View Full Version : Open Bolt vs. Closed Bolt

Badger Arms
March 18, 2001, 05:48 PM
I was reading recently that the StG 44 originally had open-bolt operation but was switched to closed bolts. The switch was made under the assumption that accurate semi-auto fire required a closed bolt. In use, however, open bolt operation was preferred.

Anybody have thoughts on what is preferred and why? I know that some guns were made to fire open bolt for automatic fire and closed for semi.

March 18, 2001, 06:56 PM
The way it was explained to me is that if you are doing some heavy-duty rocking & rolling, the chances of cook-offs are reduced by firing from an open bolt (the unfired round doesn't actually chamber until the moment it is fired). A closed-bolt design is easier to shoot accurately, particularily in semi-auto mode, because the whole bolt doesn't come crashing forward when you pull the trigger.
my $0.02...

March 22, 2001, 04:27 PM
Open bolt is terrible past 50 meteres! Give a closed bolt any day..and keep it on semi most of the time.

March 22, 2001, 06:49 PM
You have to also consider the purpose of the weapon. If the purpose of a submachine gun is to lay down a maximum amount of "walking fire" so your side can advance while the enemy is forced to keep his head down, then accurate single shots are not much of an issue. A police/SWAT application is completely different in requiring accuracy due to bystanders, etc. Also, if open-bolt guns were terribly inaccurate, then Mac's, Swedish K's, and Beretta 38A's would never beat MP5's in subgun competitions, but they do. Open-bolt guns can be quite accurate, but they take some getting used to.

March 24, 2001, 11:29 PM

I was not aware there were any subgun games/compitition...if so what are the conditions of play? ( shooting in meteres...10?, 25?,50?,75?) Does it simulate real combat or is it an arbitrary thing? ( i.e. is it a bunch of "good timers" or real combat freaks/police?)

Both closed bolts and open are capable of laying down good "cover fire", which by the way will only work against untrained/seasoned advisaries. That being said, just about all new production SMG's are closed bolt ( including mini UZI's etc.) Using your logic answer me why all these manufactures who have millitary contracts and testing recources way beyond us "pee-on's" would make the new guns closed bolt if it were so much worse than the cheaper open blot?

Open bolts are inherently inaccurate, if perchance a good operator/shooter can make good use of this system past fifty yards, then he is one in a thousand. I was issued an UZI with an open bolt, I was happy to have something, but I sure as heck would have preffered a H und K !

March 25, 2001, 01:30 AM
Izzy: There are lots of subgun competitions, and they take a variety of forms, ranging from bowling pin shoots to jungle walks, and everything in between. In some of these, LE's and civilians compete against each other, and courses usually involve no-shoots that put a premium on accurate fire. If you go to Knob Creek next month, you will see some of the best. I suggest you look for reports of some of these competitions in past and future issues of Small Arms Review. As to "good timers", I'm not sure what that means, but I think everyone has a good time competing in these events.

No one said closed bolt guns were "so much worse than the cheaper open bolt". Relax.

I'm sorry that you had such difficulty shooting your Uzi with any accuracy, but your assertion that only one in a thousand shooters can make good use of an open-bolt submachine gun past 50 yards is nonsense. Perhaps you needed more and better training with your weapon, or maybe it wasn't sighted in properly. I own two Uzi's and find them to be a pretty accurate gun; I certainly don't have any trouble hitting a paper plate at 50 yards, nor does anyone else I shoot with. At least a half-dozen other open-bolt subguns are more accurate yet. Does a closed-bolt subgun offer a general accuracy advantage due to its mode of fire? Yes, but it isn't that much more accurate, and whether it makes much difference depends on the application.

Open-bolt submachine guns have largely disappeared from military applications, but not because they were replaced by closed-bolt submachine guns. Rather, submachine guns of all kinds have been replaced by compact assault rifles that fire much more potent cartridges than any submachine gun. If your targets will be engaged at any significant distance, then no submachine gun should be your weapon of choice. Given a full range of alternatives of what to carry into battle, who in his right mind would choose to carry a submachine gun?

The few submachine guns still in production are primarily civilian police weapons. For that sort of application, where a relatively low-powered, non-penetrating, easily noise-suppressed round is usually appropriate, an MP5 or similar is a good choice. Which is what I said in my post.

Badger Arms
March 25, 2001, 05:32 PM
Hate to interrupt as this is an excellent conversation about sub-machine guns but that wasn't the spark for my qestion. The question was brought about by period reports from the front-lines about the StG44. When used in auto-only, the original assault rifle was reported to be easier to control open-bolt. The reasoning was that the bolt slamming first into the rear of the receiver and then closed where it waited for the lock time jarred the weapon off target to much.

When firing open-bolt, the gun attenuated much of the jarring. The soldier could hold the gun a wuniform way such that each subsequent shot was placed directly on target. When engineers and desk-designers rethought the design, they made it closed-bolt. The result was a gun that was twice as difficult to control in auto fire, but more accurate in semi-fire. While keeping with some idiotic philosophy, the utility of the gun was reduced. An assault rifle is for automatic fire, not for semi-auto fire.

Sub-guns are much lighter than Assault rifles. As a result, they are much more succeptible to being jarred by the large mass of the bolt swishing and slamming twice per round fired. A great deal of training is required to control the gun, but it's not impossible.

LMG's and other heavier guns should fire open-bolt. Sustained automatic fire almost dictates this method of operation.

March 25, 2001, 08:11 PM

You may be right about the training, I sure did not get enough practice with the UZI, So being that you seem to have more knowledege in the feild I will deffer to you. Just wanted to put my vote in.

Badger Armes,

Sorry dont know much about the STG44 other than the fact that no matter what the Germans would have feilded by that time ( short of an A -bomb) the Russians would have overwhelmed em' anyways. I hope our countinual posting will spur the intrest of another member to answer your question.

March 28, 2001, 01:17 AM
Badger Arms, when I went trough the mandatory Army training here we fired our assault rifles mostly in the semi-auto mode. The full-auto mode isn't much use at, say, 150 meters... It does come in handy at short distances though. So I guess what mode the gun is mostly fired in depends a lot on the situation it is used in.

March 28, 2001, 10:13 AM
Open bolt is better for subguns. In a pistol caliber subgun semiautomatic is an oxymoron, like "country music," "jumbo shrimp," or "government assistance."

Badger Arms
March 28, 2001, 03:20 PM
I'll agree with you about assault rifles, but only in the modern versions in 5.56mm, 5.45mm, and the 7.62x39. The 7.92x39 was a relatively anemic round and meant to be that way. Paired with an 11 pound weapon firing on open bolt, at 500 rpm, the STG44 was VERY controllable in automatic fire. Hits were easy at ranges out to 300 yards. Fire was more effective due to the ability to walk the rounds into the target with the first three or four rounds.

The 7.92x33 is smack between the 30 carbine and 7.62x39mm. The Russians, I feel, went the wrong direction in both caliber and power. The result was the AK-47 which fired faster and was more difficult to control. Hits beyond 150 yards were difficult. The Americans went the right way with the wrong weapon in the M-16. Still, however, they made the gun fire too fast and weigh too little to be effective in full auto fire at more reasonable ranges.