistol complete uppers.

Some cans are rated for 11.5" barrel use minimum length in Grendel, while others will take a 10.5" no problem.

Materials strength at exit pressure and blast erosion of those materials drives that discussion.

Elegant simplicity. Man that looks good. What mags are you using?

The barrel pressure is what counts and just because it is lower pressure in the chamber by no mean makes it lower pressure down the pipe. The 50BMG is a low chamber pressure round compared to the 5.56 but that doesn't mean that it wouldn't blow any suppressor off that wasn't specifically made for it.

The fact is the 6.5 uses almost 10 grains more of the same powder as the 5.56 and nearly 25% more powder than the 6.8.

It is pressure. volume and heat that determine what a suppressor can handle. The 6.5 has a lot more of all of those as it travels down the barrel vs. the 5.56 or the 6.8. While the chamber pressure may be lower the pressure down the barrel is much higher making it very hard on suppressors when operating on a short barrel. This is why when the 5.56 or 6.5 are made into SBR the flash and report are so loud as it still has expanding gas/unburnt powder with a lot of pressure.

.223 Rem loads are generally in the 22-27gr range.

6.5 Grendel is in the 26-34gr range.  6.8 is pretty close at 26-31gr for most loads, not anywhere near 25% less than Grendel.  Both have about the same case volume.

6.8 tends to use much faster-burning powders than Grendel due to shorter bullets with less bearing surface and more bore area to allow venting of pressurized gas.

You are generally correct in your final assertion that exit pressure with Grendel is higher since it has a slower burning effect with the 123gr projectiles, but not compared to 5.56 NATO.

This is why you will see specific ratings for different cartridges and different barrel lengths from suppressor manufacturers who have actually done the testing so they can provide a rating for their customers to avoid rapid erosion of the initial baffle stages and potential early failure of the can.

You can load a Grendel or a 6.8 with light projectiles and fast powders, and minimize this effect, but suppressor makers often look at the common loads used on the market.

For 5.56, that is normally 55-62gr.

For 6.8, that is normally 90-115gr.

For 7.62x39, normally 110-123gr.

For 6.5 Grendel, it is mostly 123gr, with a growing market of 100gr Wolf consumption, which has pretty low chamber pressure even for a 100gr.

Doesn't matter much if you put a 5" TBAC Ultra 5 on an 11.5" 6.5 Grendel and that can weighs 7.6 ounces.  OAL barrel+can = 15.9" roughly.

From TBAC's site for the 100% Titanium Ultra 5:

Steel or Inconel cans handle exit pressure and blast effect better if they are made well, with the weight penalty.