Measuring Lock Time of Actions...

[Bryan Blake]

As we are continuing to improve every aspect of our actions, fire control system is at our top concern as it is the number one aspect of a action that accounts for accuracy.

Here is some interesting actual data for the nerdy type like me...

As you can see, about 2 thousands of a second, or 2 milliseconds..

We are continually testing different springs, clearances, masses of firing assembly's, etc.

The yellow line is the force transducer load cell that is .003" off of the bolt face to simulate a case with .003" bump back.

 

[ISS]

Great post! Back in the day, we liked double set triggers for the light pull when set. Then we found out they slowed the lock time. Then 2 oz triggers. Now this machine of yours to measure action lock speed.

thank you very much for the testing.

ISS

 

[itchyTF]

I set something up very similar for a gunsmith friend a number of years ago. Started with a transducer but, if I remember correctly, had a problem with the firing pin hitting the hard surface. Went with a different approach that didn't "threaten" the firing pin.

 

[Bryan Blake]

The firing pin hits brass that's transferred to the load cell...

 

[rwj]

As we are continuing to improve every aspect of our actions, fire control system is at our top concern as it is the number one aspect of a action that accounts for accuracy.

What needs to be optimized to improve action accuracy?

 

[itchyTF]

I believe we considered using a "soft" metal but decided to use Zebra connector material.

 

[CharlieNC]

Cool! I can't make out that frequency but it looks very fast.. Is it from spring vibration?

 

[itchyTF]

Part of it might be bounce.

 

[marazzi59]

If you can share this, what has made the worst difference and what made the best???
Thanks

 

[Bryan Blake]

If you can share this, what has made the worst difference and what made the best???
Thanks

I have been testing lots of actions and designs from multiple manufactures, here is what I can tell you in my testing that causes potential energy (cocked position) to have less energy converted to kinetic energy (firing pin hitting the primer):

Excessive clearance between the bolt shroud and the firing pin.

Miss-alignment on the bolt bores, meaning the bolt bores are not concentric to the bolt shroud, therefore causing miss-alignment in the firing pin to the bolt bores, causing drag and binding. If an action has any contact of the spring OD to the bolt ID, will cause issues.

Any dragging of the cocking piece to the bolt shroud, including but not limited to, if the action has a cross pin that is dragging on the bolt shroud.

Straightness of the firing pin is a big factor.

If the bolt shroud is not hardened enough where the firing pin rides, and if the firing pin is not 40-42 RC, it will cause increased friction, therefore drag.

Higher pound springs only do one thing when they are heavier than needed, they are only trying to overcome friction of the fire control system. Lock time does not decrease on a nearly friction free system, after about 20 lbs of spring on the seat force (generally 22-23 in the cocked position).

Heavier firing pins greatly reduce lock time and the energy transferred to the primer when they get too heavy.

 

[marazzi59]

Sorry if I'm ignorant to this but do you build actions or are you a hardcore hobbyist like most of us here?

 

[Bryan Blake]

Sorry if I'm ignorant to this but do you build actions or are you a hardcore hobbyist like most of us here?

I would say both .

 

[marazzi59]

What actions do you build, or company you work for??

 

[Bryan Blake]

fclassproducts.com

 

[Rank Amateur]

Bryan,

Thanks for presenting data. Always interested in actual data more than (or at least as much as expert) opinion. I’m at a bit of a loss to directly interpret the traces provided as there is/are no reference/units shown. Does the display normally show a scale in either the vertical or horizontal? I.E., what permitted you to determine that the lock time was 2 thousandths of a second? I also presume the amplitude of the oscillations shown is proportional to the force measured? Again, what scale permits interpretation?

Many thanks!

 

[marazzi59]

On the list you made about what works, I assume that's a general list for most actions. Any actions require something different or do any actions respond poorly to what normally works

 

[Bryan Blake]

On the list you made about what works, I assume that's a general list for most actions. Any actions require something different or do any actions respond poorly to what normally works

Striker firing pin systems are pretty universal on what is most accurate and what doesn't, etc.

 

[ern.santos]

Very cool to see some of the equipment I use on the job find it's way to gun stuff. Did the load cell have a bridge network built in, or is that on a separate board that's not in the pic? It's also interesting to see the firing pin bounce frequency decay. I wouldn't be surprised if the fundamental frequency changes with different spring weights and firing pin configurations.

By just eyeballing the trace, it looks like the bounce decays to a stop at around 220 - 230 ms after making contact with the the bolt face.

wouldn't be surprised if it's from Interface out in Scottsdale. I used a bunch of their stuff at a previous gig.

 

[Webster]

As we are continuing to improve every aspect of our actions, fire control system is at our top concern as it is the number one aspect of a action that accounts for accuracy.

Here is some interesting actual data for the nerdy type like me...

As you can see, about 2 thousands of a second, or 2 milliseconds..

We are continually testing different springs, clearances, masses of firing assembly's, etc.

The yellow line is the force transducer load cell that is .003" off of the bolt face to simulate a case with .003" bump back.


View attachment 1589197View attachment 1589199

Can the trace detect any problems like excessive rubbing due to clearance problems.

 

[whatsupdoc]

Here is something that you might test. I always wondered if bolts with pinned
bolt heads dampen the firing pin impact and slow down the firing pin.