Tight spec 45 colt reamer question.

[singleaction]

I would like to have a gunsmith friend of mine convert a 50th anniversary Blackhawk Flattop in 44 mag to a tight chambered 45 Colt, much like is commonly done by the well known builders. I would like to buy a custom reamer from Dave Manson, but they said they would not give me advice on what a tight 45 Colt reamer spec is. Lee Martin’s article on 5-shot 45 Colts was interesting, but I’m not sure if I should go with his specs. This gun will mostly see heavy LBT bullet handloads with 0.452” bullets, but may see some Buffalo Bore, and or Grizzly Ammunition factory loads, as well. Can a very well informed individual give me proper custom reamer specs? I want the reamer to cut 0.450” to 0.451” throats, so my smith can hone up to 0.4525”, but I need the rest of the dimensions. It would make logical sense to me to make the rest of the reamer just like a SAAMI 454, but 45 colt length. However, I don’t want to assume that that would be correct. Thanks for your advice.

BTW: I use Starline brass exclusively, including some Starline made,  but Black Hills stamped once fired stuff.

[edk]

My perspective on this would be to get a reamer made to cut a 0.480” chamber. This is on the extreme tight end of SAAMI spec, however still within spec.

The next challenge is to get reloading dies that do not size your brass much at all beneath 0.480”. This is easier said than done. I have dies from RCBS, Hornady, Redding, and they all size way beneath this. There is of course some brass spring back, however the sizer dies from the respective factories all measure around 0.465”-0.470. So the answer is custom dies or make your own.

[contender]

Put in a call to 2 dogs (Fermin) to discuss this. And maybe Lee can chime in here as well.

[singleaction]

Apr 7, 2023 8:37:38 GMT -5 contender said:

Put in a call to 2 dogs (Fermin) to discuss this. And maybe Lee can chime in here as well.

I would like to see this discussed openly on the forum. I suspect it has been discussed here ad nausium, but I’m not good at using the search feature on this website to find old discussions. I have a voracious appetite for knowledge, as do a great many folks who are members here. It would be nice to see this topic discussed and/or debated inside and out for current interest and for posterity sake.

[bradshaw]

singleaction.... some .45 Colt brass fired in the Ruger 03 slips into Freedom Arms M83 .45 Colt chambers. Not all, but the chambers are close. If desire is the only reason to specify tight or minimum chambers, consider, as edk advises, special dies if necessary to compliment your chambers. As for pressure, nothing spikes pressure like a chamber which pinches the loaded round----preventing enough neck expansion to release the bullet. A tight round should be noticeable as the cartridge doesn’t freely chamber. (The condition can be disastrous in a bolt action, as cammimg leverage easily overcomes neck interference).

As to accuracy, I’d focus on the rechamber job producing the best CHAMBER-to-BORE ALIGNMENT possible. Let’s assume we start with a fine barrel, the FORCING CONE and CHAMBER-to-BORE ALIGNMENT make or break accuracy. (The highly touted crown is so far down the list as to not be on the same page. To put it Country Simple, more factory crowns are done well than done poorly.)

Accuracy: in order of importance
1) Bore & groove.
2) Forcing cone.
3) Chamber.
4) Chamber-to-bore alignment.

Note: numbers 3 & 4 can be reversed, depending on individual revolver. Acceptable chamber-to-bore runout depends #1, 2, and 3.

No matter how we slice it, revolver accuracy remains an orchestra of dimensions.
David Bradshaw

[Deleted]

Three different custom ruger smiths have told me not to change a 44 to 45. Start with a 41. They said not enough metal to ensure good ream. I did have Al Siegrist rebore a 44 anaconda barrel to 45. He told me at the start it could be problematic but I had him try anyway. It worked well in my barrel but he had a disclaimer based on past experiences.

[Lee Martin]

Match the reamer to your dies. I use Reddings and when we cut our reamer, it was made 0.0015" over the sized case. But tight chambers aren't all they're cracked up to be. They really don't let you safely increase chamber pressure (if anything, they necessitate impeccably clean chambers). The cylinder mass still has to do the work. A few extra thousandths of brass 'run' or 'swell' doesn't swing the needle one way or the other. As for case life, I can't tell much difference between tight and factory spec. At high pressure, the pockets tend to go before the sidewalls split.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[potatojudge]

I have a tight chambered 45 Colt. I've had factory JHP rounds that wouldn't chamber in it (Winchester Platinum or something) and when reloading it takes trial and error to make rounds that will drop in. I think my last round of loads was a 360 grain cast and a Lee FCD was the ticket.

Doesn't give me much confidence for a serious use gun, and it's not like we see brass or accuracy problems out of factory Rugers. Certainly out of Freedom Arms, which have looser chambers than my custom tight 45.

I think if you're looking to hot rod a necked round, like a 38-40 or a GNR cartridge, then matching your reamer spec to the dies has benefit. For straight walled cases, IMO it's just a liability.

[singleaction]

Thanks, to all, for your advice and information. That’s a lot to think about. Lot’s of folks here own custom single actions chambered in 45 colt. No two makers 45 colt chamber specs are necessarily the same. I wonder what would constitute a ballpark average in critical dimensions among major custom makers?

[z1r]

Best bet is to assemble some rounds using the dies you intend to reload with. Send those to the Reamer Maker, and they will cut you a reamer appropriate to those rounds. Speak to the maker about your intentions and they will guide you through that process.

