Rifle Scopes Well I cracked a Spuhr mount…!!

[hafejd30]

Asked a question a while back on spuhr mounts cracking. Just generally curious how big of an issue it was. While mounting my 4th spuhr mount today I got to find out for myself….

This SP-4002 appears to have the beefed up cross bar for mounting to the picatinny rail but I actually felt it crack.

Tightened each bolt so it was just slightly loose. Then slid mount forward on the picatinny rail so it contacted the rail in the front of the mount. Barely snugged each screw up so the rail was perfectly set against the picatinny. Tightened all screws to 10 inch lbs to confirm it was seated good. Then was going to step to 25 inch lbs, then finally 45 inch lbs lbs.

Tightened 1, 2, 3, 4 to 10 inch lbs in correct pattern. Same for 25
Inch lbs. Prior to getting to 25 lbs on screw 3 I felt the screw just barely give up a bit on the torque wrench. Thought “damn that felt weird…”

Look over the mount by that screw and found the crack.

I’m a bit let down to say the least. Not pissed but this definitely didn’t help my confidence in the mount….

I have a set of NF rings I hope will work until I can fix the spuhr

So for those wondering….yup they crack, even the beefed up ones. And for those wondering I’m not an amateur gun guy by any means. Mounted a ton of scopes. Blue loctite was used as recommended in the spuhr manual. Wrench used is a wheeler fat wrench. And I can confirm the torque was where it should have been when tightened. I’ve done enough I can almost guess the torque I’m applying. So it wasn’t overtorqued.

I even looked for cracks in the mount after receiving it. As it was pre owned and I read about the issues with some cracking. So it was confirmed good or it would have been a conversation with the seller at that time

Just another 2021 kick in the nuts. As everything I’ve touched lately has broke…so why not this

 

[candyx]

If it was pre owned the guy before you could of over torqued it setting it up to crack. They should make that part out of steel so it can bend instead of cracking.

 

[_Windrider_]

Never had a spuhr fail or crack. Not sure what to say other than are u sure it was inch lbs?

 

[KnowNothing256]

Never had a spuhr fail or crack. Not sure what to say other than are u sure it was inch lbs?

Not aware of Wheeler making a ft-lbs version of their FAT wrench. Not trying to be a snot, but OP described his process awfully well, think it's fair to take him at his word that he was in in-lbs.

 

[hafejd30]

Never had a spuhr fail or crack. Not sure what to say other than are u sure it was inch lbs?

The wrench used. I can assure you as I’ve tightened many mounts before that it was nowhere near over torqued. And as I just tightened the 2 screws prior to #3 I can say the wrench was working properly. Probably cracked around 20 in lbs if I had to guess when I felt it go

 

[_Windrider_]

Not aware of Wheeler making a ft-lbs version of their FAT wrench. Not trying to be a snot, but OP described his process awfully well, think it's fair to take him at his word that he was in in-lbs.

Hey. Just throwing it out there. We’ve all thought a lot of things and I’ve never used a FaT wrench. Not accusing anyone of anything.

 

[hafejd30]

I was just about to where I felt 25 in lbs would be and the wrench would do it’s thing. Then it felt like it let up a bit. Was initially thinking stripped threads or not having the driver in the head correctly which I always pay attention to making sure I do have that correct

It let up a bit. Then turned past where I figured 25 in lbs would allow me to go. It just felt different. That’s when I inspected it

If it was cracked prior then it couldn’t have been much. As this is the exact area I inspected when receiving the mount. Along with near the ring screws which is where I’ve seen them cracked as well. All looked good. Certainly not cracked like it is now

 

[Huskydriver]

So call mile high and you will be getting a new bar

 

[candyx]

I crack one but it was the thin side plate version before they beefed it up. Mile High Shooting should be able to get you a replacement.

I use the same torque wrench as well same settings and it cracked.

 

[hafejd30]

This is mounting a NF 7-35 atacr on a AXMC. I have the same mount on my AT with a 4-16 ATACR. Also have one on my savage with a Cronus BTR and on a FN SPR with Burris XTRII.

 

[hafejd30]

So call mile high and you will be getting a new bar

That’s the plan

 

[hafejd30]

I crack one but it was the thin side plate version before they beefed it up. Mile High Shooting should be able to get you a replacement.View attachment 7646572

I use the same torque wrench as well same settings and it cracked.

Those are the ones I’ve seen cracked. Before they beefed them up. Which I was surprised this one cracked. Same for the beefed up ring screws. This one is beefed up there as well

I’ve been having such shit luck lately I can break just about anything no matter how good it is

 

[Huskydriver]

Was there any oil on the screw threads possibly from cleaning the rifle?

 

[iceng]

Wow, cracking that is impressive.

Paging @308pirate I think it is. He is a screw torque guy.

 

[hafejd30]

Was there any oil on the screw threads possibly from cleaning the rifle?

The threads looked brand new. No oil or loctite on these threads even from previous owner. They used loctite on the rings but not these

***I applied blue loctite to these screws. On clean thread. (I always do and spuhr even suggested it in the manual)

So blue loctite
Clean threads
20-25 inch lbs
Cracked

 

[candyx]

I have used a larger torque wrench in the past just to make sure the scope doesn't come loose.

