Spuhr mounts prone to cracking?

[capp325]

I hope I'm not opening a can of worms, but I've noticed a couple of members reporting that their mounts cracked in exactly the same spot: along the relief cuts for the ring mounting screws.

Example 1

Example 2 (post #15)

Are those isolated incidents or is this a known issue with Spuhr? The fact that the cracks are in the exact same location suggests a design flaw.

 

[Badfinger]

I wouldn't say "prone" and we don't know the history of the mounts. #1 looks like it's mounted over a shim like you would use to go from 30mm to 34mm. They could have been over torqued, dropped, porosity in the casting, whatever. These are the only reports I've heard of and I've never had a failure of any kind.

 

[kRcu]

Never had a failure either. Three Spuhrs for me so far.

 

[SRSDriver]

Never had an issue with 4 of them in use.

 

[Dthomas3523]

Only being half a smartass here, but are we asking if two cases over five years is “prone?”

 

[capp325]

Only being half a smartass here, but are we asking if two cases over five years is “prone?”

Those are the two that I could find with a quick search. I don’t know if there are others. That’s why I’m asking the question.

 

[Kiba]

Spuhr revised the ring screw spacing a couple of years ago to leave more material around the outermost screws, possibly for this exact reason. Both of the pics you linked to are of the "gen 1" design (identified by the totally flat ring caps.) The "gen 1" ring caps get rather thin near the edges of the counterbores for the 4x outer ring screws which probably serves as a nice crack propagation point.

The "gen 2" revised mounts moved the outer ring screws in towards the center ring screw a bit to leave more material around the 4x corner ring screws, and they can be identified by a milled "trench" cut connecting the two middle ring screws. I've seen those pics of cracked "gen 1" ring caps before, can't recall ever seeing a cracked "gen 2" ring cap. Unforutnately you can't swap a gen 2 ring caps onto a gen 1 mount as the screw spacing is different.

I've had problems with one of my Spuhrs cracking the picatinny rail clamp bar... it cracked twice actually. Got prompt warranty replacement clamp bars from Mile High both times. However I think the source of the problem may have been an out of spec picatinny base on that rifle because that same mount has been installed on another rifle for several years now and the clamp bar is still intact. On the "problem" rifle it cracked two clamp bars in less than two years.

 

[supratt96]

I had a ring crack a couple years ago on one of my Spuhr mounts in the same spot as described. Spuhr sent me a new ring and did not seemed surprised about the crack. They seemed to know it was an existing issue.

 

[capp325]

A picture I found on another forum.

 

[Doitallgp]

I also had a spuhr mount side clamp crack on me but the folks at Mike High Shooting sent out a replacement.

 

[Hattrick]

And I thought they were cream of the crop

 

[Ledzep]

And I thought they were cream of the crop

Give me a wrench and I can break some shit on an F1 car... Parts breaking isn't the whole story.

 

[Rangemaster]

I have six mounts, never had any issues.

 

[spife7980]

Give me a wrench and I can break some shit on an F1 car... Parts breaking isn't the whole story.

If you worked for haas they would make you lead mechanic in a heart beat.

 

[redneckbmxer24]

The early Spuhr's definitely had some issues with ring caps cracking, I had never seen or heard of a clamp bar cracking though. I personally had two Spuhr front ring caps (one on a 30mm, one on a 34mm) crack right across two of the screw holes on each and they were properly torqued. Spuhr updated the rings a few years back though and everything forward should be good to go, if you're having trouble then it's probably because you've got an older mount. Mile High will replace the caps if they crack though and I'm sure a cracked clamp bar would be replaced too so it's really a non issue.

 

[texas_vet00]

Can someone post a V1 vs V2 photo showing the "more material around the outermost screws" please?

I think I have two of each but what the hell do I know...

 

[M8541Reaper]

For those dismissing the OP, it is a legitimate question. As for those stating they own them and defending their durability, how much use do they get? Are they kept in a case/safe until they are pulled out for the range or are the used in the field? Legitimately asking as I’ve been considering trying a spuhr after over a decade of strictly using Badger (with no complaints).

