Defiance Tenacity 8-40 scope base hardware issues

[Tilting40s]

I’ve got a relatively new tenacity action and the picatinny scope base was loose. I went to lock tight then tighten down the screws and like they always do one stripped while I was trying to back it out. (I think the gun builder I purchased the rifle from cross threaded the screw closest to the barrel but that’s another story…..

In any case I purchased new 8-40 hardware to replace the original stuff but they do not rotate in easily. If I apply lots of torque I can get them in but the threads start to mash so I haven’t tried to force it. And they are definitely 8-40 because the same hardware fits in my savage. The strange thing is the hardware for the tenacity even fits in my savage.

Am I an idiot? Am I missing something obvious here?

 

[deadly0311]

May have rolled an internal thread. Try an 8-40 bottom tap to clean the threads up?

 

[Tilting40s]

May have rolled an internal thread. Try an 8-40 bottom tap to clean the threads up?

Unfortunately all of the action screw holes are like this…. It’s not just one.

 

[MojoNixon]

Then clean all of them up.

 

[deadly0311]

Unfortunately all of the action screw holes are like this…. It’s not just one.

There’s no harm in cleaning them all

 

[AllenOne1]

I would pull the barreled action out of the stock, remove the barrel, tap all of the holes with a thru tap. Make sure that front screw isn't too long that it would hit the barrel tenon. Screw the rail back down making sure the rail is seating to the action properly.

For added security, break out the welder and weld the rail to the action. No more loose rail issues going forward.

Honestly, this is the reason that I opted for an integrated rail on my current action. I know you give up the flexibility of changing the MOA angle but I don't have to worry about that rail coming loose ever again.

 

[Tilting40s]

I would pull the barreled action out of the stock, remove the barrel, tap all of the holes with a thru tap. Make sure that front screw isn't too long that it would hit the barrel tenon. Screw the rail back down making sure the rail is seating to the action properly.

For added security, break out the welder and weld the rail to the action. No more loose rail issues going forward.

Honestly, this is the reason that I opted for an integrated rail on my current action. I know you give up the flexibility of changing the MOA angle but I don't have to worry about that rail coming loose ever again.

 

[Tilting40s]

So just got off the phone with defiance. Told them about my issue.

They said they use their own in house hardware because their actions are machined to such tight tolerances. He said a lot of hardware it’s built as precise and won’t fit.

Anyway they’re sending me 2 sets of screws so case closed.

 

[gnochi]

They said they use their own in house hardware because their actions are machined to such tight tolerances. He said a lot of hardware it’s built as precise and won’t fit.

What a stupid reason to use in-house hardware. That just means that they aren’t in spec. And by the way, that also means that said in-house hardware:

• Isn’t going to be anything resembling a high strength material, and with how tiny the heads are relative to the shank, they don’t even have geometry helping the
• Won’t fit if they nitride the action and forget to chase the threads and ream the holes afterwards
• If it gets forced in anyway, the head will strip or snap off but the threads will sure as hell remain stuck
• Screws have a great chance of galling if they, say, don’t use any thread lubricant or loctite and torque it anyway

The front screws on my new anTi came out just fine, the rear two have the heads snapped off, have broken 2 screw extractors (which I was thankfully able to extract), and are currently soaking in liquid wrench with holes down the middle.

@LongRifles Inc. are you able to unfuck this (and if so, how should I place that order)? How do you feel about 10-32 threads?

 

[LRI]

I was asked, so here goes:

"Such tight tolerances..." What does that even mean? (nothing other than a poor attempt at trying to sound cool)

In their defense (Defiance), the 8-40 pitch is typically not listed in reference material like the Machinery Handbook because it's a very uncommon thread size/pitch used almost exclusively in the firearms industry. That said, taps for this pitch have been made for decades, and there are off-the-shelf thread mill tools and gauges.

The issue one discovers is that there is a significant fluctuation in the major OD and pitch diameters from the companies making this hardware. It is my guess that Defiance has discovered this as well, and this is why they push for people to use the hardware they supply.

An example:

I buy bags of Torx head screws from an optics company. I get them 5,000pcs at a time. If I thread a receiver to fit my 8-40 GO/NOGO plug gauge, those screws fit absurdly loose. They will rattle around like a marble in a can. So, I "comp" the tool in the machine and undersize things by a couple of .001s so they fit correctly. If I use a screw sourced from someone else, it's just as likely that the hole/threads are now undersized, and the fastener requires an unreasonable amount of force to install.

This is one of the little annoying/intrinsic "tribal knowledge" type things that my staff has to be cognizant of when doing receiver work, as it's very application specific. If you take the ten most popular companies making scope bases, I can promise you that the screws are NOT all the same. We have to be very, very careful when using taps for this reason, as there is no means of adjusting the pitch diameter with a tap. Over the years, I have acquired a large inventory of hardware to address this sort of thing when conducting repairs or installing stuff where I don't have complete control of everything.

If I am to offer anything constructive to this discussion, it's this:

Firearms are the wild west in terms of dimensioning. There is no regulatory body here in the US that governs how things are made or dimensioned. SAAMI, at best, is a polite suggestion. A 30-caliber bore dimension is a prime example. A "tight" bore 30 was born because it was discovered that a particular bullet made in England (the 155grain pill used in Radway Green machine gun ammo) performs best from a .297/.3075 land/groove diameter. The ammo is junk and has no business being shot from anything other than a belt-fed machine gun. However, the international rules for Palma state the host country is who supplies ammo for the team portion of the events. Radway is what you get when you go to England. (a few others use it too)

-How many well-intentioned target shooters buy tight-bore 30-cal barrels because the assumption is made that it's better just because the word "tight" is used in the product listing?

-A lot.

Hope this helped.

C.