New DI design I have been thinking about


PDA






Dreamcast270mhz
May 28, 2011, 05:40 PM
I have been thinking about a revision to the Stoner Gas system, mainly to help with increased heat associated with the M16 and M4, as well as reducing fouling in the breech/action area.

The basic revisions I have thought about are: The gas is bled off before entering the breech, in other words as soon as the gas key opens into the action, a set of vertical vents direct the gases upward and away from the internal moving parts. The gas key shape would also change, it would protrude a bit more into the gas tube, and ideally most of the gas would be bled already, and momentum would carry the cycle.
Don't think of this in your typical AR body, the upper would have a gas deflector, to direct it towards the right, away from any optics mounted.

Once I draw a diagram detailing the modified parts, it may make a bit more sense.

If you enjoyed reading about "New DI design I have been thinking about" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Zak Smith
May 29, 2011, 02:16 AM
Gas pushing on the gas key is not what unlocks and primarily moves the bolt carrier group. It's gas that enters the piston comprised by the bolt and bolt carrier group. The extra gas vents out the RHS of the bolt carrier.

Dreamcast270mhz
May 29, 2011, 01:16 PM
Hmm. A few web articles need to be fixed then. What I'm thinking about is isolating the gas from the main moving parts and therefore reduce overall heat build up and make it a bit cleaner. I'm taking a lot of ideas of the ljungman system, although the biggest issue is that design is a tilting bolt. RHS i assume is right hand side, which means the gas exits through the breech.

What part in the Stoner system actually does the unlocking of the bolt, then?

Zak Smith
May 29, 2011, 01:54 PM
What you're describing is basically what all the piston systems do.

The gas key shape would also change, it would protrude a bit more into the gas tube, It does not protrude into the gas tube now.

Dreamcast270mhz
May 29, 2011, 02:42 PM
The basic disadvantage of the Stoner system is that the spent gas heats the parts up and is why a short stroke piston is used in almost every other NATO nation, because of inherent design flaws.

The Ljungman system uses a small piece that protrudes into the gas tube, the high pressure pushes the bolt out of the tilt and backwards, and the extra gas is bled up and out, not needing to pass through the moving parts. If you were to combine some of these advantages with the stoner system I see many of the faults in the design corrected.

Heretic
May 29, 2011, 06:22 PM
Drop the dust cover and you will see two little holes in the carrier. This is where the gas vents. Pressure behind the rings tries to push the bolt foreward, the cam pin follows it's slot to turn the bolt, unlocking it.

tyeo098
May 29, 2011, 11:09 PM
this is why my ar-15 bcg is always so dirty

Sam Cade
May 29, 2011, 11:49 PM
The basic disadvantage of the Stoner system is that the spent gas heats the parts up and is why a short stroke piston is used in almost every other NATO nation, because of inherent design flaws.



FAMAS: Lever Delayed blowback.
AKs (former Warsaw nations):Long Stroke
AK5/FNC : Long Stroke
G3 type weapons are roller delayed
L-85: Short stroke (hardly a ringing endorsement)
FAL: Short stroke but wacky.
AUG: Short stroke
G36: Short Stroke
Vz-58 is short stroke
MAG/M240 : Long Stroke
M249/Minimi: Long Stroke
MG-3 functions on zero point energy or something



..and Non-Nato:

TAVOR is Long Stroke
Chinese T91 is Short Stroke, as is the semi-mythical QBZ.
Korean K2 is Long Stroke, the K1 is DI.



....and the Swiss use a long stroke (SIG 5xx), because they are Swiss.:D

Dreamcast270mhz
May 30, 2011, 12:53 AM
^ I stand corrected. But still over half are short stroke.

MG3: Roller Locked short recoil, same as Mg42

Apocalypse-Now
May 31, 2011, 02:00 AM
what's the difference between the short and long stroke piston designs?

WaltonS
May 31, 2011, 02:13 AM
what's the difference between the short and long stroke piston designs?

Short explanation: In short-stroke or short-action, slide or bolt does all the moving, including compression of the recoil/return spring...
Long-action means that the bolt/slide and barrel compress the spring while together and it decompresses during cycling.

Someone feel free to correct me if I misunderstood.

kozak6
May 31, 2011, 02:31 AM
No.

