Sizing and locating a front sight ramp.

F

frwillia

Guest
How does one locate and install a front sight ramp?
I'm rebarreling a custom sporterized Springfield '03 that my father-in-law had built for my wife when she was in high school (1956 - 1960). It was test fired with military ammo that had corrosive primers in it, not cleaned, and the barrel was destroyed. I tried to shoot it, bullets went sideways through the paper at 50 yards. She brought it with her, along with 6 other rifles and a revolver, when we were married almost 43 years ago.

I decided to rebarrel it for her as a 43rd anniversary present. I'm almost there. The barrel is chambered, preliminarily polished, extractor groove is cut (figured out a good way to do that). Today I modified the stock so that the new barrel fits. This is what it looks like so far:

Newbarreljustinstallednotbluednofrontsight-2-C-RS.jpg


The barrel needs a front sight ramp, front sight, final polish and bluing.

I did some measuring on the old front sight as installed on the old barrel. From the centerline of the old barrel to the top of the front sight bead is 1.022". The ramp height measured from the top of the barrel to the bottom of the dovetail is 0.380". The barrel OD at the front sight is 0.594". The front sight itself from bottom of dovetail to top of sight is 0.345"

The new barrel OD at the front sight location is 0.667". To get the same height, bore centerline to top of bead, I'd need a ramp with a height of 0.345". Brownell's sells one, Williams, that mounts iwth a scre that's 0.3445" top of barrel to bottom of dovetail. That will work if this is in fact the right way to determine the required height.

My questions:

Is the above a reasonable way to figure out front sight ramp height, top of barrel to bottom of dovetail?

If not, how do I go about figuring out what height front sight ramp I need?

Once the ramp is here, what is the best way to decide where it should be on the barrel so the rear peep sight zeros about centered?

This, like some other features of this project (square threads and cutting an extractor groove), is a first for me. Any suggestions are welcome.

Thanks
Fitch
 
I'd take the old sight and epoxy it in place on the new barrel and go shoot it. If it works out then do a permanent installation, if not order another ramp.

There is only .036" difference between the old barrel and new barrel radii - so that's all that you have to make up. There should be plenty of adjustment in the rear sight to cover that.
 
henrya said:
I'd take the old sight and epoxy it in place on the new barrel and go shoot it. If it works out then do a permanent installation, if not order another ramp.

There is only .036" difference between the old barrel and new barrel radii - so that's all that you have to make up. There should be plenty of adjustment in the rear sight to cover that.
Click to expand...

Thanks for the idea. I may just do that. It's soldered onto the old barrel but I should be able to get it off - there is nothing to save about the old barrel. Worth a try anyway.

Fitch
 
Old sight came off easily and cleaned up nicely with emery paper on a dowel rod. I'll go ahead and install it on the new barrel using the screw to test it. If it works, it can stay, if it does't I'll remove it and install something else. As you suggest, there is bunch of travel in that rear sight. I can also get a slightly shorter front sight to put in the ramp if I have to.

Fitch
 
frwillia

Before you drill any holes or glue or solder the ramp on, you may want to consider simply attaching it with a few turns of tape, electricians or otherwise. It will be secure enough to test fire a couple of rounds.

JMHO

Ray
 
Cheechako said:
frwillia

Before you drill any holes or glue or solder the ramp on, you may want to consider simply attaching it with a few turns of tape, electricians or otherwise. It will be secure enough to test fire a couple of rounds.

JMHO

Ray
Click to expand...

Thanks for the suggestion. I'll do that.

When I do get to the point of installing it, the fact that there are both a screw and solder implies there might be a right order for doing the installation. I'm thinking I want to make a springloaded holder similar to the one sold by Brownells, get it aligned, use that to hold it while I solder it, "then" drill and tap the 6-48 hole for the screw. Doing it that way obviates contaminating the threads with solder or soldering the screw into the hole. Is this the right order?

