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A little physics question on velocity

612 Views 10 Replies 9 Participants Last post by  Elkein
Do blow-back style auto's sacrifice any fps/velocity due to the type of action? If you put a 10/22 next to a bolt action and all else being equal would the bolt shoot faster?

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The Perferator,

The prevailing thinking, and most 'data' out there, would say that the bolt action rifle will have a slightly higher velocity than the semi-auto rifle, everything else being equal [barrel length, ammo, etc.]...! ! ;)

However, everything else isn't equal, in that the semi-auto has a 'sloppy' chamber for reliable functioning; the bolt will have a fairly tight [not match] chamber...! ! :eek:

The idea that the moving bolt causes a loss in velocity is an old wives tale, as the bullet is long gone before the bolt begins to open...! ! ;)

So, to do a 'valid' test, one would have to have two rifles with identical chambers...! ! ;)

Until that test is run, you are 'safe'* is saying that the semi-auto looses some [ < 25 fps] velocity to the bolt action, on the average, over dozens of rifles...! ! :)

[ * No one can come up with 'data' to prove you wrong...! ! :D ]
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To do a valid test you would need a semi-auto rifle and a bolt that would take the same barrel. Head space would have to be the same on both. Not to hard so far. Then you would need ammo that would be consistant enough to not " hide " the difference between action types. Thats the hard part.
I *think* I'd read somewhere that someone said 50 FPS difference as opposed to what BigMike said, ...however... the difference in the two figures isn't that uncommon to see between one round and the next in a normal box of shells(25fps), so either way, it is statistically insignificat.

One way or the other, the answer is yes, but not by much.

Interesting piece of science :) I'll keep my 10/22 AND my bolt action .270!

The fact that the case and bolt are using SOME of the pressure (potential velocity) to move rearwards means you MUST lose SOME velocity from the bullet.
How much???
I have no idea. Could be the 25-50 fps that's already been mentioned. COULD be more or LESS.
If you could find a way to lock the bolt CLOSED on a semi auto you could find the exact amount.(After MANY hundreds of rounds) I don't know of a way to do that though.

Does'nt Ruger offer a 96/22, a lever action? If they do, then there we go. Interchangable barrels and a locking bolt. Now who has both and some free time>????
Big Mike is right, the only exception is subsonic ammo. As much as I wiggle, I dare not shoot slow stuff.:rolleyes:
Doesn't somebody make a device for shooting the 10/22 in a "bolt-action" style mode? I think it is just a lever of some kind that flips onto the bolt handle to keep it closed. I can't remember where I saw it, or if is was for the 10/22 (but I am pretty sure it was).

I know this isn't much, but I found a message on google groups while looking for the bolt locking device:

<http://groups.google.com/[email protected]#link4>

There is no data provided, but this guy claims he gets the same velocity with the bolt locked closed. Interesting, thats all.

Don't make this too difficult for your own good folks... Hold the bolt on your 10/22 forward with your thumb see if it makes a lick of difference. ( Yes I've done it, it's not that hard to hold the bolt in place on the 10/22... don't try this with a gas operated centerfire gun though unless you want a broken thumb. )
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