Break Barrel Pivot Stability

[Roadworthy]

Dealing with Crosman/Benjamin rifles one soon learns how critical the washer thickness is to the stability of the barrel.  Last week I dismantled my Diana 34 for the first time and found a major difference.  The Diana 34 pivot sleeve extends through the barrel block and into the forks on both sides.  The barrel is supported by this sleeve.  The washers only prevent side play - they don't actually stabilize the barrel.  Since the sleeve goes all the way, Diana uses a nut on one end of the pivot screw rather than having a threaded fork as Crosman does.

The Crosman sleeve only goes through the barrel block relying on the pivot washers to take up side slack like the Diana but unlike Diana these washers must also prevent any other movement of the barrel.  In other words Crosman's washers must completely stabilize the barrel - a chore handled by Diana's sleeve.

I had never seen anything with this bit of information.  That would certainly explain the stability of German barrels.  It's not the washers at all.

[Artie]

I assume you're referring to Crosman's design based on the B19 platform. I agree the RWS is a better design. Not only does the Crosman (I own two) B19 pivot not extend into the fork, there is quite often excessive clearance between the sleeve and bolt.

I have  lined my sleeve's with a rolled brass shim to tighten the clearance which corrected much of the vertical stringing. After polishing the pivot block side shim recess's I made/polished steel washers to replace the plastic ones. An additional .002" sacrificial brass shim is added to each side to further reduce side to side movement. Those can be replaced as they wear. The washers on the left side must have an inside diameter large enough to clear the pivot sleeve on these guns and thick enough to prevent the sleeve from contacting the fork. Otherwise a tightened pivot bolt will always untighten after a few cocking sessions.

Inside the forks, beside the breech and on each side I epoxied small squares of shim to absolutely prevent pivot/barrel side to side movement in the locked position.

Speaking of lock up, I filed the back edge of the locking pin pivot slot to slightly extend the pin for a much improved lockup. A 1/32" thick washer was also inserted into the back of the pin to add a bit of preload to the lock pin spring. Any issues I have with the guns now have nothing to do with lockup and the pivot design. And I do have some issues...

Good barrels are hit or miss as far as land/groove uniformity. Sometimes that can be worked out over time or with some selective polishing.

I like the lightness of the gun but for me, the lightness demands a disciplined artillery hold. A heavy scoped negatively affected my accuracy, making it top heavy and off balanced, even with very low scope rings.

Personally I think these guns would be great open sight hunting rifles because of the weight. A lightweight scope would also be helpful. That's what I'm currently experimenting with. That and a Merlin XL spring. Both are now about 11 fpe shooters. De-twanged and de-fanged.

[beachgunner]

Hi Tom. As you know, I can't even get my NP2 pivot bolt to hold the same tension any longer. I've given up even trying to thread lock it again.

You bring up a great design difference in these companies and their philosophies. I wish Crosman would adapt the German springer way of securing the pivot.

I have adjusted my bolt ONCE when I got my HW95 and that was the only time in 9K shots and cycles of opening and closing the barrel. That speaks volumes about the difference.

The funny thing about this is how much would it cost Crosman to just mimic this design? Fifty cents? A dollar? Yet they continue to let their customers get frustrated.

Excellent info and a great topic to bring up.

[avator]

What's more.... I picked up a Ruger Explorer Jr. rifle at the pawn shop. It sells new on Amazon for $53 shipped. It even has the sleeve pivot design. Come on Crosman... get with it.

[beachgunner]

What's more.... I picked up a Ruger Explorer Jr. rifle at the pawn shop. It sells new on Amazon for $53 shipped. It even has the sleeve pivot design. Come on Crosman... get with it.

Does it really? Oh man, that's embarrassing for Crosman.

Umarex makes Ruger branded air guns?? Once again, Germans making it correctly or not at all.