Hi Folks,

A forum member asked me if I would give some insight into how our M4's handle on the range because I've started threads on the AK's, pistols and .50 Barretts.

Here's a little background on what we do. We operate a high-volume range in Las Vegas. You can't bring your personal weapons in and rent lanes for an hour. Customers use only our weapons and our ammo. We only use factory new ammo and zero reloads. We keep maintenance log on EACH and every weapon to include cleanings, parts replaced and any other issues that need to be noted. We shoot approximately 400,000 rounds down range each month and the numbers have actually gone up a bit for May and June. Tourists get to shoot everything from Type 99 Arisaka's, M1 Garand C and D's, MP-44's, G43's, M2HB's, 240's, 249's, MG42's, MG34's, M-14's, Luger's, Swedish K's, M203's, M79's and you get the point. Some weapons are very rare historical weapons that rarely come out of collections or museums and see the light of day.

Here are some "facts" about OUR experience with M4's on the range.

- Some of our M4's have well over 200,000 rounds down range. Barrels have been replaced, gas tubes have been replaced, BCG's have been replaced but what sets it apart from the AK47's is that upper and lower receivers continue to function. AK's get to about the 100,000+ round count and rails on the receiver will start to crack. It's an easy fix with tig welding but they crack. We have yet to lose an upper or lower receiver from cracking.

- We get about 20,000 rounds out of bolts before we start experiencing issues. The headspace gauge will start getting closing on NO-GO but not close on field. We will lose a lug on the bolt. The bolt will start skipping over rounds in the magazine and fail to insert a round. We use LMT and Daniel Defense bolts and some will actually go longer but at about 20,000 rounds is when we will start to see issues appear.

- Gas tubes will erode away at the FSB after 12+ months

- Charging handles will "stretch" allowing the locking lever and spring to fly out

- Hammer pins and disconnectors on the 8.5" full-auto's will break after approximately 4,000-5,000 rounds regardless of the buffer weight

- We have yet to lose a single flash hider as compared to muzzle brakes on an AK-47. The muzzle brakes will literally split in half, looking a like bird with his beak open and go flying down range.

- We no longer use ANY piston conversions or factory pistons guns with the exception of the HK-416 "knock-off" TDI upper. I purchased a FACTORY brand-new MR556 and it started keyholing after only 10,000 rounds. I was SO pissed because I spent all that money on the gun and it couldn't last 10,000 rounds. I had barrels from before we even opened the range with 1,000's of rounds on them from J&T Distributing (chrome-lined) that didn't keyhole well into the 80,000-100,000 range. I don't know who makes or made the J&T barrels but I was so pissed that actually wasted the money on a MR556 and that's all I got from it. I purchased two of the 14.5" TDI knock-offs approximately 6-8 weeks ago and they have been on the line daily with ZERO issues. I only purchased them because people will come in specifically request the "416" and even they've never handled a weapon their entire lives, they KNOW that the top half isn't the "416 like in COD/MW".

- USGI mags have outlasted all of the other brands. We use UGSI (Brownell's with tan follower) and on a mag for mag basis, they have outlasted Pmags and a few of the other mags that we get from mfg'ers with new weapons. We don't have to worry about various generations with different weapons like the MR556, SCAR, F2000, Tavor or a couple of others that use AR15/M4 magazines.

- Cleaning bolts and carriers is such a pain in the ass as compared to our AK's, G36's, SCAR's, ACR's and most other platforms. We throw them in the ultrasonic cleaner filled with Simple Green (EPA, OSHA and disposal concerns for us) and they never full remove the carbon from the bolts. The armorers spend so much time cleaning them and keeping all the parts together as compared to most other platforms.

- The only piston system to last on the range so far is the HK416 and TD415 system. Ever other systems we have tried has failed in one way or another. I won't say who's broke or how they broke so PLEASE don't ask. Each mfg has their own system for cleaning intervals and we may not follow their way. We have a way of cleaning and keeping records that suits our needs because of so much use.

- There is company that has an AR system that has some "parts don't need lubrication" and that failed before the end of the first day. I don't think some mfg's understand that people REALLY use their weapons and when you're rocking full-auto all day they NEED lubrication. My armorers and RSO's were laughing when it seized it up because we knew there was NO way it would last on our range.

- The parts that we see break more often are the bolt cam, bolt lugs shearing off, firing pins and gas keys shearing off the bolt carrier.

These are just a few of the things that I can think of on the top of my head. Please feel free to ask questions and I will try to respond sooner than later depending on my schedule.

