My Ruger SBH is back from the factory.

[Bazoo]

Some might remember I have a Ruger super blackhawk 44 magnum and it was leading badly. Well long story short I sent it back to Ruger for the second time and it appears they have worked it over. New barrel per the paper included, which appears to have an 11 degree forcing cone cut. And a new cylinder though it's not mentioned.

Previously by slugging my cylinder throats and measuring with calipers, I had 4 at .433 and 2 at .434. Now by the same method all measure .432. Yes I know this is not the best method but it's all I have.

I slugged the bore and it measured .429. I feel a slight resistance at the threads, but so little that I can push the slug through with my thumb on the brass rod. All of my thumb force, but still that ain't much when you're talking compressing lead. So I'm thinking maybe it's not a thread restriction but a burr or irregularity in the rifling. Opinions?

It appears they tested it with lead bullets instead of copper bullets also.

So, after 4 years of frustration, minimal enjoyment and shooting, I have hope.

I'm going to shoot it before I do anything. If need be I'll fire lap it, we'll see bout that though.

I just wanted to share this little piece of happiness with y'all.

Thanks for listening.

[nicholst55]

Stainless or blue? That Ruger stainless barrel steel is HARD, and fire-lapping will take a while. If you shop around, you can buy an inexpensive micrometer for not a lot of money - maybe not a Starrett, but probably good enough for what most of us will use it for. You can also buy individual pin gages from a few places, if you don't need a complete set. Hope your Ruger performs now!

[Bazoo]

It is a blued 4 5/8" barreled gun. I need a micrometer, just ain't got the extra funds for one right now.

[megasupermagnum]

If you can push the slug through, you don't have a problem. Load with .431" bullets, and you will have the perfect setup.

[DougGuy]

Bazoo, I have tried numerous times to suggest things in a number of your posts to help you sort out issues and diagnose problems, but you seem to ignore every reply I have made in the last couple of years, so I will try once with this one before I concede that it is a lost cause.

You can best check for thread choke by patching a plastic cleaning jag rather tightly in the barrel with a paper towel folded over, once the jag is moving, any change in resistance to keep it moving is a change in bore diameter. If you feel a slight increase at the barrel/frame juncture, this is thread choke and it is mild, easily firelapped if this is a blued gun, quite a bit more difficult if it is stainless as Ruger stainless is some very tough stuff and very slow to firelap. This much change in resistance on the jag is approximately .0005" to .001" of measurable choke.

If the jag stops and you have to force it, the choke is more severe, in the neighborhood of .002" or so. Harder to firelap, but not impossible.

If the jag stops and you have to beat it with a hammer, you are close to .0035" ~ .004" of choke and this is too much to firelap, either a replacement barrel or sending it out for Taylor throating are about the only two solutions for this much choke.

Generally if you can push a soft lead ball through the bore, and it slides into the cylinder throats without much effort you are pretty good. The fact that your throats are now somewhat consistent in size is the biggest improvement you got, since this alone is the most important dimension in the cylinder, not the actual diameter of the throats. You can size to fit the throats either with a sizing die, or you can shoot a soft enough alloy that the pressure of firing will obturate your boolits to throat diameter upon firing. Either way works. It is all but impossible to size to uneven throats.

Jacketed bullets are a soft lead core swaged into a gliding metal jacket, loaded on top of sufficient charges of powder, the pressure of firing will obturate these to throat diameter, they will happily swage down to go through the choke, and provided there is enough pressure after this point, which with most magnum calibers there is, they will once again obturate and seal in the bore once the choke is cleared. Soft lead cast boolits will do the same if you can scratch them with a thumbnail. Harder alloys will not obturate once they are past the choke.

Load with .431" bullets, and you will have the perfect setup.

No. Size to a light drag fit in the throats.

[megasupermagnum]

Maybe it's just me, but I feel like worrying about .0005" is taking things a little far with bullet sizing. Although I now realize his stated dimensions were measured with a calipers, so they could easily be off from stated.

[Bazoo]

Doug, I appreciate your help. I went back and read your posts in my previous thread about the guns problems. It was you that suggested sending it back to Ruger. I will reconsider all of what was suggested there.

[Bazoo]

Bear with me as I ask a dumb question. Why is a caliper not able to give an accurate measurement? I measure a particular jacketed bullet occationally and it measures .308. So if I slug my throat, why is the measurement from a caliper useless but that from a micrometer good?

If my calipers hit right on the .432 mark is that not .432? If they hit halfway between, wouldn't that be close to half?

[W.R.Buchanan]

If my calipers hit right on the .432 mark is that not .432? If they hit halfway between, wouldn't that be close to half?

IF the calipers are accurately calibrated, this would be mostly true. The other part is that the vast majority of people can't get a truly accurate measurement with calipers simply because they don't get repeatable results. It is easy to screw up a caliper measurement.

With calipers you must get them onto the diameter of a round part exactly at 90 degrees to the part. You do this by holding pressure on the jaws with your thumb while wiggling them around until you get the smallest measurement... Then you need to do it a couple more times to make sure your measurement repeats. If it does you're good, if it doesn't your measurement wasn't accurate to begin with and you need to do it again until it does repeat.

It is easier to get an accurate measurement with calipers on the OD of a part, than on the ID. On the ID you must make sure the caliper is exactly at 90 degrees to the hole you are measuring and parallel to the axis of the bore.. If it is cocked at all you will get bogus readings,,, and they probably won't repeat, which is your first clue that your reading is bad. Also the jaws of the caliper must be directly across on the Diameter of the Hole. You are looking for the largest possible reading in this case.