Wikipedia explains it fairly well.
http://en.wikipedia.org/wiki/Gas-operated_reloading

Apocalypse-Now
May 31, 2011, 02:44 AM
ok! i just did some googling, and here's what i came up with on long stroke vs. short stroke:

the short stroke AR and an independent piston that pushes back on the bolt carrier, and then is arrested, at which point it's driven back forward by a spring.

this system has the advantage of spreading the recoil forces both forward and backwards, making the gun more controllable under rapid fire. however, the piston spring can wear out quickly, and there isn't as much mass driving the next round forward into the chamber.


the long stroke has a long piston rod that is attached to the bolt group and is driven all the way back with it, as in the m1 garand. less controllable during rapid fire, less parts, and inherently more reliable, as with the AK47.


am i right? (i majored in design, it didn't take me long to understand lol)

Dreamcast270mhz
May 31, 2011, 07:44 AM
Yeah that about right.

And the Differences between the Stoner and Ljungman systems-

Ljungman- Tilting bolt, gas pushes directly on bolt carrier which unlocks and travels back, excess gas vents out top

Stoner- Rotating bolt, gas pushes on gas key, which allows it to travel into the bolt, unlock bolt and then exit out ejection port.

The Stoner design has several inherent faults, such as: Heat buildup alters temper of metals, burns off lubricants and warps parts. Tight clearances make dirt, sand, mud more of an issue. Lack of adjustable gas system makes it difficult to cycle under heaviest conditions.

What I propose to reduce the issues:

Change the way the bolt unlocks to allow for the following

Isolate the hot gas from the inner working parts of the system, by directing it up and away from the system before it can enter the breech.


The way the bolt locks change i propose is simple: Make it so the carrier moving unlocks the bolt, but if the carrier cant move, like during firing, the bolt stays shut.

With this, it is possible to make the gas key more like the Ljungman system, where it terminates the gas tube and is acted on by the gas moving rearwards, but is directed out and up through the above system in my older posts before it can reach the moving parts.

Heretic
June 1, 2011, 01:52 PM
The carrier moving to the rear does unlock the bolt(via the cam pin). If you re-direct the gas, there won't be anything to move the carrier to the rear.I guess I don't understand what you're getting at.

JustinJ
June 1, 2011, 05:20 PM
"this system has the advantage of spreading the recoil forces both forward and backwards"

Huh? How is that accomplished in a way that long stroke isnt?

Bartholomew Roberts
June 1, 2011, 06:08 PM
The basic disadvantage of the Stoner system is that the spent gas heats the parts up and is why a short stroke piston is used in almost every other NATO nation, because of inherent design flaws.

The Stoner design has several inherent faults, such as: Heat buildup alters temper of metals, burns off lubricants and warps parts.

Why do you believe that the Stoner design gets hot enough to alter the temper of metals and warp parts?

Dreamcast270mhz
June 1, 2011, 06:24 PM
Heretic,

The point is for the gas to impact the carrier via a cylinder recess inside the end of the gas tube, then at the termination of the gas tube for the gas to be dispersed out a top vent. This is the same way the Ljungman design works and at this point the gas has imparted sufficient momentum for the bolt to fully cycle.

Bart

The hot gases progressively heat up the rifle, and aluminum warps a whole lat easier than steel does. The hot gases also have the potential for lubricants to burn off, complicating the issue. Why is it the Swedish had such few problems with the AG42 and we have so many more reports of issues with the M16? Eugene later developed the AR-16 and 18, both with a short stroke piston, and no other NATO service rifle today uses the system, so the other nations must have obviously been concerned with one or more of the faults that are inherent to the design, lending to its mediocre performance against say the G36, or the FAMAS.

alemonkey
June 1, 2011, 06:32 PM
The hot gases progressively heat up the rifle, and aluminum warps a whole lat easier than steel does.

None of the parts that get excessively hot due to the DI system are made of aluminum. If DI caused metal to lose its temper we would be seeing an awful lot of kabooms. The only warping I've ever heard of is if someone runs the gun full auto for an extended period of time and warps the stainless steel gas tube.

rbernie
June 1, 2011, 06:48 PM
The hot gases progressively heat up the rifle, and aluminum warps a whole lat easier than steel does. It's been pretty well proven (by testing to destruction, with the tests videotaped for all to see) that the barrel of an AR pattern rifle will heat up and warp to uselessness before any other part of the rifle gets hot enough to deform or otherwise malfunction.

