Well, I finally did it. My stock (6-48) screw setup on my .416 M70 let go this weekend. I had just about convinced myself tehy'd last forever, as they'd been happy for 583 full-house rounds and 120 lighter loads. I learned a valuable lesson, as the iron sights were set up for a different load.

I was shooting off-hand, so it broke both rear screws before I noticed.

I can take care of drilling and tapping, but what size screw should I use? 8-40 seems popular, is that big enough? Also, where can I get the highest quality Torx-head screws?

I'd like to only do this once!

The steel Weaver-style bases have room for a .200 diameter head about .100 thick.

Any help or advice appreciated.

Don

Yes, use 8-40 they will work on any caliber..Leupold, Talley make good Torx and one is as good as the other in 8-40....

I'm surprised the 6-48's broke on a 416, thats unusual...I have only had that problem with larger calibers, perhaps you twisted them while installing them, this can happen very easily with torx head screws...

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Ray,

Thanks for the advice.

The original screws were slotted. I don't think I over-torqued them - but I did not use a torque wrench. I installed them with blue loc-tite, as is my usual practice.

The scope is a 1.75-6X Leupold VariX-III. It seems unhurt.

Don

Don, I put 8-40's in the bases of all the rifles I build, even the wee ones like 22-250's. Brownells has the screws and you will need a counterbore (also from Brownells) & no. 19 drill for the bases in addition to the taps & tap drill. The big bads, 458 Lott and up, get 10-32's. And I use all steel Weaver style bases, the Leupold QRW's. Plus Leupold QRW rings. Nothing else comes close. (you need a detachable scope and iron sights on a heavy anyway) I have seen everything happen, even seen the windage screws on the rear bases (Redfield and older style Leupold) shear under recoil. The front rotary dovetail on this type mount is especially noted for loosening under recoil.

You said "Weaver style bases". Are they aluminum?? If so toss them. Get steel bases. Use heat treated screws. Epoxy everything in place. Screws, bases, everything. It will not come loose or break if you do so. If you ever need to remove the bases heat them enough to break down the epoxy. The reason screws break is that it gets a little loose and the scope and bases get a progressively longer running start. When that happens something is bound to give. The epoxy trick absolutely prevents it.

Scot,

I said "steel Weaver-style bases".

I have always used the blue loc-tite on lesser calibers in the past. I may try your epoxy trick with the bigger screws.

Thanks,
Don

Don,

I agree 100% with Scot's findings. Use one of the "glue" epoxies not the hard type we use for bedding.

We can also buy some stuff in Australia (I think it has Tricloretane or some similar name)that rots epoxy off. You warm the mounts, unscrew them, and stick the action into this stuff and the epoxy just falls off after brief time and leaves the action as clean as can be.

Mike

Scott, Leupold "Weaver Style" bases are made of steel. The term "Weaver style" refers to the physical size and appearance, not the material. The Leupold "Weaver Style" Quick Detachable rings are all steel and very, very strong and sort of bullet proof. I use them on the Benchrest, Tactical, 1000 yard and 50 BMG rifles I build, not a single problem. And I use them on the heavy rifes such as 416 Rem, 458 Lott, etc. Anything made by the company "Weaver", is another story.

John,

Are using the standard ones or the expensive ones they list under law enforcement.

Mike

I use a .338 RUM for long distance target competition. I had to come up with an excetionally bullet proof mounting setup.

I used Leupold steel weaver style bases, and used golf club head epoxy to set them in place. This particualar epoxy has a high shear strength, which is what you want. To remove the mounts, take a hot air gun or a large soldering iron and heat the mounts/screws. Be sure NOT to heat the receiver above 350 degrees, do NOT use flame, take the receiver OUT of the stock. I saw the aftermath of someone who broke the previously stated rules and set his stock on fire, and had to be persuaded that he had probably ruined the heat treat of the receiver while he was at it. Golf club head epoxy is formulated with disassembly in mind and it has to stand up to tremendous impact loading.

With the epoxy, about the only reason for going with the bigger screws is to clean up screw holes that are not perfectly aligned with the centerline of the receiver.

Rust,

This sounds like a good tip.

I have never seriously hunted golfs, and am ignorant, so where would I go to get this magic epoxy? A pro shop on a course?

Don

Don. A local club repair shop should have some. Failing that, in the back of golfing magazines are the usual ads for suppliers of golfing supplies.

Epoxy adhesives nowdays are formulated for specific applications. With the new and expensive carbon fiber shafts on some clubs, the epoxy used to attach the club head has to melt at a lower temperature than the adhesive used to laminate the carbon fiber. Temperature control is a must there more so than heating a receiver.