Thanks
Fitch
 
Fitch,

Just go ahead and plan on soldering on the old base using a good 95/5 tin - silver alloy. That is Silvaloy or Force 44 type solder and flux. You can always adjust for front sight height by putting in a new sight insert if the rear sight won't accomodate the change in height. This keeps things "original" and is the best solution. I would not try to tap for the 6-48 screw as you only have about .160" barel wall thickness to work with (if you have left the chambering at 30 cal). This is "doable" with careful work, but is time consuming and won't add any significant strength over a proper solder joint.

Scott
 
shevelin said:
Fitch,

Just go ahead and plan on soldering on the old base using a good 95/5 tin - silver alloy. That is Silvaloy or Force 44 type solder and flux. You can always adjust for front sight height by putting in a new sight insert if the rear sight won't accomodate the change in height. This keeps things "original" and is the best solution. I would not try to tap for the 6-48 screw as you only have about .160" barel wall thickness to work with (if you have left the chambering at 30 cal). This is "doable" with careful work, but is time consuming and won't add any significant strength over a proper solder joint.

Scott
Click to expand...

Scott,

That's doubtless good advice, but I may not be able to resist installing the screw anyway. :D

I bought the Hi-Force 44 ribbon solder and Comet-Flux #4 from Brownell's before I started in anticipation of soldering on the ramp.

While I've drilled and tapped hundreds of holes, I've never drilled and tapped a hole as small as 6-48 and it's a skill I'd like to have, so I ordered 6-48 plug and bottom taps a couple of days ago. I already have a good set of number drills.

I've thought about how to drill the hole with very controlled depth. My plan is to get the barrel located on the mill, use my smallest center drill to make a dimple for starting the tap drill, move the chuck to an appropriate distance from the barrel with the drill able to slide in the chuck, lock the quill, set the depth stop collar to 0.080" using feeler gages, let the drill touch the barrel and tighten the chuck. Then release the quill and drill the hole with the spindle speed set pretty high, like 2500 rpm or so. I've used this approach before, though not with a drill this small.

What I still don't know is if I should solder it on first, then drill and tap the hole, or the reverse. My inclination is to solder first, drill and tap second but I don't know if this is the best way or not.

Fitch
 
The screw may help to hold things inline but it won't be doing anything after you sweat it all together. You could just as well use a pin to align the assembly before soldering or just clamp it properly. Silver solder with that much surface area is many, many times stronger than a tiny screw with a couple of threads engaged. I'd spend my time and energy on making a perfect solder joint rather than fooling with a screw.
 
MilGunsmith said:
Just solder it. Front and rear sights on magnum double rifles are just soldered on.
Click to expand...

OK, I'm convinced. No screw. Solder only. That eliminates the question, and also the wait for the taps to arrive (but I'm glad I ordered them anyway).

Thanks Scott, henrya, MilGunsmith.

I just bought small variety pack of compression springs, now I'm going to head for the shop and make a tool to hold the ramp in place with spring pressure while I solder it.

I figure I can make a spring loaded plunger with a point that is a 90 degree (45 to a side) point. Size it so that fits in the the dovetail and bears against the screw hole. The other end can fit in a collet in the mill. I can easily set up the receiver dead parallel to the mill table, the spindle is as perpendicular as I can make it, and with the DRO I can center the mill over the barrel with no trouble at all. So with a springloaded plunger tool to go in a collet in the mill spindle I should be good to go. Bottom line, I can use the mill as a convenient jig to set it up and hold it while solder it.

Time to make chips. It's tough, but somebody has to do it.

Fitch
 
Todays installment was miking a spring loaded holder that I can put in a collet in the mill. The tapered tip of the holder will sit in the screw hole in the bottom of the dovetail. With the spring load it will keep the ramp where it belongs when the solder melts.

This is the outside of it:

RampHolder-2-C-RS.jpg


This is what's inside it:

RampHolderPieces-4-C-RS.jpg


The body is made from 1/2" drill rod, the plunger was made from 5/16" brass rod, the spring came from Home Depot, the set screw was in my loose parts archive.

