Subsonic Grendel?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • AmishEskimoNinja
    Bloodstained
    • Sep 2013
    • 47

    Subsonic Grendel?

    I picked up my Silencerco Hybrid a couple of week back. Although I expect to be using it on a lot of stuff, My 20" AA Grendel was one of the target hosts. Anyway, while poking around for info I ran across this video:



    I had no idea subsonic Grendel was possible. The poster claims to be using IMR8208 and 160 gr RN bullets.

    Has anyone else tried this?
    Last edited by AmishEskimoNinja; 04-23-2017, 02:21 PM.
  • Nodak
    Warrior
    • Nov 2016
    • 160

    #2
    I have a Crux Saxon can in waiting and am also interested in subsonic loads. I would like to try some to get a nice consistent 1000fps load with a 140 to 160gr bullet

    Comment

    • dpete
      Warrior
      • May 2016
      • 222

      #3
      I can understand trying to get a Grendel subsonic if it is the only AR you have. Even if it is you can easily put a 16" 300 BLK upper on your lower and have a rifle that was designed to function with subs. Subsonic is subsonic no matter if its a .264 bullet or the .308 of the BLK. If you intend on hunting with it, a 220 grain sub out of a BLK will have more punch at effective range than a 140-160 grain out of a Grendel. The one advantage of a Grendel sub might be longer range due to BC.

      Comment

      • AmishEskimoNinja
        Bloodstained
        • Sep 2013
        • 47

        #4
        Originally posted by dpete View Post
        I can understand trying to get a Grendel subsonic if it is the only AR you have. Even if it is you can easily put a 16" 300 BLK upper on your lower and have a rifle that was designed to function with subs. Subsonic is subsonic no matter if its a .264 bullet or the .308 of the BLK. If you intend on hunting with it, a 220 grain sub out of a BLK will have more punch at effective range than a 140-160 grain out of a Grendel. The one advantage of a Grendel sub might be longer range due to BC.
        My problem with 300 BLK is that besides the ability to go subsonic, the Grendel is better in pretty much every way. (longer range, more muzzle energy, cheaper to relead, people walk over and ask what you're shooting...) So if you can do subsonic with it, that makes it better in every way.

        Comment

        • dpete
          Warrior
          • May 2016
          • 222

          #5
          Originally posted by AmishEskimoNinja View Post
          So if you can do subsonic with it, that makes it better in every way.
          In the video is he just shooting suppressed or subsonic suppressed? There is a difference and in the video its impossible to tell. Yes I know what his video title says. Without a chronograph saying he is under 1050fps (or preferably under 1000fps) he has no idea. A Grendel like any other rifle is easy to suppress. Getting it subsonic is another matter. If he did thats great. His barrel also appears to be much shorter than 20".

          What powders will cycle and fully function a subsonic shooting Grendel? If 8208 XBR does thats great. There are quite a few that will fully function a 300BLK SBR and 3 or 4 that will cycle 16" barreled rifles.

          The Grendel has a larger case capacity to contend with filling adequately compared to a BLK, and then you have to use lighter bullets that are designed to go supersonic. A 20" Grendel barrel is designed to shoot supersonic bullets accurately. To encourage subsonic velocities you would probably need to go the sbr route for your Grendel to cut muzzle velocity. Extra length promotes speed. Do short Grendel barrels come with pistol gas systems? Pistol gas is recommended for BLK subs with any length barrel.

          Yes a Grendel would have longer range but to what end? None of the bullets for a Grendel are designed to expand at subsonic velocities so unless you want to rely on a bullet tumbling upon impact you are left with it pencilling through the animal if you want to hunt with a subsonic Grendel. There are now bullets specifically made for subsonic hunting with a BLK.

          BLK and Grendel bullets cost about the same, BLK brass can be had very cheaply from several sources or free if you pick up your own 223 brass and convert it. Grendel brass isn't cheap or common in comparison. Powder charges for my 2 subsonic BLK rounds are 8.8 and 9.7 grains so powder cost/round isn't much.

          I'm sure you can get a Grendel to work with subsonic bullets with enough effort and experimenting. Sure, shooting subs at the range is fun(especially with a suppressor) but to me it would be a range only rifle unless I'm wrong about Grendel designed bullets expanding at subsonic velocities.

          I love my Grendel. If I had built it first I probably wouldn't have built my 308AR but I love it too. My 300BLK sbr and suppressor will be in the woods this fall again, only this time with expanding subsonic rounds to thump a deer, and my Grendel and 308AR will get their turns too.

          If you get your Grendel to fully function and stay subsonic please let us all know what you did.