Zak Smith
June 1, 2011, 06:55 PM
All this talk about critical faults of the AR-15/M16 gas system is somewhat ridiculous considering the M16 has been in service for almost 50 years, and there are rifles such as "Filthy 14" that have gone tens of thousands of rounds without substantial cleaning.

Sam Cade
June 1, 2011, 07:22 PM
Heretic,
This is the same way the Ljungman design works and at this point the gas has imparted sufficient momentum for the bolt to fully cycle.

The ljungman system handily avoids the issue of hot gas inside the reciever by venting it directly into the shooters face.





The hot gases progressively heat up the rifle, and aluminum warps a whole lat easier than steel does.

How hot do you think an AR receiver gets in normal operation?



Why is it the Swedish had such few problems with the AG42 and we have so many more reports of issues with the M16?


Because they are sweden and the rifles were mostly used for parades and such post war. :D
Both the Swedes and the Egyptians ditched their Ljungman pedigreed rifles the very moment something better showed up.



and no other NATO service rifle today uses the system,
M16/M4/C7/C8 rifles are in service in various capacities with most NATO nations.

Danes in Afghanistan
http://kaalhauge.weblogs.asb.dk/files/2008/06/livgarden-i-afghanistan.jpg

SAS in Afghanistan
http://www.milsim.se/wp-content/uploads//2009/06/sas-group.jpg


lending to its mediocre performance against say the G36, or the FAMAS.

Got cites? Preferably French or German sources.

Bartholomew Roberts
June 1, 2011, 07:34 PM
The hot gases progressively heat up the rifle, and aluminum warps a whole lat easier than steel does. The hot gases also have the potential for lubricants to burn off, complicating the issue.

You know, I've seen IR videos of M4s doing multiple magazine dumps - 300 rounds and more on full auto and based on the temperature scale, the bolt carrier and bolt never exceed 250F (and that's being generous). So it seems to me that the "hot gases" argument as to internal parts is nonsense since none of those parts are going lose temper at those temperatures.

What actual evidence do you have that any of things you state are happening (parts losing temper, aluminium warping, etc.) are actually happening? I've read the PDFs of NSWC Crane regarding tests to destruction and watched the videos of several tests to destruction and the only thing I've ever seen warp on an AR15 pattern rifle are the gas tube and the barrel - both of which are made of steel and will last long past the design parameters of the AR15 or any modern infantry rifle.

Why is it the Swedish had such few problems with the AG42 and we have so many more reports of issues with the M16?

I'd guess we have more reports of problems with the M16 because it has been more thoroughly tested/used in actual combat over the past 50+ years than the AG42 ever did in its 20 years as the service rifle of Sweden. Much like the safe queen that sees 250 rounds a year will be "flawless" while the exact same rifle being shot 3,000 rounds in a weekend might not run so smoothly.

In any case, I'm curious if these assumptions you are making are valid; because I consider myself fairly well-read on the topic and they seem like nonsense to me. So if you have some data that supports what you are saying here, I'd love to see it.

Eugene later developed the AR-16 and 18, both with a short stroke piston

Yes, because having sold the rights to the AR-15 to Colt, Eugene was going to have a difficult time with patent lawyers trying to build a DI AR-18.

no other NATO service rifle today uses the system

15 NATO nations and 65 other nations use the M16. As it turns out, the M16 is a fairly successful system - so successful that even many short-stroke piston variants copy it in terms of ergonomics, barrel extension, bolt design, etc. So it shouldn't be a big shock that nations that want a DI military rifle buy an M16 instead of trying to develop their own from scratch.

And just to nitpick, the new British L129A1 SDM is a NATO service rifle and it uses the exact same Stoner system.

Dreamcast270mhz
June 1, 2011, 08:20 PM
When I say NATO service rifle I mean the standard rifle, as in the most common and numerous rifle fielded by x nation's particular Army. If you break it down for Europe, the countries I remember off the top of my head:

UK- L85A1
France- FAMAS
Germany-G36
Belguim- F2000
Czech R- VZ58
Slovakia- VZ58
Poland- AK
Romania- AK
Austria- AUG

Now I did look up and indeed there are some militaries that use the C series of M16 derived weaponry. I stand corrected

What I know regarding France and Germanys current weapon adoption was that the Ar platform had at least one entry, but it was beat out by domestic competitors.