Every quality brand has issues from time to time. That’s the nature of the beast. But you can’t state that a product is the best if it is only used 3-4 times a month and spends its life going safe/car/range/car/safe. Have you dropped it, slammed it around (besides on one or two props a year), fell on it, etc? That’s how you know if it’s quality kit.

On the flip side, you also have the end user factor to consider. Most dudes are more likely to blame the equipment and not themselves for when stuff goes wrong/breaks. ....despite them not following specs or proper maintenance requirements.

 

[Kiba]

Can someone post a V1 vs V2 photo showing the "more material around the outermost screws" please?

I think I have two of each but what the hell do I know...

Gen 1

Gen 2

Note how the gen 2 moved the 4x outboard screws in towards the center a bit more leaving additional material at the outside webs, this makes them less susceptible to cracking.

Spuhr also revised and added additional material under the screws on the clamp bars a while back.

Older style flat clamp bar, I've cracked 2 of these at the outermost screw holes.

Newer clamp bar with extra material thickness under the screws. Besides the extra thickness, the outer 2 screws are no longer as close to the edge of the clamp bar.

 

[LawnMM]

I think I've got three mounts and one set of rings for years and never had an issue. Two mounts are Gen 2 and the other plus the rings are Gen 1.

The rings are on my match gun and have seen the most use. No issues. If there was an issue, I've every faith Mile High would give me replacement parts walking in the door.

Buy with confidence.

 

[Hollywood 6mm]

I've got a first gen mount that had 2 cracks develop in one ring cap. They were torqued with Fix it Sticks and a 25 in/lb torque limiter after I had several screws walk loose. I contacted Mile High and they replaced both caps and all 12 cap screws at no charge.

 

[candyx]

This is the torque wrench I used tightening my Spuhr mount and I didn't experience any cracking at all even using the extension.
.

 

[redneckbmxer24]

This is the torque wrench I used tightening my Spuhr mount and I didn't experience any cracking at all even using the extension.
.View attachment 7258321

You must work out a lot, I need at least a 6’ piece of pipe in the end of mine to hit enough torque.

 

[RNP]

If anyone has a problem with side clamps or top caps please contact us for warranty replacement.
Mile High Shooting
303255-9999
Thank you

 

[Hollywood 6mm]

If anyone has a problem with side clamps or top caps please contact us for warranty replacement.
Mile High Shooting
303255-9999
Thank you

I just wanted to say that MHSA has been excellent to deal with on Spuhr warranty issues. Hakan made the right choice for a group to handle CS for him in the US.

 

[Eostech]

Two out of two gen 1 36mm mounts developed cracks and one ring even split. Those mounts were some of the first 36mm made and I think as the external dimension are the same as a 34mm the caps and sides were thinner (not 100% on this). At the time I think they said something about the batch of alloy, spuhr replaced both no trouble. I'd have to drag up the emails to check what they said 100% because it was a while ago, should have pictures of the failures though.

 

[SBT GMG]

Now I'll have to run and check mine! I've had a few and used a few on customers builds, no problems so far that I'm aware of. One of my .308s with a Spuhr gets used pretty hard, its twin .300WM doesn't- I train mostly with the .308 to save $ and barrels. Knowing people, some of this issue may be due to folks not using a torque wrench, but who knows. There was a recall on my motorcycle years ago on the rear wheel hub, and that was the problem- it was designed for a very specific torque and people overtorqued the lug bolts, cracking the hubs. BMW had to put moron resistant hubs on the bikes, basically. I never had a problem. I have several torque wrenches and use them. Frequently.
Yes, Mile High is outstanding to deal with. Love those guys! My only complaint with them is that I have to drive through Denver to get there. I'd rather knaw a finger off than drive through Denver.

 

[Doitallgp]

Gen 1

View attachment 7258261


Gen 2

View attachment 7258262

Note how the gen 2 moved the 4x outboard screws in towards the center a bit more leaving additional material at the outside webs, this makes them less susceptible to cracking.

Spuhr also revised and added additional material under the screws on the clamp bars a while back.

Older style flat clamp bar, I've cracked 2 of these at the outermost screw holes.

View attachment 7258268

Newer clamp bar with extra material thickness under the screws. Besides the extra thickness, the outer 2 screws are no longer as close to the edge of the clamp bar.