Well, I visited several golf stores. I found some that admitting using epoxy, but none sold the stuff. (In Texas, at least one of 'em would have told me to bring in the rifle...) The ones that would talk to me said they just used "normal epoxy".

I wound up re-installing the bases last night using Devcon "2 Ton Epoxy" - a slow curing clear epoxy. Found it at WalMart. May have to go Nuclear to get it off. I just hope it stays on!

Don

Don,

Haven't you heard about the problems with Devcon 2 Ton Epoxy on blued metal??? Apparently it is highly corrosive due to some sort of chemical reaction......

Only joking:-) Let us know if this stuff works. One question, did you epoxy the screws in as well or block the holes with a release agent???

Pete

Don G,
I have used that before, works well, low heat from a propane torch will make it come off easily, and you clean up with your finger nails and a bronze/brass bristle brush, if you ever want to remove it.

I think "JB Weld" is the best, as it is designed for joining metal to metal. Low heat from a torch takes care of it too. It is also a nice dark gray color that looks good if it shows under any poor tolerance parts. Glass bedding your scope bases.

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Good huntin' and shootin',
RAB

Pete,

Nope, I cleaned the whole works with acetone -- screws, action, bases -- then glued threads, heads and all. I kept the inside of the Torx heads clean so I can get a good grip when I try to pull them.

Dok,

I use JB Weld a lot, I think it bonds best also. I did not use it because I did not know if it would release with reasonable heat. Many epoxies give up at 250F, which
sounds reasonable to me...

I cleaned up all the excess with acetone before the epoxy set. It made a nice, clean job. I was very careful to dry fit everything to check for bolt clearance, etc. before gluing it on. I hope to shoot it some this afternoon. I don't expect any problems.

Don

Well, one of the reasons I did mention golf club epoxy was the low let go temperature. Other epoxies would work as well but may have higher let go temperatures.

One way of avoiding overheating would be a temp stick, essentially a crayon formulated to melt at a given temperature, simply draw a mark and if it melts, you've reached the temperature for that particular temp stick.

I would personnally avoid an epoxy with a let go over 400 farenheit as sustained heating at this level could actually alter the heat treat of the receiver. If you ever have to remove the mounts, use the minimum heat that will do the job.

Years ago, I recall some folks soldered their mounts in addition to the screws. A little more difficult to do a satisfactory job, it presented certain difficulties. I feel that epoxy is superior.

My favorite mounts/rings so far are Leupold Mk4 mounts and rings. With the epoxy the mounts are very robust, and with the rings lapped in a very accurate removable ring system. The 1/2" ring nut tightens the rings to the mounts very solidly. An extra scope could be easily set up for a given rifle.

I use mostly large objective scopes, so I have gotten used to using the Burris Signature Zee Rings for the Weaver-style bases.

These have the Delrin "eyeballs" in them that allow for misalignment in the bases as well as protecting the scope from marring. There is no need for lapping your rings with this setup. The self aligning rings hold the scope firmly enough that the 1.75-6x32 Vari-X-III never moved on my 416 even after the rear base came loose.

When the rear scope mount screws sheared on my 416 the scope was left hanging by the front mount only. (The rear base stayed on the ring base.)

The scope was absolutely unmarked by the torsion of firing with only the front base. The scope appears optically undamaged as well. I know of no other ring type that would have left the scope without a mark.

You can also get offset Delrin "eyeballs" with built-in offsets that allow you to correct for mis-alignments in the mounts and even give the scope a bias for use out to 1000 yards.

The rings come off with a dime or screwdriver in about 30 seconds. At 100 yards I get a perfect return to zero within my shooting ability. (Call it +/-.05)

The only downside is that the rings do not come in a Low height. This means the 32mm bell is about .150 off the barrel. All my other rifles I get from .020 to .060 off the barrel, and I do like the low mounting. I will put up with the height for the other advantages - until I get a set of QRWs.

Don

[This message has been edited by Don G (edited 06-10-2001).]

I like the Burris Zee rings, on rifles that don't recoil a lot. I had been setting up a .338 RUM as a long range target rifle, and the Burris' would not hold a large objective 8.5 X 25 scope against the recoil for extended bench sessions. 40 rounds or more in a day. OF course, the hotter loads run recoil into the very serious range.

I don't particularily like the design of the clamping to the mounts on the Zees. I feel that a larger screw other than slotted head should have been used. Putting enough torque on the screw has a tendancy to deform the slot and run the risk of a slip and gouge.

My favorite attachment is that of the the Leupold Mk4s. That big 1/2" nut is just right and a spin tight driver is just the ticket.

I may end up modifying a set of the Burris rings...