I have no doubt that the AR is a successful weapon, but the following excerpt from the defense industry daily article says it all:

Like its predecessor the M16, the M4 also has a reputation as an excellent weapon – if you can maintain it. Failure to maintain the weapon meticulously can lead to jams, especially in sandy or dusty environments. Kalashnikovs may not have a reputation for accuracy, or lightness – but they do have a well-earned reputation for being able to take amazing amounts of abuse, without maintenance, and still fire reliably. The Israeli “Galil” applied these lessons in 5.56mm caliber, and earned a similar reputation. Colt’s M16 and M4 have never done so.

I'm not trying to derail my own thread by any means but the fact of the matter is, the AR series doesn't exactly have a stellar track record, from the same article:

3rd ID soldier: “I know it fires very well and accurate [when] clean. But sometimes it needs to fire dirty well too.”

25th Infantry Division soldier: “The M4 Weapon in the deserts of Iraq and Afghanistan was quick to malfunction when a little sand got in the weapon. Trying to keep it clean, sand free was impossible while on patrols or firefights.”

82nd Airborne Division soldier: “The M4 is overall an excellent weapon, however the flaw of its sensitivity to dirt and powder residue needs to be corrected. True to fact, cleaning will help. Daily assigned tasks, and nonregular hours in tactical situations do not always warrant the necessary time required for effective cleaning.”

75th Ranger Regiment member, SOCOM: “Even with the dust cover closed and magazine in the well, sand gets all inside; on and around the bolt. It still fires, but after a while the sand works its way all through the gun and jams start.”

The 507th Maintenance Company, ambushed outside Nasariyah in 2003 during the opening days of the ground invasion of Iraq, might concur with all of the above. The post-incident report released by the US Army had this to say:

“Dusty, desert conditions do require vigilance in weapons maintenance… However, it is imperative to remember that at the time of the attack, the 507th had spent more than two days on the move, with little rest and time to conduct vehicle repair and recovery operations.”

And this isn't 10 years ago, this is much more recent and with this basis I think I'm entitled to make improvements to the design.

Even if it is not affected nearly as much as believed by hot gases from the tube, using ideas from the ljungman have some clear advantages:

Reduction in fouling in breech and chamber, reducing need to clean the rifle

Lowered heating, as a rifle as a general rule operates better at cooler temperatures.


Now onto the one comment that is puzzling:

The ljungman system handily avoids the issue of hot gas inside the reciever by venting it directly into the shooters face.

Amusing, but unless your face is directly over the bolt carrier I can't see this happening, since the bolt carrier is a little distant from the comb of the stock, where your cheek lays. Even so, have you actually handled an AG42?

I have, and while sort of awkward my face was not anywhere near where the breech opens during firing.

I never made any claims regarding the ergonomics of an AR, they are great and I love my friend's AR, a gas piston variant in .308. I wouldn't, however be able to justify the $1300
he shelled out for it in my budget.

Owen
June 1, 2011, 08:24 PM
So the action being filled with sand is somehow the fault of DI?

Dreamcast270mhz
June 1, 2011, 08:30 PM
No, but it can compound the issue. Also, very little can be done about that besides loosening the tolerances the rifle, heresy in the eyes of many AR people. So, i'm focusing on the improvement of the gas system to better aid in the rifle functioning under heavily fouled conditions

rbernie
June 1, 2011, 08:33 PM
Please explain.

Sam Cade
June 1, 2011, 08:43 PM
Amusing, but unless your face is directly over the bolt carrier I can't see this happening, since the bolt carrier is a little distant from the comb of the stock, where your cheek lays.

Your eye is directly in line with the gas tube, its business end is right in front of your face.

Even so, have you actually handled an AG42?

Oh yes.I have had a couple. Ive got a couple Hakims and a Rasheed now.

The pictures I linked above I made just for you, just for this thread.

And here is me, with a Hakim, bolt open. Take note of where the gas tube protrudes.
Ya better wear glasses if you have one of these. I find grit/unburnt powder all over my head and face every time I shoot.

