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Is pinning the rail to receiver a good idea?

boltfluter said:
They will hurt nothing. I am surprised more rails are not pinned. Just my personal opinion with nothing to back it up. I am just happy we have a topic worthy of conversation. Nice job Jerry. Carry on! :D:D:p

Paul
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Thanks paul. The rail I pinned is for a 7 saum that is getting a 32" straight profile barrel....stiffness is needed. The rail is a NF with 33 moa of elevation gain. --Jerry
 
If we're going tout work experience I've been involved in things mechanical for about 50 years. Ranging from tractors & combines to Top alcohol Dragsters to musical instruments. The last 18 of them as a degreed Engineer. I too have worked in a power plant. No thanks, there's 10,000 ways to die working around those tea kettles (but they do have some cool tools!!).

I think that I would have shrink-fit a sleeve over the action on such a combo instead of wasting time by weakening the action with puny little dowel pins. Or better yet threaded one end of the action's OD, made the sleeve with clearance, made a piloting gland nut, and used custom recoil lug to put the action under tension. Anyone who doubts this needs to revisit their Strength of Materials class textbook. Mine had an exercise in it that specifically addressed bending strength in such a design. And if the rules allowed it I'd go with a barrel block bedding so that heavy barrel isn't hanging off the end of the action in the first place.

But I forget, Jerry can't see this.
 
ntsqd said:
If we're going tout work experience I've been involved in things mechanical for about 50 years. Ranging from tractors & combines to Top alcohol Dragsters to musical instruments. The last 18 of them as a degreed Engineer. I too have worked in a power plant. No thanks, there's 10,000 ways to die working around those tea kettles (but they do have some cool tools!!).

I think that I would have shrink-fit a sleeve over the action on such a combo instead of wasting time by weakening the action with puny little dowel pins. Or better yet threaded one end of the action's OD, made the sleeve with clearance, made a piloting gland nut, and used custom recoil lug to put the action under tension. Anyone who doubts this needs to revisit their Strength of Materials class textbook. Mine had an exercise in it that specifically addressed bending strength in such a design. And if the rules allowed it I'd go with a barrel block bedding so that heavy barrel isn't hanging off the end of the action in the first place.

But I forget, Jerry can't see this.
Click to expand...
Why does it matter so much? I don't get it!
Clearly, what Jerry has done is a practical way of stiffening the action. Maybe you can contribute by running some numbers to calculate how much stiffer his setup makes the action.

From my standpoint, I think it's a good idea. I think that it's best to minimize many of the variables like action flex from tuning. I strongly believe that tuning is mostly about managing vibration so, making the action stiffer by a considerable amount would, in my thinking, isolate the barrel more, as the part of the gun where frequencies occur that are easiest to manage, with a tuner....i.e., less noise from underlying vibration. IOW, make tuning more consistent and predictable.

Of course, my brain is just trained to look at all things gun related as possible influence on vibration and tune. Sure, he could use a setup like you describe or just buy a Panda action or sleeve his Remington and accomplish much of the same, probably more.
 
ntsqd said:
If we're going tout work experience I've been involved in things mechanical for about 50 years. Ranging from tractors & combines to Top alcohol Dragsters to musical instruments. The last 18 of them as a degreed Engineer. I too have worked in a power plant. No thanks, there's 10,000 ways to die working around those tea kettles (but they do have some cool tools!!).

I think that I would have shrink-fit a sleeve over the action on such a combo instead of wasting time by weakening the action with puny little dowel pins. Or better yet threaded one end of the action's OD, made the sleeve with clearance, made a piloting gland nut, and used custom recoil lug to put the action under tension. Anyone who doubts this needs to revisit their Strength of Materials class textbook. Mine had an exercise in it that specifically addressed bending strength in such a design. And if the rules allowed it I'd go with a barrel block bedding so that heavy barrel isn't hanging off the end of the action in the first place.

But I forget, Jerry can't see this.
Click to expand...
Barrel blocks are a terrible way to hang a long heavy barrel on unless the block is 3 inches square and glued in. Seen way too many on guns trying to make 17 pounds and they dont shoot. Then they need bedded, pinned and screwed in. Matt
 
Alex Wheeler said:
Screws are for clamping. Pins for shear forces. I usually do both, pin and 8-40. I have had rails come loose with taper head screws. With the aggressive brakes and heavy scopes theres a lot of shear forces. I had an issue with one in particular, 8-40 and a 1/8" pin, ended up beating the pin hole out! Went to 5/32 and added a second pin. I think the more effective muzzle brakes are the biggest problem. They have gotten so effective it must be like hitting a wall when the bullet exits. Never had a problem with a light scope or radial brake.
Click to expand...

Alex,
I bought 5/32" pins and even 3/16. I sat them various places on the rail and decided in the end that 2 x 1/8" pin on each end, spaced as widely as I could get them, was my best overall option.

