Origin of the Midlength

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[ARCHIVED THREAD] - Origin of the Midlength

Posted: 2/16/2006 11:23:26 AM EDT

Hey AR historians, help me out with this one.

First there was the 20.

Then there was the 10" carbine with collapsible stock. There were functioning problems so it went to 11.5". Blast was horrendous and ballistics were awful so. . . .

A 14.5" was created. Why 14.5? This allowed mounting of a bayonet and much improved ballistics over an 11.5. But. . .

It's a short barreled rifle for us civvies. So. . . .

16" CAR. Unfortunately, while it had a bayo mount, you could not mount a bayonet because the flash hider was too far away. Plus, that long barrel just looks kinda funny poking all the way out there (personal opinion). So. . .

Cut back to 14.5 and permanently install a flash hider. Problem solved! Or. . . .

Stretch the handguard out and keep the forward barrel length the same as the 14.5 or 20 and

Voila!!! (my apologies for speaking French) a Midlength! First developed my Armalite (the new one) if I am correct.

What are the advantages of a Middy over a 14.5 or 20?

1) More forearm real estate for all of those unnecessary accessories.

2) A little less gas pressure than a carbine for more reliable functioning (somewhat debatable).

3) Easier to maneuver than a 20 while still retaining good ballistics.

4) No skinny barrel awkwardly poking out too far (personal opinion)

Any others? Please feel free to fill in any gaps I missed or correct any (gasp!) errors I may have made.

Posted: 2/17/2006 12:19:51 AM EDT

[#1]

How about that it just plain looks good.

you covered it pretty good.

Posted: 2/17/2006 1:57:21 AM EDT

[#2]

You can also mount a bayonet correctly on a Middy 16" barrel.

Posted: 2/17/2006 2:16:27 AM EDT

[#3]

Short for CQC and weight perhaps.

Posted: 2/17/2006 3:17:31 AM EDT

[#4]

Don't go mixing up the length of the gas system with the bbl length. 14.5" and 18" midlength bbls are not that uncommon nor 16" rifle bbls.

Do a search and read about what the differences are between the different length systems on different bbl length.

Posted: 2/17/2006 4:21:47 AM EDT

[#5]

Quoted:
Hey AR historians, help me out with this one.

First there was the 20.

Then there was the 10" carbine with collapsible stock. There were functioning problems so it went to 11.5". Blast was horrendous and ballistics were awful so. . . .

A 14.5" was created. Why 14.5? This allowed mounting of a bayonet and much improved ballistics over an 11.5. But. . .

It's a short barreled rifle for us civvies. So. . . .

16" CAR. Unfortunately, while it had a bayo mount, you could not mount a bayonet because the flash hider was too far away. Plus, that long barrel just looks kinda funny poking all the way out there (personal opinion). So. . .

Cut back to 14.5 and permanently install a flash hider. Problem solved! Or. . . .

Stretch the handguard out and keep the forward barrel length the same as the 14.5 or 20 and

Voila!!! (my apologies for speaking French) a Midlength! First developed my Armalite (the new one) if I am correct.

What are the advantages of a Middy over a 14.5 or 20?

1) More forearm real estate for all of those unnecessary accessories.

2) A little less gas pressure than a carbine for more reliable functioning (somewhat debatable).

3) Easier to maneuver than a 20 while still retaining good ballistics.

4) No skinny barrel awkwardly poking out too far (personal opinion)

Any others? Please feel free to fill in any gaps I missed or correct any (gasp!) errors I may have made.

Okay... let me see if I can fix this for you...

Quoted:
Hey AR historians, help me out with this one.

First there was the 20"

After this, it appears that I don't understand the time line, or the gas system v. barrel length or how they effect the function of the rifle enough to post editorials about any of this.

That looks better.

================================================

Here, fixed this one up too....

Quoted:
You can't mount a bayonet correctly on a Middy 16" barrel.

