Loss of accuracy using a bayonet...

[Shane Tuttle]

I just wondered if there's truth to loss of accuracy firing your rifle with a bayonet attached. I'm mainly talking about older military rifles such as Mausers, etc.
My second question is what exactly causes it?

My guesses were:
1. when the bayonet is attached, the mounting ring being affixed to the end of the muzzle does not allow the barrel to move naturally during bullet travel inside the gun.
2. The concussion by the bullet rebounds off the bayonet, pushing back on the bullet. Kinda like how an aircraft flying close to the earth is provided extra "lift" called ground effect.

Any clarification is kindly accepted.

 

[Shane Tuttle]

Should this thread be in the Art of Rifle?

 

[Bud Helms]

Yup. Here we go.

 

[bennnn]

I would call it more of a change in POI when certian bayonets are on/off or in/out instead of a loss of accuracy.. If you are wondering about a particular rifle,, do some tests with the bayonet on and off, (or folded/unfolded) about 100 rounds of each should tell you everything you need to know about the way that one rifle will perfom.
Here comes the M-44 infantry to back me up......

 

[Jimro]

Barrel vibrations have a lot to do with accuracy.

Mounting a big old knife on the muzzle of your barrel affects those vibrations, and therefore changes accuracy. In some old rifles, like the M44, it normally has a positive effect in tightening groups. Some old school target barrels had a nearly unturned portion of barrel right next to the muzzle to keep the muzzle on target when the rifle round was touched off. Kinda cool to see a barrel taper down a bit but have a knob on the end, I think Lothar Walter still offers that contour.

Anybody who has played around with a xylophone knows that different lenghts and masses of metal produce different frequencies when struck. A hollow steel rod (such as a rifle barrel) will vibrate in a figure 8 pattern, a long lobe and a short lobe intersecting at one point. Adding mass changes the frequency.

The point of vibration where the bullet leaves the vibrating muzzle has a lot to do with accuracy. A load that always seems to have horizontal stringing is probably leaving the barrel during the long lobe portion of vibration with double digit variation in fps. As a side note this is why many benchresters swear by short stiff barrels, they vibrate at higher frequencies. Considering the low impulse power of most benchrest rounds (by comparison only to other modern cartriges) a low amplitude at high frequency would result in very small movement at the muzzle.

But back to the figure 8 movement at the muzzle.

A load that varies in the double digits in fps, but consistantly groups tightly is probably leaving the barrel during the short lobe since the muzzle is actually moving less in either the X and Y axis than on the long lobe. This is what Dan's "Optimal Charge Weight" loadup tries to find, a load that consistantly exits on the small lobe.

Hope this explains things a bit.

Jimro

 

[4EVERM-14]

Accurate rifle are consistant in their vibrations and barrel oscillations during firing.
Loose fitting appendages [bayonets] upset that consistancy.
Flyers occur or large shot groups result most of the time.

 

[Shane Tuttle]

Jimro,
That was one heckufan explaination!
Thanks.

 

[Scorch]

Bayonets and other attachments can affect POI and accuracy due to their weight and the fact that they are not attached very tightly, as mentioned by another poster.

Barrels with a taper and a larger diameter portion on the end are called "running boar" barrels, because they are used (mainly in Europe) in moving target shooting events called running boar shoots. They typically have a damping on movement by the shooter, providing for a very smooth swing on the target. In this type of shooting, you are not allowed to use outrigger stabilizers, as used on some target rifles, so the barrel functions well for that.

 

[Mannlicher]

frankly, if you are in a situation where you really need to 'fix bayonets', then accuracy would be about the last thing on your mind. If you can't hit your target at a couple of feet, then you are screwed anyway.

 

[Shane Tuttle]

If I was in the war back then, I don't think I'd wait until I can tell the eye color of the enemy before I "fix the bayonet".

 

[Mike Irwin]

I have a type 38 Japanese Arisaka.

With the bayonet dismounted it tended to shoot 3" groups about 4" high at 100 yards.

With the bayonet mounted and the same ammo, the groups open to about 5" and they shift down about 2" and to the left about 2 inches.

 

[Eghad]

When you fix bayonets I dont think long range shooting is in the plans..

 

[Shane Tuttle]

Understood, but my point to the question is soldiers still had to fire their weapon with bayonets affixed. Don't think I'd get an arguement there. So, I just wanted to know the truth in accuracy or inaccuracy, that's all. And, like Mr. Irwin pointed out, the groupings are much different at even 100 yards. To me, if I was in the war back then, I'd want to know how my rifle shot in both scenarios. With that, accuracy would be the FIRST thing in mind.

 

[hksigwalther]

IMO, only one way to find out for sure. Go out, get a rifle that accepts a readily available bayonet, get the baynoet, run the test yourself. (Any reason is a good excuse to buy a firearm.)

(Tried it with my MN M44, no change in anything despite other folks saying they've seen some changes in POI. Surplus ammo.)

 

[Limeyfellow]

This was one of the reasons why after WW1 they started designing rifles with much shorter bayonets as those 18 inch things would really cause the point of impact to shift substantially (up to several inches at a 100 yards). Didn't have much impact on your windage though. The later bayonets have a much lesser effect of only a few inches shift.

Some rifles like the Russian Mosin M44 carbine were even designed to be fired with the bayonet out and if you have the bayonet stowed away it will effect the poi off where it should be.

 

[Scribe]

The Imperial Russian army didn't worry too much about bayonets changing POI because standard practice was to have the bayonet fitted at all times, even to the extent that they frequently did not issue a scabard. After the revolution bayonets bacame the victim of political correctness because Lenin described the bayonet as ' a weapon with a worker on either end.'
I am told this is one of the reasons why the M.38 Mosin Nagant had no provision for one. Then close quarter experience in the Great War Patriotic War showed that this political correctness placed the Communist worker at something of a disadvantage to the Fascist worker. Hence the M.44.