          Comment

          • LRRPF52
            Super Moderator
            • Sep 2014
            • 8569

            #6
            There have been several members that cracked the subsonic Grendel code dating back to the older forum days. Most used 160gr Round Nose or some 140gr bullet.

            Problem with 300 Whisper is that most of the 200+gr bullets are meant to be pressured up by a magnum with 63,000 to 65,000psi under them, so their jackets are very tough and they don't have consistent uncorking and hand off to the rifling in the 300.

            Bill A. went to Ranier bullets and asked if they could make a heavy pistol bullet in .308 that works well with the 300 AAC/Whisper, so they did. Those expand at pistol velocities without breaking the bank.

            The 6.5mm 160 Hornady RN is a low speed bullet that normally does 2200-2500fps from a 6.5x54 Mannlicher or 6.5x55 Mauser, but I'm not yet sure what threshold it has for expansion on the bottom end.

            I personally find the Grendel supersonic suppressed to be very quiet, especially with a good can on it. You don't have some of the muzzle blast issues from SBR .308, and you don't have the high-pitched crack of 5.56 that I often hear.

            I will say that some of these newer cans are getting really good with supersonic suppression, to the point where I personally have little interest in subs other than in the shoot house or tight shooting bays.
            NRA Basic, Pistol, Rifle, Shotgun, RSO

            CCW, CQM, DM, Long Range Rifle Instructor

            6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

            www.AR15buildbox.com

            Comment

            • Klem
              Chieftain
              • Aug 2013
              • 3509

              #7
              Originally posted by dpete View Post
              In the video is he just shooting suppressed or subsonic suppressed? There is a difference and in the video its impossible to tell. Yes I know what his video title says. Without a chronograph saying he is under 1050fps (or preferably under 1000fps) he has no idea. A Grendel like any other rifle is easy to suppress. Getting it subsonic is another matter. If he did thats great. His barrel also appears to be much shorter than 20".

              What powders will cycle and fully function a subsonic shooting Grendel? If 8208 XBR does thats great. There are quite a few that will fully function a 300BLK SBR and 3 or 4 that will cycle 16" barreled rifles.

              The Grendel has a larger case capacity to contend with filling adequately compared to a BLK, and then you have to use lighter bullets that are designed to go supersonic. A 20" Grendel barrel is designed to shoot supersonic bullets accurately. To encourage subsonic velocities you would probably need to go the sbr route for your Grendel to cut muzzle velocity. Extra length promotes speed. Do short Grendel barrels come with pistol gas systems? Pistol gas is recommended for BLK subs with any length barrel.

              Yes a Grendel would have longer range but to what end? None of the bullets for a Grendel are designed to expand at subsonic velocities so unless you want to rely on a bullet tumbling upon impact you are left with it pencilling through the animal if you want to hunt with a subsonic Grendel. There are now bullets specifically made for subsonic hunting with a BLK.

              BLK and Grendel bullets cost about the same, BLK brass can be had very cheaply from several sources or free if you pick up your own 223 brass and convert it. Grendel brass isn't cheap or common in comparison. Powder charges for my 2 subsonic BLK rounds are 8.8 and 9.7 grains so powder cost/round isn't much.

              I'm sure you can get a Grendel to work with subsonic bullets with enough effort and experimenting. Sure, shooting subs at the range is fun(especially with a suppressor) but to me it would be a range only rifle unless I'm wrong about Grendel designed bullets expanding at subsonic velocities.

              I love my Grendel. If I had built it first I probably wouldn't have built my 308AR but I love it too. My 300BLK sbr and suppressor will be in the woods this fall again, only this time with expanding subsonic rounds to thump a deer, and my Grendel and 308AR will get their turns too.

              If you get your Grendel to fully function and stay subsonic please let us all know what you did.
              +1,
              I couldn't say it better myself (well done dpete).

              I have access to both the 6.5Gr and a 300BLK. It doesn't make sense to me to attempt to load a 20" 6.5 Grendel to be subsonic, I know it's an interesting project but there's a lot you have to overcome; a long barrel, a large case and a rifle-length gas port. You need to guarantee 80% of the available space is full of powder to make it safe to shoot horizontally. The heaviest 6.5 bullets are also a limiting factor. It should be relatively easy to do this with high bulk powders like Trail Boss but it won't cycle the AR. The holy grail is to reliably cycle the weapon at subsonic velocities. The lower volume of a 6.5 barrel relative to a 30cal might mean that you could get away with the gas port further out than pistol length but I suspect rifle-length will be too far.

