How to take best advantage of a low mass carrier

[Nitrider]

I recently purchased a low mass carrier from RCA and want a little help wringing the most out of its benefits.

All other upgrades thus far have made a noticable difference with minimal tuning. This one evades me though.

The overall muzzle movement of the gun doesn't feel like it has changed. Admittedly, I was running higher pressure ammo [XM193] than usual when testing it. One benefit is that the gas settings were turned down considerably, but that may have been a side effect of using higher pressure ammo than the usual PMC Bronze.

Before I move forward, here's the pertinent info on the rifle it is being installed in. I've put roughly 200 rounds through it in this configuration.

-16" Mid length gas Ballistic Advantage Hanson profile barrel

-SLR Sentry 7 adjustable gas block

-Vltor VC-1 muzzle device

-Vltor A5 buffer tube

-Vltor H0 buffer with weight tuned down to 2.8oz [originally 3.8oz and standard A5 buffer is 5.3oz]

-Tubbs CS Flatwire spring that has been slightly trimmed so that it offers the same resting pressure as a standard rifle length buffer spring [stock spring is still intact if needed]

-RCA low mass bolt carrier [no adjustable gas key]

The buffer weight has been reduced to 2.8oz because any lighter than that and signs of excessive bolt bounce showed up on high speed footage.

The only other details I have to share is that this rifle feels great and is well balanced but is way lighter than I anticipated. It weighs in at 6 lbs 6 oz which includes my red dot, flashlight, and sling. [NOTE: I'm not lightening the reciprocating mass to save weight, but to reduce the secondary recoil impulse of the rifle for faster follow up shots]

For what it's worth, I realize that I am not running a muzzle brake and that this rifle is very much on the light side, both of which are not optimal for reducing recoil. I'm somewhat reluctant to run a muzzle brake due to excessive concussion and flash. I guess I'm trying to see how much a rifle's muzzle rise can be tamed without the aid of a muzzle brake without sacrificing reliability.

So, what's next if anything? Tune it by installing a softer/stiffer spring, reduce buffer weight further, buck up and install a muzzle brake?!

[tacticalCOWBOY]

I would run a break. That's my 2 cents

[JohnLTD]

The muzzle brake / comp is the missing link. I don't think there's any way around it.

[Mark Gale]

Of course you meant to say carrier bounce...

Carrier bounce is not an issue that needs to be resolved unless you are experiencing a malfunction as result of it. It's uniquely a select fire issue and is extremely rare to the extent that it causes an issue with an AR-15. That being said, the overall weight of the buffer assembly really has nothing to do with the phenomenon. The reciprocating mass, or lack thereof, inside does.

I'm no spring engineer but I don't believe trimming coils will reduce spring rate, only the number of active coils.

Muzzle movement is not always a parts issue. Learning to shoot the carbine properly will have a big affect on muzzle control. Muzzle control is largely a body position and weapon interface issue. I'd suggest you start shooting a local 3 gun or rifle match and attend a shooting class or three with a reputable instructor.

[Nitrider]

Thank you for the replies!

TacticalCOWBOY and JohnLTD- From my understanding, a good muzzle brake is the cheapest, easiest, and most effective way to reduce recoil/muzzle rize [depending on design]. If I had to go with a new muzzle device, what would be a good one that won't blow out my eardrums? I've heard some positive things about the PWS FSC556 as a middle of the road choice, but also hear that it's still loud. Also, I would go to the range and try out some other people's gear, but up here in Montana there's mostly but a bunch of dirt shooters. Hah!

Mark Gale- You are very correct; carrier bounce. Sometimes I abbreviate "BCG" to just "bolt", which is inaccurate.

I agree with your assessment of carrier bounce; it's not a problem until it manifests itself as a malfunction. Thus far, no malfunctions have shown themselves by running the low mass setup. I have only viewed the high speed footage and found a completely arbitrary point that I thought was too much bolt bounce. I could be wrong, but I assumed [from my very limited background in physics] that the buffer system operated by acting as a deadblow to the carrier. If a full mass carrier [11oz] is used with a 1oz buffer, carrier bounce will be severe. If a low mass carrier [8oz] is used with a 4oz buffer, then much of the carrier bounce would be mitigated.

Both offer a reciprocating mass of 12oz, but the latter provides a better buffer to carrier weight ratio. Again, this is my understanding of the concept. I could be very wrong.

