Lister, It truly depends on how tight your revolver's throats are. If the throats are under .4515" for a 45 cal or are oval (both are quite common) then yes indeed, it will affect accuracy with jacketed bullets. After the throats are reamed to .4525", it optimizes the gun for lead bullets but accuracy with jacketed bullets will be just fine. Larger throats will loose a little pressure with jacketed bullets so muzzle velocity will typically drop about 25 fps ... not a bad trade for better accuracy. The same data holds true for a 44 cal only the throat diameters should be .4305" and for a 357 cal, .3585" diameter throats. Most high quality bullet manufacturers have settled on precise .451" jacketed bullet diameter for 45 cal, .429" diameter for 44 cal, and .357" diameter for 38/357 cal. Lead bullets should be at least .452" for 45 cal, .430" for 44 cal, and .358" for 38/357 cal. There can be huge variations in lead bullets ... in fact the ones I use in my 45 are swaged and made by Hornady. They are .454" diameter but shoot exceptionally well in several of my revolvers reamed to .4525".
Here's what you can do to test your revolver. Remove the cylinder from the gun and make sure it is clean. Try to insert high quality .451" jacketed bullets .... nose first into the front of the throats. You should be able to push the bullet through the throat with slight finger pressure. If the bullet won't pass through all the throats, you will need to ream them to get decent accuracy with jacketed bullets. Test all six because Ruger uses a "gang" reamer at the factory to power ream all 6 at once. That means some holes may be perfect while others are either too tight, too loose, or oval. Repeat the same test with a high quality .452" lead bullet. This time use a separate bullet for each throat because the throat will resize the bullet and give false indications. In a lead bullet optimized gun, the .452" bullets should pass through the throats with light finger pressure. If your throats have not been reamed, I can almost guarantee you the bullets won't pass through the throats without a hammer.
Here's the concept for bullets and revolvers ... Unlike semi-autos where the bullet just transitions direct from the case to the bore, revolvers have a few more problems to resolve. First is cylinder-to-bore alignment. There's no such thing as perfect C-T-B alignment and with Rugers, "close" is about the best you can expect. Not to worry ... Ruger does some nifty engineering to compensate. Ruger designs their revolvers with a little cylinder play. The cylinder latch allows several thousandths of + and - side play while the base pin is a bit loose and allows a couple thousandths of vertical play. When a round is fired, this play allows the cylinder to move a tiny bit to self align with the bore as the ogive of the bullet enters the forcing cone. Assuming there is enough play, the bullet will enter the forcing cone with minimal distortion (shaving). Side note: next time you check a Ruger SA for cylinder play, don't bitch if it isn't mouse ear tight. Also, replacing the base pin with a custom pin can raise the cylinder where it will shave bullets. Leave the factory base pin in the gun ... it's part of the nifty design.
Mean time, when a round is fired, the bullet begins to exit the case and starts into the throat under considerable pressure. Chamber pressure forces the bullet to take the shape of the throat. If the throat is too tight it acts like a die and sizes the bullet down in diameter. If the throat is slightly larger that the bore (highly desirable), chamber pressure will cause the base of the bullet to expand until it is the same diameter as the throat (.4525" in a 45 cal).
If C-T-B alignment were perfect, you wouldn't need a forcing cone. As stated above, that ain't gonna happen with a Ruger so the factory cuts an 8 degree forcing cone to provide a transition from the cylinder to the bore. So what we should have is a bullet that is slightly larger in diameter than the bore being pushed by a huge amount of pressure (7 tons in a 45 Colt, 18 tons in a 44 Mag). This forces the bullet to seat in the bore very tight and forms a really good pressure seal. If the bullet remains sealed in the bore until it exits, accuracy will be optimum and lead fouling will be minimal. Oddly enough, material from an oversized bullet will be reshaped not shaved off. High pressure does weird things.
Here's what happens if things aren't what they are supposed to be ... If the throat is too tight, the bullet will get sized down smaller than bore diameter. This has the same effect as shooting smaller diameter bullets. It becomes impossible for the bullet to seal in the bore so hot gasses blow by the bullet. This vaporizes the circumference of the bullet and leaves lead residue behind. Pressure lost to blow-by will reduce the muzzle velocity considerably. As more rounds are fired, lead fouling continues to build up which distorts the bullets and causes accuracy problems. Bottom line ... poor accuracy and too much fouling. If the forcing cone has machine marks or other corruption (very likely in a Ruger), using an 11 degree reamer will provide a smooth transition from mouth to bore and be a bit more forgiving if C-T-B alignment is off.
I highly recommend doing the cylinder throat chamfering and the 11 deg forcing cone. Between the two, that old Ruger will shoot some mighty fine groups with minimal fouling. Sorry for the "book" ... hope it helped.