Posted: 2/17/2006 4:38:05 AM EDT

[#6]

Thanks gunzilla. Always helpul to have positive feedback. Hmmm.
I would like to hear your thoughts about this topic if you can keep your insults to yourself. If not, don't need you.

Posted: 2/17/2006 4:52:27 AM EDT

[#7]

Quoted:

================================================

Here, fixed this one up too....

Quoted:
You can't mount a bayonet correctly on a Middy 16" barrel.

I guess you have a broken Middy

, it works on mine smart guy.

Posted: 2/17/2006 5:06:16 AM EDT

[#8]

Quoted:
Quoted:

================================================

Here, fixed this one up too....

Quoted:
You can't mount a bayonet correctly on a Middy 16" barrel.

I guess you have a broken Middy , it works on mine smart guy.

Actually, yours does not mount *correctly* (or you have a broke middy) as your barrel is a half inch too short for the bayo to line up as intended on the flash hider, which is why I underlined correctly in the first post -- it works, but not correctly, forgive me for being one of the pesky people that sticks to facts.

Posted: 2/17/2006 5:25:11 AM EDT

[#9]

Hey Gunzilla: Contribution instead of Criticism! Keep up the good work!

Posted: 2/17/2006 5:48:07 AM EDT

[#10]

The earliest "middy" I know of is the Colt in Reed Knight's collection photographed by SMGLee:

The earliest production "middy" I can think of is the SR-25K, which dates from 1994, if I remember correctly.

Posted: 2/17/2006 6:00:42 AM EDT

[#11]

Quoted:
Hey Gunzilla: Contribution instead of Criticism! Keep up the good work!

Well... I am certainly glad that I can start the day with your approval, that means a lot to me.

Let me get this straight, in your whopping two weeks here, you have the whole thing pegged huh?

You know that I am not at all a contributor to the forum

You have a grasp on the history and principle of operation for the AR platform that is second to none.

And now, you are grading other peoples post... thank for the little smiley face.

I was just chatting with one of the mods a day or two ago about how much this forum has changed over the past few years and "self appointed" and "self annointed" experts are one of the biggest problems -- but I'll tell you what sport, you got it... thanks for taking the lead around here and setting us straight: I shall refer all techical questions in post to you from now on.

out

Posted: 2/17/2006 6:01:34 AM EDT

[#12]

I have no idea the real reason behind it, I think it could have been one of those feel good fixes that was not realy needed to fix a problem that wasnt that big of a problem at all, or maybe it was to help improve velocity by giving the powder more time to burn behind the bullet, I am not sure, I think it looks cool and I would like to get one someday but to tell you the truth I have no need for one at this time, my 14.5 does the trick just fine for me.

Posted: 2/17/2006 6:23:52 AM EDT

[#13]

Quoted:
Quoted:
Hey Gunzilla: Contribution instead of Criticism! Keep up the good work!

Well... I am certainly glad that I can start the day with your approval, that means a lot to me.
Let me get this straight, in your whopping two weeks here, you have the whole thing pegged huh?
You know that I am not at all a contributor to the forum
You have a grasp on the history and principle of operation for the AR platform that is second to none.
And now, you are grading other peoples post... thank for the little smiley face.
I was just chatting with one of the mods a day or two ago about how much this forum has changed over the past few years and "self appointed" and "self annointed" experts are one of the biggest problems -- but I'll tell you what sport, you got it... thanks for taking the lead around here and setting us straight: I shall refer all techical questions in post to you from now on.
out

Gunzilla VS Fogofwar

Posted: 2/17/2006 6:26:56 AM EDT

[#14]

Quoted:
Quoted:
Hey Gunzilla: Contribution instead of Criticism! Keep up the good work! hr

Well... I am certainly glad that I can start the day with your approval, that means a lot to me.

Let me get this straight, in your whopping two weeks here, you have the whole thing pegged huh?

You know that I am not at all a contributor to the forum

You have a grasp on the history and principle of operation for the AR platform that is second to none.