 

[just browsing]

Doesn’t Spuhr recommend using oil on the cross-bolts to obtain the true torque values? I seem to remember that being the case with the past mounts I’ve had from them, though I’m not sure how exactly that would contribute to or prevent cracking.

 

[hafejd30]

In a little while I’ll put the mount back on the rifle and see how well it contacts the rail itself. Maybe an issue with the way the rail is designed

I’ll post a pic when I do that

 

[hafejd30]

Pics of where the crack occurred

 

[hafejd30]

Pics of the spuhr manual

 

[hafejd30]

I did remount the spuhr and finished mounting the scope. Leveled up and rings torqued to 25 inch lbs. zero issues with the rest of the mounting procedure

 

[Ravenworks]

Doesn’t Spuhr recommend using oil on the cross-bolts to obtain the true torque values? I seem to remember that being the case with the past mounts I’ve had from them, though I’m not sure how exactly that would contribute to or prevent cracking.

No,oil increases torque

 

[hafejd30]

Well, I stuck a case in a Redding type s 308 resizing die after using too much lube so I feel your pain

We’ve all been there

The rcbs stuck case remover is a wonderful thing. I’ve only needed it once thankfully

 

[candyx]

Its prone to cracking at the center line of the holes as the clamp is tightened stretching it in opposite directions with pin point load at the screw in the center. Depending on the grade of aluminum of the side clamp it appears to be brittle. Depending how many times the clamp is used could be the weak point of the design.

 

[hafejd30]

Its prone to cracking at the center line of the holes as the clamp is tightened stretching it in opposite directions with pin point load at the screw in the center. Depending on the grade of aluminum of the side clamp it appears to be brittle. Depending how many times the clamp is used could be the weak point of the design.

It be a cool feature if they had the option of a titanium bar like the Nf ultralight rings use

I’m not going to bash them or sell all my spuhr mounts but it be awesome to see a bulletproof system so you don’t have this issue

 

[iceng]

The contact with the rail is a bit odd. I'd expect it to be a better fit.

One sphur (or 2, someone else had identical) over thousands sold ?

Could have been a bad batch of material which caused the crack, which is out of their control. I've always found alloy bends and smudges rather than break, however have had unusual failure when we were doing stress testing at a previous job. Purely to find the best material for the job.

 

[candyx]

The contact with the rail is a bit odd. I'd expect it to be a better fit.

One sphur (or 2, someone else had identical) over thousands sold ?

Could have been a bad batch of material which caused the crack, which is out of their control. I've always found alloy bends and smudges rather than break, however have had unusual failure when we were doing stress testing at a previous job. Purely to find the best material for the job.

When mine cracked spuhr wanted the number inside the clamp for their records.

 

[hafejd30]

The contact with the rail is a bit odd. I'd expect it to be a better fit.

One sphur (or 2, someone else had identical) over thousands sold ?

Could have been a bad batch of material which caused the crack, which is out of their control. I've always found alloy bends and smudges rather than break, however have had unusual failure when we were doing stress testing at a previous job. Purely to find the best material for the job.

I’ll check my other 3 Tomorrow and see how they line up compared to this one on the picatinny rail. My plan is

Contact Mile High
Get Replacement
Mount scope

If the new one does the same then I’m not sure what to do

If the new one mounts as it should then maybe the previous owner caused something to fail on this one and I just completed the fail

I believe these are 7075 which if I recall is strong but doesn’t flex very well. I can definitely see why it would crack but again I have used several spuhr mounts before without issue

I’ll let you guys know how this plays out. Hopefully they will replace for free. I’m not original owner so we’ll see how this turns out

 

[sjmpcc022]

Any manufactured anything made out of anything metallic can fail anytime, Its called metallurgy . I'm sure Spuhr would stand behind this mount, hopefully.

I would suggest to check out F3R Machine in Horicon, WI. They make a spectacular mount for half the price of a Spuhr. As an almost 30 year tool and die maker, I don't see one reason to spend twice the money on a Spuhr mount.

Check out their website, watch the video. f3rmachine.com

 

[hafejd30]

Any manufactured anything made out of anything metallic can fail anytime, Its called metallurgy . I'm sure Spuhr would stand behind this mount, hopefully.

I would suggest to check out F3R Machine in Horicon, WI. They make a spectacular mount for half the price of a Spuhr. As an almost 30 year tool and die maker, I don't see one reason to spend twice the money on a Spuhr mount.

Check out their website, watch the video. f3rmachine.com

Mounts look good. May give one a try in the future. For now will wait to see how the spuhr turns out as I already own the spuhr

If I tighten the replacement and it cracks. Then I’ll be open to other options

This is mounted on a 30 MOA AI rail so highly doubt the rail is an issue and will not be replacing it

If need be I’ll torque my NF rings to the AXMC and if they hold up I’ll likely just get a set of them as I have 3 sets on 3 rifles and like those as well

 

[sjmpcc022]

Mounts look good. May give one a try in the future. For now will wait to see how the spuhr turns out as I already own the spuhr

If I tighten the replacement and it cracks. Then I’ll be open to other options

This is mounted on a 30 MOA AI rail so highly doubt the rail is an issue and will not be replacing it

If need be I’ll torque my NF rings to the AXMC and if they hold up I’ll likely just get a set of them as I have 3 sets on 3 rifles and like those as well

I'm sure the mount wasn't the issue, or the AI rail, physics was.

