Point of Aim w/ Varied Calibers in Convertible Revolvers

[Mr. Mosin]

Searched. Couldn't find this. Here it is. Something like the Ruger Blackhawks or Vaqueros that are factory shipped 45 Colt and ship with an additional .45 Auto cylinder, or factory shipped .38 Spl/.357 Magnum, and come w/ a spare 9mm Luger cylinder... how do the various cartridges compare "Point of Aim" to "Point of Impact" wise, when similar grain wieght bullets are used ? How do they fare w/ fixed sights (Vaquero) vs adjustable (Blackhawk) ?

Buddy and I were talking, and he is musing over buying one, solely for the "9mm Luger SA revolver" aspect of it.

 

[AK103K]

I just picked up a SS Ruger Blackhawk in 357mag, with a 9mm cylinder. Havent really shot it a whole lot yet, but from what Ive seen so far, at 10-15 yards, with the sights zeroed for the 357, the 9mm shoots about an inch or two lower.

Both shoot well too.

 

[sparkyv]

Yup, I'd expect a different POI for the different calibers, similar to shooting specials in a magnum. Not so great with fixed sights, but I'm not a fan of continually farting with adjusting my sights at all either. I've pretty much given up on this otherwise attractive option. More of a gimmick, to me. YMMV

 

[Fyrstyk]

I have a 45 colt/45ACP Blackhawk. I find that with a 200 grain RNFP bullet in both calibers, the point of impact is only a few inches off at 25 yards. Beyond that, the difference becomes much more.

 

[Bill M.]

My 9 mm cyl shoots a good ways from the .357 loads. 3 “ or so at 10 yards. POI varys with loads that much with the .357 also. I have a red dot on it and figure out where to hold each session for each load. I keep the sight set for full power loads at 25 yards.

 

[wagonburner]

I have almost no variance at 20 yards between shooting 454 Casul and 45ACP in my Freedom Arms mod 83, even when I have shot cast 454 and ball 45ACP.

I suspect it depends more on the consistency of how the cylinders fit in the gun than the caliber itself.

 

[.308 Norma]

I have almost no variance at 20 yards between shooting 454 Casul and 45ACP in my Freedom Arms mod 83, even when I have shot cast 454 and ball 45ACP.

I suspect it depends more on the consistency of how the cylinders fit in the gun than the caliber itself.

Being a picky wise guy here: if the 454 Casull and the 45ACP weren't the same "caliber," just swapping cylinders to shoot them both in your Freedom Arms mod 83 wouldn't work worth a crap no matter how well your cylinders fit.

 

[GarrettJ]

I suspect it depends more on the consistency of how the cylinders fit in the gun than the caliber itself.

I will always agree that consistency is a good thing. But for POI shifts, velocity will be the primary determining factor.

When shooting my T/C Contender with the .44 barrel, I find 240 gr. bullets hit almost a foot higher at 800 fps (.44 Spl) than at 1600 fps. (.44 Mag).

And that’s all from one chamber/barrel. Additional factors such as different chambers and cylinders are likely not going to improve things.

 

[wagonburner]

I will always agree that consistency is a good thing. But for POI shifts, velocity will be the primary determining factor.

When shooting my T/C Contender with the .44 barrel, I find 240 gr. bullets hit almost a foot high0p,er at 800 fps (.44 Spl) than at 1600 fps. (.44 Mag).

And that’s all from one chamber/barrel. Additional factors such as different chambers and cylinders are likely not going to improve things.

At distance yes. I’m talking 20 yards.

Your case isn’t the same as a convertible with two cylinder though. You’re shooting a 44 spl out of a 44 mag chamber, so your issue is that your bullet has to jump the distance between the case mouth and throat. With a convertible you shoot different calibers out of chambers that match the caliber.

I have 460 BFR and shot some 45 Colt cowboy loads some time ago and they were grouping a few inches higher than the 460s I was shooting. The 45 Colt was also not grouping as well as the 460 ammo. I was shooting at 25 yards.

 

[wagonburner]

Being a picky wise guy here: if the 454 Casull and the 45ACP weren't the same "caliber," just swapping cylinders to shoot them both in your Freedom Arms mod 83 wouldn't work worth a crap no matter how well your cylinders fit.

LOL. Bummer, so you think I wasted my money buying that 357 cylinder?

 

[TonyAngel]

I had a 9mm/.357 black hawk. You can decrease the difference between the two by getting 9mm projectiles sized for your barrel.

Rememeber, 9mm are .355 cal while the .357 is, well....

It still left me dialing when I switched cylinders though. Just not as much.