And now, you are grading other peoples post... thank for the little smiley face.

I was just chatting with one of the mods a day or two ago about how much this forum has changed over the past few years and "self appointed" and "self annointed" experts are one of the biggest problems -- but I'll tell you what sport, you got it... thanks for taking the lead around here and setting us straight: I shall refer all techical questions in post to you from now on.

out

I have made no such assertions. That is your interpretation. Where in any of my posts on this topic have I made that assertion that I am an expert? I laid out a topic and asked for comments and corrections, not insults. Guess I should have been a little clearer on that.

About me: 43 year old average middle class white boy. Army vet. Former Class III dealer. Dabbled in High Power rifle. Been around AR's and M-16's since 1980. Got out of it for a few years and now I am back. I am a hobbyist and that's it.

I believe in constructive criticism and contribution to any forum I am on. I don't insult, even when insulted. But I will respond when insulted. I'm one noob you can't squish.

Lets let bygones be bygones and move on. I promise this will be my last response to anything you "contribute."

Posted: 2/17/2006 7:49:24 AM EDT

[#15]

I just snagged this from another post... it helps to set up the fundemental understanding of the system as it applies to the carbine length gas system v. riffle system.

In order to understand this, there are a few things about the functioning of the AR that have to be defined, I am away from most of my notes and stuff, so most of the figures given are from memory... but should be pretty close. For this description, the standard rifle gas system is with the gas port located at 13.0" and having a 20" barrel... the standard carbine system is with the port at 7.5" and a barrel of 14.5"

The pressures at the gas ports are: 13.5K for the rifle and 26K for the carbine -- or twice as much.

The dwell time (the time that the gas system is charged with high pressure) is determined by the amount of barrel after the gas port. These are nearly identical between the rifle and the carbine.

Pressure from the port is regulated only by the size of the gas port and the diameter of the barrel.

These two factors determine the internal bolt pressure, the maximum pressure that is obtained in the bolt carrier/piston combination -- for the rifle this pressure is about 1000psi and for the carbine it is over 1500psi, half again as much.

When the rifle is fired, primer shot sets the bullet forward until it contacts the rifling, at this point the powder charge detonates and sets the shell case fully back, binds the action and start to propel the bullet. The bullet jumps slightly again and is etched by the rifling... it stops again very briefly as the pressures build to a point for the bullet to overcome the mechanical advantage of the rifling twist and the bullet starts to spin, at this point the chamber pressure is at max, 50K plus (there are some that believe there is another, third stop the bullet makes and some testing suggest this may be true).

As the chamber pressures start to climb, the brass case expands and becomes plastic, this is essential to seal the case in the chamber -- the correct term for this is Obturation, when the case is obturated and sealed, it is stuck in the chamber, practically welded in really.

The Lock Time, or the time that the action remains locked with no attempt to start unlocking is very important... on the rifle, the lock time is about 550 microseconds, the lock time for the carbine is about 375 microseconds -- this may not seem like much, but it is much shorter of a time, also keep mind that the chamber pressures are twice as high in the carbine when the unlocking starts.

What does all of this mean? When the carbine is fired, the system attempts to unlock earlier than intended and while the case is still fully obfucated... this results in the action bind delaying the unlocking and stressing the system. As the 5.56N is not drastically tapered, "squirting" is not a big problem in most guns. When the internal bolt pressures finally unlock the bolt, the velocity of the reward movement in the carbine is much higher than what the rifle was designed for, it also must start extraction of the obfucated case... as you know, the AR does not have any sort of initial extraction, perhaps the single biggest shortcoming of the design. This has been known to cause ripped case heads...

At this point, as the bolt start to unlock, it is rotated to unlock... due to much higher velocities with the carbine, the rotation of the bolt creates enough centrifical force to "float" the extractor... the extractor on the AR is not balanced and the forward part of it weighs more -- some argue that the pressure of the extracted cartridge case keeps the case head against the bolt face, but the fact is that the extractor does float and the contact with the case rim becomes "soft". For this reason, it is much more likely that the extractor will simply pop off, rather than actually rip the case.

