problem with bumpfire...


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mystery
March 31, 2010, 09:20 PM
hello, i joined this forum because i need your help. i was shooting with my friend in his farm and everything was normal untill i bumpfire my ak-74, for some odd reason the bullets ended hitting the target sideways. This is the first time something like this happen, i have shot about 300 rounds with it very accurate from 100 and 200 yards, hitting center mass with no problem, untill my last 20 rounds that i bumpfire for fun at 15 yards from the target, and anyone explain why this happen? BTW the rifle is century build :scrutiny:

http://img149.imageshack.us/img149/6452/0331101829.jpg

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Shear_stress
March 31, 2010, 09:22 PM
Barrel overheating, most likely. Makes bullets squishier.

mystery
March 31, 2010, 09:25 PM
i run like 2 mags in 5 mins....

Shear_stress
March 31, 2010, 09:27 PM
i run like 2 mags in 5 mins....

You said you had already been shooting the rifle for some time before you started bump firing. Also, is this a Tantal?

mystery
March 31, 2010, 09:31 PM
no, it's not a tantal, it's a US made barrel/receiver and bulgarian parts.

Shear_stress
March 31, 2010, 09:35 PM
Besides heat, bumpfiring could have loosened up the muzzle device.

Sam1911
March 31, 2010, 09:36 PM
There have been stories floating around that many of the US-made AK-74 barrels were made to the US ".22" standard (.224") instead of the Soviet .220" standard. The oversized condition can cause key-holing because 5.45x39 mm ammo isn't .224".

If you're SURE that you were getting perfect strikes in slow fire and only got keyhole strikes while firing quickly, that's a new one on me.

Jacketed bullets do not get squishy from excess barrel head from rapid firing -- but that's a pretty funny answer! :D

I'd contact the manufacturer and explain your problem. Some have fixed the problem, if what I've read is true, but it requires a new barrel.

Shear_stress
March 31, 2010, 09:46 PM
Jacketed bullets do not get squishy from excess barrel head from rapid firing -- but that's a pretty funny answer!

No they don't ;) but hot barrels will cause keyholing in full autos.

HB
March 31, 2010, 09:52 PM
bumpfiring could have loosened up the muzzle device.

This makes the most sense to me. I would give it another test before spending any time and money.

HB

Sam1911
March 31, 2010, 10:37 PM
Might want to read the last few posts in this thread:

http://www.thehighroad.org/showthread.php?t=491989&page=2

Uncle Mike
March 31, 2010, 11:27 PM
many of the US-made AK-74 barrels were made to the US ".22" standard (.224") instead of the Soviet .220" standard. The oversized condition can cause key-holing because 5.45x39 mm ammo isn't .244".

Well there it is....

Also, some of the 5.45 ammo coming in lately is said to have "bad bullets"....we took some of this 'bad bullet' ammo back from a customer who had similar results, while we did not do any exploratory surgery on the remaining rounds, the customer said he pulled some apart, halved the bullets and of the batch he did, not one core weighed the same or had the same length cores....don't know, but that was his explanation!

PS. the ammo we sold was almost 2yrs old, manufactured in August of 2008 IIRC.

jmorris
April 1, 2010, 09:29 AM
I'd contact the manufacturer and explain your problem.

They will say bumpfiring is your problem, stop it and problem solved.

Sam1911
April 1, 2010, 10:33 AM
They will say bumpfiring is your problem, stop it and problem solved.


I don't believe I'd mention bumpfiring. Simply that the rifle is keyholing.

A rifle that was originally designed to fire full-auto should be able to maintain reasonable mechanical accuracy (not have the bullets destabilize in flight, at least!) at any achievable rate of fire.

Bumpfiring is silly and a waste of ammo, sure, but if there is a problem with the barrel the manufacturer should fix it -- not give you a song-and-dance about silly uses "causing" the problem.

627PCFan
April 1, 2010, 10:54 AM
Maybe undercharged cases? Not enough velocity to stabilize, but still enough to get down the barrel?

Jeremy2171
April 1, 2010, 11:18 AM
Is it still accurate now (slow aimed shots)or does this happen all the time now...

Shawn Dodson
April 1, 2010, 12:48 PM
Have you ruled out that your bullets aren't hitting the ground in front of the target and then ricocheting into it?

Strahley
April 1, 2010, 01:05 PM
Stop bumpfiring

What do I win?

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