V/R
Ron

ps: I am sure there are some grammatical errors as I tend to read the words into a sentence that are not there. Some sort of dyslexia-type of issue that plagued me through eight years of college.

I’m very interested to hear how these hold up.

Just FYI, KAC representatives have never told the public about the steel material used on the E3 Bolt.

Don't know how I missed this thread.

I'll be visiting you guys next month for some full auto fun while I'm out there.

Awesome

@HendersonDefense That's great to hear, I'm sure you'll be pleased.  The only thing I'd make sure to mention is to have them give you some spare extractors / springs as they use a different dual spring design vs. the traditional. I'm sure for you they'll throw in a whole bunch (and even some extra extractors) for free!

Thanks for all the informative content, Rob.

Have you extensively used a Sig MCX, or did were those avoided because of your previous experience with piston ARs?

Thanks.

thank you

quote error

THIS. For the Love of God and All That Is Good, THIS. Would be interesting to see how the Rattler and the Virtus line handle that kind of usage. Sig says, "To Hell And Back" so lets see how it manages.

On SigTalk a user is shows how to replicate a hammer follow malfunction.  You can slowly ease the Bolt forward and keep pressing the trigger... the hammer will go before the Bolt is in battery.  Also the receivers are 6061 Aluminum?

I'm very tempted to get the Rattler, .300BLK but have a feeling I'm walking into a mistake.

You should probably wait for at least the 4th gen of the MCX.

What would be cool would be to get a few of these enhanced bolts from each manufacturer (DD, KAK, JP, ARP, etc) run them and see how enhanced they really are.

Ron,

Sharps Rifle Company also makes an NP3+, S7 tool steel plus heat treated Reliabolt at a cheaper price (89$) than LMT or JP. I use them in my heavy use suppressed SBRs and have no problems.

Reliabolt

@HendersonDefense

There has been several broken reliabolts, I have yet to hear of a broken LMT enhanced bolt.

How is this not a sticky yet

+ a billion

Yeah, I've seen a couple of them not work when people showed up to classes

@HendersonDefense as a quick thanks for the invaluable info log out and log back in!

Just read this entire thread over the last few days and have to say it's a treasure! Ron's contributions here have been superb! This thread is a thing of legend!

Re the dog fight in the PSA forum, I'm guessing it stemmed from the experience Ron had when PSA skimped on the second cap screw on their 9mm AR BCG's and used a pin instead. That cost saving measure poked it's head out in the form of gas keys breaking off in short succession (obviously after many rounds down range but not as many as a colt :D). Here's a quote from Ron, around Page 10 of the thread.

"The PSA 9mm bolts are a bit different from the Colt models and I don't know if it was to cut costs, increase production or what the reason is but they shortened the key on top and eliminated one of the cap screws. We have Colt bolt carriers with 200,000+ rounds that continue to run but the PSA bolts (four out of five) have suffered from a lost key. The one cap screw shears (also held in by a roll pin) and the weapon can no longer be charged back because the charging handle has nothing to grab. Again, I don't know why the didn't use the Colt design of two cap screws (just like a standard 5.56 gas key uses) instead of one but we have yet to lose a key on a Colt bolt carrier. Since the key is only used for charging the weapon, the armorers decided to just weld the key in place and that has fixed the problem so far."

Great thread. Thanks Ron.

@Hendersondefense

Any update on the Enhanced LMT bolts?  Did you pick up spare extractors / springs with them?

Thanks!

Also wondering about the LMT bolts and possible longer life

If he comes back and says that they don't last any longer than a normal bolt I'm going to be pissed haha.  These things are pricey.  I definitely would like to see him run an SR15 as well bc I am really interested in comparing the reliability and longevity of the standard Colt milspec bolt vs LMT enhanced vs E3 (and I sure as hell don't have the money to do it )

I apologize gentleman, we still haven't purchased the bolts. We haven't needed any due to our amount in inventory but I know they are starting to run low.

V/R
Ron

@HendersonDefense don't forget to order extra enhanced extracors and extractor springs with the bolts as those are proprietary parts, and are the only part of the bolt that should wear and need replacing.

Add LMT and DD bolts are definitely GTG?

@Hendersondefense

How many cycles do you find the tan follower brownells USGI mags to last vs. the M3 Pmags?  How many cycles do you figure one magazine goes through in one day at your range?  One week?  Thanks!

The LMT's?

I wonder if they used just the bolt, or if they used a whole BCG? I've heard several tales of people having problems putting the LMT bolt in a standard BCG, and issues with short stroking in midlengths.

