.358 DPMS-pattern AR; It's ALIVE!

[1stmarine]

Here is a 250gr "brush" load in the dangerous game momentum department.



Although for tough to kill animals I would probably resort to a partition or swift bullet, something hot and heavy.
And also keep in mind giving the extra freebore for the AI magazines and extra COAL is very easy.
IMO ideal freebore for the heavies is .120" w/o no apparent detriment to accuracy with any other load and this
is normal due to the large bearing surfaces and smooth leade angle.




Projected HITS at 100 yards.

 

[1stmarine]

Cool!

The minor diameter of 5/8-24 is .580"-.587". That's plenty of meat with a .358 bore, even if you were using a hot number like the .358 STA. Heck, I've seen more than one .300 mag threaded 1/2-28.

Simple math right?
These are not 22LR nor pistol rounds. Eventually the crown will swell and accuracy will suffer.
The other day I saw a 6.8 barrel with 1/2" threads.Big mistake too.
In my opinion the 1/2" threads should be avoided even for the 223.

 

[1stmarine]

He would concur with your assessment

Nice buck. Love that rifle. never understood why they didn't become more popular int he USA along with the 358W. The perfect marriage IMO.
Fashions, marketing, under-powered factory loads, not much clear information about ballistics, etc...I guess???

 

[Berger.Fan222]

Sorry, but no! You're comparing very mild 30-06 loads to some pretty extreme 358 loads that may or may not be possible to achieve. But assuming 2550 fps from a 358/225 is possible lets compare it to other cartridges. A 180 gr Accubond in 30-06 can be loaded to nearer 2900 fps, not 2700 fps.

Maybe in your rifle, but I've never gotten anywhere near that with safe pressures in the 30-06's I've loaded for. Could barely get to 2880 fps with a 165 grain bullet with a 30" barrel. In my sporter with a 22" barrel, I could barely get to 2700 fps with a variety of 180 grain bullets.

All rifles are different, but in my 20 years of reloading experience, I've found the reloading manuals and QuickLOAD to be fairly reliable predictors of the velocity potential of a cartridge at safe (SAAMI spec) pressures. QL Suggests 2750 fps is the max possible (peak SAAMI pressure) with the 180 Accubond and H4350 with the 30-06 and a 24" barrel. The Hodgon Guide shows most powders (at max SAAMI pressure) max out at 2650 to 2800 fps. The Nosler manual shows max loads from 2723 to 2812 fps, depending on the powder.

Consequently, suggesting that most reloaders can safely push the 180 grain accubond to 2900 fps in their rifles is inaccurate and irresponsible. 2700 fps is not "very mild" with the 180 accubond in a 30-06. With many rifles and powders, it will be near, at, or above the max load. Starting (mild) loads are 2400-2600 fps, depending on the powder.

 

[Elkins45]

Eventually the crown will swell and accuracy will suffer.

I have never seen this happen.

 

[GooseGestapo]

I own, load, for both .358 and .30/06. I think velocities for BOTH are somewhat overly optimistic.
From my 20"bbl BLR, I've been able to reach 2,500fps with accuracy and function of the action without "stickiness" with 200gr bullets. 2,400 reasonable with 225gr ( FROM 20"bbl.)
Likewise, I've seen 2,800 possible from 24" bbl .30-06 with a 180gr. I've gotten 2,900 closing in on 3,000 with 165gr and 3,100 with 150gr, but these will be too much for any but a "camming" type bolt action. (I.e. A M98 Mauser or Remington M700). I've found that a Savage M110 type action or something like the BLR will balk with these higher pressures.

The .358win IS under appreciated as are all the .35's.
But let's remain "SANE" with velocity expectations. I believe Buffalo Bores velocities are a bit overly optimistic, except from a 24" or longer barrel.
And if I'm goi to carry a rifle that big or heavy, It'll be my Ruger M77 Hawkeye African in .375Ruger. It DOES get 2,800fps with a 270gr bullet.

 

[Driftertank]

But, all arguments about ballistics aside, my original point is that, reports from the field suggest that the .35s have always lived in an odd little corner of the firearms world where the numbers can't explain how they just work so well on game. They don't make incredible velocity numbers, or have amazing SD or BC"s. They have always been dismissed as having too much recoil, too little speed, energy, weight. The .45-70 was always famous for throwing a big chunk of lead that would go through anything, the magnums have always wowed with massive energy and big shock on impact. The .35s however, always trundled along, beloved by a small group of woods hunters who realized that inside of 300 yards, they just do the job with a minimum of fuss, expanding reliably, penetrating deeply and rarely destroying much meat beyond the impact area.

