6.5 Grendel Subsonic Loads.

Be careful -- low-volume ratio loads can detonate. Mangement not responsible for load data. Use at your own risk.

Moderators: mpallett, bakerjw

Post Reply
Jonnybassist
New Member
Posts: 1
Joined: Mon Oct 09, 2017 11:05 am

6.5 Grendel Subsonic Loads.

Post by Jonnybassist » Mon Oct 09, 2017 11:17 am

OK fellas, I've searched the forum and found a few threads about finding a subsonic load for the Grendel that still functions the riffle. Yet no one has actually posted the load that works in the AR platform and accomplishes the mission. Can someone please let me know how close they gotten or if they have actually found the load that works?...

User avatar
fishman
Silent But Deadly
Posts: 1444
Joined: Sun Dec 20, 2015 9:15 pm

Re: 6.5 Grendel Subsonic Loads.

Post by fishman » Mon Oct 09, 2017 11:42 am

I'm not saying it isn't possible... but why bother?
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

thecameraman79
Senior Silent Operator
Posts: 106
Joined: Mon Nov 25, 2013 10:21 am

Re: 6.5 Grendel Subsonic Loads.

Post by thecameraman79 » Wed Oct 11, 2017 3:21 pm

300 BLK

cdhknives
Silent But Deadly
Posts: 156
Joined: Sat Jan 17, 2015 6:19 pm
Location: South Texas

Re: 6.5 Grendel Subsonic Loads.

Post by cdhknives » Mon Oct 16, 2017 5:20 pm

I'm sure you could get close with a suppressor for extra back pressure, Trail Boss, heavy bullets, and some tuning. Let us know how it goes. Check your twist rates too.

In my experience the "1 rifle for subs and supers" is a failed experiment, even after trying adjustable gas blocks, bolt actions, and multiple sighting options. I love my Grendel but see no advantage in using it for subsonic work. Your mileage may vary...that's what makes this hobby so much fun!
YHM Phantom 30 cal, 22lr form 1 build, 45 cal form 1 in progress
Atlas 10x36

thecameraman79
Senior Silent Operator
Posts: 106
Joined: Mon Nov 25, 2013 10:21 am

Re: 6.5 Grendel Subsonic Loads.

Post by thecameraman79 » Tue Oct 17, 2017 7:36 am

Trailboss isn't a good choice if he wants to try to get the weapon to cycle. It's why there are no 300 BLK loads using TB unless you want a SUPER quiet bolt action AR.
cdhknives wrote:I'm sure you could get close with a suppressor for extra back pressure, Trail Boss, heavy bullets, and some tuning. Let us know how it goes. Check your twist rates too.

In my experience the "1 rifle for subs and supers" is a failed experiment, even after trying adjustable gas blocks, bolt actions, and multiple sighting options. I love my Grendel but see no advantage in using it for subsonic work. Your mileage may vary...that's what makes this hobby so much fun!

cdhknives
Silent But Deadly
Posts: 156
Joined: Sat Jan 17, 2015 6:19 pm
Location: South Texas

Re: 6.5 Grendel Subsonic Loads.

Post by cdhknives » Tue Oct 17, 2017 5:45 pm

That's why my 300BO is on a side charger upper. Suppressed subs and it is a straight pull bolt action, full power operates like a normal AR. No adjustments required. I did all the tricks to get subs to cycle. It can be done easily enough. It then hammers the crap out of the action when shooting full power. Same should be true for 6.5 Grendel.

Trail boss loads are published by Hodgdon for the 300aac...but only for 110-150 grain loads. For the Grendel using the published rules for developing TB loads should also work. Getting the rifle to cycle is a whole 'nuther story and all the tricks of the 300aac light bullet sub shooters might be in play to get it to work.
YHM Phantom 30 cal, 22lr form 1 build, 45 cal form 1 in progress
Atlas 10x36

thecameraman79
Senior Silent Operator
Posts: 106
Joined: Mon Nov 25, 2013 10:21 am

Re: 6.5 Grendel Subsonic Loads.

Post by thecameraman79 » Wed Oct 18, 2017 10:21 am

I run subsonic 90 and 110 gr subs in my 300 BLK Rem 700 and they are as quiet as can be. I've shot them single shot out of my AR and they are super quiet too but they don't budge the bolt at all. The amount of tuning (removed the recoil spring completely?) to get them to cycle would be insane. I'd actually love to see that you got yours to cycle a AR using trailboss and being subsonic. Got a video somewhere?

If by some miracle he got it to run using trailboss like you said he wouldn't be able to run full power loads without destroying the weapon. My guess is he's trying to find a load like 300 BLK that will run supers and subs with a switch of the magazine.

I recommend picking up a 300BLK upper. I'm thinking there is a reason it hasn't been done in 6.5 Grendel.

kimbell_bush
New Member
Posts: 1
Joined: Mon Jan 06, 2020 5:13 am

Re: 6.5 Grendel Subsonic Loads.

Post by kimbell_bush » Mon Jan 06, 2020 5:22 am

Have you guys looked into using a pistol buffer spring system. Perhaps subsonic loads would cycle with that. Curious, would the pistol buffer spring and brace cause issues by going back to super sonic loads?

Post Reply