Dreamcast270mhz
June 1, 2011, 08:48 PM
Well the Ljungman rifles and the MAS 49 both had a clearer track record than the AR for reliability. Understandably, they were produced in smaller numbers/not used nearly as much, but besides that, they seemed to serve both nations fairly well. The MAS 49, especially, could be cleaned with gasoline and motor oil and function just fine, and the french had plenty of desert colonies, Algeria, Tunisia, Morocco, Mali, etc. All after the 1949 adoption of the MAS 49. Yet, we never hear any trouble with them under sandy conditions, yet we all know some parts of Africa have had a history for bloody tribal violence, and French colonies I'm sure were no exception. Thus two logical explanations can be assumed:

There was never enough of the fielded in those nations for a signifcant number of reports to be filed

Or

They functioned reliably under those conditions and therefore I feel sufficiently safe in saying that the design used was/is more reliable

Dreamcast270mhz
June 1, 2011, 08:56 PM
@Sam

You know your stuff obviously. As said I handled and never actually got to shoot it.

Do notice, however I said a gas deflector would be installed. Basically a curved piece of metal that directs the gas to the right, away from the rifle.

Also, on the ag42 isn't the opposite true? http://world.guns.ru/userfiles/_thumbs/Images/rifle/9/1288259801.jpg

I don't even see the design now I look at it as ever really accomplishing as much as I'd like. Oh well, I better stop trying to make the horse drink, the AR platform is currently not thirsty.

Zak Smith
June 1, 2011, 09:02 PM
The way the rotating 7-lug bolt is affected by sand has zero to do with the gas system.

19&41
June 1, 2011, 09:03 PM
You might also have a look at the 1941 Johnson semiautomatic rifle. It uses a lockup system similar to the AR system with no gas nor piston impingement.

Sam Cade
June 1, 2011, 09:06 PM
Also, on the ag42 isn't the opposite true?

opposite of what?

Dreamcast270mhz
June 1, 2011, 09:07 PM
Now I'm looking at a new type of delayed blowback, one that may be a lot cheaper than HKs system...


@Sam

Nevermind, looked up elsewhere and saw the diagrams I was looking at did not show the protrusion from the tube.

Sam Cade
June 1, 2011, 09:15 PM
Follow the link, look at how the bolt protrudes in the diagram?

Oh I see. That is a patent drawing.. In the actual rifle the carrier has a recess for the gas tube.


Not my picture:

http://www.picturescraze.com/guns/8909/ljungman+ag-42+rifle.html

mr.trooper
June 1, 2011, 09:18 PM
DramCast - The fatal flaw in your logic is that BOTH piston and DI guns will reach similar temperatures during sustained fire.

The only thing between the bolt and the gas in a short-stroke IS that piston, which is being hit will all of those hot vapors. Heat then transfers.

In theory a piston may DELAY the heating of some parts, but in my experience with guns like the SKS and FAL, they will still get plenty hot after a bout of sustained fire. The difference will only be measured in a magazine or two of ammo.

Dreamcast270mhz
June 1, 2011, 09:20 PM
I've abandoned this design in favor of designing a delayed blowback action

Tommygunn
June 2, 2011, 12:11 AM
I've abandoned this design in favor of designing a delayed blowback action

Check out early Thompson Submachine guns for ideas ..........;)

Sam Cade
June 2, 2011, 12:17 AM
..........;)


Blish lock? LOL!

Dreamcast270mhz
June 2, 2011, 09:09 AM
Once I draw up diagram I will post about it. The Blish Lock, it got me nowhere so I am going with a multi-stage system

Tommygunn
June 2, 2011, 11:48 AM
The Blish Lock, it got me nowhere so I am going with a multi-stage system
__________________

Oh goodie. Remember an old Henry Ford axium; "The more there is to a machine, the more there is to go wrong with it."

Heretic
June 2, 2011, 11:51 AM
Sounds to me that the problem would be addressed better with "sand cuts" similar to south african(I think) FALs.

Didn't soldiers used to throw awat the blish lock? Seems I remember reading that the thompson worked as well without it.

Justin
June 2, 2011, 01:10 PM
No, but it can compound the issue. Also, very little can be done about that besides loosening the tolerances the rifle, heresy in the eyes of many AR people. So, i'm focusing on the improvement of the gas system to better aid in the rifle functioning under heavily fouled conditions

I've shot AR-pattern guns in conditions more adverse than most owners will experience, including blowing sand and wind.

I've shot them to the point where the hand guards became uncomfortably hot.

I've gone thousands of rounds between cleanings.

Guess what?

Under those circumstances, at no point did the rifles jam because of any feature inherent to the design.

Additionally, my AR-pattern guns are capable of engaging targets out 500 yards under field conditions, and I've even pushed that as far out as 600 yards when shooting from a rest.


