Geissele MRGG-S adopted by USSOCOM in 6.5 CM.
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Has anyone broken a geissele bolt yet? Im curious to how they are holding up. Maybe the mrgg-a will kill the 6 arc for military use but the weight savings can't be ignored imo.
Just because we get endless propaganda from the USM, as things currently stand they love the Geissele 5.56 BCGs currently. The 6 ARC bolts that were submitted for testing all survived and exceeded the testing parameters.
Good to know. I’m waiting for Geissele to release the Mrgg, but it’s hard to ignore the gfr in terms of practicality, and they seem to be holding up well. Odds are I’ll end up getting both. Expensive times….
To me, they are just completely different animals. Small frame vs large frame, with appropriate setups of both rifles you end up with substantial weight saving with the 6 ARC. To me, the 6ARC is a really nice upgrade to a weapons platform that the majority of US Troops are familiar with. It gives you better terminal ballistics at any range vs. 5.56. The MRGG is a dedicated gas gun sniper system, not really an assault weapon. Heavier rifle, larger optic, dedicated range finding and thermal bridge.
I agree with everything here. I have both a LMT MWS with a 6.5 Creedmoor barrel, and a LMT MRP with a 6.5 Grendel barrel. In terms of general handling the smaller lighter Grendel is a dream to carry and shoot. However the Creedmoor while heavier, and less suited for assaulter type roles, allows much more confidence when engaging targets beyond 600 yards. Terminal effects are vastly different. They really are two different animals with overlapping capabilities depending on barrel length and optic choice.
This is the way my Children...
I've been using YM for Many Years without issues, they use 9310 Steel.
Badlands Shell Shock is pretty interesting stuff and certainly has application in both 556 and 6.5 CM ammo... 55gr at 3k fps out of 10.3" barrel is crazy (3300fps out of 14.5" barrel). $0.70 or so a round for 55 fmj and $1.25 or so a round for 77 otm is pretty reasonable and should hopefully come down as production ramps up. Their 308 M118LR equivalent is way too expensive but hopefully they can figure that out (they have a blank page for 6.5 CM so excited to see what happens here).
Personally, I'd love a 100gr ELD VT or similar bullet pushed silly fast from a short (~14.5") 6.5 CM and a 130 AR Hybrid that is +200 fps from what we are used to today.
Personally, I'd love a 100gr ELD VT or similar bullet pushed silly fast from a short (~14.5") 6.5 CM and a 130 AR Hybrid that is +200 fps from what we are used to today.
Ive been using Rubber City for many years and their bolts are also made of 9310 MPI batch inspected Shot peened.
Ill have to check em out. I am running a JP bolt now but know its just a matter of time/firing schedule before it gives up the ghost.
I really need to get a GFR upper.
6.5mm Grendel Complete Bolt Only - Welcome to Rubber City Armory
Blacknitride+ Enhanced 6.5mm Grendel Complete Made of 9310 MPI batch inspected Shot peened. .136 Bolt Face Type II Depth **DO NOT USE WITH TYPE I BARRELS AS EXCESSIVE HEAD SPACE WILL OCCUR.**
rubbercityarmory.com
Great idea to put a bomb next to your face.
Firearms are designed around a typical brass cased cartridge. Safety factors in design are factored around this. Gas systems are designed around a specific impulse and gas volume.
Unless the firearm was designed to handle these high pressure rounds (destructive and non destructive testing to make sure you keep half your face when it DOES fail) you would have to be insane to shoot this through a normal AR. Not to mention the wear and tear on a gun not designed to handle those pressures/spikes.
Agree 100% and that was my thought initially but I guess the new case material is lighter / stronger than brass (not a high bar to be lighter / stronger than brass) which allows for thinner case wall to hold the same pressure. Thinner wall = more volume in the case which reduces pressure for an equivalent powder charge. Up the charge to bring pressure back to 62k and velocity increases. Pretty interesting upgrade and seems to cost about $0.30 / round more in the 556 platform
I love it when all these guys talk about the military should use these way over pressure rounds from cottage industry loaders
I think reading what goes into military ammo testing and requirements should be required for all.
I was talking to a Crane guy twenty plus years ago and suggested they try my load launching 155’s out of a 308. He explained cost and testing requirements to me. I understood why they choose velocities they do
As to grains testing on the 6.5’s. It’s been up
In the air. At one time they said 147 was the bomb but last I heard two months ago now it looks like a bullet in the 140 grain range will win out
I think reading what goes into military ammo testing and requirements should be required for all.
I was talking to a Crane guy twenty plus years ago and suggested they try my load launching 155’s out of a 308. He explained cost and testing requirements to me. I understood why they choose velocities they do
As to grains testing on the 6.5’s. It’s been up
In the air. At one time they said 147 was the bomb but last I heard two months ago now it looks like a bullet in the 140 grain range will win out
From what I understand the pressure is not increased, because the case internal volume is increased with the material they are using instead of traditional brass cases. Increased case volume = lower pressure
I haven't broken any JP, Rubber City Armory or Young Manufacturing Bolts, but that doesn't mean much because I don't torture my Custom Precision builds.. Bartlein Barrels be spendy.