I only pound this drum because F3R is a Wisconsin company, I'm a Wisconsin guy, and their mount is a tremendous value!

I've purchased two and they are the real deal.

 

[m1match]

Spuhr and Mile High do stand behind their products, but I have personally seen two Spuhr mounts crack at the same place on the clamping bar as the OP. The two cracked ones that I've seen were owned by friends who scrupulously used FixIt sticks of the proper torque to mount them on their rifles and they don't abuse their equipment in any way. I can only conclude that this is a real problem with Spuhr mounts that should be easily fixed by changing the material or spec of the clamping bar.

 

[hafejd30]

I'm sure the mount wasn't the issue, or the AI rail, physics was.

I only pound this drum because F3R is a Wisconsin company, I'm a Wisconsin guy, and their mount is a tremendous value!

I've purchased two and they are the real deal.

I’m in the UP of Michigan and would have no issues trying their mount in the future!

 

[308pirate]

No,oil increases torque

Lubrication doesn't increase torque. Only you can increase or decrease torque by applying less or more force at the end of the wrench (or changing the moment arm)

What lubrication does is reduce the joint's friction which leads to more fastener tensile stress per unit of torque input. The joint is tighter for the same torque input compared to the same joint, with the same torque input, but with no lubrication.

 

[308pirate]

Pics of where the crack occurred

View attachment 7646682View attachment 7646682
View attachment 7646683

It's very possible that you had a hidden flaw or stress riser in that clamp and that you did nothing wrong.

 

[phlegethon]

It sucks this happened, but flaws creep into every manufacturing process. I don’t think they are x-raying every mount as it comes off the line. I’m sure they will cover it under warranty and I don’t see this as a widespread problem.

 

[AXMC]

Sorry that happened! I've had 2 crack in the exact same spot and I'm also meticulous with my torque values. Contact Mile High. They'll want the lot # inside the clamp (I assume to report back to Spuhr so he can track if it was a bad lot of alloy etc) and will get you taken care of with replacements.

 

[jbonnie]

F3R says on their website they have 36mm 1.5” 2OA cantilever mount in development! The grail for ZCO guys!!

 

[jbonnie]

F3R says on their website they have 36mm 1.5” 20 MOA cantilever mount in development! The grail for ZCO guys!! Fixed typo

 

[supercorndogs]

Doesn’t Spuhr recommend using oil on the cross-bolts to obtain the true torque values? I seem to remember that being the case with the past mounts I’ve had from them, though I’m not sure how exactly that would contribute to or prevent cracking.

All torque values are assumed to be wet unless noted as dry.

 

[M77]

Faulty product simple as that , I've had the top of the caps hairline crack. Replaced and gtg

 

[308pirate]

All torque values are assumed to be wet unless noted as dry.

Wut?

It's the opposite

 

[THEIS]

Hi,

Torque values are calculated based on "Dry" utilization.

Reduced Torque with Lubricated Bolts

Lubrication effect on bolt tension and torque.

www.engineeringtoolbox.com

Torque Calculator | Fastenal

www.fastenal.com

https://www.antiseize.com/PDFs/torque_specifications.pdf

Sincerely,
Theis

 

[AXMC]

Spuhr's though, are a wet torque (they come pre-lubricated).

 

[Maurygold]

This is weird. I have a cracked mount in the exact same location as the above. Ordered a new one thinking something crazy happened but will be giving them a call for the $60 replacement.

 

[supercorndogs]

Wut?

It's the opposite

Bullshit.

 

[supercorndogs]

Hi,

Torque values are calculated based on "Dry" utilization.

Reduced Torque with Lubricated Bolts

Lubrication effect on bolt tension and torque.

www.engineeringtoolbox.com

Torque Calculator | Fastenal

www.fastenal.com

https://www.antiseize.com/PDFs/torque_specifications.pdf

Sincerely,
Theis

Not in the automotive and diesel industry. And not according to the people who gave the class on torque wrench calibration.

I think I see the disconnect here. When an automotive manual gives a torque values, it is considered to be lubricated unless other wise noted.

 

[M8541Reaper]

This happens to you because you left the QC sticker on your Nightforce. You've angered the gods and are being punished accordingly.

Regardless, that sucks man. Perhaps use this as an excuse to buy yourself a Condition 1 mount from Badger? That shit is pure sexiness and you aren't cracking one of them.

 

[lennyo3034]

It be a cool feature if they had the option of a titanium bar like the Nf ultralight rings use

I’m not going to bash them or sell all my spuhr mounts but it be awesome to see a bulletproof system so you don’t have this issue

Same torque wrench you used.

 

[hafejd30]

View attachment 7646962
Same torque wrench you used.

Well then……