Did that particular Geissele have the small port? If so, was it  silenced? Installing a silencer can make it run like a normal rifle. It won’t necessarily malf all the time in cold weather, it’s just more likely to happen than with a normal gas port.

Normal size ports don’t run at 950 rpm. Barrels will be killed by throat erosion long before gas port erosion becomes an issue.

Your oversized ports will run fast. What would your favorite gun run at with a can?

Whatever the gas port size is on the 11.5 Super Dooty. It ran suppressed or not.

You’re continuing to use the word “oversized” without understanding what it means. The standard gas ports are normal sized. The ones you’re advocating for are undersized. If the cyclic rate increases to 950 rpm, the silencer is sub-optimal for normal AR-15 rifles. There are plenty of low back pressure silencers on the market. If you want to build a rifle around a flawed silencer, that’s your prerogative, but don’t pretend that normal rifles are abnormal.

What source are you using to determine standard/normal port sizes across barrel length and gas system combinations?

They need to make a Putin blemula batch of barrels for wolf shooters

Gas ports so huge you can use it as a piss tube

Never understand why folks shoot wolf steel case through a $1500-2000 AR.

Here you are arguing for special cans instead of normal cans to allow you to use oversized gas ports instead of normal ones. For what it’s worth I acknowledge the existence of three ranges of gas ports. Small, regular and large. I like regular and small. You seem to like large.

“Large” is normal. The typical AR-15 rifle has always been able to run low pressure .223 ammunition, from the 60s to today. Any rifle that doesn’t run that stuff has an abnormally small gas port. IDK what qualifies as a “normal” silencer, but the Surefire SOCOM series seems to be one of the most widely used and it runs fine with full size gas ports.

The ability to run low pressure .223 ammo is probably the best litmus test. An early 20” model from the 60s can do it, as can a 1990s M4A1, as can most of today’s commercial rifles. Going to a smaller gas port is a deliberate deviation from the standard pattern.

My standard for cans is Surefire or KAC. And a 20” gun runs anything. By the time you get to 11.5 they should have a .070 or smaller port and that doesn’t like Wolf in all conditions, but larger is too damn large with a can in the heat.

I liked my .058” M4 barrel when I had one for instance.

Yes!  You are doing what KAC should have done.

Excellent excellent work. I will be happy to send mean email responses to people complaining "optimum" means it should run trash

Lets please promote full power 5.56 again. Even the ammo has been water down cause people want to run 5.56 in 223 guns. I want my full power IMI M193 back

Sounds like you need to label some ALG barrels for wolf versus G replacement barrels.

Finally got around to testing the The BRT EZTUNE gas tube with the larue barrel.  It works as claimed.

...

I have used those on a few barrels with good results

Have you considered testing one of their barrels?  I have had good results with CHF chrome lined barrel they offer

Wanted to give a belated update informing everyone that Geissele did eventually do me right and sent a full barrel replacement for my issues  The new barrel was from their Super Duty line and was not another commercial line. From what I could tell, the SD barrels have a better phosphate finish and seem slightly more rugged, and may even be slightly thinner on the taper of the barrel but not by much. They look almost identical except for the finish.

I even spoke with the company's VP personally about the matter. He was very nice and said they were going to get to the bottom of what happened.

As for the new barrel, it has functioned perfectly so far with all the 223 and 556 that had been fired through it, but that has been a pretty limited sample size as I have only had time to function test it. Won't ever be putting steel through this setup.

I am still almost certain the issue on the old barrel was the chambering moreso than the gas port, but I could be wrong. The VP said they test fire every barrel before they leave the factory, so 8 have no idea.

All I know is, the new barrel works. It has been installed on a phenomenal setup now. I will post a photos when I can.

I thought the G SD barrels had a proprietary gas length?

Only the 16" SD barrels.

Yeah, apparently the 16" SD barrels are supposed to mimic the same gas setup/impulse as a 14" mid-length.

The gas block shoulder on the SD is also slightly shorter to accommodate specifically the Super G gas block.

I will say this though, the Mk12 Crane-spec gas block is much tighter on the barrel than the Geissele gas block, that's why I tend to think the issue with the civilian G barrels was in the chamber rather than gas port. It also perhaps explains why even slightly underpowered non-mil 223 brass stuff tried to lock up the action upon firing. It's seemed way more than just a small gas port. It seemed like nothing, not even full powered mil 855, wanted to move the action of the weapon properly, but that's just my speculation.

https://www.firearmsnews.com/editorial/geissele-super-duty-rifle-review/452747

Sitting on my parts shelf . . .