The LMT bolt is meant for use in their enhanced BCG, which has a longer track for the cam pin. It also vents gas out of the ejection port; it's designed around the M4A1 carbine, a 14.5" carbine-gas barrel and H2 buffer, running M855 or other full-power 5.56 rounds. It really comes into its own when a suppressor is added.

Only reason the military never adopted them is because they won't function in an M16.

Pretty sure it's the carrier you're thinking there and not the bolt. The carrier has the extra vent hole in it to help with excess gas, which has nothing to do with the enhanced bolt.

I put the LMT Enhanced bolt with a standard carrier in a 14.5 midlength and it ran like a top, no issues what so ever. This was with all range of ammunition too, including some weaker .223 loads.

Yea I’ve run several in standard carriers and they have always been perfect.  He’s def thinking about the carrier (which has always worked perfectly for me as well)

Not to nit pick, but the green highlighted portion above is precisely what the holes in the scallop on the side of a standard bolt carrier do - vent gas out the ejection port.  LMT may vent more because of the extra hole, but it’s not something they invented.

Edited to fix typo.  My fingers sometimes go sort of phonetic when I'm typing.

Because nobody would read it then lol

Much earlier in this thread, @HendersonDefense stated that he had observed fewer failures out of the 20" ARs, though it was qualified by the caveat that they put fewer rounds through those guns.

If there is something to it, I'm wondering if it's due to the length of the gas system or the stock / recoil system.  In other words, would we expect a 20" AR with a carbine buffer and tube be as prone to failure as 16" carbines, or would they be more like the 20" rifles with fixed stocks?

Asking because I'm thinking that a Magpul Fixed Carbine stock (which still mounts on a carbine buffer) or a Magpul SL might be a damned good combination with a pencil profile 20" rifle barrel.

It is a well known fact in the industry that the 20" AR (the original platform) is the most reliable of the variants.  That's how the gun was designed, and yes it has to do with the gas system and to a lesser extent the rifle buffer / spring.  Army testing has also confirmed this fact.

We use M16A1-style rifles (non-Colt lowers) every day of the week now because of the various packages and to my knowledge, we have zero issues with those. When I stop in there today, I will get information on the performance of the M16A1 and M16A4 configurations that customers shoot all the time.

V/R
Ron

While they didn't invent the vent hole, they changed the position on the enhanced bolt carrier. Run suppressed and you note the difference post haste. Rather than at the side direct, they moved higher towards the top.

You're absolutely correct.  The post I responded to sounded like venting the excess gas out the ejection port was new, which is not true.

The evidence shows their enhanced venting DOES make a (often HUGE) difference, especially when you are running full auto and/or suppressed - especially suppressed because of the increased pressure.  Managing the pressure dump from inside the carrier reduces wear and internal stress, and should make the gun run a lot cleaner, too.

Recent Reliabolts or that early batch with the bad heat treat?

In addition to the modified cam pin track that increases time it takes to unlock the bolt, allowing for pressures to drop thus reducing the stress on the lugs.

lol I have a Trijicon TA31 and Geissele SSA-E on my Palmetto A4 build.  Sounds crazy but I wouldn’t have it any other way, though.  It’s CHF premium but I’m starting to become a believer in their Freedom line of products as well.

Checking back for LMT or any other updates

@Hendersondefense

Sounds good Ron!  What info did you find out?

Thanks!

We haven't lost any bolts in our 20" guns and that includes one that just went down for "keyholing". I believe I purchased the barrel from Del-Ton about five years ago and it more than served it's purpose.

V/R
Ron

Hotdamn brother the 20 inch guns just keep on running. Eugene Stoner was a genius! Great thread!

Bumping/tagging.

Also, with regards to "super bolts" like the LMT, the JP, and the Sharps--In addition to the problematic Relia-bolt, Sharps has a DLC-coated XPB, for "Xtreme Performance Bolt". I'm curious as to how these premium bolts hold up as well, I'm debating whether it's worth getting one in my current rifle.

Just finished reading this thread.  WOW!

It's pure gold.

I've been reading ARFCom for years as a guest, but I registered just to say thank you for these comments. My fiancée is a psychologist for the VA. She deals with those guys too and I hear her words echoing in your statements. Our Father's served and she saw what the VA did and didn't do for them & she wants to change that. I sincerely appreciate what you and she does for our vets.

THANK YOU.

(Sucks I had to cull the comments so short to fit 2000 character limit for new accounts, but I do understand why.)

This

Ron you are a good man and changed that NCOs life.

Well done