For my Custom Hard Use Carbines, like the SOLGW Broadsword / Geissele Chrome Lined Heavy Barrels Builds the Geissele Complete Enhanced BCG’S have been absolutel Rockstars.
Back to the Grendel/ARC's Bolts the YM HMB Bolt design is a pretty damn solid improvement over the traditional Mil-spec, I've also noticed less wear around the cam pin itself.
The only caveat that I will mention is that after the initial 150-200 round brake in cycle, unless I know the Bolts I'm using are using all SpringCo Springs and Gas Rings I replace them. It's a cheap/easy upgrade to any Bolt that I know for a fact will increase the reliability and longevity of the bolts performance.
Since this thread has drifted significantly from the original topic I’ll go ahead and join the tangent.
6ARC: the biggest problem with 6ARC is that AR lowers and bolts really aren’t made to accommodate the cartridge. The only way to truly run right is to deviate from the standard and make a new bolt, barrel extension, lower, and magazine. That still doesn’t overcome the limitations of the cartridge as it was constrained to the AR magazine. If you need a whole new gun to reach the reliability and durability performance requirements of a combat system, why limit to the 6ARC? The .264 LIC/.264 USA has tremendous potential in that space, and is basically the optimal general purpose rifle cartridge.
High pressure ammunition:
The U.S. Army opened the box on this with Next Gen, and like it or not, it’s going to continue. Ammo manufacturers working in the HP world have done a pretty good job of using case materials to contain the pressure, and are using novel propellants that get the projectiles moving at increased velocities early in travel and drop pressure dramatically much earlier than more traditional loads, thus keeping port pressure in a safe area for function. Of course, this doesn’t solve every aspect and risk of HP ammo, but it helps a lot. Guns built from the ground up for HP ammo (like the M7) with backward compatibility with standard pressure ammo are really what’s going to be needed for these programs.
Overall program thoughts:
It would be entirely possible to field a .246LIC rifle with a 14.5-16” barrel that was optimized for HP ammo that could directly overtake the current MRGG-A program at lower weight and with increased magazine capacity.
6ARC: the biggest problem with 6ARC is that AR lowers and bolts really aren’t made to accommodate the cartridge. The only way to truly run right is to deviate from the standard and make a new bolt, barrel extension, lower, and magazine. That still doesn’t overcome the limitations of the cartridge as it was constrained to the AR magazine. If you need a whole new gun to reach the reliability and durability performance requirements of a combat system, why limit to the 6ARC? The .264 LIC/.264 USA has tremendous potential in that space, and is basically the optimal general purpose rifle cartridge.
High pressure ammunition:
The U.S. Army opened the box on this with Next Gen, and like it or not, it’s going to continue. Ammo manufacturers working in the HP world have done a pretty good job of using case materials to contain the pressure, and are using novel propellants that get the projectiles moving at increased velocities early in travel and drop pressure dramatically much earlier than more traditional loads, thus keeping port pressure in a safe area for function. Of course, this doesn’t solve every aspect and risk of HP ammo, but it helps a lot. Guns built from the ground up for HP ammo (like the M7) with backward compatibility with standard pressure ammo are really what’s going to be needed for these programs.
Overall program thoughts:
It would be entirely possible to field a .246LIC rifle with a 14.5-16” barrel that was optimized for HP ammo that could directly overtake the current MRGG-A program at lower weight and with increased magazine capacity.
Agreed on all of the above with the exception of 264 as a bore diameter.
I know 25 cal is all the hotness right now, but I do think a 6mm or 25 cal would make more sense. The 6.5 CM large frame AR already can't take advantage of the heavy for caliber bullets so why use a smaller case with the same diameter? I would think stepping down one or two bore sizes might be good to allow for those heavy bullets to be loaded to mag length especially if OAL is going to be constrained further
Do you think current 6arc mags with have reliability issues in dirty environments because of the lack of clearance in the mag due to case size?
.264 is easier to get a good penetrator into than a 6mm.
6ARC has problems in magazines because the AR magwell isn’t wide enough to properly stack the rounds. Needs a wider magazine and therefore wider magwell. SureFire and Magpul did it right.
Would you want a new feed ramp to conform to the new mags, or is the mag correction enough by itself with existing geometries?
Have you played with the Geissele made 6ARC Specific Magazines??
I've done quite a few Custom 6ARC builds now and when utilizing Geissele Mags, the newer wider feed ramp barrel extension and a A5 Buffer system I have yet to have and issues with reliability with any of the Hornady Factory Ammo.
I've been running ASC mags since day one with my RTR 22" 6ARC, RCA AGK BCG and Geissele buffer and spring with zero issues what so ever. Stupid accurate and not a single feeding issue.