I have to tell you that it doesn't matter how long you've been doing this, everyone is susceptible to screwing up. I do this everyday and I have to check my readings each and every time or else I get bit by a reading that is bigger than what is actually there and the end result is when you dial in the cutter the exact amount to get you to the finished measurement, you find out you come in undersize and scrap the part.

I've only done this about 5,000 times. You'd think I'd figured it out by now. Take solace in knowing that NOBODY is immune from this error in technique. Just get in the habit of taking every measurement several times to make sure it repeats. Then you'll be golden.

Randy

[megasupermagnum]

One other thing is that the jaws on calipers usually have a flat spot, even if it looks very sharp. Works great for OD measurments, but ID measurements would then be slightly small. If you have a few sizers, the best thing to do would be as Dougguy says. Just size to the biggest that gives a slight resistance in the throat.

[Bazoo]

Randy, thank you for that detailed response. . I figured out to do as you have described, and I do have a feel for it. My calipers haven't been calibrated.

[nicholst55]

Individual gage pins: https://www.meyergage.com/products/i...ual-gage-pins/

Take a look at Amazon for micrometers. They have some cheap micrometers (yeah, I know), and they have some very decent mikes for under $100.

[DougGuy]

If you do decide to get gage pins, (which btw is the best way to measure your throats), get the half thou sizes also, as .001" increments are too coarse for accuracy. I use the ZZ minus set -.0002"

I like the Mitutoyo 193-211 0"-1" (normally under $50 on fleabay) this has an analog digital readout in .001" but you can accurately guess how many 0001" as the last digit's position in the window is pretty easy to determine. The thimble also reads in .0001" iirc. VERY helpful is a micrometer stand that holds the mic for you and leaves both hands free, I highly recommend one of these as they allow you to devote much more attention to holding the material to be measured confidently. Worth it's weight in uhh gilding metal?

When I first started doing cylinders I didn't have any pin gages. I used jacketed bullets for gaging throats. It was assumed that if a bullet was a light drag fit in the throat, that was the correct fitment, and the actual mathematical reading of the throat wasn't really important at all.

My own 7 1/2" SBH had one of those cylinders that Ruger made on the Hitachi machine with 3 cutters, each cutter cut two throats, they would gang ream 3 throats, then index the cylinder over one hole and gang ream the other three. As the cutters wore, they would cut smaller and smaller holes until techs changed them. Problem with that was they would only change the most worn one when it got too small to meet tolerance (whatever that was?) and they would leave the others in service until they no longer could pass muster. Now they have 3 cutters, cutting throats in pairs with 3 different diameters, the new cutter would cut .432" throats, the others could be any random size and mine were 2 at a very generous.432" with 2 more being .430" and the last 2 were .429" this causes the gun to shoot to different points of impact as throat sizes create varying resistance and therefore cause variances in pressure on firing, the gun recoils differently when throats are .002" or more between diameters, impossible to size to uneven throats, it's just a no win situation for the shooter or reloader trying to cope with uneven throats.

So I honed mine to fit some Lee C430-310-RF boolits I had just gotten from a member here, sized .432" and all was good, light drag fit in the throats, and I loaded up 50 or so rounds for hunting and they sat for 5 or 6 months. I went to sight the gun in and half the loaded rounds wouldn't chamber! To my dismay I then discovered that cast boolits DO grow as they sit and age harden. Some had picked up .0003" some had grown more.

Now we know why that .0005" is important, because you MUST have a bit of wiggle room if you shoot cast with any amount of antimony in the mix.

[Harter66]

Great to see the RRH worked out . Sounds like it should shoot now .

The passive search for tools has paid off for me . I just set a max price I'll pay for a tool or set of tools better than what I have or a minimum tool .
I ended up buying a 0-1,1-2,2-3" set of micrometers . They are older tools but they are mechanically perfect and as accurate as my gauges . I gave a whole $40 for the 3 tools on par with Starret 1955 in spite of one maker having sold out in 1935 . I have others but I'm separated from them . These are an upgrade from the Craftsman 0-1" but just a companion to the 1-2" Starett , I paid $80 for in 1990 new .

You just have to keep things in mind and they will come up .

[onelight]

Bazoo it's great to hear that Ruger fixed your gun up for you I hope it shoots good .
It sounds like it is set up better than most of the Rugers I have or have had and most of them I am happy with.
Go shoot it and see how it works odds are good you can find a load it likes just like it is.

[jonp]

I didn't see it in your post, bazoo but when you measured the throats on the original cylinder did you slug the barrel at the same time?

Good to see that Ruger stepped up and fixed your problem but it seems like it could have been done a lot faster if you had slugged the barrel and then sent the cylinder to DougGuy.

If your funds are limited then http://www.igaging.com/ has some stuff that gets good reviews. I would think it would be good enough for our use but not aerospace or something like that.

DougGuy and W.R.Buchanan posted much good information in this thread

[LUCKYDAWG13]

[Bazoo]

Jonp, sorry I missed your question. Yes I slugged the barrel the first to round. It was .430 and my throats were .433/.434.

The issue was severe leading.

[Bazoo]

So I fired 30 shots with minimal leading. Leading right at the beginning of the rifling, could still see the rifling, and it brushed out with about twenty strokes. So, first thing I'm going to try is adding more tin to my ww alloy. Then Ill explore other options to reduce leading. Accuracy seemed good, but I'll test more and see.

[725]

Bazoo,

Don't know if it would help but, I recut my forcing cone and as far as I can tell, it helped a little. Just a thought. 725