Good comment on the muzzle brakes. I hadn't thought about that. thanks, Jerry
 
gunsandgunsmithing said:
Why does it matter so much? I don't get it!
Clearly, what Jerry has done is a practical way of stiffening the action. Maybe you can contribute by running some numbers to calculate how much stiffer his setup makes the action.

From my standpoint, I think it's a good idea. I think that it's best to minimize many of the variables like action flex from tuning. I strongly believe that tuning is mostly about managing vibration so, making the action stiffer by a considerable amount would, in my thinking, isolate the barrel more, as the part of the gun where frequencies occur that are easiest to manage, with a tuner....i.e., less noise from underlying vibration. IOW, make tuning more consistent and predictable.

Of course, my brain is just trained to look at all things gun related as possible influence on vibration and tune. Sure, he could use a setup like you describe or just buy a Panda action or sleeve his Remington and accomplish much of the same, probably more.
Click to expand...
Why wouldn't it matter? Is pinning the rail a good idea for increasing receiver stiffness? Sure, especially when done as carlsbad has said to do it and assuming a steel or SST rail rather than an aluminum one. Is it the best idea? Maybe, sure, and probably not. Depends on the goal.

If you're ultimately concerned with vibration you need to look at how what you're proposing to do is going to change the system's natural frequency. Most of the time that means doing it and then analyzing the pre- and post results because the analysis tools to model the system aren't all that common, nor is the knowledge needed to do the work that way or interpret the results. I haven't gotten into this myself because its way, way more math than I want to deal with, but I believe the most applicable process is called "Modal Analysis." I'm sure that some of the top guys out there are using it and probably holding this knowledge to themselves as one of their array of "secret weapons." Given the little that I know about the effort level involved I wouldn't share it either. First because it can be a lot of bloody tedious work and second because it will be different for each different rifle's set of modifications.
I do know that the results can't always be exactly predicted by the proposed process. Sometimes a simple geometry change, that appeared innocent enough, can have rather drastic consequences. Or a material choice for a part of the exact same part (within mfg tols anyway) can effect those drastic consequences. For example, ponder what making that rail out of magnesium might do to the way that the system responds to vibration. It will be different and just now thinking about it I suspect its worth a preliminary investigation.

All of that aside, if the torque on the screws can be set to a high enough clamp load and if the rail is properly fitted to the receiver I doubt that adding the dowel pins will change anything in this application. That isn't to say don't do it if you feel differently. It is to say that I don't expect there to be a gain from the condition that I just described above. If you don't have or can't get that condition (I can easily see the screw size being rather limiting), then pinning would be a good way to achieve better stiffening.

For the record, it wasn't the pinning of the rail comments that I took offense to. It was the "have fun with your tractors" snide comment that I took offense to.
 
ntsqd said:
Why wouldn't it matter? Is pinning the rail a good idea for increasing receiver stiffness? Sure, especially when done as carlsbad has said to do it and assuming a steel or SST rail rather than an aluminum one. Is it the best idea? Maybe, sure, and probably not. Depends on the goal.

If you're ultimately concerned with vibration you need to look at how what you're proposing to do is going to change the system's natural frequency. Most of the time that means doing it and then analyzing the pre- and post results because the analysis tools to model the system aren't all that common, nor is the knowledge needed to do the work that way or interpret the results. I haven't gotten into this myself because its way, way more math than I want to deal with, but I believe the most applicable process is called "Modal Analysis." I'm sure that some of the top guys out there are using it and probably holding this knowledge to themselves as one of their array of "secret weapons." Given the little that I know about the effort level involved I wouldn't share it either. First because it can be a lot of bloody tedious work and second because it will be different for each different rifle's set of modifications.
I do know that the results can't always be exactly predicted by the proposed process. Sometimes a simple geometry change, that appeared innocent enough, can have rather drastic consequences. Or a material choice for a part of the exact same part (within mfg tols anyway) can effect those drastic consequences. For example, ponder what making that rail out of magnesium might do to the way that the system responds to vibration. It will be different and just now thinking about it I suspect its worth a preliminary investigation.

All of that aside, if the torque on the screws can be set to a high enough clamp load and if the rail is properly fitted to the receiver I doubt that adding the dowel pins will change anything in this application. That isn't to say don't do it if you feel differently. It is to say that I don't expect there to be a gain from the condition that I just described above. If you don't have or can't get that condition (I can easily see the screw size being rather limiting), then pinning would be a good way to achieve better stiffening.

For the record, it wasn't the pinning of the rail comments that I took offense to. It was the "have fun with your tractors" snide comment that I took offense to.
Click to expand...
Thats exactly the kind of work I get into testing and experimenting with, as well as my tractors. One of which is calling my name right now. Gotta do some bush hogging for a few hours today. Then back to the shop to fill some flag and tuner orders.