This is what I did anytime I had a "custom" reamer ground.

A customer wanted a rifle built using an 8x57 case necked up to .338". First reamer guy provided me a drawing that was simply based on the existing 8x57 reamer dimensions + 0.015" (difference in bullet size). This led to a chamber with a grossly oversized neck. We measured the 5 or 6 commonly available cases to determine min & max dimensions between the suppliers. Settled on 2 brass makers and spec'd a reamer that would accommodate those cases after being run through his sizer. Resulting chamber was capable of extremely tight groups, but would also not require extensive case preparation, or cause issue in the field.

[edk]

One has to keep in mind there is extreme variation in the 45 Colt unlike most other cartridges. Do you ever hear anyone say tight 44 mag or a tight 357 mag? The difference between the chamber of my Colt Anaconda and my Redding size die was 0.022”. My S&W 25 was 0.020”. They would fire 0.458” rifle bullets. The cartridges would rattle in the cylinder. So “tight” in the context of 45 Colt does not necessarily have to mean tight as in problematic. It can also be construed as not sloppy or normal.

Now one certainly could base a reamer off a 0.466” Redding sizer and cut a tight chamber. Now that “tight” could work quite well but no longer adhere to SAAMI standards and likely not chamber most factory ammunition.

It is important to determine the goal here. There is more than one viable approach. We do not want the kind of tight that makes the revolver frustrating or even dangerous to use. As has been pointed out there is so much in play with respect to a revolver’s orchestra of dimensions we have to just let it go at some point.

As far as the ideal approach goes, it would be wasted on a revolver, but this was my best experience. Mike of OTT created several custom Contender and Encore barrels for me. First a dummy round was prepared with premium components. Next the dummy was carefully measured and entered into a CAD system. A premium barrel blank was put into his EDM and the chamber burned. After tweaking the CAD parameters, a set of die blanks were burned. Barrel performance is exemplary, sizing is effortless and case life terrific. No reamer or die manufacturers were involved at any point in the process.

[reboundspring]

IMHO I agree with the gent who suggested the minimum SAAMI chamber. In my revolver builds, I find that line boring the new cylinder in a couple of steps gives the best chance of accuracy.
After line boring to the un-honed throat diameter, the cylinder is chambered from the rear in the mill. I use a long piloted chamber reamer in a floating reamer holder for this operation.
Then finish honing and polishing of the chambers.
Best alignment with the bbl threads at any rate. Centering the bore of the barrel in the lathe before threading is critical to accuracy, as well as a polished to gauge spec forcing cone.
It is a game of dimensions. The reamer bushing for line boring has to be accurately made and I make mine to screw in to the face of the cylinder, not relying on the front of the frame for squareness.
The frame front is surface ground square to the face for the cylinder after line boring, so the barrel will be square to the chambers.

I didn't invent any of this. I learned this stuff from talking to John Linebaugh (R.I.P.) who built better SAs than I ever will, Dave Manson of reamer fame, and Andy Horvath of Diagonal Gun Shop.
Lots of good revolver mechanics out there. Guys who specialize do the best work usually, such as Hamilton Bowen, because they do it all the time, and are invested in their reputations for quality.
Talk them.

[singleaction]

Apr 7, 2023 8:11:08 GMT -5 edk said:

My perspective on this would be to get a reamer made to cut a 0.480” chamber. This is on the extreme tight end of SAAMI spec, however still within spec.

The next challenge is to get reloading dies that do not size your brass much at all beneath 0.480”. This is easier said than done. I have dies from RCBS, Hornady, Redding, and they all size way beneath this. There is of course some brass spring back, however the sizer dies from the respective factories all measure around 0.465”-0.470. So the answer is custom dies or make your own.

In John Linebaugh’s article, which is still posted on his website, John said that he uses 0.480” 45 colt chambers in his 45 Colt revolvers. So, does this mean a straight 0.480” the whole length of the chamber? Loaddata.com shows a 45 colt cartridge drawing with the case body diameter as 0.480” at the base and at the case mouth, with a 0.456” bullet diameter (which I assume is the old hollow base soft lead bullets used in the black powder era with 0.454” groove barrels.). Loaddata.com’s 454 Casull drawing shows a straight body with a base outside diameter at 0.478” and mouth outside diameter of the same 0.478”, with a 0.452” bullet diameter. As far as currently manufactured brass is concerned, are not 45 colt and 454 Casull case dimensions the same other than case length and primer pocket dimension? If this is true, then why would you not simply have your 45 Colt chamber cut just like 454 chambers, but at 45 Colt length? Another question is: Should there be any taper in the chamber from front back, and is there a lead and a lead angle that is ideal for LBT and SWC cast bullets?

loaddata.com/Cartridge/45-Colt/256

loaddata.com/Cartridge/454-Casull/412

www.johnlinebaughcustomsixguns.com/writings

[singleaction]

FWIW, the base diameter of my lot of Star Line 45 Colt brass mostly measures 0.475” with a small percentage closer to 0.476”.

[reboundspring]

Slug your intended .45 barrel. Make sure the cylinder throat of the chamber is .0015 thousandth bigger than groove diameter for best accuracy. Veral Smith of LBT wrote about this years ago.
Also he suggested slugging your .45 barrel after installation to make sure there was not a tight spot where the barrel screwed into the frame, or from over-tightening at the barrel shoulder.
Squashing the bullet in a tight spot will undo all your efforts to get a perfect cylinder chamber.