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Old August 23, 2005, 04:38 PM   #1
Para Bellum
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Over/under-double barrel only opens rough-runnig after firing 00 buckshot

My TOZ 34 EP (pic below) opens fine after firing birdshot after clay pigeons.
I now tried 00 Buckshot with it.
After firing buckshot, it's pretty tough cracking the barrels open.
It needs a lot of more force.

Is this due to the fact that this is a cheap and 30yrs old gun (with yet only approx 200 shots fired). Or is this a general 00 Buckshot-thing. Maybe because the higher force of the load presses the back of the cartridge much stronger to the firing-pin-plate?

Thanks for you time and thought.

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Old August 23, 2005, 05:25 PM   #2
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CHECK the shells! If they are splitting, DO NOT USE THE GUN UNTIL A GUNSMITH HAS CHECKED IT!
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Old August 23, 2005, 05:56 PM   #3
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Shells show no cracks (pics), data of ammo used

thanks Death from Afar. I kept the shells, can't find any cracks (pics below).
I received that gun as a present after it hadn't been used for 30 years.
Therefore I had it tested at the proofhouse (C.I.P.) before I shot it. It passed the tests.

Should a normal over/under double-barrel open smoothly even after firing 00 Buckshot?

The Datasheet of the buckshot ammo used is linked here





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Old August 23, 2005, 06:27 PM   #4
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It may be the base of the shells is swelling enough when firing that they are sticking in the chambers. Will they push back in easily and close, or are they really tight. I would guess that it is steel based shells that don't shrink enough after shooting.
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Old August 24, 2005, 03:00 AM   #5
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kudu

thank you for your post:
Quote:
It may be the base of the shells is swelling enough when firing that they are sticking in the chambers. Will they push back in easily and close, or are they really tight. I would guess that it is steel based shells that don't shrink enough after shooting.
so, i guess it's ok?
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Old August 24, 2005, 03:51 AM   #6
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I would suggest using another shotgun for buckshot!
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Old August 24, 2005, 07:26 AM   #7
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Ummm....Older guns often have short chambers. What length chambers are in the gun?

You might have 2 3/4" chambers and the slugs are 3" !

It looks like the mouth of the fired shells are not completely open.

Remember, the chamber length must equal the length of a FIRED shell!!!!

IIRC 2 3/4 equals 70MM, 3" equals about 76MM

The shells have a marking of 8,6MM!!!!


I would cease and desist firing the particular brand of slugs in that gun.
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Old August 24, 2005, 11:32 AM   #8
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You need to stop firing those shells immedeatly. Those are at least 3 inch shells and I'll bet you anything that chamber is for 2 3/4 only. It should be engraved on the barrel close to the reciever.
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Old August 26, 2005, 05:06 AM   #9
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2 3/4 vs 3", The shells fit to the gun

Quote:
You might have 2 3/4" chambers and the slugs are 3" !

It looks like the mouth of the fired shells are not completely open.

Remember, the chamber length must equal the length of a FIRED shell!!!!

IIRC 2 3/4 equals 70MM, 3" equals about 76MM

The shells have a marking of 8,6MM!!!!


I would cease and desist firing the particular brand of slugs in that gun.
Thanks guys, but: It is a 67,5mm (2,75" gun) and the buckshotshells used fit, they are 67,5mm shells:



The 8,6mm indicates the shot diameter.

So, what could be the problem? Do your over-under guns also open as unwillingly after firing 2,75" 00 buckshot?
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Old August 26, 2005, 06:34 AM   #10
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Is the weight of the birdshot and buckshot the same ?
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Old August 26, 2005, 06:49 AM   #11
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mete, buckshot is 33,2% heavier...

no way. The Buckshot weight is: 515gr (33,2g) and the birdshot weight is 387gr (25g). So the buckshot is 33,2% heavier...
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Old August 26, 2005, 06:55 AM   #12
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Looks like high brass, which usually means a higher dram rating than target loads. Does the box indicate a dram equivalent, or give the pressure of the shell?

OK stupid me, I just read the data sheet, which naturally does not show US SAAMI data.

The shells obviously have more power than normal target loads, and may be deforming the brass base more than normal.

Check the primers after firing, are they protruding out of the pocket? Even an ever so slight protrusion can affect opening in doubles, particularly the bottom barrel in O/U's.

Try a different brand of buckshot!
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Old August 26, 2005, 07:35 AM   #13
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yes, these shells are pretty much stronger than target loads. The primers however are plain with the shell bottom. Maybe the bottom of the chamber needs do be cleaned and greased a little. Could simply be too much friction after the strong load gets pushed back.

Did any of you experience the same problem?
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Old August 27, 2005, 02:08 PM   #14
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I experienced the same problem with a single shot I really liked. cheap shells shot would not eject after firing but you could remove them easily enough. higher quality shells with more power would really stick and would require prying with a knife for 10 minutes to get them out. I cleaned the barrel really well several times and especially scrubbed the area where the shell opens in the barrel, oiled it well, and have not had any further problems.
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Old August 28, 2005, 04:56 PM   #15
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Difficult opening of a break action firearm can be a sign that the cartridge that has been fired developed a higher pressure than the arm was designed to use. Check the pressure to which your gun has been proofed.

The Data sheet you've provided shows that the cartridges you've used develop a mean maximum pressure of 740 bar, (10,700+ psi, though the testing methods of the CIP differ somewhat from those of SAAMI). Many European shotguns are designed to use ammunition developing about 480 bar (7000 psi). (It may surprise some North American readers, but there is very little, if any, difference in the performance of shotgun ammunition to be gained through this increase in pressure).

Please, for your own safety, do not oil or grease the chambers. This will markedly increase breech thrust, that is, the cartridges will not, as they expand, secure themselves in place in the chambers. Rather, if used in oiled chambers, the cartridges will hammer the breechface- even in very strong guns this can lead to cracked actions and other problems.

Bob
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Old August 29, 2005, 03:56 PM   #16
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Thanks everbody for your kind advice!
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