I made the whole thing in the 9" South Bend using the 4J chuck so that everything would be as close to on a true center as I could get it. The lower end of the body is drilled 1/4" (I didn't have a 1/4" chucking reamer or I'd have reamed it. the other end is drilled 5/16" to a depth of 1-1/2". The 5/16" hole is tapped 3/8-16 to a depth of 9 turns or just over 1/2".

The long end of the plunger was turned, and then sanded with emery paper with one end in the 4J, the other on the live center, to a sliding fit in the drilled 1/4" hole. The other end was turned to a sliding fit in 5/16" hole that had been threaded 3/8-16. The spring is supposed to have 12 lbs maximum working force. That should be plenty. I can adjust the prload on the spring by how far in I turn the setscrew.

Tomorrows installment will be to go ahead and solder the ramp in place.

Fitch
 
Fitch,

Nice tool. If you are only going to use it once, it is overkill, but I don't think that is a problem when it gives you so much fun. Since you are enjoying learning your tools you might like some other feedback on this project : You are now going to solder this thing while in the mill - take care to protect your mill from the (corrosive) dripping flux and the torch flame (or you will regret doing this). I prefer to work in a rough vise with the parts just clamped together properly - I have a bunch of ratty vice-grips. I suggest that you forget the advertised ribbon solder method - hoping to put solder between two parts and thinking that they will give you a good joint after heating a bit is possible, but it just doesn't usually work out all that well. You will find that the solder will not cling to all the surfaces when trying to solder steel (you can ribbon/paste solder brass, copper, etc., but steel is much tougher) You normally need to make sure that the surfaces to be joined are tinned, which usually requires a bit of scrubbing while the parts are exposed to heat, flux and solder. After tinning you could use a piece of solder ribbon to join things, but it is just as easy after tinning to make a capillary joint to fill any joint spaces, meaning that when the work is up to temperature a touch of the solder wire at any edge will feed into the joint all the needed solder. The problems that you will encounter when you first try to do this kind of work mostly arise from poor cleaning of the parts, overheating of the flux due to haste in "getting on" with things, and poor part fit up. A pressure clamp such as you have devised will work, but when you put a ribbon underneath the parts there is always the possibility that things will shift when heated (but that is the value of your fixture).

I normally don't try to drill and tap any barrel that has less that .200" wall thickness. I want .150" depth for a number 6 screw, which alighns with the basic "square" shape needed for minimum thread strength, and I want .050" over the bore at the muzzle to ensure things won't dimple from pressure. The procedure is a bit like you describe (but deeper than .080"), so the sequence is a twist drill to .150", then a bottom drill with a flatted drill, then a plug tap to start (a taper tap won't even start), then the bottom tap. Using a center drill to start is OK, then number drill (#33 for this short thread), then the tapping process. This is not rocket science for the mechanics out there, but it may be new to you.

Scott
 
Scott,

Thank you for the input. I've soldered a lot of electrical and plumbing connections, but not steel. I've brazed a bunch of steel, but not soldered it. I've brazed hydraulic fittings together to create hybrids - the brazing sucks right into the joint if it's prepared properly, but it has to be a lot hotter than solder - too hot for this application.. Reading your post I think I have a bunch of work to do to clean all the old solder off the ramp and get it shiny clean, then tin it. I think tinning the barrel will be a lot harder, on the other hand I can get the barrel really clean. At the moment at least I'm not sure how to contain the solder to the footprint of the ramp on the barrel.

I have a 3" long cut off piece of this barrel from the muzzle. I may do some practicing with that before I work on the real barrel.

Thanks
Fitch
 
Use a piece of soapstone, what welders use to mark out before torch cutting. Mark all around the base and it will help to contain the solder.
 
MilGunsmith said:
Use a piece of soapstone, what welders use to mark out before torch cutting. Mark all around the base and it will help to contain the solder.
Click to expand...

Thank you - I have some soapstone I use for marking things to cut.

I'm going to do some more reading today and then do an experiment on a barrel stub tomorrow, before I try the real thing.

Fitch
 
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