....

Here's an accuracy update on the new Super Duty barrel setup (zero malfunctions so far BTW).


Best group seen so far is . 75MOA with 75g match loads.





Caveat is that the barrel has also gotten up to 2-2.5 MOA with the same ammo. That's probably just shooter inconsistency, though.

Biggest thing I did notice about the SD barrel, however, was that it almost likes mil-spec M193 and M855 as much as it does match-grade stuff.

Was able to get 1MOA with Lake City M193 and about 1.75 MOA w/IMI m855. Honestly never seen that before. Most Chf, chromed combat type barrels typically produce 3+ MOA with m855 that I've seen.

Also note that an H2 buffer should be used in this setup, just like the factory made super duty line. Carbine buffer was throwing mil-spec stuff at 1-2 o'clock. H buffer about 2-3 o'clock. Other than that the new setup has run very smoothly.

@Molon

Looking forward to it.  Appreciate all the work you do

Is that 3 shots?

I like to shoot a couple 5 shot groups and @Molon typically shoots 10 to get a better idea of accuracy.  Picking one 3 shot group will leave a lot of room for error.

With respect,
The smaller the number of rounds you shoot in a group, the less meaningful it is. 3 rd cherry-picked groups aren’t consistent from group to group, because its not a significant sample size. I would suggest at least 5, but 10 is much better. The numbers yielded will be larger and don’t sound as good on the internet, but they are more representative of the barrel/ammo, and more comparable.

This is why stating group size is meaningless without also revealing the total number of shots.

No, you weren't.

Return Of The M193 Clones




clone:  one that appears to be a copy of an original form


Part 1

Genuine US Military M193 can no longer be sold to civilians, thanks to the Clinton Administration.  The ammunition that is sold on the commercial market with some form of “M193” in its nomenclature is often referred to as an “M193 clone” because it “appears to be a copy” of genuine M193, but we generally have no idea what specifications of MIL-C-9963 that this ammunition has passed, or has even been tested for.

Genuine M193 must be tested for and pass all of the specifications laid out in the mil-spec, MIL-C-9963.  The required areas of testing included in MIL-C-9963 range from velocity, accuracy, chamber pressure and port pressure to waterproofing, temperature stability, bullet extraction, case hardness, fouling and much more.  

M193 is loaded with a 55 grain FMJ bullet with a cannelure.  The bullet itself, must meet required specifications in order to be used in genuine M193 ammunition.  For example, the specification for the thickness of the gilding metal jacket of the bullet is 0.021" with a tolerance of - 0.002".    For comparison, the jacket of Hornady’s 55 grain FMJ bullet has a thickness of approximately 0.028”.  

Jacket thickness can have a significant effect on terminal ballistic properties, particularly that of fragmentation.  Even the composition of the copper alloy used for the jacket and the lead used for the slug must meet mil-spec requirements for genuine M193.

Genuine M193 can only be charged with powder that has been specifically approved by the US Military for use in this cartridge.  If the ammunition in question is not loaded with one of the approved powders, it is not genuine M193 and naturally we have no way of determining what powder was used in a load simply by visual inspection.

Genuine M193 will have the annealing iris visible on the shoulder and neck portion of the case.  It will also will have crimped and sealed primers. Genuine M193 has a crimped case mouth along with sealant at the case mouth.

In 2010, I posted an in-depth evaluation of four different brands of M193 clones that were readily available at that time.
(Attack of the (M193) Clones)

For this article, I evaluated recent production lots of the same four brands of M193 clones (though not necessarily the same manufacturers.)


Winchester M193



This lot of Winchester M193 is loaded in Lake City brass with a 2021 headstamp.  The case-head stamp exhibits the octal station identifiers found on Lake City SCAMP machinery.  The brass cases have the annealing iris still visible.  The rounds are charged with ball powder.

The primer pockets are crimped, but do not have any sealant.  The case mouths are also crimped, but also have no sealant.








The lot number for this lot of Winchester M193 is pictured below.  The “WLC21” in the prefix of the lot number indicates that this lot of Winchester M193 was manufactured at Lake City in 2021 under Winchester “management.”









Federal XM193




This lot of Federal XM193 is loaded in Lake City brass with a 2021 headstamp.  The case-head stamp exhibits the octal station identifiers found on Lake City SCAMP machinery.  The brass cases have the annealing iris still visible.  The rounds are charged with ball powder.