As far at training goes, I'm on board with ya. I plan on attending a few classes sometime soon. A good friend of mine just attended one recently and passed along some much needed information. That being said, I'm still looking for the best way to mechanically reduce minimize muzzle drift in this rifle. [Without a brake, until I break down and get one; Ha!]

But back to the original question, is a lightweight carrier a plug-n-play type of part or does it need tuning to reap it's benefits?

What positive experiences have you [everyone] noticed after installing this item?

[jtaylor996]

The good compensators talked about on here lately are the Miculek, the Seekins ATC (I have this one, it's not offensive at all), Dynamic Resistance, and Gas Hog.

[jon49erfan]

The PWS and Miculek comp are both very loud. A low mass carrier is a plug and play part but best utilized with a way of adjusting gas.

Edited October 6, 2014 by jon49erfan

[Iowashooter]

comps are loud there really is no good way around it. I use my competition rifle while coyote hunting and I just wear electronic muffs so I can still hear but am not deaf if I take a shot. I have a Miculek on my DPMS 3g1 and for the price it would probably be all anyone would need. I put the Seekins ATC on my new build and it feels a little less concussive. With the Seekins it might have a little less of an excessive flash with its design but I have not shot it in low enough light to take notice of the flash.

[Nitrider]

jtaylor996- Thanks for the reccomendations. The Seekins looks interesting as it uses slightly softer angles to engage gas coming out of the ports. I wonder if that may reduce the angle at which the port pressure is redirected? Is it non-offensive compared to all other brakes?

The Gas Hog might be even more promising, except for the price! I wonder if it's concussion is similar to running a bare muzzle, which is quite acceptable in my book.

jon49erfan- Good to know about those comps. They both strike me as loud by design. Loud is subjective anyway.

Since I have an adjustable gas system, I should be taking full advantage of the low mass carrier immediately, right? I don't need to purchase different springs or adjust the ones I currently have?

To all-

I guess I'm coming at this from a salesman's point of view. Think Feature, Advantage, Benefit.

For example, A Post-It note features a sticky backside. This is advantageous because it allows you to place your note on any surface. The benefit of this is your notes are now more visible and your information is more easily found.

A low mass carrier features a lighter weight than a standard mass carrier. This is advantageous because less mass is reciprocating in your rifle. The benefit is... ???

To achieve that [not yet clearly defined] benefit, is there a certain way the bolt carrier should be implemented, or just drop it in and adjust gas?

[Nitrider]

Iowashooter- Agreed, muzzle brakes go BOOM! There's no way around it. Glad to have another vote for the Seekins.

To all-

I'm still wary of a muzzle brake's concussive nature and how badly they flash. Plus, I kind of like the idea of tuning a rifle without a muzzle brake, knowing that when I do install one that the rest of the rifle is in proper working order.

Also, I know that Brian Enos is a forum that is pretty much dedicated to competition shooting sports, but I don't want my rifle to only be a practical choice for broad daylight competition shooting.

[Stlhead]

What exactly are you building this rifle for? You say that you don't want a rifle that is only practical for day competition use. By that do you mean you want a rifle that would be appropriate for night competition use as well, or do you have "other" uses in mind?

[Doug H.]

Iowashooter- Agreed, muzzle brakes go BOOM! There's no way around it. Glad to have another vote for the Seekins.

To all-

I'm still wary of a muzzle brake's concussive nature and how badly they flash. Plus, I kind of like the idea of tuning a rifle without a muzzle brake, knowing that when I do install one that the rest of the rifle is in proper working order.

Also, I know that Brian Enos is a forum that is pretty much dedicated to competition shooting sports, but I don't want my rifle to only be a practical choice for broad daylight competition shooting.

Sounds like you want a suppressed carbine that can double as a competition gun when the Zombies aren't around.

Doug

[Nitrider]

Stlhead- I'm a big fan of keeping my gun collection to a minimum. One long range rifle, light weight rifle, shotgun, full size pistol, and compact pistol. Pretty much anything I own I try to keep relevant as both a competition and defense weapon. I know this isn't exactly optimal for either endeavor but it allows me to justify gun purchases a little better and frees up more cash for ammo.

