Is my Contender frame stretched?

[Whistler]

I'm having some accuracy issues with my Contender. I have three barrels (.44, .30-30 and .357 Max), all of which shoot about 4" groups at 35 yards. I'm worried that my frame is stretched since I bought it used. I heard one of the signs is that you can see a light gap between the end of the barrel and the breech face, but that this could also be a case of worn barrels and/or locking pins. The feeler gage let's .002" inside easily, but the .004" will not go in at all, so I'm judging the gap to be .003".

The frame has serial number 117XXX.

Here is my .44 Mag barrel and my .357 Max:


http://img6.imageshack.us/img6/2470/20120323001258.jpg
http://img217.imageshack.us/img217/9798/20120323001631.jpg

[trcuda]

.003 is not an uncommon amount of frame/bbl gap. To check and see if your frame is stretched you need to look for a "stretch" mark inside the frame. You can see this by looking down into the internals of your frame when the bbl is off. The stretching will occur in the cut that allows the locking bolt rollers to pass down into the table. That is the notch that is just in front of the breech face. Stretching will look like a light line in the blueing. Extreme cases will show maybe a 1/8" stripe.

How is the bbl lockup? If you get any movement at all when it is closed that can be an accuracy killer. This would not be caused by stretching but by under/over sized locking bolts. Are the locking bolts on your bbls all blued? Over sized bolts are left in the white by TC. This is probably not the cause because you said your having problems with all 3 bbls but it is worth checking. If you have some slop in the lockup check your hinge pin. It should not have any noticeable wiggle in either the bbl hole or the frame holes. The pin will probably slid through with no resistance but if you can get noticeable side to side movement that is bad. If you have a gross amount of slop in either the only cure is an over sized pin.

Also check your scope mounts if you are using a scope. The 44 and 30-30 are kickers, especially in the 10" bbl lengths. Will certainly kick loose a mount that was not tightened properly. Make sure your base screws are not bottoming out before your base is tight. You can do this by loosening all the screws and tightening one down all the way. You should not be able to wiggle the base AT ALL. If you can shorten the screw 1 thread and try again. Once you have that screw good back it out and do the same thing with the next until you have all 4 the right length. I have seen iron sights from the factory that had screws too long too but it is much more common to see it in scope bases.

It is doubtful that you have worn out bbls. If the bbls are in good condition (no rust or damaged crowns) you should easily get 2" groups at 50 meters. It would take a lot of shooting to wear one out and the odds of getting 3 worn out ones are poor.

Tim

[uscra112]

That's about the same barrel-to-frame clearance that my Gen 1 has with both my .357 Max barrel and my .22 Hornet barrel. Next question is how much clearance you have with a cartridge in the chamber. That's your headspace. A quick functional check of headspace is to simply fire a primed but unloaded shell, and the look at the primer protrusion afterward. If your headspace is excessive for all three barrels, you may well have a stretched frame.

If the hinge pin slides through with no appreciable resistance it's way too loose, IMHO. The pin should be a light press fit in the barrel lug, and a drag fit in the frame. i.e. you should be able to push it through the frame with your thumbs, but with some significant effort, and to get it through the barrel lug it should require a mallet, but not a sledgehammer.

The fix is to make pins that fit, which can be done using hardened steel machine dowels. Pin gages from gageshop.com let you evaluate the actual diameters of the frame holes and the lug holes, then you can dress down a dowel to proper fit using a lathe or drill press and a diamond lap. This did a lot for the accuracy of my old Gen 1. A much better fix than the "oversize pins" the vendors sell, IMHO.

Double ditto on the scope mount. It took a world of work to get the scope mount on my Max barrel to sit still. Frankly, I no longer think the heavy recoiling rounds are a good idea in an old Gen 1. I'm sticking to my Hornet, except for deer season.

[Whistler]

The hinge pin takes a light tap with a tool to remove when the barrel is mounted on the frame, but it falls right through all three barrels and the frame when I try them separately. I will look for a new hinge pin. Thanks guys!

[Tatume]

The gap you are seeing is not the headspace. You have to measure headspace at the firing pin bushing. See Mike Bellm's website for everything you ever wanted to know about Contenders, including how to measure headspace and frame stretch, and how to correct it.

http://www.bellmtcs.com/store/

[Whistler]

I've been reading up some on hinge pins and there seem to be a lot of accuracy to get there if fitted properly.

This is from the Mike Bellm site:

Do the simple wiggle test with the stock pin in each of the three holes, barrel lug and the two frame holes. If you can feel ANY movement at all on the pin when you try to wiggle it in each hole, it indicates you need a larger pin to take the play out of that hole.

I don't have access to a lathe, so I'll try to find someone who can make me a couple of pins to try with. At first I attempted to make one myself, I used an old drill bit, but it was impossible to get even and soon got out of hand. It didn't take much going from "huge" to it being smaller than my original one. I'll need someone with a precision lathe.

These are the measurements for the pins I'm ordering if anyone wonder and want to check (or make) your own:

.3748" x .920" (9,52 x 23,4 mm)
.3752" x .920" (9,53 x 23,4 mm)
.3756" x .920" (9,54 x 23,4 mm)

My factory pin is .3744".
The pins that Mike Bellm sell are .3752"

[flipajig]

I don't remember the site but there is some one who is making and selling oversized hinge pins.

