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45 Colt cylinder throat ?'s

This is a discussion on 45 Colt cylinder throat ?'s within the Gunsmithing forums, part of the Firearm Forum category; To preface this discussion; I did use the search function and have learned much from posters such as Iowegan and Varoom. My technical knowledge and ...


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Old September 8th, 2019, 05:13 AM   #1
 
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45 Colt cylinder throat ?'s

To preface this discussion; I did use the search function and have learned much from posters such as Iowegan and Varoom. My technical knowledge and mechanical skills come from 32 years as an aircraft mechanic and an unfinished engineering degree (such is life).

In the last year I've purchased a brand new Blackhawk Bisley convertible, stainless, 45 Colt/ 45 ACP and a new to me 2000 vintage Vaquero, blued/color case, 45 Colt (low round count).

I recently began reloading for the 45 Colt cartridge and began reading many topics on rugerforum.net. One topic I noticed that was brought up many times is the Ruger 45 Colt cylinder throat diameters are quite commonly undersized, oval, etc. Having reloaded different calibers for 20+ years I am familiar with chamber pressures, accuracy and things that affect them. As I get further into my current reloading for my 45 Colts, I began to investigate dimensions of components and my Bisley and Vaquero.

Last night I measured the cylinder throats for my Vaquero and Bisley (haven't measured the ACP cylinder yet). I used my dial calipers (not the most precision measurement tool, but it's what I have). The Bisley Colt cylinder throats measure out at 0.450 (all 6 as best as I can tell) and the Vaquero has 4 cylinder throats at 0.450 and 2 at 0.490.

Has anyone sent their Ruger's back to the factory and requested that they ream them to 0.4525?

For a DIY I did visit the 4D rental website. I was suprised when reading posts and visiting the 4D website that a jig and drill press or lathe wasn't required to ream a cylinder.

For those that have hand reamed their cylinders, have you experienced any steps/procedures that could lead to a mistake that could be avoided so as not to ruin a cylinder? I liked the use of a cut spent case as mentioned by Iowegan.

I'll stop now as I probably could use the search function instead of bringing this topic up again. If I'm beating a dead horse, I apologize to those that think so.

Thanks all.




Last edited by FlyingFinn; September 8th, 2019 at 05:21 AM. Reason: sp...
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Old September 8th, 2019, 05:51 AM   #2
 
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Finn, it sucks that your Vaquero has 2 chambers that are that big at .490".
Better that they come undersize as you can always ream them, not much you can do if they are way big. I'd have Ruger replace that cylinder.

I don't think Ruger will honor anyone's request to open up their cylinder's throats if they are at .450"
Ruger will politely tell you that they are "within specs".
Sounds like with your background you won't have any problem doing the work yourself with the rental tools.

I haven't broken down and bought the Manson reamer yet. My Flattops were reamed by Bobby Tyler in Texas. But I do have the tools for forcing cone modification and chamber chamfering.
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Old September 8th, 2019, 06:04 AM   #3
 
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Oops! Correction not 0.490 for 2 cylinders. It's 0.449 for the 2.
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Old September 8th, 2019, 10:24 AM   #4
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FlyingFinn, It's very difficult to get an accurate measurement with a caliper in a round hole. If you really want accurate measurements, use a set of pin gauges. Knowing the actual throat diameters isn't important …. what is important is when a .452" lead bullet won't pass through the throats with just finger pressure. That tells you the throats (all 6) need to be reamed to a uniform diameter of .4525". This will give you a mere .0005" slack …. just enough where .452" bullets can be pushed through without using a hammer.

Ruger ships their 45 Colt (and 45 ACP) cylinders optimized for .451" jacketed bullets where a couple thousands too tight really doesn't matter much and it's why they consider tight throats "in spec". For optimum accuracy and "period correct" tradition, most people load 452" lead bullets in their 45 Colts, which does present an accuracy and bore fouling problem when throats are too tight.

Over the years, I have reamed many dozens of Ruger cylinder throats and learned as I went. I like to use a lot of cutting oil in each hole then after the hole is reamed, I clean up the reamer and apply more cutting oil before starting the next hole. This results in a smoother and more uniform cut. When you get oil on your hands and on the cylinder, things get pretty slippery so have some rags available to keep your hands and the cylinder surface oil free.

It's virtually impossible to ream a hole without leaving some lines in the metal so after reaming, I put a section of 3-M abrasive pad (maroon color) on a worn out 38 cal bore brush then hone each hole with the bore brush mounted in a low speed drill. A few seconds will burnish the cutting lines out, leaving the throat looking factory finished.