View attachment 7258269

Can confirm my replacement was noticeably more “durable looking”

 

[SBT GMG]

I checked mine- the .308 has a "first gen", the .300 has "2nd gen" rings but the clamp rail looks like the original version. Both are in good shape. I'll be buying another one shortly for another build.

 

[clubsportmark]

I have 6 or 7 sets of spuhr mounts. All of which I love and have also found their service second to none. When I accidentally torqued up my hunting spuhr Mount the same as the ISMS and knackered it, they kindly replaced it.

Anyway. To the point in hand, I noticed yesterday than on one of my clamp bars had cracked. Always torqued to 45 inch lbs, so not at fault there. It’s also kindly being replaced. However in checking others I noticed that the underside of one of mounts is different to the others. See pic. Now I wondered if anyone knew if this was a gen 1 / gen 2 thing or if different models have different designs?

 

[AXMC]

They are based on the height of the mount....your low mounts ending in 1 (3001, 4001, 3601, 4011, 4901 etc) will have the exposed clamp screws. The higher mounts (3006, 4006, 4002, 4602 etc ) will have enclosed clamp screws.
Hope this helps

 

[SBT GMG]

I have 6 or 7 sets of spuhr mounts. All of which I love and have also found their service second to none. When I accidentally torqued up my hunting spuhr Mount the same as the ISMS and knackered it, they kindly replaced it.

Anyway. To the point in hand, I noticed yesterday than on one of my clamp bars had cracked. Always torqued to 45 inch lbs, so not at fault there. It’s also kindly being replaced. However in checking others I noticed that the underside of one of mounts is different to the others. See pic. Now I wondered if anyone knew if this was a gen 1 / gen 2 thing or if different models have different designs?

Yes, it looks like the design of the Spuhr mount has evolved a bit over the years. Like you I own 2 different generations of mount. I noticed the relief grooves around the center of the rings on the later mounts, thinking that Spuhr was reducing the weight of the mount slightly, but didn't notice the change in bolt spacing.
Like any other quality product, I think Spuhr is updating the mount as experience is gained. Early on some people complained about the weight of the mounts, and the later mounts have more relief cuts to remove material where it isn't needed. A few people had cracking around the outer ring cap bolts, and those spacings were changed slightly. I believe the mounts are made from 7076, which is a really tough alloy, but all aluminum is subject to stress hardening. I doubt that vibration is an issue in this case, but it doesn't seem to be a common problem considering the number of these mounts being used. Spuhrs costomer service, as well as Mile Highs is excellent, so I'd think that your problem can be resolved. I continue to use Spuhr- as far as I can tell it's still the most reliable mounting system available.

 

[Hardpan]

Gen 1

View attachment 7258261


Gen 2

View attachment 7258262

Note how the gen 2 moved the 4x outboard screws in towards the center a bit more leaving additional material at the outside webs, this makes them less susceptible to cracking.

Spuhr also revised and added additional material under the screws on the clamp bars a while back.

Older style flat clamp bar, I've cracked 2 of these at the outermost screw holes.

View attachment 7258268

Newer clamp bar with extra material thickness under the screws. Besides the extra thickness, the outer 2 screws are no longer as close to the edge of the clamp bar.

View attachment 7258269

I’ve cracked a gen 2, 45 inch lbs per Spuhr spec using a fix it sticks torque limiter. Mile High replaced it no questions asked. Got a gen 1 from them. I feel it doesn’t matter what gen it is, just the batch of metal used at the time.

 

[viking78]

I have also 3 Spuhr mounts, and I have never had any problems with the mounts, or the rings.
I use a torq driver, base clamp 5Nm and scope rings it depend of the scope manufacturer.
Kahles it was 2,4Nm and Vortex it´s 2Nm.
Follow the manual and you dont have problems.

 

[Stoweit]

Had a few, never had a problem, my favorite mount for a PRS style rifle.

 

[longgunJR]

I wouldn't say "prone" and we don't know the history of the mounts. #1 looks like it's mounted over a shim like you would use to go from 30mm to 34mm. They could have been over torqued, dropped, porosity in the casting, whatever. These are the only reports I've heard of and I've never had a failure of any kind.

Woah woah woah!!!....

“Porosity in the casting” aren’t this milled from solid? Or a forging? If this are made from casted material they’re definitely overpriced if that’s the case.