[uscra112]

Bellm sells an oversize pin. He also sells a reamer. But reaming strikes me as simply recreating the looseness problem at a larger size if the pin used isn't properly fitted.

OTOH if Whistler's pin is tighter in the frame than in the barrel lugs, then reaming the frame must be done to get the frame holes at least equal to the barrel lugs.

I bought about ten gage pins to get a clear picture of what the situation was. You need to know to a "tenth" what the diameter of each hole is before you really know anything. At $2.50 each, (Grade Z) the gage pins are pretty cheap. Notice that at each nominal value (half-thou intervals) there is a "plus" and a "minus" pin. You need both.

Here's a horrible thought - what if the barrel lug holes are oval? All of the breech thrust in the Contender is transmitted to the pin, and an old barrel that has been fired a lot may have pounded the holes oblong. THAT problem will not be revealed by the gage pins. Perhaps by "blueing up" the holes with Prussian blue and pushing the tightest possible pin through you will see spots that are not contacting?

The above is why I say that the Contender is a weak action. A much better design for a break-open is the old (Civil War era!) Maynard. It had a lug on the barrel which engaged a mortice in the frame as the action closed, and the action was held tightly closed by a toggle, not a sliding bolt. (The sliding bolt was abandoned by US shotgun makers about WW1, BTW). The pivot pin played no part in resisting the thrust force on firing. The Maynard was an accurate rifle - it was quite often used for competitive shooting at 200 yards, and won its' share of matches.

Finally, there's no reason not to cut a gage pin to length to make your pivot pin. They're good steel and heat treated. And they come in any size you can imagine. And they're cheap!

[ohland]

Bellm sells an oversize pin. He also sells a reamer.

I have bought three 1x Contender / G2 hinge pins and one Encore hinge pin from Bellm. In each case, the hinge pin fit is like a vault. I have not needed a reamer to install his hinge pins. It does not seem to me that Bellm has ever urged reaming as the first course of action to address hinge pin fit, but rather, it is the last option.

For extreme fit problems, Mike tells you up front that IF you do ream out the hinge pin, that dedicates the frame to like reamed barrels...
http://www.bellmtcs.com/store/item.php?pid=616&

Mike Bellm talks about oversized pins and reamed holes.

Opposition to Oversize Hinge Pins
http://www.bellmtcs.com/store/index.php?cid=216

But note:
Bellm Oversized Hinge Pins
http://www.bellmtcs.com/store/index.php?cid=7

"Reamers for Contenders and Encores are seldom needed except for the larger Encore pins. In the event you find you need to ream either a barrel or frame hinge pin hole to match the larger opposing hole in order to get a good fit, a variety of reamers are offered under the "Tools" menu to the left. You are welcome to buy reamers of course, BUT I recommend that you do not buy any reamer until you find you actually need it. Start with the 1x pin, and if you find it is loose in an opposing hole, go to the 2x pin. If reaming one of the holes is necessary, then consider the reamers."

:popcorn:

[uscra112]

Agreed - I don't think Bellm is urging reaming either, unless something is drastically worn. I also took a look at that Brown captive pin he goes on about, and I agree that the Brown idea is a bit off. If the pin is so loose in all three holes that it can float, capturing it ain't going to do any good.

As I said in my first post - I believe the pin should be very tight in the barrel lug. All rotation should occur in the frame holes. This gives the greatest lateral stability. If the barrel lug is bigger than the both frame holes, however, either the lug must be sleeved or one or both of the frame holes must be reamed to take a pin that is a tight fit in the lug. The latter is easier for the kitchen table gunsmith, the former is the right way. Reaming without an alignment fixture is always chancy - too easy to get the holes oversize or oval.

All the more reason to buy some gage pins and see what you've actually got, before making any changes at all to the lug or the frame. We had a saying in the machine tool business, "You can't make it any better than you can measure it".

If at all possible, I advocate using a pin that fits even if it has to be custom made. This may mean making a pin with two or even three steps, but that's actually easier to do than it appears, as long as you have a lathe or a substitute, and a tenths micrometer in addition to the gage pins.

[leadman]

The stretch on an early Contender (gen 1) can be seen on the outside of the frame where the standing breech meets the frame if you get the light just right. I have one that the left side shows a little stretch but the right does not. Was told this is common. The barrels on this frame are accurate enough for 400 yard shooting so a little stretch does not seem to always be a problem.
What it a problem is ammo loaded with no regard to including the barrel to frame clearance in the sizing of fired brass. I use an automotive feeler gauge to measure the clearance between the end of the cartridge and the breech face. It is best to remove the extractor from the barrel the first time at least until you get a feel for measuring this. I try for .0015" clearance. This allows for good lockup of the action which is needed to get good accuracy.

[cbrick]

And what hasn't been mentioned yet is the locking bolts. Early barrels had a single bolt and was changed I think in the mid 80's to a split bolt. The split bolts will give better/more consistent lock up and could help with accuracy. Also check the bolts on all three barrels to see if they seat the same, i.e. in far enough.

Rick