The other thing i like about the .358 in particular is the efficiency. Like i said, i dont have chrony data yet, but I've done a lot of research that seems to indicate that, all else being equal, the .358 gives up very little velocity as barrel length drops. The case capacity to bore ratio means flame propagation and pressure curve is rapid, and the relatively high surface area of obturation compared to the bearing area all adds up to where most of the recorded velocities for rounds fired from 20" barrels, compared to 16.5" barrels, velocity loss seems to be less than 100fps, often closer to 50fps....making this a very good choice for a carbine.

So, hopefully next weekend I'll be back with some groups and chrony results, and we'll find out if my aspirations bear out.

 

[Nature Boy]

Anytime the subject is the .358 win there's bound to be a spirited discussion on its merits. It never fails

Generally in these 3 camps:

1. It's the greatest thing since Thor's Hammer
2. It's just a tarted up .30-30 brush gun cartridge
3. "...three-fifty-what????...."

 

[MachIVshooter]

I think velocities for BOTH are somewhat overly optimistic.

The .358win IS under appreciated as are all the .35's.
But let's remain "SANE" with velocity expectations. I believe Buffalo Bores velocities are a bit overly optimistic, except from a 24" or longer barrel.

I agree. 2,550+ FPS with a 225 gr in a 20" or 22" barrel is into .350 Rem Mag territory, which has 28% more case capacity than the .358 Win. I'm loading 225 gr. Accubonds ahead of 58 grs. IMR4895 to hit 2,600 FPS in a 22" Remington 673.

I also agree that .35s are underappreciated, but I don't see it changing. We have our go-to calibers in this country, and where big game hunting is concerned, the .264", .323" and .358" caliber rounds just don't get the love the deserve, overshadowed by .257", .277", .284", .308", .338" and .375".

 

[1stmarine]

Hi guys,
I am not giving these comparisons with the intention to diminish any other cartridges or to start arguments that can get quite boring, but to provide a more meaningful reference
perhaps some people can relate to.

The 30-06 is a very nice round that can be pumped like everything else and the buffalo bore rounds I attached as reference are no exception.

Quick-Load is an excellent software to get started but understandably cannot be 100% precise and account for everything.

The Buffalo Bore, Double Tap and others including my chrono are well tested and reliable so there is nothing over optimistic about anything here. They are simply hot hunting rounds
loaded to full power that the 358 takes happily to 62K psi with modern brass, powders and primers. I posted those on purpose not just because they are "superformance" style
but because they are tested in popular firearms like the 22" Ruger I posted. Actually I get a tad more speed from the krieger 5R barrel than the ruger 77 tested by buffalo bore.
the 200 and 225gr bullets shoot pretty flat comparable to countless other calibers larger and small and will put a lot of momentum on the target.

The 250gr like double tap is a true brush load where 338,30 and smaller calibers will struggle with the brush, and in terms of momentum on the target, it leaves some popular big bore brush
hunters behind not only in trajectory/speed but also momentum. The ballistics of the 35 and 375 calibers are pretty decent with considerable grain options and they can be moved
by smaller cases and small magnums. I like the 358 because its cost vs. performance (Value) and compatibility options with the 357 and 9mm. I just got 3K 200gr speer TMJ for
$12cents each. Awesome value for many 35 caliber rounds and those cheap bullets will pulverize a deer or a hog although they might not be the first choice for that.

The heavy recoil claim is not that realistic really. This doesn't recoil a lot more than a 30-06 with a 180gr bullet and a lot less than the typical 180gr winmag yet killing potential at
the average/moderate hunting distances is similar than the 300 win mag. The 35 caliber premium heavy bullets (frontal section) has a lot to do with it.
Also if you study the 35 whelen's killing power you will see one could tackle anything. Another amazingly simple and economic powerhouse combined with the 35 caliber bullets.

Perhaps these cartriges are overlooked because they are seen as utilitarians and yes they are utilitarians but make no mistake about the huge power factor they can provide.

Energy says something about a caliber but doesn't mean much at the muzzle nor tells the story about the killing power at any other distance. Once we get into certain larger calibers
more sectional density is not needed and it takes a back sit yet grain and big holes take charge to get the job done quickly. IMO ethical hunters like that.