But I think you're on to something with the night competition aspect. I hate the idea of an overly specialized gun becoming worthless in certain scenarios, whatever the scenario may be. If my trip to the shooting range runs late, night shoot, indoor shoot, etc. Big nasty comps suck indoors and make you near blind at night. I once saw a guy with a AN PVS-14 running an AR with a JP muzzle brake on it. One word: hilarious.Everytime he shot it was like someone flicked the lights on and off. I just don't want to be that guy.

Doug H.- Solid advice. A friend of mine just purchased a Saker 5.56 and let me run it on my AR. Very fun, soft shooting, and oh so quiet. It's made me wonder if I should get one of my own and use the Saker muzzle brake as a mount. Fast and loud when I want it, quiet when I don't. Funny though, I'm still trying to figure out what to do with that hot can after shooting it. You can't even really transition to a pistol unless you want to burn holes through any clothing it touches.

[openclassterror]

Add weight. A LOT of weight. Without a brake, it's the only way to tame the rifle. Other than a suppressor, that is. Any brake should require the use of hearing protection, but then again any 16" barreled AR should never be fired without ear-pro anyhow. The light buffer reduces the amount of mass striking the rear of the buffer tube during the recoil impulse. When used in conjunction with reduced gas, it greatly reduced the bump when the carrier bottoms out during cycling. More "felt" recoil in the AR comes from the carrier cycling than from the cartridge itself.

[Stlhead]

It seems like a nice can would be the ticket.

[GreenDragon64]

What about the Nordic Corvette?

[TonytheTiger]

What about the Nordic Corvette?

Ditto. I've always thought it was a cute comp but never heard much about it.

[Stlhead]

If the OP is thinking he may be shooting this thing with no hearing pro, a can would be way better than any comp. the extra weight will also settle the gun down quite a bit.

[Nebwake]

If you want a duty/ defense rifle, I would not run a lowmass system. Also I am not sure I would run a lowmass system with a suppressor either. These game guns are really meant to run under closed conditions, during the day, not mud and rain and cold, be clean and have proper lubrication. If you want to make a gun do both, id get a second upper with full mass system and get a suppressor if you want some recoil reduction.

[Nitrider]

openclassterror- I hear ya on the weight thing. Like I said, this gun came out unexpectedly light. My friend's rifle weighs around 10.5 lbs with his suppressor. It's very smooth to shoot, but would be a bear if you had to carry the thing.

As far as noise goes, I will be using ear protection with any rifle I use, muzzle brake or not. I am just borderline paranoid about premature hearing loss. I don't want my hobby to cripple me later in life.

Thank you for the expanation of the low mass setup. This is what I anticipated it did, but I wanted to hear it out of someone's mouth.

Stlhead- I think you're right, the extra weight and handling characteristics of the suppressor could be really beneficial. Is there any negative to running a suppressor in a multigun match other than increased length?

GreenDragon64 and TonytheTiger - What would the Corvette offer that other muzzle devices don't?

Nebwake- Is there any reason that you wouldn't run a low mass setup in a duty/defense gun? I only ask because I've heard this before, but haven't gotten any real substantial evidence that it would cause failures. Honestly, half of the reason I purchased the low mass setup was to test this out for myself. I agree that it could potentially narrow the window of successful operation, I just want to see if when tuned properly if it gives me any problems.

I'm inclined to agree with you about running the rifle suppressed with low mass components. If gas wasn't adjusted properly, the extra pressure could have that gun cycling insanely fast. Also, I still have my full mass carrier and am not opposed to re-installing it. I just wanted to experiment with this for intellectual fun.

Edited October 7, 2014 by Nitrider

[RigPig]

I think the best way to dial in a low mass bolt carrier is with the adjustable gas block. Starting with the gas block all the way open and using the lightest .223 load you have, shoot a few rounds and dial the gas block down until the rifle quits cycling, then open it back up a couple notches. I run a JP LMOS in the comp rifle, with the lightened BC, JP tuned rifle spring and JP low mass rifle buffer. I run these behind a Nordic 18" rifle barrel that has a gas port that is supposedly tuned to run a low mass system with a fixed gas block. I haven't had any reliability issues. I can't "feel" any reduced recoil, but my Vortex Razor HD 1-6x staying on the target at 6 power doesn't lie. I notice less reticle movement even at 1x. I use an Apex brake as well.

[FishnHuntIN]

If you're worried about concussion and flash, the Nordic comp will not fit your bill, IMHO. I've had several RO's mention they hate mine, and I remember during my research it was mentioned as a loud/concussive brake. Doesn't bother me, though.