              Unfortunately just getting a dedicated subsonic Blackout upper to compliment your 65Gr upper will require a second 30cal suppressor. If both uppers have the same thread rate a 30cal suppressor will work for both 30cal and 6.5mm but obviously not the other way round.

              Bearing in mind a suppressor only mitigates muzzle pressure - Not the sound made by the bullet travelling through the air down range. Different suppressors or even unsuppressed has no influence on the sound a supersonic bullet makes as it breaks the sound barrier forward of the gun. Or the sound made by the shape of the bullet as it passes through air (supersonic or subsonic). Suppressors only mitigate sound at the firing point.

              Getting the 6.5gr cycling subsonic in a 20" barrel is like forcing a square peg into a round hole. But if you can get it to work I'll be interested to hear your solution.




              The 300BLK shooting subsonic is similar to a Colt .45 (220gns doing 1,000fps). A subsonic 6.5Gr would be similar to a 9mm handgun.

              Comment

              • dpete
                Warrior
                • May 2016
                • 222

                #8
                Originally posted by LRRPF52 View Post
                Problem with 300 Whisper is that most of the 200+gr bullets are meant to be pressured up by a magnum with 63,000 to 65,000psi under them, so their jackets are very tough and they don't have consistent uncorking and hand off to the rifling in the 300.
                Bill A. went to Ranier bullets and asked if they could make a heavy pistol bullet in .308 that works well with the 300 AAC/Whisper, so they did. Those expand at pistol velocities without breaking the bank.

                The 6.5mm 160 Hornady RN is a low speed bullet that normally does 2200-2500fps from a 6.5x54 Mannlicher or 6.5x55 Mauser, but I'm not yet sure what threshold it has for expansion on the bottom end.

                I personally find the Grendel supersonic suppressed to be very quiet, especially with a good can on it. You don't have some of the muzzle blast issues from SBR .308, and you don't have the high-pitched crack of 5.56 that I often hear.

                I will say that some of these newer cans are getting really good with supersonic suppression, to the point where I personally have little interest in subs other than in the shoot house or tight shooting bays.
                I would guess, and its only a guess, that a 6.5 bullet designed for a Mannlicher or Mauser wouldn't expand much if at all below 1600-1800 fps. That would leave it laser beaming a .264 sized hole straight through whatever animal was shot with it when used as a sub at 950-1050fps.

                Its true that Ranier did make a bullet intended to be a sub for the BLK. The trouble is they made it at 180 grains which makes it a very heavy super, or a very light sub, its in the limbo between the two. The easiest subs to cycle a BLK and stay the quietest are the heavies, 220 grains or more. Yes the jacketed bullets that heavy are designed for magnum rifles but as 300BLK subs they work great whether they "uncork" and engage rifling adequately or not. I'll never complain about the 3/4-1" groups I get from a bullet going 970fps at the muzzle being shot at 50 yards. 50-100 yards is max for hunting distance for me with subs and I truly don't anticipate taking a shot at a deer thats longer than 50. Bullet drop of a 220 grain sub out of a BLK sighted in at 50 yards is 1" per 10 yards between 50 and 100 yards. Knowing your holdovers in a multiple reticle scope is a must. The situations and areas I'll hunt with a sub will be my bow stands.

                With technology advancing and suppressors getting better and better at reducing muzzle blast even supersonic shooting rifles will not be as loud. But unless the bullet leaving that rifle is going slower than the speed of sound the instant it leaves the muzzle it will always break the sound barrier and create its sonic mini-boom(crack). No suppressor made can stop the sonic crack of a bullet when it leaves a barrel, only loading the cartridge to go slow enough does that.

                Comment

                • AmishEskimoNinja
                  Bloodstained
                  • Sep 2013
                  • 47

                  #9
                  Originally posted by Klem View Post

                  I have access to both the 6.5Gr and a 300BLK. It doesn't make sense to me to attempt to load a 20" 6.5 Grendel to be subsonic, I know it's an interesting project but there's a lot you have to overcome; a long barrel, a large case and a rifle-length gas port. You need to guarantee 80% of the available space is full of powder to make it safe to shoot horizontally. The heaviest 6.5 bullets are also a limiting factor. It should be relatively easy to do this with high bulk powders like Trail Boss but it won't cycle the AR. The holy grail is to reliably cycle the weapon at subsonic velocities. The lower volume of a 6.5 barrel relative to a 30cal might mean that you could get away with the gas port further out than pistol length but I suspect rifle-length will be too far.
                  I guess more than anything I'm interested due to the love of 6.5G, and the fact that I already have everything needed to reload it. I'm interested in your comment about 80% fill required for safety. I've never heard of that before. Is the concern you could get incomplete burn?