The changes you're proposing aren't heresy so much as a demonstration of your lack of experience with the design. Had you actual first hand experience with running and maintaining these rifles, you'd realize that you've got a fairly hard row to hoe if you intend to actually improve on the design.

Sam Cade
June 2, 2011, 07:02 PM
No, but it can compound the issue. Also, very little can be done about that besides loosening the tolerances the rifle, heresy in the eyes of many AR people.

You need to get your terminology correct if you want people to take you seriously.

In this context that word does not mean what you think it means.

Tolerance is the acceptable level of dimensional variation of a part.

The phrase you are looking for is "designed in clearances as they apply to Fit."

http://en.wikipedia.org/wiki/Engineering_fit

Sam Cade
June 2, 2011, 07:10 PM
Oh goodie. Remember an old Henry Ford axium; "The more there is to a machine, the more there is to go wrong with it."

Oh that is a good one!!

Kalashnikov was full of pithy bits like that:
" Anything that is complex is not useful and anything that is useful is simple."

Justin
June 2, 2011, 07:12 PM
The AR15 has much fewer parts than even a Model-A.

Dreamcast270mhz
June 2, 2011, 10:25 PM
I think since I've abandoned this whole discussion it may be better to just lock this thread

Tommygunn
June 3, 2011, 12:36 AM
Didn't soldiers used to throw awat the blish lock? Seems I remember reading that the thompson worked as well without it.

No, the Thompson will not work without it. The Thompson bolt contains three basic parts, the bolt, the actuator (the "knob" that is used to cock the weapon) and the Blish device. If you remove the Blish and try to cock it the actuator moves back without the main bolt, but the sear won't do anything as it locks up against the bolt, which remains forward.

Sam Cade
June 3, 2011, 01:40 AM
Seems I remember reading that the thompson worked as well without it.

The M1/M1A Tompson was a blowback, they dumped the Blish lock since it didn't do much of anything and added complexity and expense.

Tommygunn
June 3, 2011, 12:22 PM
Sam, about a year ago I read an article, I believe in a magazine called Military Antiques, which dealt with the issue of the Blish device. It was controversial from the start. A big question was what, if anything it did.
It was John Thompson's contention that it worked by a phenomenon callled differential of friction. The device, being made of a different metal than the rest, delayed the recoil through friction.
The authors of the article obtained a 1928 Thompson and an extra Blish Lock. They first established the actual firing rate of the Thompson they were using, then milled off the ears of the extra Blish (the trapezoidal projections present in the above photograph is what I am refering too, for those who don't know how Thompson's work). When they assembled this altered lock into the weapon, they determined that the rate of fire had increased by about 200 RPM.
The device actually does work. What I forget is how they established HOW it works. It doesn't work the way Mr. Thompson claimed; it works through a principle of leverage, since the Blishlock slides up and down inside the bolt at a different angle than the cuts inside the receiver are angled at.
The conclusion however is really unchanged; the Blish was eliminated in the M1 and M1A1 versions and simpler methods were employed to keep the rate of fire down to what the army desired, or closely enough to satisfy the army atleast. Despite the fact it actually did work albeit differently than originally believed, it was too complex and expensive for wartime production.
Despite that fact, I stubbornly insist I like the 1928 Thompsons better than the later versions. Just got rocks in my head 'bout it, I guess.;)

Sam Cade
June 3, 2011, 02:59 PM
they determined that the rate of fire had increased by about 200 RPM.
*snip*


It was the just the weight removed. The was Blish literally dead weight...and it was a good thing. :D

From an old AR article:
Indeed, the Small Arms staff at Enfield predicted the alteration of the design of later Thompsons by removing the Blish lock completely and then firing the gun remotely under safe conditions. The results were instructive: “The rounds were fired, both ejection and extraction being satisfactory. The gun functioned well and the condition of the spent cases was found to be identical with that of the spent cases … fired with the wedge assembled to the gun.”

I wonder how they modified them, exactly, since IRRC you can't just pull the lock out and have a functional firearm.



the Blish was eliminated in the M1 and M1A1 versions and simpler methods were employed to keep the rate of fire down to what the army desired, or closely enough to satisfy the army at least.

The bolt weight was increased by a couple ounces.

Tommygunn
June 3, 2011, 08:54 PM
I believe a beefier recoil spring was introduced as well.
Here is, I think, the 1928 Thompson bolt disassembled.

If you enjoyed reading about "New DI design I have been thinking about" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!