[openclassterror]

If you want a duty/ defense rifle, I would not run a lowmass system. Also I am not sure I would run a lowmass system with a suppressor either. These game guns are really meant to run under closed conditions, during the day, not mud and rain and cold, be clean and have proper lubrication. If you want to make a gun do both, id get a second upper with full mass system and get a suppressor if you want some recoil reduction.

Interesting perspective on low mass. I shoot mine in competitions year-round, down to about 10 degrees in snow and mud, up to about 110 in the summer. I also clean it MAYBE once every 5,000 rounds, or before a major match. Gets a spray of CLP if it starts to feel gritty. I was the ONLY competitor on my Ironman squad this year with no rifle malfunctions, and the only malfunction it has had in over a year was magazine-related. My rifle does not even have a forward assist. I think the majority of the guys who run low mass guns hard have sorted out the issues from early on and gotten them reliable. Or abandoned them and gone back. Not many guys running low mass and living with an unreliable gun.

[Nebwake]

Nebwake- Is there any reason that you wouldn't run a low mass setup in a duty/defense gun? I only ask because I've heard this before, but haven't gotten any real substantial evidence that it would cause failures. Honestly, half of the reason I purchased the low mass setup was to test this out for myself. I agree that it could potentially narrow the window of successful operation, I just want to see if when tuned properly if it gives me any problems.

I'm inclined to agree with you about running the rifle suppressed with low mass components. If gas wasn't adjusted properly, the extra pressure could have that gun cycling insanely fast. Also, I still have my full mass carrier and am not opposed to re-installing it. I just wanted to experiment with this for intellectual fun.

A few reasons (keep in mind I am not really a weapon "expert" per se, so take this advice with a grain of salt and I am sure someone will chime in here, but I have carried AR platforms in the performance of my job for the last 16 years in many nasty places.)

First, a low mass system tends to have a faster cycle rate, this needs to be tuned with less gas (adjustable gas block), get a low gas system really dirty and it will not be able to keep cycling as long as a full (over gassed) system will.

Second, the light weight carrier will not have the energy to push a round into battery as well as a full mass system in a dirty gun. As soon as you start adding heat, carbon buildup and not enough lube, the gun will not run.

Third (JP rifles says not to do it)

Fourth, there are no forward assist serrations on JP lo mass systems (although noted by others many systems do like the RCA you have)

All that said, would I hesitate to use my 3 gun rifle in a defense situation if I needed to? sure, although shooting a comped rifle inside sucks pretty hard. Mine is super reliable, but... I have not had it jammed up with mud and dirt and sand and I keep it pretty clean. Would I take it to the desert with me? absolutely not. If my life really depended on it, my JP rifle (as is right now) would be about last on my list. But it is sure fun to shoot!!!

Edited October 7, 2014 by Nebwake

[Nebwake]

If you want a duty/ defense rifle, I would not run a lowmass system. Also I am not sure I would run a lowmass system with a suppressor either. These game guns are really meant to run under closed conditions, during the day, not mud and rain and cold, be clean and have proper lubrication. If you want to make a gun do both, id get a second upper with full mass system and get a suppressor if you want some recoil reduction.

Interesting perspective on low mass. I shoot mine in competitions year-round, down to about 10 degrees in snow and mud, up to about 110 in the summer. I also clean it MAYBE once every 5,000 rounds, or before a major match. Gets a spray of CLP if it starts to feel gritty. I was the ONLY competitor on my Ironman squad this year with no rifle malfunctions, and the only malfunction it has had in over a year was magazine-related. My rifle does not even have a forward assist. I think the majority of the guys who run low mass guns hard have sorted out the issues from early on and gotten them reliable. Or abandoned them and gone back. Not many guys running low mass and living with an unreliable gun.

I agree with everything you said here, the key is sorting out the issues. These low mass guns can be VERY reliable, just like my 1911's and 2011's are. But it takes messing around with them and tuning them just right, with the right ammo and right gas level to get them to be reliable. I along with everyone here, would consider you a true weapon expert and certain that you have fired more bullets out of AR platforms than I have so I value your opinion, but if I was in a sustained gunfight, I know I would trust a full mass system with forward assists over a low mass system and this comes from first hand experience.

Edited October 7, 2014 by Nebwake