Trigger stuck (could not fire), Brno 602

[gballard137]

So it’s possible because the trigger is 2 separate parts it may not be pulling the sear forward to let release the firing pin

 

[osne]

So it’s possible because the trigger is 2 separate parts it may not be pulling the sear forward to let release the firing pin

Theoretically yes, that could be it. But since it works 99% of the times, and has only failed to work specifically when I attempt to fireform 416 brass, I'm not sure.

 

[Dewald]

It sounds like some of the cases are to long for the chamber of the rifle, or the shoulders are to far forward for the chamber. The correct action would be to have it checked with a set of go/ no-go gauges

You can try to put some engineering blue on cases and chambering them, looking for where they make contact with the chamber, or if the case mouth touches the rifling.

If the case mouth is what is causing this, trimming them a bit shorter will solve the problem. If it is a headspace problem, rather go through the effort on a DG rifle and have it sorted out by a gunsmith. You don’t want a .450 Rigby that is not 100% reliable

 

[fourfive8]

Get the rifle checked ASAP by a smith who knows BRNOs/CZs. As previous posts have alluded... The one big design flaw, IMO, that so many are in denial about on these actions, is the separation of the trigger attachment from the rest of the action. Obviously one group is in conflict with the other as the mechanism goes into battery.

 

[Bob Nelson 35Whelen]

Here is a picture of the trigger on the bottom metal

View attachment 537638

@gballard137
Similar set up to the SMLE trigger. They can be affected but the screw tension and bedding as well.
I would bed the bottom metal to reduce the risk of it bending when the action is torqued down. Pillar bedding will help as well. It only take a millipoofteenth of a bend to upset the apple cart.
Headspace CAN'T affect the trigger in any way, so I would seriously look at bedding the bottom metal.
Bob

 

[Ontario Hunter]

@gballard137
Similar set up to the SMLE trigger. They can be affected but the screw tension and bedding as well.
I would bed the bottom metal to reduce the risk of it bending when the action is torqued down. Pillar bedding will help as well. It only take a millipoofteenth of a bend to upset the apple cart.
Headspace CAN'T affect the trigger in any way, so I would seriously look at bedding the bottom metal.
Bob

Head space can affect the bolt which can affect the trigger, especially if the trigger is separate from the receiver/bolt. If head space is wrong and loading a shell binds the bolt, it can take it out of alignment with trigger. I have seen this occur when undertaking my current 404 rebuild. The 30-06 barrel on the BRNO vz.24 action was not installed properly. When I loaded a couple of decapped reloads to test the action I had trouble closing the bolt and it wouldn't dry fire.

 

[Hunter4752001]

Two potential issues:
a. The Brno ZKKs had two different standard trigger pawl lengths, one for the 600/601 and one for the 602. If your rifle was tinkered with in the past it may have the wrong length.
b. Both the ZKK and the 550 did have bushings for the action screws, however unlike the other parts which were identical between the models, the bushings were different part numbers which suggests they were different dimensions. If your rifle is a ZKK fitted into a CZ550 stock, it is possible that there may be a problem in matching the trigger pawl engagement to the sears.

In either case, a dangerous game rifle needs to work 100% of the time. Take it to a smith who knows the system.

 

[gballard137]

@gballard137
Similar set up to the SMLE trigger. They can be affected but the screw tension and bedding as well.
I would bed the bottom metal to reduce the risk of it bending when the action is torqued down. Pillar bedding will help as well. It only take a millipoofteenth of a bend to upset the apple cart.
Headspace CAN'T affect the trigger in any way, so I would seriously look at bedding the bottom metal.
Bob

I agree with Bob. When the bolt is closed headspace of the brass won’t affect the trigger as the bolt is in the same position even if you don’t have a cartridge in the chamber.
It’s possible that because you have used a 550 Stock that the bottom metal and action is further apart.
Also Maybe there is another issue that ain’t related to the trigger being in 2 pieces that is being overlooked just because it is a 2 piece trigger.
Everyone has different ideas and even if we disagree with someone it’s better to voice your idea and it be wrong then too not say it and that could have fixed the issue

 

[Lance Hopper]

I have 7 of these and the only time I had anything remotely close to this, the trigger was coming in contact with the trigger guard on the underside front portion of the curve.

