Diana 34 observations on pellet to breech fit

[outdoorman]

Checking the fit of JSB Exact Jumbo 15.89gr .22 cal pellets in my Diana 34. First photo shows how the bottom of the pellet is slightly raised above the breech surface with pellet just pressed in with pellet pen or finger. Second photo shows slight deformation to this area of the pellet when the barrel is closed. Third photo is the same pellet after being pushed through the barrel and then reinserted in the breech. This shows that the skirt is nearly reformed to original and I suspect that with compression from actual firing that it completely reforms the pellet. Also, these barrels are choked so that helps to reform the pellet skirt. Last photo shows a pellet that I pushed through a 5.55mm pellet sizer. Even though the pellets are supposed to be 5.5mm, I measure them with calipers at 5.70mm Sizing the pellets to 5.55mm causes the velocity to drop by 15fps Think I will not worry about the slight deformation of the skirt as it seems to have no effect on accuracy and gives maximum velocity. I know some people like to use a pellet seater and I have done that as well but this can significantly affect velocity depending on how far you seat them. I was surprised at the 15fps difference with the slightest of difference in seating depth. I've noticed variations with different tins of these pellets where one tin will have relatively thin skirts and others thicker as you can see in the last photo. Four pellets from one tin on the left and another tin on the right.

 

[Chachoze]

You should use a pellet seating tool to seat the pellet flush with the bottom of the breech which should prevent the pellet getting damaged when the breech closes.

Experiencing a loss in fps when you pellet sizing tool to make your pellets uniform in size is common especially if you are sizing them down greatly, The sizers will collapse the skirt inward to fit the sizer, Since the skirt has been scrunched down it isn't able to build as much back pressure in the breech before traveling down the barrel. Some air rifles are ok with this, other not so much.

 

[Skillet]

I’ve fixed this problem before by chamfering the breech just a haze. Remove just enough metal to easily seat just below flush.

 

[sonny]

Might just be the picture but the breech looks a little jagged too in the lower right quadrant

 

[seven08]

As was told here recently my new 34 .22 has a looser pellet fit than my old one. The photo shows the JSB pellet position as dropped into the breech and seated by gravity. No press engrave needed at all like my older 34 requires. I use a rounded golf pin to lightly seat it or else it will fall right out with a tap if rifle is turned pellet down. The rifle is very accurate even though this may be a manufacturing flaw.