Here an article about the BLR + 358 marriage although no mention of the premium hunting loads ...

http://www.chuckhawks.com/browning_BLR_358.htm

 

[SHOOT1SAM]

Driftertank,

You're my new hero!! I'm really not an AR guy, but always thought if I went that way, an AR-10 in .358 Win. was the way I would do it; unfortunately, eye issues have me shooting less-recoiling calibers these days (my all-time favoritest, bestest rifle, EVER, was my .358 Norma Magnum-broke my heart to finally sell it, but it needed a good home). I'm very happy for you that your project has paid off in such a satisfying way!

Sam

 

[Driftertank]

Driftertank,

You're my new hero!! I'm really not an AR guy, but always thought if I went that way, an AR-10 in .358 Win. was the way I would do it; unfortunately, eye issues have me shooting less-recoiling calibers these days (my all-time favoritest, bestest rifle, EVER, was my .358 Norma Magnum-broke my heart to finally sell it, but it needed a good home). I'm very happy for you that your project has paid off in such a satisfying way!

Sam

Well, keep an eye out, because i plan to keep sharing as my development of loads and experiences progresses.

I've seen a few clips of .358 ARs, and in my research for the build i came across a lot of "company X makes a barrel for them. I think it would be cool to build one" on forums, but never saw where anyone said, "I made one. I used these parts. I get this velocity with this load and it groups like this." I didnt even know if it would be reliable right out of the gate, or if i would have to modify magazines, or extractor springs to get proper feeding or extraction, because i couldn't find anyone's experience building or shooting one. I intend to remedy that, put the information out there so there's at least ONE known good combo, and maybe inspire other people to try it out.

However I should take a moment to point out the biggest shortcomings, in my opinion, of the caliber: it's not a round for plinking, or use as a range toy. Factory ammo is scarce and kinda spendy. Handloaders will find it simple to feed, but in spite of the parts I've used giving the impression of being "tactical", it's really best suited as a hunting caliber. Unless you're the type of shooter who just likes having something different and unusual, it's not a great choice for purely recreational shooting.

 

[Nature Boy]

The heavy recoil claim is not that realistic really. This doesn't recoil a lot more than a 30-06 with a 180gr bullet

It may not be on paper, but my experience with the .358 in the small, light carbine BLR is that you don't want to sit at the bench and pound through 100 rounds in one sitting. In hunting situations it's not a problem because you never feel it.

When adjectives for my .358 come to mind, "pleasant to shoot" isn't high on the list, but that's not what it's meant for. There are times when all you need is a tack driver, other times you need a ball peen hammer.

 

[Gtscotty]

It may not be on paper, but my experience with the .358 in the small, light carbine BLR is that you don't want to sit at the bench and pound through 100 rounds in one sitting. In hunting situations it's not a problem because you never feel it.

When adjectives for my .358 come to mind, "pleasant to shoot" isn't high on the list, but that's not what it's meant for. There are times when all you need is a tack driver, other times you need a ball peen hammer.

I had a 35 Whelen and a 9.3x62, and I'd agree on the recoil. Both were substantially less fun to shoot than full power loads in my .30-06, which is exactly what you would expect for a 250gr bullet at 2,500 fps, and a 286gr bullet at 2,400 fps given that recoil is a function of the conservation of momentum. In the end since I was only hunting deer and hogs, they didn't offer any real advantages over my other rifles, and came with a substantial increase in recoil, so they moved along to other owners. I'm all for people shooting what they like though, and a .358 will kill Bambi just as dead as a .308.

 

[Arizona_Mike]

I've always had a spot in my heart for mid bores. However, keep in mind that these "super" "light magnum" etc. kind of loads are heavy charges of slower burning powder that give the same peak pressure but a longer "push". Gas port pressures are an issue and they probably will loose more in short barrels than conventional loads.

I'm a big fan of the 375 SOCOM on paper but there are no good bullet choices right now. 375 H&H bullets act like solids and .375 Win bullets act like grenades. The latter's jackets are also too soft for the rough semi-auto ride. A barrel that might give 1/2 MOA single loading gets 2 MOA semi-auto but to the bullets getting beat up.