As with the Winchester M193, the primer pockets of this lot of Federal XM193 are crimped, but do not have any sealant.  The case mouths of this lot of Federal XM193 are also crimped, but also have no sealant.






The lot number for this lot of Federal XM193 is pictured below.  The “WLC21” in the prefix of the lot number indicates that this lot of Federal  XM193 was manufactured at Lake City in 2021 under Winchester “management.”






IMI M193




This lot of IMI M193 is loaded in IMI brass with a 2021 headstamp.  The annealing iris is visible and the rounds are charged with ball powder.  The primer pockets are crimped and sealed and the case mouths are also crimped and sealed.








Prvi Partizan (PPU) M193





The PPU M193 brass has a 2020 headstamp and the annealing iris is visible.  The primer pockets are crimped and sealed, as are the case mouths and the ammunition is charged with ball powder.

















Part 2

Aside from aspects of M193 clones that can be assessed by visual inspection, the two main aspects of M193 clones that we can assess via live fire testing to determine if an M193 clone adheres to the US mil-spec are velocity and accuracy (technically precision).  The velocity specification for M193 as cited in MIL-C-9963F states:

"The average velocity of the sample cartridges, conditioned at 72 degrees, plus or minus 2 degrees Fahrenheit (F), shall be 3165 feet per second (ft/sec), plus or minus 40 ft/sec, at 78 feet from the muzzle of the weapon.  The standard deviation of the velocities shall not exceed 40 ft/sec."

The velocity specification is for a 20” test barrel.  Depending on multiple variables, this velocity specification equates to a muzzle velocity of approximately 3270 ft/sec, plus or minus 40 ft/sec.

As an aside, after reading the above specification, some of you may be wondering, “Why 78 feet from the muzzle?”  The answer to that question is that this specification is simply an historical hold-over from the days when “circuit” chronographs (e.g. Le Boulenge Chronograph and the Aberdeen Chronograph) were used at Aberdeen Proving Ground, Frankford Arsenal and Springfield Armory.  These types of chronographs required a significant distance between their first and second screens to produce accurate results.

As an example, when using the Boulenge Chronograph, the first screen of the chronograph was placed 3 feet in front of the muzzle and the second screen was placed 150 feet beyond the first screen.  For those of you who might not be aware of the following fact; chronographs determine the velocity of the bullet at a point that is midway between the first and the second screen (i.e. not at the location of the first screen).  Therefore, with the above spacing, the velocity of the bullet is determined for a point that is 75 feet from the first screen.  So, add the three feet (from the muzzle to the first screen) to the 75 feet (the midway point of the screens) to obtain the “78 feet from the muzzle” distance.





I chronographed the four M193 clones evaluated for this article from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt barrel with a 1:7” twist.

Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings.  If there is, the chronograph “flags” the shot to let you know that the data is invalid.  There was no invalid data flagged during this testing.

The velocities listed in the table below are muzzle velocities as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program. Each string of fire consisted of 10 rounds over the chronograph.









Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release.  Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.





Atmospheric conditions

Temperature:  72 degrees F
Humidity:  78%
Barometric pressure:  30.02 inches of Hg
Elevation:  950 feet above sea level


The muzzle velocities of the four M193 clones are listed in the table below, along with the standard deviations and coefficients of variation.





For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.  

The mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.






For comparison to the velocities of the M193 clones evaluated for this article, the next table shows the muzzle velocities of the four M193 clones that I evaluated in 2010 (also fired from a 20” Colt barrel.)








Part 3

The US accuracy specification for M193 cited in MIL-C-9963F is as follows:

“The average of the mean radii of all targets of the sample cartridges, fired at 200 yards, shall not exceed 2.0 inches.”

These averages are from 10-shot groups fired from machine rested, bolt-actioned, heavy test barrels. All things being equal this specification equates to a mean radius of 1 inch at 100 yards (the distance at which I tested this ammunition).

I conducted an accuracy (technically, precision) evaluation of the four M193 clones following my usual protocol.  This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any Group Reduction Techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was used. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.







The Wind Probe . . .





The test vehicle for this evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar Walther barrel.  The barrel has a 223 Wylde chamber with a 1:8” twist.















Prior to firing the M193 clones, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 52 grain MatchKing.  That group had an extreme spread of 0.64”.







Prvi Partizan (PPU) M193

Three 10-shot groups of the PPU M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

3.00”

2.28”

3.48”

for a 10-shot group average extreme spread of 2.92”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.80”.

The smallest 10-shot group . . .




The 30-shot composite group . . .