I heard some have had issues but I have had none
22" Rainier Ultramatch MOD2 6 ARC +2 Gas
Rubber City Armory BCG with AGK
MEGA Billet AMBI lower
MEGA SBU Thick Walled Billet Upper
Geissele Super Braided 42 and H1 Buffer
Geissele Premium Mil-Spec Buffer Tube
LaRue Tactical MBT-2S Straight Bow Trigger w/JP Spring
Battle Arms Development Ambi Safety
Magpul PRS Lite
I heard some have had issues but I have had none
22" Rainier Ultramatch MOD2 6 ARC +2 Gas
Rubber City Armory BCG with AGK
MEGA Billet AMBI lower
MEGA SBU Thick Walled Billet Upper
Geissele Super Braided 42 and H1 Buffer
Geissele Premium Mil-Spec Buffer Tube
LaRue Tactical MBT-2S Straight Bow Trigger w/JP Spring
Battle Arms Development Ambi Safety
Magpul PRS Lite
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I’ve got a bunch of different mags, they all work. Geissele mags also work great…
Primary issue is making sure the rifle is gassed properly, so that the BCG goes back far enough… I’m using a JP silent buffer system with an Odin works adjustable gas block.
6.5mm Grendel Complete Bolt Only - Welcome to Rubber City Armory
Blacknitride+ Enhanced 6.5mm Grendel Complete Made of 9310 MPI batch inspected Shot peened. .136 Bolt Face Type II Depth **DO NOT USE WITH TYPE I BARRELS AS EXCESSIVE HEAD SPACE WILL OCCUR.**
This is the exact bolt I am using in my 22ARC. I bought it as a complete BCG. Very impressed with the machining.
Thats the RCA bcg with adjustable gas key. I run one on all my builds. So much easier than an AGB and runs great.
That's exactly what I'm hoping for!
...and with an osprey barrel, it should probably be a little more accurate than an Odenworks barrel (no idea who makes their barrels).
...and with an osprey barrel, it should probably be a little more accurate than an Odenworks barrel (no idea who makes their barrels).
Keep in mind these comments are coming from someone that is ammunition manufacturing adjacent. If we have heard it once, we have heard it 100 times that rounds bigger than 6mm "kick too hard, uncomfortable recoil impulse, hard to stay on target after you break the shot, heavier load out," Like it is non stop.
Ironically, your company and others like them have made it really hard to adopt another cartridge and platform. The AR platform in 5.56 is so proven, so reliable, so adjustable and customizable, so versatile that it is extremely difficult to compete with. The idea with 6 ARC is that you get to stay with a small frame gas gun (and keep almost all the positive things I just mentioned about the AR) and extend the range of the weapon and the lethality of the weapon without going into the negative comments about larger calibers.
Yes, the feed ramps need to be adjusted for proper feed.
Yes. The Geissele and Duramag magazines were both pretty decent for a compromised round stack. This isn't a dig at them, they took the common approach of using a standard AR lower which most users want, and provides the user with more options. But they all fall way behind the performance of the dedicated 6.8 SPC/LWRCI-derived 6ARC magazines. What's on the market is going to be fine for 95% of hobbyist users, but what's required for government testing is a different animal, especially when it comes to layered environmental factors and full-auto fire.
We were able to do some pretty cool things with a 6ARC carbine, but SureFire was able to do it all, and that's why they're the best option that currently exists. They did a better bolt design and a better magazine than anyone else, and that's what really makes the difference. The strength of the SF bolt also allows them to exceed the 55kpsi limit of most 6ARC, which gets projectile velocity into a band that gets practical gains.
I have see a lot of people float into and out of 6ARC in demanding competitions mostly due to reliability, reliability that is directly correlated to operating pressure, magazine reliability, and parts life. That does NOT mean that 6ARC is "bad", just that it isn't optimal in an AR without pretty significantly deviating from the standard. This really shouldn't be a point of disagreement, as the AR system we all know was designed for 5.56. Changing cartridge head diameter, cartridge shoulder location, and distance from shoulder to meplat comes with consequences.
People have an interesting perception of caliber, cartridge, velocity, weight, capacity, carried ammunition, and recoil that is highly variable and not reflective of reality in many cases. Requirements matter, but requirements can also be an exercise in futility when they're poorly informed or expressed. I have shot the FN .264LIC rifle and it has recoil that is more similar to 7.62x39, 6ARC, or hot 77gr 5.56 than anything else. Of course, operating system and system weight effect that perception, but it offers more than 6ARC can, all else being equal, without needing to get into the extreme pressures that also bring compromises.
The PDW was pretty cool, but that program pretty much went away when .300 BLK hit the system. The gun itself had some good things going for it, but needed more development. The 6x35mm cartridge was definitely ahead of its time, but it was also created to meet specific requirements, requirements that have been superseded in the contemporary space. That said, as needs become more defined, there will likely be a need for something similar, and we'll be there when it comes down.
Man even if it was in 5.7 or something similar it would be so cool. A light handling small, low recoil PDW with ability to throw in AP ammo would be awesome. Honestly that is what non-frontline troops should be issued. Something that can get good hits out to about 300 which is really the max practical range of most soliders anyway.
Yessiree.
Would probably need to be something more in the 6mm-7mm projectile diameter to payload appropriately for current body armor concerns, but that's exactly the application.