Mike

 

[1stmarine]

It may not be on paper, but my experience with the .358 in the small, light carbine BLR is that you don't want to sit at the bench and pound through 100 rounds in one sitting. In hunting situations it's not a problem because you never feel it.

When adjectives for my .358 come to mind, "pleasant to shoot" isn't high on the list, but that's not what it's meant for. There are times when all you need is a tack driver, other times you need a ball peen hammer.

Very True.
None of the full power loads are meant for long shooting sessions and will beat you up like an old rug.
But recoil is also a relative thing depending on the rifle, shooter, etc... and one thing the 358 can be loaded with 147-180gr 357 affordable pistol bullets and milder loads
and also be an excellent round for silhouette shooting, hunting deer/hogs, even plinking on the cheap without all the commotion and recoil of large game loads.
One could gear up around one single bore and supplies that will work with a decent amount of very popular casings. A smaller expander/mandrel is all is needed for 9mm bullets.

Think about it...

380
9mm luger
38 super
357 sig
38spc/357 magnum
357 maximum
35 rem
358 winchester
35 whelen
358 RUM (ouch!)
etc...

 

[1stmarine]

Cool!

The minor diameter of 5/8-24 is .580"-.587". That's plenty of meat with a .358 bore, even if you were using a hot number like the .358 STA. Heck, I've seen more than one .300 mag threaded 1/2-28.

Hi,
the minor diameter is less than that but what is really relevant is not the minor diameter but the wall
thickness after you subtract the bore size. This leaves us with 97 thousands that is not much.
The barrel will work but hardly the best choice for the caliber.
Anything below .100 or even .110 is not that great, specially for high pressure cartriges. This is why
I suggest to stay away from 1/2x28 threads in 223 too.
Here is a chart of popular threads. I also added one I have been using for the 35 gunner that is 3/4x16 but
otherwise one could use the one used in the 338 lapua and other 33 calibers that is 3/4x20 tpi.
Blue line indicates typical threads for those calibers and others in the same bore.
The wall thickness in red means not the ideal. Green is ok.

 

[Gtscotty]

Hi,
the minor diameter is less than that but what is really relevant is not the minor diameter but the wall
thickness after you subtract the bore size. This leaves us with 97 thousands that is not much.
The barrel will work but hardly the best choice for the caliber.
Anything below .100 or even .110 is not that great, specially for high pressure cartriges. This is why
I suggest to stay away from 1/2x28 threads in 223 too.
Here is a chart of popular threads. I also added one I have been using for the 35 gunner that is 3/4x16 but
otherwise one could use the one used in the 338 lapua and other 33 calibers that is 3/4x20 tpi.
Blue line indicates typical threads for those calibers and others in the same bore.
The wall thickness in red means not the ideal. Green is ok.

What are you basing this generalized minimum thickness on? Are you calculating hoop stresses at the minor diameter? Wouldn't you need to know pressure (load and barrel length specific), along with material type and heat treat to make any kind of useful assessment on whether there is enough thickness at the end of the barrel? What are you using for stress concentration assumptions for the angles at the lands a threads. What does "not great" mean, obviously there are millions of 1/2"x28 threaded barrels out there, what problems do you suppose the 0.107" wall thickness is causing them... Obviously you are not calculating based on failure criteria, what are you calculating (some ammount of strain?) to determine acceptable muzzle wall thickness?

 

[1stmarine]

What are you basing this generalized minimum thickness on? Are you calculating hoop stresses at the minor diameter? Wouldn't you need to know pressure (load and barrel length specific), along with material type and heat treat to make any kind of useful assessment on whether there is enough thickness at the end of the barrel? What are you using for stress concentration assumptions for the angles at the lands a threads. What does "not great" mean, obviously there are millions of 1/2"x28 threaded barrels out there, what problems do you suppose the 0.107" wall thickness is causing them... Obviously you are not calculating based on failure criteria, what are you calculating (some ammount of strain?) to determine acceptable muzzle wall thickness?

I don't think there is one single formula that can determine this, it is a lot easier than that. It is based on measured average crown swelling over time.
Of course the round itself, length of the barrel, material, heat, like other variables have an impact but it can get really bad up to .002 over the bore diameter in the worse cases.
Measurable accuracy degradation happens faster in terms of top accuracy life and not proportional to throat erosion. In fact it can happen with minimum throat erosion.
While this is not critical for millions of shooters, it is for some, and why some vendors offer the 5/8 threads with the 223. Harrison for ARP published research on this subject.
The same reason the standard for the 338 lapua is M18x1 or 3/4x20 and not 5/8x24 that would be roughly the same wall thickness as a 223 with the standard 1/2" threads.
Some who threaded the lapua with 5/8x24 are finding out the hard way as in most cases long top accuracy life is expected from these rifles. I think 4000 shots as prescribed by AI.
In most cases, if one wants to get more accuracy life it is easily to fix by cutting, re-crowning and threading to the proper side.

