Trigger stuck (could not fire), Brno 602

[osne]

Has anyone else ever experienced that after closing the bolt on a Brno Zkk-602 (or a 600), the trigger gets stuck and is impossible to pull (i.e the firning pin doesn’t release and the cartridge therefore can’t be fired)?

I experienced this today in my 602 which is a 450 Rigby, re-chambered from the original 458 win mag.

I should say that i was using re-sized 416 Rigby brass, that I wanted to fire form. Some fired as expected and were fire formed to perfect shape. But after closing the bolt on some of the cartridges, the trigger simply couldn’t be pulled (it went stuck).

I suspect that the slightly different dimensions of the 416 brass cases somehow caused tension/pressure on the bolt, in a way that somehow interfered with the trigger and/or bolt mechanism… but I can’t figure out exactly WHAT / HOW the problem was caused from a technical point of view?

I recall having occasionally experienced the same issue with my Brno 600 in 30-06, when using standard 30-06 brass.

Anyone else who has experienced the same, or have any thoughts on how it can be explained?

Again, it only happens sometimes… could it be that the Brno trigger-/bolt mechanism is very sensitive to cartridge dimensions, so that the trigger somehow gets stuck even if dimensions of the brass are within what should be tolerable dimensions?

 

[osne]

Trying to figure this out while enjoying a proper cigar by the way

 

[deewayne2003]

One thing to consider - the 602 trigger mechanism is mounted to the floor plate/trigger guard assembly…. Hence, the pressure of the action screws can affect the trigger.

I would suggest checking the stock bolts are torqued correctly.

 

[Ontario Hunter]

Uh oh. You better have someone check the head space with go - no go gauges. I would have that done before firing it further.

 

[Ontario Hunter]

One thing to consider - the 602 trigger mechanism is mounted to the floor plate/trigger guard assembly…. Hence, the pressure of the action screws can affect the trigger.

I would suggest checking the stock bolts are torqued correctly.

Good advice considering the design. How is it bedded?

 

[R.M.C.]

Can't help you with your problem but had to comment on that gorgeous ashtray, I've got something similar being made by Amara taxidermy in South Africa. Mine is from a zebra leg. Beautiful.

 

[osne]

One thing to consider - the 602 trigger mechanism is mounted to the floor plate/trigger guard assembly…. Hence, the pressure of the action screws can affect the trigger.

I would suggest checking the stock bolts are torqued correctly.

Thanks for posting your reply, @deewayne2003. I think you may be on to something here. Could very well be related to the somewhat special design of the Brno's trigger being attached to the floor plate rather than to the mechanism itself. I suspect that even a minimal deviation in brass dimensions could result in the mechanism being moved ever so slightly off position versus the floor plate mounted trigger, and that the perfect connection between the two being affected as a consequence? The torque seems correct, but I suspect the above reasoning may still be the cause.

 

[osne]

Good advice considering the design. How is it bedded?

@Ontario Hunter - it is glass bedded all the way (from fore-end of the stock through both the front- and rear mounting points of the action).

 

[osne]

Can't help you with your problem but had to comment on that gorgeous ashtray, I've got something similar being made by Amara taxidermy in South Africa. Mine is from a zebra leg. Beautiful.

Thanks @R.M.C. ! Yes, I love it. It was made from one of the fore foots of my 2020 buffalo bull (hunted with Ernest Dyason from @Spear Safaris ), by Trophy Solutions in Limpopo. I hope your zebra tray comes out very nice!

 

[Ontario Hunter]

@Ontario Hunter - it is glass bedded all the way (from fore-end of the stock through both the front- and rear mounting points of the action).

Hmmm. That sounds odd even if the receiver and trigger are separate entities. Everything should be adequately anchored. Again, since this a rechambered barrel, you trusted head space was checked before the gun went back to you. Can't hurt to have it checked. Do you have a custom stock on the gun? Aftermarket trigger?

 

[deewayne2003]

@Ontario Hunter - it is glass bedded all the way (from fore-end of the stock through both the front- and rear mounting points of the action).

If you want to make sure the floor plate is consistently torqued you need pillars in that bedding if they are not already present.

If you wanted it bomb proofed, I would do cross bolts and pillars.

Also I would consider Graycliff cigars; especially the 30yr Vintage reserve.

 

[gballard137]

The trigger that interlocks with the sear that releases the firing pin may be too short or may get stuck and can’t be pulled. Does the trigger have a spring that keeps tension on the trigger?

 

[John Wasmuth]

Measure the fired cases vs the cases that wouldn’t fire. Sounds like your bolts not closing all the way.

 

[gballard137]

Here is a picture of the trigger on the bottom metal

 

[DWB]

Just to make sure? Did you maybe re-install it and it did not go where it should?

Also have a ZKK602 in 450 Rigby without issues.

Did you not maybe bump the safety slightly forward?

Best mod on mine has been a Mod70 type safety!

 

[osne]

The trigger that interlocks with the sear that releases the firing pin may be too short or may get stuck and can’t be pulled. Does the trigger have a spring that keeps tension on the trigger?

It is not too short, but I am fairly sure that the interlocking between trigger and sear (as mentioned in your comment above) is where the problem lies. What I can’t figure out is why only some cartridges seem to cause problems (trigger mechanism is a long way from the chambered cartridge)?

 

[osne]

Just to make sure? Did you maybe re-install it and it did not go where it should?

Also have a ZKK602 in 450 Rigby without issues.

Did you not maybe bump the safety slightly forward?

Best mod on mine has been a Mod70 type safety!

Safety is a mod70 3-position on mine to

 

[osne]

The trigger that interlocks with the sear that releases the firing pin may be too short or may get stuck and can’t be pulled. Does the trigger have a spring that keeps tension on the trigger?

Yes, it is the original brno trigger which does have a spring

 

[gballard137]

Yes, it is the original brno trigger which does have a spring

Is it the original stock?

 

[osne]

Is it the original stock?

The stock is actually an standard CZ550 stock, so not quite original for the Brno 602 (but almost)