Winchester M193

Three 10-shot groups of the Winchester M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

2.21”

2.65”

2.09”

for a 10-shot group average extreme spread of 2.32”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.72”.


The smallest 10-shot group . . .




The 30-shot composite group . . .





Federal XM193


Three 10-shot groups of the Federal XM193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

2.36”

2.67”

1.77”

for a 10-shot group average extreme spread of 2.27”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.66”.


The smallest 10-shot group . . .




The 30-shot composite group . . .






IMI M193


Three 10-shot groups of the IMI M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

1.84”

2.86”

2.16”

for a 10-shot group average extreme spread of 2.29”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.64”.


The smallest 10-shot group . . .




The 30-shot composite group . . .





The table below summarizes the accuracy/precision results for this article.






For comparison, the next table summarizes the accuracy/precision results from the 2010 evaluation.








…..

Almost four months later and still no word on the size of their gas ports.  

..

But they sure updated prices the other day...

Oooof, That extra $50 $80 must be funding their QC department

Damn!  The original price of $270 was the main draw for these until all the QC issues started popping up.  At $350 you have better, vetted options like Centurion, DD, and BRT.  Hell even Hodge just adjusted their barrel prices to $390.

And the BRT CHF barrels are only $325.

....

I may have missed it but have you tested the BRT CHF barrels yet? I know it was on "the list".

I'm excited to see the results. There are some smaller companies out there (BRT, Sionics come to mind) that seem committed to no-nonsense, quality kit.

Any updates on gas port resizing?

Maybe "after the holidays".

Their M855 has also been watered-down.

IMI M855 2021




For those who might not beware of this, IMI has been “down-loading” their 5.56mm ammunition for the last few years.  The lot tested for this post is from 2021.

Legacy lots of IMI M855 have had muzzle velocities in the neighborhood of 3110 FPS when fired from a 20” Colt AR-15. This lot of M855 had a muzzle velocity of 3015 FPS with a standard deviation of 15 FPS, fired from a 20” Colt A4.

A 10-shot group of this ammunition fired from my Lothar Walther barreled AR-15 at a distance of 100 yards had an extreme spread of 1.95”.






....

.....

.062" gas ports would seem to be designed for full time suppressor use. It would also explain short stroking problem unsuppressed.

Anyone building a rifle at home should be capable of incrementally opening the gas port with hand tools and plenty of lube.

I never understood why anyone would run Wolf steel through any rifle.

Name one manufacturer that builds AR-15's with SAAMI .223 chambers, I'll wait.

So did Geissele cave on this and go the other direction? Their site now lists the gas port size of the 16" Mid Length barrel as .078 (.076 for the 14.5" barrel) which is too damn big IMO.

My Colt 6960 has a .071 which seems to be a sweet spot for a 16" mid gas barrel to run anything suppressed or not but I'm looking for a midlength barrel (leaning 14.5") with a really small gas port to use for a dedicated suppressor host with a TurboK suppressor (which is a super gassy can). I was thinking these Geissele's with a .062 port might be just the ticket but not if they have .076-.078 ports now. That just seems like it would be way over gassed even for shit steel cased ammo unsuppressed.

https://www.ar15.com/forums/AR-15/BRT-Optimum-Accuracy-Evaluation/118-778084/

.....

I think he’s referring to bolt guns of which there are quite a few .223 calibers and for their ignorance we get to pay the price.

I went through this with a Geissele mid-length 16". Mine was .062"and wouldn't run with even a carbine weight buffer. Wouldn't even try to unlock. I worked my way up one numbered drill at a time, test firing each time, and at .073" my Super Duty build started to cycle and lock on an empty mag without the can on. With the can on at .073" I am still throwing my brass to around 4 o'clock. So, for me, .073 was perfect. I rarely shoot without a can on, but I still demand that my rifles run without one, like they should.

I agree, .078 is a tad big, but I've used several FN mid-length 16" barrels over the years, and all of them are .078. With a heavier buffer they still shoot fairly soft and definitely aren't lacking gas.

Yup.  The 16" mid-length TRIARC Track 2.0 barrel that I evaluated has a 0.0695" gas port diameter and is the smoothest cycling 16" mid-length that I've ever fired.


...

I know, SGammo takes credit for that (no clue if actually true or not) but I hate it.

Most people spending ~$300 for a chrome-lined barrel, do so with the expectation that they shouldn't have to use drills/reamers on the gas port just to get the damn thing to cycle.

...

Looks that way . . .




....

It would make more sense to me to have a 0.078 on a 14.5" and 0.076 on a 16," I wonder if they QC their website?