                  Originally posted by Klem View Post

                  Unfortunately just getting a dedicated subsonic Blackout upper to compliment your 65Gr upper will require a second 30cal suppressor. If both uppers have the same thread rate a 30cal suppressor will work for both 30cal and 6.5mm but obviously not the other way round.
                  I've got a Silencerco Hybrid, so its good from 9mm to 458 SOCOM and 338 Lapua.


                  Originally posted by Klem View Post
                  Getting the 6.5gr cycling subsonic in a 20" barrel is like forcing a square peg into a round hole. But if you can get it to work I'll be interested to hear your solution.
                  Sounds like a challenge. I recently tackled 9mm Major, so I guess I'm ready for the next reloading challenge...

                  Comment

                  • Klem
                    Chieftain
                    • Aug 2013
                    • 3509

                    #10
                    Originally posted by AmishEskimoNinja View Post
                    ... I'm interested in your comment about 80% fill required for safety. I've never heard of that before. Is the concern you could get incomplete burn?

                    Sounds like a challenge. I recently tackled 9mm Major, so I guess I'm ready for the next reloading challenge...
                    The issue of having too much space in a case I am referring to relates to two dangerous phenomena; Flash-Over and Secondary Explosion Effect (SEE).

                    Flash-over is when the case is horizontal and the powder is level with gravity. A larger than normal surface area of powder is exposed to the primer spit as it goes off. You get a dangerous spike in pressure as more powder than normal goes off at the same time, and the gun blows up - Ironically because of too little powder, not too much.

                    The other phenomenon is SEE, where there is not enough sympathetic combustion due to lack of powder and/or the primer spit not starting the deflagration properly (e.g. powder not densely packed against the primer hole). The powder may smoulder and then a secondary pressure spike happens when all the powder goes off at once. again, KABOOM!

                    The 80%-rule is just a popular safety convention. I am sure there is a 'fudge factor' built into that percentage but then again... it's all risk.

                    We used to use Dacron from sleeping bags to fill the space and push the powder up against the primer hole. Dacron is inert and burns up cleanly leaving no residue in the barrel/suppressor.

                    The average range for hunting with subs for me is 100M. The difference between 100 and 150 is a big drop so don't even bother going any further. Again, it is like hunting with a handgun. No hydrostatic shock. Bullets don't fly apart and they typically act like monoliths. The most you can hope with a monolith is for it to tumble. It is all down to bullet placement and then having to use follow-up shots to humanely kill it. I have tried a lot of 'expanding' bullets. This includes a couple dedicated for subsonic; 220gn Outlaw State Bullets and the newer 220gn Blackout Bullets. Neither have expanded like their website photos. I have gone back to the tried and trusty 220SMK. At least it tumbles every time on hitting flesh. You hear a slap followed by a loud 'zing' as it tumbles out the other side and heads off into the sunset. Feeds reliably and has enough weight to keep the powder and velocity to below 1,050fps, and still cycle. Dpete is right, the 180gn Ranier is just too light to keep subsonic yet reliably cycle the action (I haven't tried it but the bullet weight says it all). LeHigh are the same, their 'subsonic' offerings are too light to cycle. Great in a bolt gun but no good for building cycling pressure in an AR.


                    (9mm Major is simply pandering to IPSC's arbitrary rules by overloading a calibre and stressing your gun's action. Just compete in Minor).

                    Comment

                    • Chrazy-Chris
                      Warrior
                      • Aug 2015
                      • 169

                      #11
                      Originally posted by Klem
                      I did some research as I have not heard this term 'uncorking' used before. I understand it is just a metaphor for pressurised release of a bullet jumping into the lands.

                      In my experience 200+ gn subsonics are just as accurate as lighter weight supersonics. Here is a four-round 220SMK subsonic group shot in the last few days from a 300BLK. Only one group as it was a check zero; 0.75MOA. The average is usually around 1.2 MOA. Using an Aimpoint sight from a bench rest. For a round with an effective range of 150metres 1.2MOA implies that 'uncorking' is a non issue.

                      Wow! That's an incredible group especially for using a red dot. I use the 220gr Sierra Pro Hunters for my subsonic 300blk loads. Mine is just for plinking and they work great, especially since they're the cheapest I've found.

                      Comment

                      • Klem
                        Chieftain
                        • Aug 2013
                        • 3509

                        #12
                        Originally posted by Chrazy-Chris View Post
                        Wow! That's an incredible group especially for using a red dot. I use the 220gr Sierra Pro Hunters for my subsonic 300blk loads. Mine is just for plinking and they work great, especially since they're the cheapest I've found.
                        Don't forget it is a bench rested gun and it is unusual. Normally averaging 1.2MOA so sometimes it's 1.5MOA. The barrel is a Ranier Ultra Match which also explains it.