Lister, Unless your Ruger has some other problem, I guarantee your 45 will shoot much tighter groups if you ream the throats. If you plan to shoot only jacketed bullets, you can ream them to .4515" but that size reamer is pretty hard to come by. You can buy a reamer from Brownell's or send your cylinder to the Cylinder Smith. I recommend reaming to .4525" so lead bullets will shoot well too. See http://www.cylindersmith.com/
I concur with Iowegan's recommendation about sending your cylinder out to the cylindersmith if you are not up to the task. The cylindersmith fixed up a 45 Blackhawk of mine, made a big improvement in accuracy, and cylinder leading.
superbearcat, Lead bullets foul when the seal between the bullet and bore is breached. This can be a result of not matching bullet hardness to chamber pressure (the higher the chamber pressure, the harder the bullet must be), or because the bullet diameter is too small for the bore. The formula for bullet hardness (rated in Brinell Hardness Number or BHN) is BHN=chamber pressure in psi divided by 1400.
Gas checks are bore sized copper wafers crimped into the base of the bullet that help keep the pressure from venting around bullet. They really work when you push lead bullets beyond their normal limit. Gas checks don't help if the throats are too tight or if the cylinder-to-bore alignment is off.
I had the cylindersmith open up my Accusport Bisley (both cylinders) to .4525". Where does one come up with one of those 11 degree forcing cone reamers? How is this process accomplished? Who could a person hire to have this done if he/she didn't feel like tackling it themselves? I can't imagine it would be an expensive process. I am LOVING this site!
Thanks Iowegan! I just got done searching brownells for that reamer, but all I could come up with was forcing cone reamers for shotguns. You sure were Johnny on the spot with that reply! I was gonna come back in a couple of hours to check. Thanks again!
Just ordered a set of each for throats and for forcing cone from Brownells. See how it goes . From the IBOK it looks quite straight forward. I have two Rugers to do and if all goes well, I'll suggest doing a friends new .45 Colt.... I am sure I'll be getting other .45 Colts down the road too.....
Thanks for the 'book'! Printed out and will file....
Well, I got the tools. No brass guide came with the reamer. From the IBOK, I should be able to just cut the head off an old .45 brass case, chamfer it and use that as a guide. The guide is just to keep the cutter away from the case side of the cylinder wall right? (IBOK doesn't say anything about the reason for it ... may be obvious to others, but took me a few minutes looking at the pictures to figure it out ... after I had the tool in hand ) .
The tools you asked about are available from Brownell's (and maybe Midway and others). The forcing cone job isn't hard and the tools come with good instructions plus Iowegan has generously provided us with his IBOK which covers the topic in detail.
I'm quite sure this is a pretty common procedure for Rugers and you should be able to find a local 'smith who'd be happy to do the procedure for you.
I know of no place you'll get information like you'll find in this forum, this thread, and the IBOKs.
rclark, Read the very first paragraph in the document. Yes, it is a cutoff 45 Colt case and is used for two purposes. It prevents you from cutting the chamber and it helps keep the reamer squared with the throat.
Thanks! Finished the job on two revolvers. Not difficult at all. Just 'oily' . Now the bullet just drops through with a tiny bit of finger pressure on both cylinders. I used the T-Bar from the forcing cone tool to turn.
Also it is VERY VERY easy to overdo the forcing cone. I would suggest check after one/two turns. I took 'couple' of turns as 5 turns of what I thought was very 'light' pressure before checking like a dunce. I overdid the first barrel a bit. Eat into the grooves by about 1/16. . Hope that won't hurt it. Next barrel I did 3 turns and that was just right. Just touched the grooves as it should. Both have nice bright rings.
Today I will go out and shoot 'em and see if it helps.
Veerrrry interesting. I shot both of my .45s today with the new throats set to .452 and with the 11 degree forcing cones. Nothing else changed.
Using same loads as I used before : 6g of TB under a 250g RNFP.
Range : About 20 Yards.
Vaquero : Used to shoot 3" high and about 2" to the left. Now it shots 0" high and about an 1" to the left. I can live with that!
BlackHawk : Used to shoot around center with sights adjusted. It shot about 3" high and 2" to the right. Adjusted sights and back shooting around center but tighter groups. I get more bullet holes 'touching' now than before. . I can live with that!
I am not a good shot by any means as my groups are not 'all touching', but I can 'really' see a big difference from the way these guns shot before to the way they shoot now. I guess you could call me sceptical before, but am a believer . Well worth the $170 in tools to get 'em to shoot straight. Now it is just me that has to get 'better'!
Way . Thanks for the IBOK.
I guess I was really surprised that 'average' point of impact changed so much. I had it in my mind that it would just might tighten the group around where it 'used' to shoot. Interesting.
My wife gave me a NMBH 45/45 for our 30th a few years ago. Didn't shoot for sour owl-you know what. I was disappointed as I have Ruger 357s and 41s and 44s that do shoot. I cast and shoot w/w almost exclusively, then an issue of Handloader told of the 45 chamber problem. I was on the phone to Brownells the next day. Nice fix and fun too. Then later I discovered this forum, Long way around, I guess. Thanks to all the fine folks here I just keep learning, good feeling for an old dog.