 

[R eight]

I had something similar happen to a 602 in 375H&H around 20 years ago. I had owned the rifle for around 10 years. I'd bought her new and had a gunsmith replace the original set trigger and do a trigger job. No issues for around 10 years. After the failure I took it into a local gunsmith and got him to have a look at it. IIRC he said that the metal had worn/fatigued for some unknown reason. He replaced it and no issues ever again.

That was the only issue that I ever had with that rifle. I had another 602 in 458Win Mag. If I used soft points I would sometimes have feeding issues. Solids worked okay. 2 trips to the gun smiths for repairs...problem not fixed. Rifle moved on. Both 602's were tack drivers.

 

[osne]

Thanks all, I really appreciate everyone’s ideas and comments - really great!! I have ordered a new trigger från American Hunting Rifles, which (due to its’ design) should fit better with the sear.

Will update this thread again once the new trigger is installed and tried out!

 

[osne]

I agree with Bob. When the bolt is closed headspace of the brass won’t affect the trigger as the bolt is in the same position even if you don’t have a cartridge in the chamber.
It’s possible that because you have used a 550 Stock that the bottom metal and action is further apart.
Also Maybe there is another issue that ain’t related to the trigger being in 2 pieces that is being overlooked just because it is a 2 piece trigger.
Everyone has different ideas and even if we disagree with someone it’s better to voice your idea and it be wrong then too not say it and that could have fixed the issue

Yes, bottom metal and action seem to be 1-2 mm further apart than when installed in original stock, and I think that may be the problem.

 

[osne]

Trigger from Wayne at AHR arrived today and is now successfully installed. The long straight top part that connects with the action sear has a better fit with the sear than the original trigger, due the slightly longer distance between action and bottom metal (an effect from the glass bedding of the stock).

The original trigger was fine 99,9% of the time, bit this new one (which actually goes into the ”keyhole” of the sear) should be 100% as there is no room for trigger to disengage with the sear).

 

[osne]

Original trigger-to-sear engagement (not my picture)

 

[osne]

Trigger-to-sear engagement with AHR custom trigger (not my picture)

 

[fourfive8]

That is good news! Hopefully that 100% solves the problem. Two things about those BRNO/CZ triggers, a question for the engineers who orinalluy designed them 1) Why put a set trigger on an obviously hunting, non-target rifle? 2) Why disconnect the two trigger parts- with one attached to the action and the other attached to the bottom metal? Both never made sense to me and never will.

 

[osne]

That is good news! Hopefully that 100% solves the problem. Two things about those BRNO/CZ triggers, a question for the engineers who orinalluy designed them 1) Why put a set trigger on an obviously hunting, non-target rifle? 2) Why disconnect the two trigger parts- with one attached to the action and the other attached to the bottom metal? Both never made sense to me and never will.

Agree with your questions 100%. These design flaws are among the very few weaknesses of the BRNO rifles. I do think however that this was changed with the release of the CZ 550 lineup that was launched after BRNO’s 600, 601 and 602 models were discontinued sometime in the 80’s or so? Not 100% sure, but I think the CZ triggers are of more traditional construction, i.e. Installed as an integrated part of the action itself?

 

[Hunter4752001]

Your photos above show that the trigger you had trouble with was the set trigger arrangement. ZKKs (600, 601 & 602) often came with two triggers, the set trigger and the standard trigger (like the one from AHR). Although I've seen several 375s with the set trigger, L'm not sure they came with them originaly. I don't believe the set trigger was supplied for the 458 version. That would suggest someone has added it latter. The trouble with 602s these days is that most have been through many hands and a great many have been tinkered with by people who should have left them alone.

 

[fourfive8]

For certain some of the BRNO 602s in 375 HH came with the set trigger from the factory. And just looked at a picture of a factory BRNO 602 in 458 Win Mag with that same set trigger arrangement. Not sure about other calibers.

The CZ 550 is a different design but does (did) come in an adjustable set trigger configuration.

The CZ Single Set Trigger System - CZ-USA

A lifetime of hunting will expose you to a multitude of situations. You will be presented with fleeting opportunities that require a quick shot and when hunting dangerous game you must be prepared for the life or death shot to stop a charge. On the other hand, most shots will…

cz-usa.com

 

[Sideshow]

@osne did you have any more issues with this 602 ? cheers ss