Can any one confirm this?

 

[Stoweit]

I don’t think these are cast.

 

[SBT GMG]

I talked to the owner years ago, when I first noticed Spuhr in the US market.. Nice guy, very helpful. My understanding was that they are milled from 7076 bar stock.

 

[Electric B]

This has happened twice

 

[Hardpan]

This has happened twice

How much torque are you using?

 

[Electric B]

18 with my fat wrench

 

[Reload10]

On the podcast @lowlight said him and Mile High just did a video about Spuhr's and user error, specifically torque wrenches that overtorque. Hopefully it's posted soon.

 

[Lowlight]

There is no way 18 inch pounds has twice cracked and broke a spuhr mount,

18 is nothing, this stuff is users doing it you don’t crack or break AL with 18 inch pounds

wow

 

[Hardpan]

There is no way 18 inch pounds has twice cracked and broke a spuhr mount,

18 is nothing, this stuff is users doing it you don’t crack or break AL with 18 inch pounds

wow

I agree. 18 is nothing and wouldn’t put enough pressure on the metal to crack like that. Maybe your fat wrench is defective or it’s torque rating is messed up.. Wouldn’t be the first one I’ve seen broken. I suggest a fix it sticks kit. You could get either individual or all in one torque limiters. I use the 15 that came with mine. Shooting a 6.5 creed my screws have never loosened up. Just my 2 cents

 

[Average guy]

There is no way 18 inch pounds has twice cracked and broke a spuhr mount,

18 is nothing, this stuff is users doing it you don’t crack or break AL with 18 inch pounds

wow

I listened to the podcast covering this. Here are a few thoughts on torque.
1. Follow manufactures torque specs
2. Torque in manufactures tightening sequence. If no sequence provided wot from center of screws out.
3. Once fasteners are torqued check every fastener once for correct torque.
4. Keep the torque wrench in your tool box after this. On click style torque wrenches torque stacking is a very real issue. I work with assemblies that call out torque specs in the thousands of foot pounds. These assemblies are subjected to great forces. Normally there is an initial torque and maybe a retorque after a prescribed amount of time. Then the fasteners are never touched.

Most of the issues with these breakage threads are due the issues outlined in your podcast.

 

[Lowlight]

We see it all the time,

Guys go over and over checking "torque" but instead they keep hitting it and hitting it, increasing the issues and causing problems

if you are not sure it's right, put a damn witness mark on it, hitting the screws every time invites problems

 

[MikeRTacOps]

18 inch pounds ? Noooo way Jose LMAO

But what would I know

Mike R.

 

[Average guy]

We see it all the time,

Guys go over and over checking "torque" but instead they keep hitting it and hitting it, increasing the issues and causing problems

if you are not sure it's right, put a damn witness mark on it, hitting the screws every time invites problems

Exactly. Torque the fucker the correct way and move on. It would be like retorquing the heads on your engine before you drive your cat every time

 

[Hardpan]

Exactly. Torque the fucker the correct way and move on. It would be like retorquing the heads on your engine before you drive your cat every time

Perfect analogy guy, well said

 

[chevy_man]

Woah woah woah!!!....

“Porosity in the casting” aren’t this milled from solid? Or a forging? If this are made from casted material they’re definitely overpriced if that’s the case.

Can any one confirm this?

How do you think they make bar stock? It's all melted and "cast" at some point.

There are a ton of variables that effect the structure of the metal. A bad batch of bar stock that had issues at the foundry would make sense, especially when you consider how many mounts could be cut from a 20' stick.

 

[Average guy]

How do you think they make bar stock? It's all melted and "cast" at some point.

There are a ton of variables that effect the structure of the metal. A bad batch of bar stock that had issues at the foundry would make sense, especially when you consider how many mounts could be cut from a 20' stick.

I’ve literally cut thousands of feet of aluminum plate / bar stock and have never encountered what you are theorizing. Bar stock is far more than some aluminum poured in a mold. Research how aluminum bar stock is made and you will see what I’m talking about. Full disclosure I don’t own a Sphur mount and probably never will. It’s just maddening seeing all the bullshit thrown around. Do parts fail, sure. But some of the practices people are using are mostly to blame.