Defiance Tenon Dimensions on their Prefit actions

[Longtine88]

For the life of me I can't believe someone has not took their "Guarantee 0.001" tolerance and challenged it with their actions. So I think from here on out I'm going to start recording all their prefit actions and note their dimensions in a spread sheet and try to get some kind of standard base line that their lawyers won't give out. Aggravates me to for some reason. So I am going to start measuring my actions and recording every one their dimensions. Has anyone here done it yet or am I the first. It would be hard to believe I'm the first. They will look something like this one when I'm done.

 

[WeiserBucks]

Every reputable gunsmith I know records the relevant dimensions of every single action and barrel they touch.

 

[Bob Wright]

So the barrel supplier and the receiver supplier are going to split the +/-.001 tolerance to arrive at that number. That's really good machining between numerous machine shops in play for chambered barrels and an action they don't have access to.
You must be from the "show me state"!
I will be interested as well. The mechanical drawings are good too.

Good on them if they do it. They should be keeping records of the critical dimensions to arrive safely on that assurance.

 

[adk hunter]

Ok. Love the details. May not have the skill set to follow this deep into this rabbit hole but...

My question is, at what ten thousandth or hundredth does it start to matter? I bought a prefit here and when fit properly the cartridge engraving is ever so slightly too low to be fully read. All gauges, factory ammo and handloads work and it shoots lights out.
I am sure a real gunsmith could attend to this in various ways and measure which part or parts are off but I can tell you the joy of not having to be at the mercy of a gunsmith is freeing. Did I just have a barrel chambered and assembled by an amazing 'smith? Oh yeah! Are incredible actions and prefits here to stay? 1,000%
Thanks for the info Longtine88.

 

[khmplus]

From the Defiance website, the .001" is in reference to headspace, not every dimension, as I understand it.

 

[Longtine88]

From the Defiance website, the .001" is in reference to headspace, not every dimension, as I understand it.

Agree but there are key measurements that could affect their .001" guaranty ultimately in the end.

 

[WeiserBucks]

Agree but there are key measurements that could affect their .001" guaranty ultimately in the end.

They guarantee their product to .001", they have no control over the tolerances of a prefit or custom fitted barrel supplied by any manufacturer or gunsmith.

 

[khmplus]

From the Defiance website:

Defiance is a manufacturer of high-quality bolt-actions. Because of the bolt and receiver combination in the Tenacity (with integral lug) action we can achieve headspace consistencies of +/- .001" action to action. The decision of a builder to use a Defiance action with a barrel designated as "pre-fit" is the decision of the builder. On our actions that have a guaranteed headspace we can maintain this consistency, but have no control over the quality and consistency of barrel manufacturers or gun builders' machining abilities.

Pre-fitting a barrel is possible, but only when you have consistently machined actions, and an equally precise chambering of barrels. Defiance's position on pre-fits is; if you choose to use pre-fit barrels on our actions, you should only do so if final fit up is done by a reputable gunsmith to insure proper headspace and fit.

 

[Longtine88]

They guarantee their product to .001", they have no control over the tolerances of a prefit or custom fitted barrel supplied by any manufacturer or gunsmith.

Agree to that also. I'll post another one tonight and show what I am talking about. Other measurements on their action that puts their guarantee out.

 

[Bob Wright]

From the Defiance website:

Defiance is a manufacturer of high-quality bolt-actions. Because of the bolt and receiver combination in the Tenacity (with integral lug) action we can achieve headspace consistencies of +/- .001" action to action. The decision of a builder to use a Defiance action with a barrel designated as "pre-fit" is the decision of the builder. On our actions that have a guaranteed headspace we can maintain this consistency, but have no control over the quality and consistency of barrel manufacturers or gun builders' machining abilities.

Pre-fitting a barrel is possible, but only when you have consistently machined actions, and an equally precise chambering of barrels. Defiance's position on pre-fits is; if you choose to use pre-fit barrels on our actions, you should only do so if final fit up is done by a reputable gunsmith to insure proper headspace and fit.

And that's how they can declare their actions are suitable for prefit barrels. The "headspace" mentioned above requires a chambered barrel. That then requires a gunsmith to perform a final fitting of the 2 components which may require final machining.
I would think barrel manufacturers of prefits will leave the barrel critical fit ups slightly biased to guarantee it will need machining to finish the headspace.

 

[biednick]

And that's how they can declare their actions are suitable for prefit barrels. The "headspace" mentioned above requires a chambered barrel. That then requires a gunsmith to perform a final fitting of the 2 components which may require final machining.
I would think barrel manufacturers of prefits will leave the barrel critical fit ups slightly biased to guarantee it will need machining to finish the headspace.

I've never seen a shouldered prefit that required any machining. Every one I've used threads in the action, gets torqued down, and headspaces properly. As long as the action and barrel manufacturer can hold ~.001" tolerance on the critical dimensions (which may mean tighter tolerances on some dimensions where tolerance could stack) they'll thread together and headspace properly. Requiring machining defeats the purpose of a prefit.

 

[Bob Wright]

It's this part that the receiver mfr is declaring its up to the owner and the smith may need to "fit" to achieve final headspace:

Pre-fitting a barrel is possible, but only when you have consistently machined actions, and an equally precise chambering of barrels. Defiance's position on pre-fits is; if you choose to use pre-fit barrels on our actions, you should only do so if final fit up is done by a reputable gunsmith to insure proper headspace and fit.

It is possible to have to machine to establish headspace. They are saying it's the barrel manufacturers tolerances that are at play. It may fit perfectly or it may need one machining operation to set it properly.

 

[JuddL]

There is .004-.006 in between the go and no go…in the machining world, that's a mile.

 

[Longtine88]

So here is an example of who is wrong. Defiance AntiX SA .480" bolt face for a 22 creedmoor. A friend received a 22 creedmoor prefit from a known manufacturer. I will not say who. The attached below is how I would cut the tenon for the measured action. Notice how Measurement A is 0.004" shorter than the Bolt face measurement. I typically see that these two measurements are generally the same. But this bolt is different. I measured the Overall shaft length of the prefit barrel and it was 0.963". Same measure measurement I measured the actions to front lug. No clearance. Bolt will not close. So now I have to fix his problem on a barrel that was suppose to be good to screw down, torque, go gauged check and shoot. I checked 3 other actions on some SA anti's and those 3's "A" measurement to front bolt lugs were all .967". If this bolt would have been a little longer then the barrel prefit would have worked. Also note the bolt face measurement B is .967" and the toe of bolt is .813" making a recess depth of .154". I generally see this as a .150" measurement. So who's wrong...company A who's receiver it is or Company B who cut the prefit for him? It's not a guarantee prefits work unless the action made is exact or at least set's a tolerance for the instead of calling them 0.001". With the lugs 0.004" longer than the bolt face creates excess protrusion.