Balanced extractors and different designs have been developed (LMT), but the best solution to date has been stronger extractor springs and spring buffers. That about covers the FTE issues...

Back to bolt velocity. The high speed of the bolt has a couple of other detrimental effects, one of the most common is that the bolt is cycled so fast that as it returns to battery, it actually has enough force to "bounce" off of the barrel extension when closing and locking... this bounce back is very small, but can be enough to cause the weapon not to fire... this "bolt bounce" is pretty well known.

One other problem is that the bolt can cycle so fast the magazine spring can not keep up with it and the round stack is not properly aligned and forced back into place before the bolt returns to batter -- therefore there is no new cartridge picked up and the bolt closes on an empty chamber, this is what some call "ghost loading", or bolt-over-base jams... this is far worse in full auto fire as the bolt does actually move faster in full auto than semi auto; this is due to the fact that the top cartridge in the magazine does not apply force to the bottom to the bolt causing drag.

The common solution to this issue is to use a stronger recoil spring and a heavier buffer... this works, but is treating the symptom, not the problem.

PigTail and expansion chamber gas tubes attempt to fool the rifle into thinking that the gas port is, located further away that it really is, but they are not as good of a solution as actually moving the gas port out...

I guess that about covers it for a quick rundown, of course all of this is not nearly as simple as it sounds.

Of course that is somewhat brief... but a decent overview. Now, the middy (for the purposes of this discussion, a rifle with the gas port located at appx 9.5") was developed by Mark Westrom. One of the big problems with the Carbine length system was its use on 16" barrels... now we had the high pressures of the 7.5" gas port and a longer dwell time that further exacerbated the problems.

The middy moves the port out 2" and is just about perfect for the 16" barrel... port pressures are around 18K and the internal bolt pressure drops to much closer to the original 1K, the dwell time is slightly reduced to offset the still increased pressure, but this system is smooth, much more reliable and has the added benfits of longer sight radius, extended handguards and a much more practical 16" barrel.

Now, the .mil like the idea, but it precludes some goodies that require a *proper* distance between the bayo mount and FS, as well as the GL moutning issue. There is a system that uses a modified gas block/FSB with a middy gas system, carbine handguards and retains SOPMOD compliance, GL, Bayo and all of that junk... barrel is just under 16" on it -- I like it a lot.

Posted: 2/17/2006 7:53:48 AM EDT

[#16]

I am sure in the long run that the mid length has its advantages over a regular M4 but I dont think anyone told my M4 that cause it seems to not know it cant pick up a second round out of the magazine. Please dont tell it, I dont want any malfunctions.

Also, I do want a mid length someday, but I just dont need one right now.

Posted: 2/17/2006 7:59:20 AM EDT

[#17]

Quoted:
Now, the .mil like the idea, but it precludes some goodies that require a *proper* distance between the bayo mount and FS, as well as the GL moutning issue. There is a system that uses a modified gas block/FSB with a middy gas system, carbine handguards and retains SOPMOD compliance, GL, Bayo and all of that junk... barrel is just under 16" on it -- I like it a lot.

So THAT's the reason why the M4Ward/Aardvark was devolped... Makes much more sense now!

Posted: 2/17/2006 8:07:59 AM EDT

[#18]

Gunzilla VS Fogofwar

Only on pay-per-view

Posted: 2/17/2006 8:29:36 AM EDT

[#19]

Middy Pr0n time!!!
Sold from Talon Arms

Forum Member who has one

I want to have the m@n sex with that upper.

Posted: 2/17/2006 8:59:48 AM EDT

[#20]

n00bs- Gunzilla was correct when he said "CORRECTLY" so you don't need to give him sass or bullshit just because you didn't pick up on the "CORRECTLY" part of it.