Have a good one!
 
Whats all this pissing about? Pinned rails are quite common, they work. PS magazine had a good article about a one piece rail pinned to the action and they actually measured deflection of the action before and after. None of this is new, and whether or not pinning increases shear and stiffens the action really is not debatable.
I was a mechanic for 14 years and also drag raced, you cant compare 8 hardened fine thread fly wheel bolts torqued to 85lbs each to 4 little 8-40 screws.
 
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Alex, You are clearly wrong. There are, and will always be, those who want to debate it. ;)

I think the best reply in this whole thread is alinwa who wants to go do it just because it is "wikkid".
 
Alex Wheeler said:
Whats all this pissing about? Pinned rails are quite common, they work. PS magazine had a good article about a one piece rail pinned to the action and they actually measured deflection of the action before and after. None of this is new, and whether or not pinning increases shear and stiffens the action really is not debatable.
I was a mechanic for 14 years and also drag raced, you cant compare 8 hardened fine thread fly wheel bolts torqued to 85lbs each to 4 little 8-40 screws.
Click to expand...
Off Topic...I miss PS magazine.
 
gunsandgunsmithing said:
Why does it matter so much? I don't get it!
Clearly, what Jerry has done is a practical way of stiffening the action. Maybe you can contribute by running some numbers to calculate how much stiffer his setup makes the action.

From my standpoint, I think it's a good idea. I think that it's best to minimize many of the variables like action flex from tuning. I strongly believe that tuning is mostly about managing vibration so, making the action stiffer by a considerable amount would, in my thinking, isolate the barrel more, as the part of the gun where frequencies occur that are easiest to manage, with a tuner....i.e., less noise from underlying vibration. IOW, make tuning more consistent and predictable.

Of course, my brain is just trained to look at all things gun related as possible influence on vibration and tune. Sure, he could use a setup like you describe or just buy a Panda action or sleeve his Remington and accomplish much of the same, probably more.
Click to expand...
But are not the vast majority of tuners used on very stiff custom actions. The 700 actions were deemed obsolete many years ago and replaced by the customs some of which are very competitively priced with the over modified 700's of today. No alone the 1000.00 loss in resale value.

I take randomly placed dowels "driven" into any object in a less than precision manner as a hack. Forgive my attitude here but I've seen my share of valuable objects hacked on and virtually turn things into scrap, by guys self proclaiming their superior abilities.

That is in no way pointed at anyone on this site, but it is a very valid observation in the machine business. I have experienced plenty of horrors over the years.

I believe that when it comes to accuracy that it has long ago been accepted that accurate workmanship is paramount.
 
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Alex Wheeler said:
Whats all this pissing about? Pinned rails are quite common, they work. PS magazine had a good article about a one piece rail pinned to the action and they actually measured deflection of the action before and after. None of this is new, and whether or not pinning increases shear and stiffens the action really is not debatable.
I was a mechanic for 14 years and also drag raced, you cant compare 8 hardened fine thread fly wheel bolts torqued to 85lbs each to 4 little 8-40 screws.
Click to expand...
Alex I was referring to engines with 10-12 times the torque that your race cars had. Some of these non-tractors have 15,000 hp. They are not anymore common in Montana than a Grizzly on the north coast.Believe me those cranks and flywheels don't have 10 times the bolts or surface either. 700 remingtons were at one time the epitome of competitions also, but times have changed.

From what is being claimed here is that I should be dusting off our old drill press and drilling, reaming, and driving pins into me Bats, Pandas, and my yet to be designated Borden.:rolleyes::rolleyes::rolleyes:

But Alex you don't pin your customs either, do you.
 
TRA said:
Alex I was referring to engines with 10-12 times the torque that your race cars had. Some of these non-tractors have 15,000 hp. They are not anymore common in Montana than a Grizzly on the north coast.Believe me those cranks and flywheels don't have 10 times the bolts or surface either. 700 remingtons were at one time the epitome of competitions also, but times have changed.

From what is being claimed here is that I should be dusting off our old drill press and drilling, reaming, and driving pins into me Bats, Pandas, and my yet to be designated Borden.:rolleyes::rolleyes::rolleyes:

But Alex you don't pin your customs either, do you.
Click to expand...
I think customs are a complete different subject. They don't have that big cutout going over the top. They usually have metal over the top which would act like the pinned Remington scope rail, except better. They also don't have that the cutout in the bottom. Most times they are slightly bigger diameter. Those factors make them much more rigid. Matt
 
Alex Wheeler said:
.....
I was a mechanic for 14 years and also drag raced, you cant compare 8 hardened fine thread fly wheel bolts torqued to 85lbs each to 4 little 8-40 screws.
Click to expand...
Why not? Both sets of fasteners are doing exactly the same job. Totally different circumstances, but same job.
 
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