 

[wally]

I will make a custom 'shorty' brake as well and also an adapter for standard 5/8x24 threads so one could use regular brakes and suppressors

Your build, your gun, but I'd rethink the 5/8-24 threads since its "standard" for .30 caliber suppressors and muzzle devices. I'd suggest 9/16-24 or .578-28 which are common for .40 and .45 suppressors so you don't put a .30 attachment on your .358 muzzle by mistake and ruin your day.

 

[1stmarine]

Your build, your gun, but I'd rethink the 5/8-24 threads since its "standard" for .30 caliber suppressors and muzzle devices. I'd suggest 9/16-24 or .578-28 which are common for .40 and .45 suppressors so you don't put a .30 attachment on your .358 muzzle by mistake and ruin your day.

There are many of wide devices out there with 1/2" as well as the M13-M16 and 5/8 threads, mainly for 9mm, 40 cal etc... pistols because of the lower pressure.
Anyway I ended up making a custom brake. Socom or lapua tipical threads will work great too. plenty of device there although some 338 might need opening up.
But I understand, one could never say one will not make that mistake.
Perhaps is a good idea to stamp all similar devices or make something for the them to stand out from each other the same way we do with with AR mags or clamp
locktite the thread adapter to the device so will not thread in other firearms.
In my case I barely swap things, specially critical components like bolts and things like that.

 

[Gtscotty]

I don't think there is one single formula that can determine this, it is a lot easier than that. It is based on measured average crown swelling over time.
Of course the round itself, length of the barrel, material, heat, like other variables have an impact but it can get really bad up to .002 over the bore diameter in the worse cases.
Measurable accuracy degradation happens faster in terms of top accuracy life and not proportional to throat erosion. In fact it can happen with minimum throat erosion.
While this is not critical for millions of shooters, it is for some, and why some vendors offer the 5/8 threads with the 223. Harrison for ARP published research on this subject.
The same reason the standard for the 338 lapua is M18x1 or 3/4x20 and not 5/8x24 that would be roughly the same wall thickness as a 223 with the standard 1/2" threads.
Some who threaded the lapua with 5/8x24 are finding out the hard way as in most cases long top accuracy life is expected from these rifles. I think 4000 shots as prescribed by AI.
In most cases, if one wants to get more accuracy life it is easily to fix by cutting, re-crowning and threading to the proper side.

Of course it's not a single formula, it's a series of non-trivial formulas for a pressure impulse in a thick walled pressure vessel complicated by the internal rifling and external threading. Per your description, I guess the assumption would be that either the hoop stress at the end of the barrel, or the axial stress at the end of the barrel would be exceeding the yield stress of the barrel steel causing small permanent deformation with each shot that eventually builds up to .002". You'd have to make a series of assumptions to even start the calculations, and then the results would be determined by: inside radius, outside radius (not just thickness), yield strength of the specific steel and heat treat being used (different heat treats of 4150 and 416 can have radically different yield stresses, not to mention 4140, 410, etc.) and the residual pressure at the end of the barrel (affected by chambering, load and barrel length). This kind of calculation would really best be done using FEA.

The point of my post was that you would have to know all of these specific variables to calculate whether a specific threading was ok on a specific barrel bore using a certain steel with a certain cartridge (the residual pressure at the end of a 22" .338 Lapua is likely to be quite different than at the end of a 22" .338 Federal, or .50 Beowulf). To state as a given fact that 0.110" is the correct minimum barrel thread thickness for any length barrel, in any "high pressure" chambering, in any kind of steel is, as far as I know, impossible. Even to take some experimental observations from a few calibers and extrapolate them to every caliber between .223 and .50 is .... well you know what they say about extrapolating in engineering school... don't do it. Of course, if you've tested a statistically valid number of barrels from each of the calibers and configurations listed above to the failure criteria, then you could probably make the statements you have about at least the type of steel you tested with some level of confidence .