You didn't need to claim to be an expert to come across as having the attitude of one and that's exactly what Gunzilla was talking about. He relayed a story about self proclaimed know-it-all experts on these boards and you inferred he was talking about you. You could have just taken what he said for what it was worth and stood back to think about going any further with arguing or sass...

Was it mentioned yet that Armalite developed the first 'production' midlengths?

more Gratuitous Midlength PORN:

Posted: 2/17/2006 9:11:43 AM EDT

[#21]

For a carbine I prefer the mid-length gas system because they cycle smoother and are more pleasant to shoot.

Posted: 2/17/2006 9:24:58 AM EDT

[#22]

Quoted:
Now, the .mil like the idea, but it precludes some goodies that require a *proper* distance between the bayo mount and FS, as well as the GL moutning issue. There is a system that uses a modified gas block/FSB with a middy gas system, carbine handguards and retains SOPMOD compliance, GL, Bayo and all of that junk... barrel is just under 16" on it -- I like it a lot.

Gunzilla,
Thanks for that explanation!

Any chance of a pic of this creature you speak of?

Posted: 2/17/2006 9:32:49 AM EDT

[#23]

The advantage of the midlength is not having a pinned flash hider or SBR registration along with being able to attach a bayonet correctly. Why does this matter? Well if you ever wanted to get a Can down the road it would be an easy addition in this configuration but also retain the bayonet mounting capability. I wish I had gone mid-length on all my M4 type rifles but instead they are all 14.5" with the exception of a Colt M4A3 I had for a while which had a 16" barrel- I sold it, kicking myself in the arse.

Posted: 2/17/2006 9:33:54 AM EDT

[#24]

Quoted:
Was it mentioned yet that Armalite developed the first 'production' midlengths?

You know, I forgot about the middy AR-10's, but those were Dutch as in AI not ArmaLite. Only think they made 100 of them?

Guess that is what you are refering to?

Posted: 2/17/2006 10:00:54 AM EDT

[#25]

Quoted:
more Gratuitous Midlength PORN:

www.torrenga.com/~jrybicki/ar15/brownstripe.jpg

Did I hear Middy pr0n?

The advantages have already been discussed.

WIZZO

Posted: 2/17/2006 10:04:32 AM EDT

[#26]

Get those nOObs JosephR!!!

Ya'll don't fuck with those Team Members now...

THEY BITE!!

By the way, Sabre Prices have gone up a lot due to the steel shortage, TheMocoMan..

Just before I decided to get another Middy barrel too...

Posted: 2/17/2006 10:11:22 AM EDT

[#27]

Quoted:
Quoted:
more Gratuitous Midlength PORN:

www.torrenga.com/~jrybicki/ar15/brownstripe.jpg

Did I hear Middy pr0n?

i31.photobucket.com/albums/c352/WIZZO499/100_0088a.jpg

The advantages have already been discussed.

WIZZO

Now you've done it!!

Posted: 2/17/2006 10:32:29 AM EDT

[#28]

Not sure of the time line and do not have any personal middy porn to offer, but this is the version I have heard

The mid length gas system was created to provide carbine shooters the same sight radius as the rifle shooter

the greater the distance between the rear and front sights, the easier and more proficient operation for the shooter.

Why the middy? Site radius.

When? dont know

Posted: 2/17/2006 10:42:42 AM EDT

[#29]

Quoted:
Not sure of the time line and do not have any personal middy porn to offer, but this is the version I have heard

The mid length gas system was created to provide carbine shooters the same sight radius as the rifle shooter

Although the dissipator model already addressed that issue before the middy became popular (but it retained the carbine gas system, AFAIK)

Posted: 2/17/2006 10:52:18 AM EDT

[#30]

Quoted:

Nice! Thanks for sharing that bit of history.

Posted: 2/17/2006 12:34:29 PM EDT

[#31]

I thought I said I thought Armalite was the first to make a PRODUCTION midlength, no?