                        I tried the 220 Pro Hunters a while back hoping the soft point would expand on flesh. Unfortunately it just goes through and out the other side like a laser beam. It gets slightly bent if hitting bone but that was about it. They also pigeon-toe inwards when loaded in a standard GI mag on the ribs. The 220SMK is more pointed so it does not touch the ribs like the blunt Pro Hunters. I find they are also more accurate.

                        Comment

                        • dpete
                          Warrior
                          • May 2016
                          • 222

                          #13
                          A picture of a 5 shot group from my load development using 225 grain Hornady BTHP at 50 yards. Bullets designed for magnums can and will shoot lights out at practical ranges from a subsonic/suppressed Blackout.

                          Comment

                          • Cockednlocked
                            Bloodstained
                            • Jun 2016
                            • 50

                            #14
                            Originally posted by AmishEskimoNinja View Post
                            My problem with 300 BLK is that besides the ability to go subsonic, the Grendel is better in pretty much every way. (longer range, more muzzle energy, cheaper to relead, people walk over and ask what you're shooting...) So if you can do subsonic with it, that makes it better in every way.
                            Loading subs for Grendel because you can is okay, but why drive a Ferrari if you want a bicycle? Use the platform designed for the job. I own both a Grendel and a 300BLK, and I shoot them in their own realm of performance. Certainly, there's a spot where both are fairly equal, but Grendel's strong suit is reaching waaaaay out and touching something. You can still suppress it, (and as loud as mine is, I should consider that), but you'd be better suited, I think to build yourself another upper in BLK. Go hog wild and go the SBR route and have a nice, compact .30 cal rifle that makes no more noise than a .22 rimfire.

                            Comment

                            • AmishEskimoNinja
                              Bloodstained
                              • Sep 2013
                              • 47

                              #15
                              Originally posted by Klem View Post
                              The issue of having too much space in a case I am referring to relates to two dangerous phenomena; Flash-Over and Secondary Explosion Effect (SEE).

                              Flash-over is when the case is horizontal and the powder is level with gravity. A larger than normal surface area of powder is exposed to the primer spit as it goes off. You get a dangerous spike in pressure as more powder than normal goes off at the same time, and the gun blows up - Ironically because of too little powder, not too much.

                              The other phenomenon is SEE, where there is not enough sympathetic combustion due to lack of powder and/or the primer spit not starting the deflagration properly (e.g. powder not densely packed against the primer hole). The powder may smoulder and then a secondary pressure spike happens when all the powder goes off at once. again, KABOOM!

                              The 80%-rule is just a popular safety convention. I am sure there is a 'fudge factor' built into that percentage but then again... it's all risk.

                              We used to use Dacron from sleeping bags to fill the space and push the powder up against the primer hole. Dacron is inert and burns up cleanly leaving no residue in the barrel/suppressor.

                              The average range for hunting with subs for me is 100M. The difference between 100 and 150 is a big drop so don't even bother going any further. Again, it is like hunting with a handgun. No hydrostatic shock. Bullets don't fly apart and they typically act like monoliths. The most you can hope with a monolith is for it to tumble. It is all down to bullet placement and then having to use follow-up shots to humanely kill it. I have tried a lot of 'expanding' bullets. This includes a couple dedicated for subsonic; 220gn Outlaw State Bullets and the newer 220gn Blackout Bullets. Neither have expanded like their website photos. I have gone back to the tried and trusty 220SMK. At least it tumbles every time on hitting flesh. You hear a slap followed by a loud 'zing' as it tumbles out the other side and heads off into the sunset. Feeds reliably and has enough weight to keep the powder and velocity to below 1,050fps, and still cycle. Dpete is right, the 180gn Ranier is just too light to keep subsonic yet reliably cycle the action (I haven't tried it but the bullet weight says it all). LeHigh are the same, their 'subsonic' offerings are too light to cycle. Great in a bolt gun but no good for building cycling pressure in an AR.


                              (9mm Major is simply pandering to IPSC's arbitrary rules by overloading a calibre and stressing your gun's action. Just compete in Minor).
                              Great info. I had no idea there was a safety element to under-loading a rifle cartridge. I guess I'll steer clear.

                              On your 9mm Major comment, I can't disagree with your logic, but putting 9mm minor in a gun specifically designed for 9mm major is like putting Goodyears you bought at Walmart on a Ferrari.

                              Comment

                              Working...
                              X