I know that ARP offers 5/8"x24 threaded barrels, have thought about picking up one myself so that I can use an existing 5/8" trifecta device I have laying around (save $90). Do you have a link you could post to the research paper he published?

 

[MachIVshooter]

Your build, your gun, but I'd rethink the 5/8-24 threads since its "standard" for .30 caliber suppressors and muzzle devices. I'd suggest 9/16-24 or .578-28 which are common for .40 and .45 suppressors so you don't put a .30 attachment on your .358 muzzle by mistake and ruin your day.

IMO, if you're too lazy to check bore size through your can and peek down the bore to make sure you're not gonna get a baffle strike, you deserve to have your investment damaged.

 

[1stmarine]

Hi @Gtscotty,
I understand however all the cartriges I mentioned above can run at 62K psi with the exception of the grendel, scom and beo.
I didn't really extrapolate anything. The crown swelling have been measured in a huge amount of barrels.
The further one stays from .100-110 the better. So 5/8 is a great choice for 308-311 bores and below.
1/2" threads will be a great choice for 204 and 17 calibers or lower pressure 22's like a 22LR.
Should that stop everyone from buying a 223 barrel with 1/2" threads? probably not but there are better choices.
This is like the M4 style profile in commercial AR15 barrels. There is no one single good reason for having the slot cut for
M203 grenade launcher this way reducing the minor diameter of the barrel.
The same way there is no reason to profile down the barrel to .625 right ahead of the chamber when in some rapid fire cases
this causes irrecoverable stress in that area and in extreme situations might even cause the weakest single point of failure
even before the gas block or gas tube goes that is what we would expect. We have seen this condition in countless extreme tests.
We know many people are not going to go Rambo with their barrels but this explains why a different distribution of the dimensons
helps with heat, harmonics and the top accuracy life of the barrel.
Also it doesn't mean one should never buy a pencil barrel, there are uses and situations for this but IMO a barrel with a medium
profile socom-type is only 6-8 ounces more or so and it is inherently more accurate and durable by design like the larger threads.
IMO the carbine porting and 1/2" threads and M4 profile should have never existed and even if somehow one finds
reasoning to make those horrible decisions for the military instead of redesigning the grenade launcher bracket and what not,
then for sure, for any civilian use, there is no one good single reason as far as I know.
Some will say the price but if the demand was there in the first place it is actually easier/faster and potentially less expensive to
produce a better barrel w/o fancy cuts.
Anyway, I am probably diverting from the original objective of the thread so sorry about that.
I hope this helps someone somehow.

 

[Gtscotty]

Hi @Gtscotty,
I understand however all the cartriges I mentioned above can run at 62K psi with the exception of the grendel, scom and beo.
I didn't really extrapolate anything.

They can run 62k psi peak pressures when the bullet is just starting down the barrel, but they should have different pressures at the end of the barrel, where it matters for this discussion, depending on things like expansion ratio, barrel length and the powder burn rate. I mentioned the Beowulf because you posted it in your chart and applied the .110" thickness criteria to it. You mentioned that lots of crown swelling tests have been done (I'd like to read about them if you have a link), but unless they have been done on all the calibers in your chart, you'd be mostly extrapolating the results from the chamberings that have been tested (I'm guessing largely .308 and .223 in who knows what steel) to the rest right?

The further one stays from .100-110 the better. So 5/8 is a great choice for 308-311 bores and below. 1/2" threads will be a great choice for 204 and 17 calibers or lower pressure 22's like a 22LR. Should that stop everyone from buying a 223 barrel with 1/2" threads? probably not but there are better choices.

So what happens when you are at .095 vs .110? What kind of reduction in accurate barrel life should be expected? Has this ever been quantified in any way? Do you believe this would be uniform across all of the chamberings in your chart? If we really don't know whether the muzzle will expand in various kinds of steel (different strengths) and barrel lengths how can we say that larger is "better" in any meaningful way? If you don't know all the variables of a given barrel, I think we can agreed that you can't really calculate the actual impact of the barrel threading size, and at best the .110 thickness mentioned is a pretty rough guideline.

I guess we are a bit off topic, but I like to think we're leaving relevant and factual info on the site for any one who stumbles upon this thread in the future to consider.

As for the stuff on m-4 profile barrels, I'm not sure the significance to this thread/discussion, but I agree, I don't have any use for the grenade launcher cut.