Posted: 2/17/2006 12:36:39 PM EDT

[#32]

Quoted:
I thought I said I thought Armalite was the first to make a PRODUCTION midlength, no?

You meant ArmaLite of Illinois? Did not think you meant that, considering I mentioned the SR-25K and the year 1994 a few posts above yours.

Posted: 2/17/2006 12:41:16 PM EDT

[#33]

OK FINE! I thought they were the first to make a 16" midlength for civilians

oh and to chris- n00bs is spelled with two ZEROs, not O's

Posted: 2/17/2006 12:55:06 PM EDT

[#34]

n

b

Posted: 2/17/2006 1:05:59 PM EDT

[#35]

Quoted:
OK FINE! I thought they were the first to make a 16" midlength for civilians

oh and to chris- n00bs is spelled with two ZEROs, not O's

But what if the n00b is FAT?

ETA: I've never used the word n00b obviously...

Posted: 2/17/2006 1:35:50 PM EDT

[#36]

Quoted:
Quoted:
more Gratuitous Midlength PORN:

www.torrenga.com/~jrybicki/ar15/brownstripe.jpg

Did I hear Middy pr0n?

i31.photobucket.com/albums/c352/WIZZO499/100_0088a.jpg

The advantages have already been discussed.

WIZZO

Nice photo WIZZO. what trigger are you running on that middy?

Posted: 2/17/2006 3:03:33 PM EDT

[#37]

The mids don't have the same sight radius as a rifle; but they do have a better sight radius than a carbine. I think the primary advantage is the smoother recoil impulse due to the longer gas system; but still in a handy carbine package.

And since we are doing mid-porn...

Posted: 2/17/2006 3:40:47 PM EDT

[#38]

you guys are forgeting the most important factor....

the C

l !! factor

Posted: 2/17/2006 6:19:57 PM EDT

[#39]

Quoted:
Nice photo WIZZO. what trigger are you running on that middy?

Standard. It looks polished because it is. It originally had a rib of flashing down the front of it that was just sharp enough to bug the hell out of me. I whipped out the dremel and fixed the flashing problem and decided to make it look uniform and just decided to take the rest of the finish off since I wasn't going to bother spraypainting it.

It hasn't rusted at all and is quite smooth on my finger now. I'm happy.

WIZZO

Posted: 2/17/2006 7:09:53 PM EDT

[#40]

I started the thread so I might as well contribute a pic.

This is my Katrina Gun. I was out of gun stuff for several years but Katrina brought home the need to have a good perimeter defense weapon. I lurked for six months on this forum to get back up to speed. Thanks to all ARFCOM members (including Gunzilla

) for your contributions. I couldn't have done it without you.

I have a photographer friend that is going to do shoot some pics of this gun that may. . . MAY. . . come slightly close to Stickman's craft. We shall see.

Thanks again to ARFCOM for making a literal 10 year dream come true.

fogofwar out

P.S. The funniest thing about this whole topic is that I am the board grump and noob-squisher on another board that shall-not-be-named. What comes around goes around. Karma is a bitch!

peace

Posted: 2/17/2006 8:39:32 PM EDT

[#41]

Quoted:
Quoted:
Now, the .mil like the idea, but it precludes some goodies that require a *proper* distance between the bayo mount and FS, as well as the GL moutning issue. There is a system that uses a modified gas block/FSB with a middy gas system, carbine handguards and retains SOPMOD compliance, GL, Bayo and all of that junk... barrel is just under 16" on it -- I like it a lot.

So THAT's the reason why the M4Ward/Aardvark was devolped... Makes much more sense now!

why I have no idea of what you are talking about? Someone named a gun the Aardvark... what a strange man that must be

Oh, to clarify... Mark may not be the guy that "invented" the midlength system, we had played with moving the gas port around and found locations that work well with different barrel lenghts (like the 18" barrel, Intermediate System!) -- But, Mark is the man to give credit for bringing it into production, setting the standard and making is common today.

[ARCHIVED THREAD] - Origin of the Midlength

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