I have found using Manson throat pilots (other than the 448" one supplied) are all but worthless. Why? The bushing must be small enough to fit in a tight throat and it only provides guidance for the first few twists. After that, the rear of the reamer can wander and make oval holes or even get carried away and damage the chamber. You will note …. the pilot exits the throat well before the reamer, leaving the reamer unguided. That's why I use cutoff spent cases as a rear guide. The cases provide guidance all the way through the throat, making it almost impossible to damage the chamber or to end up with an oval throat …. one of the very reasons for reaming in the first place. When you make brass guides, use a spent case that has NOT been resized, other wise the reamer won't fit. I use a tubing cutter to cut off the usable part of a 45 Colt case then a round file to take the cutting burr off. The first time a cutoff case is used, place it in a chamber and ream it along with the throat. After the first use, it will then be sized perfect for the next throat. These cutoff cases typically last for about 10 cylinders.

Last edited by Iowegan; September 8th, 2019 at 10:47 AM.
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Old September 8th, 2019, 01:11 PM   #5
 
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Thanks Iowegan!

I haven't tried a .452 lead bullet. I tried passing a Speer jacketed bullet through the throat with finger pressure and it wouldn't reach the cannelure crimp on any hole. The Speer jacketed bullet measured an exact .452". I'll try a cast bullet today.

I do have a micrometer set.

I may look into pin gauges for this caliber.

Last edited by FlyingFinn; September 8th, 2019 at 01:26 PM. Reason: sp
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Old September 8th, 2019, 05:24 PM   #6
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FlyingFinn, No need for further measurements or a lead bullet …. if the .452" jacketed bullet wouldn't pass through the throats, you do need to ream them.
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Old September 8th, 2019, 06:58 PM   #7
 
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My old Central Tool 0-1" micrometer (found set at yard sale years ago) only measures to 3 decimal places. Anything finer is an eyeball calibration guess.

VAQUERO:

I used one cast bullet for each cylinder. Not an exact science, but better than using dial calipers.

I had 4 cylinders in a row that measured exactly 0.451" (no need for 4th decimal point). No matter which way I turned the bullet, I got 0.451".

Then there were two. Two cylinders side by side. The cast bullets that came out were hard to measure. Almost as if the holes were not "round".

One hole I call #5 (painters tape around cylinder and marked) I had measurements of the cast bullet as follows; 0.4495, 0.450, 0.451. Yes, I guessed a 4th decimal point. I must have fiddled with that bullet in the micrometer for awhile, turning and turning. Trying to get a surface that measured the same in at least 3 spots.

Hole #6; 0.4505, 0.451 I didn't fiddle with the bullet as much with this "hole" as I suspected it is like hole five; out of round.

Of course this was done by pounding a cast bullet through a hole, so accuracy is only so so. Maybe pin gauges would be better, don't know never used them.

Thanks Iowegan!

Kind of answers my question I had when I was buying some bullets for reloading. Hornady and Speer bullets identified specifically for 45 colt were marked 0.452". But Nosler bullets for the 45 Colt were marked 0.451". Maybe Nosler should also mark their boxes; "Ruger Only". These were all jacketed bullets.

Off topic but here is my mini rant; My vocation of many years has created in me something I call "Precision Measurement Disorder". Even all my measuring tools and taps/dies at home in my tool cabinet are in one drawer I call the PMD drawer. I HATE working on house stuff, from lumber to plumbing the sizes do not match the label! I am a bit frustrated that a firearms manufacturer is starting to "measure" up to house stuff.

Last edited by FlyingFinn; September 9th, 2019 at 05:35 AM. Reason: which gun added
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Old September 8th, 2019, 07:02 PM   #8
 
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And I thought my bad shooting was "entirely" my fault. Maybe not so much.
Attached Images
File Type: jpg Vaquero15yd.JPG (2.38 MB, 17 views)
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Old September 9th, 2019, 05:56 AM   #9
 
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Now that I measured the Vaquero cylinder throats with a little more precision and discovered that the cylinder throats need to be reamed to .4525.

Do I need to be concerned about the bore diameter of the barrel? Without measuring I would guess it is 0.451. If it is, will that be a problem with .452 jacketed bullets?

I haven't measured both of the Bisley cylinders yet.

Last edited by FlyingFinn; September 9th, 2019 at 05:56 AM. Reason: sp
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Old September 9th, 2019, 09:09 AM   #10
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FlyingFinn, There's absolutely nothing you can do about an out of spec bore …. except replace the barrel. SAAMI standards are +or- .0005" so your bore should measure well within these standards. Many people try to slug a bore but without the right equipment like Cerrosafe, a micrometer accurate to .0001", and curved shim stock, you won't get accurate results. The way most people try to slug a bore, it would be about as precision as marking a log with a piece of chalk then cutting it with an axe. Further, even if you get accurate measurements, what can you do if a bore isn't perfect? The answer is pretty much "nothing". That's why using bullets with the right hardness is important.

If you have the proper throat diameters (.4525"), use the right bullet diameter (.452"), proper hardness lead bullets are malleable enough to "reshape" under pressure and form a good seal between the bore and bullet …. even if the bore is slightly too tight or too loose. The formula is Bullet Hardness Number (BHN) = chamber pressure divided by 1400. So if you shoot SAAMI standard pressure loads, you want a BHN 10 bullet. As noted earlier, Hornady "cowboy" swaged 255gr bullets are BHN 10 and work exceptionally well.

I have slugged a good many Rugers and never found a single barrel that was out of spec. Yes, it is possible but it is very unlikely. About the only time you may have a bore size issue is with foreign made "clones" or older Colts where they are .454". Back in 1951, SAAMI changed the bore diameter for 45 Colts from .454" to .451" to make 45 Colt barrels compatible with 45 ACP bullets. Ruger never made guns that long ago so all their 45 cals will have .451" bores. I guess what I'm saying is … sometimes you just have to trust the manufacturer.
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Old September 9th, 2019, 09:58 AM   #11
 
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Thanks Iowegan! I've downloaded your pdf on cylinder throat reaming.

I see the part number in your photo for the cylinder throating reamer is 513-000-01. Looking it up on Brownells the part number shows a suffix of WB. New part number? It is out of stock as of now.

Is the pilot pack(513-000-02wb) worth it? Or is the spent brass case the ticket?

I believe I found the correct kit for the 11 degree reamer on Brownells. Will order.

Saw your tip on the HF 1/2" chuck in another post. Good tip as there is a HF store where I live.

If my BH convertible 45 ACP cylinder measures out at .451, should the throat be reamed to .4525 also?

Thanks

Last edited by FlyingFinn; September 9th, 2019 at 09:59 AM. Reason: sp
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Old September 9th, 2019, 10:38 AM   #12
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FlyingFinn, Read the last paragraph in post #4 above. I bought a "pilot pack" with my first throat reamer and used them exactly once before I came up with a much better guide (cutoff spent 45 Colt case). I can think of hundreds of things I'd rather spend 72 bucks on than nearly useless pilots.

The "WB" in Brownell's part number makes no difference.

Quote:
If my BH convertible 45 ACP cylinder measures out at .451, should the throat be reamed to .4525 also?
Your option. I have three 45 Convertibles so I reamed the worst 45 ACP cylinder to .4525" so I can shoot lead bullets and avoid the lead fouling. The other two are right at .451" so I did not ream them, rather I use regular 230gr jacketed .451" bullets that I load for my 1911s. I hardly ever use the 45 ACP cylinders and if I do shoot them, I will likely use jacketed bullets. The cylinder I did ream was grim …. it had throats tighter than .448" …. so tight that the factory .448" pilot wouldn't pass through ….. way too tight even for .451" jacketed bullets.
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Old September 9th, 2019, 11:30 AM   #13
 
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Thanks again Iowegan!
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Old September 9th, 2019, 03:26 PM   #14
 
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BH stainless convertible Bisley;

45 Colt/45 ACP cylinders all 12 throats measured at 0.4515" (used my calibrated eyeball to get that 4th decimal point).

I even "felt" less resistance when "tapping" the cast lead (0.452") bullets through. I doubt I could push a bullet through with just finger pressure though.

After measuring 18 cylinder throats with this method, I'd have to say it is a near guess on accuracy. I like Iowegan's method better; If a bullet won't pass through without just finger pressure, the throat(s) need(s) to be reamed.
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Old September 13th, 2019, 05:02 PM   #15
 
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New in box reamer arrived via ebay auction today.

I also bought 3 Scherr-Tumico vernier style micrometers from a retired machinist this week. So no more calibrated eyeball guesses for the 4th decimal place.

Now I need to find my spare 1/2" chuck somewhere in my shop. I put it somewheres so it wouldn't get misplaced. Guess what..I don't know where somewheres is. Probably end up going to HF as their somewheres is easier to locate.

I also have to go shoot again, as I tumbled and resized all my shot brass.

Not sure on the forcing cone treatment. As of right now I'm planning on shooting jacketed bullets primarily. Not sure if a 11 degree cut will be ok. I'm still learning/reading/searching.
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