 

[GarrettJ]

Your case isn’t the same as a convertible with two cylinder though. You’re shooting a 44 spl out of a 44 mag chamber, so your issue is that your bullet has to jump the distance between the case mouth and throat. With a convertible you shoot different calibers out of chambers that match the caliber.

I’m not sure I follow your reasoning.

Yes, the bullet has to travel farther from case to rifling when fired from .44 Spl brass vs the longer .44 Mag brass. But the bullet has to jump even farther to the rifling if I’m shooting .45 ACP vs .45 Colt I’m my Ruger Convertible revolver. The fact that they use different cylinders is irrevelant with regard to bullet jump distance.

 

[.308 Norma]

LOL. Bummer, so you think I wasted my money buying that 357 cylinder?

 

[wagonburner]

I’m not sure I follow your reasoning.

Yes, the bullet has to travel farther from case to rifling when fired from .44 Spl brass vs the longer .44 Mag brass. But the bullet has to jump even farther to the rifling if I’m shooting .45 ACP vs .45 Colt I’m my Ruger Convertible revolver. The fact that they use different cylinders is irrevelant with regard to bullet jump distance.

No, that's not bullet jump. If the case mouth sits flush against the chamber throat, there is no jump. The cylinder throat is sufficiently small (.329 - .330) to prevent blow by and burning the edge around the bullet base.

A 44spl case mouth is about .14 - .15" from the throat in a 44 mag chamber. Ergo, the 44spl has to "jump" that .15" to get to the throat mouth of a 44mag chamber.

 

[GarrettJ]

No, that's not bullet jump. If the case mouth sits flush against the chamber throat, there is no jump. The cylinder throat is sufficiently small (.329 - .330) to prevent blow by and burning the edge around the bullet base.

A 44spl case mouth is about .14 - .15" from the throat in a 44 mag chamber. Ergo, the 44spl has to "jump" that .15" to get to the throat mouth of a 44mag chamber.

Ok. And this causes a large, repeatable POI shift how?

I’m not trying to be argumentative. I’m just trying to understand. I’m not following the logic.

Thanks

 

[Bill M.]

Just for the record. My 9 mm cyl for my Blackhawk has tbullet diameter throat diameters at the end where the cartridge rests and is the bore diameter at the front of the cylinder. The long throat is tapered. A well thought out and machined idea from Ruger. Loading oversized bullets does not work since they will not chamber. and are too large for the throat if they did. The gun shoots fine with 9mm bullets. Maybe they expand enough to fit the bore?. I am told that many makers use the same barrel for for their 9mm guns and their .38 caliber guns.

 

[wagonburner]

Ok. And this causes a large, repeatable POI shift how?

I’m not trying to be argumentative. I’m just trying to understand. I’m not following the logic.

Thanks

Well for starters you’re burning your base edge - the gas will flow past the base of the bullet as it leaves the case exposing the sides of the bullet. This doesn’t happen if the case mouth is flush to the throat.

The bullet is also not supported as it enters the throat, which can cause it to be shaved and deformed as it enters the throat. Unlike barrel throats that are cone shaped to help align the bullet as it enters the barrel, the chamber throats in a cylinder has a sharp and abrupt edge as to align with the case.

 

[JeeperCreeper]

Just about all 45 ACP and cheap load 45 LC in my Blackhawk Convertible have the same practical accuracy, POI, and precision at pistol ranges.

However, shooting nuclear 45LC loads is different. Could be my flinching though too because I'd rather shoot a 454 Redhawk or 500 Smith before shooting hot loads out of my Blackhawk.

 

[GarrettJ]

Well for starters you’re burning your base edge...

Everything you write would support a general degradation of accuracy. But it’s not uncommon to see equal accuracy from a short cartridge vs. a long one. We are talking about the change in POI. Going from Magnum to Special or short-chamber cylinder to long, one often gets a different point of impact, but with the same group size.

I was contending that the difference in velocity causes this. I still don’t see what a short vs. long chamber or a short vs. long case would have to do with it.

Again, just trying to understand your logic.

 

[lincen]

My experience with a Ruger Vaquero 357/9mm mirrors those above. Where I’ve seen more difference in POI is with my 327’s. Velocity is indeed the variable with the different 32 rounds.

 

[wagonburner]

Everything you write would support a general degradation of accuracy. But it’s not uncommon to see equal accuracy from a short cartridge vs. a long one. We are talking about the change in POI. Going from Magnum to Special or short-chamber cylinder to long, one often gets a different point of impact, but with the same group size.

I was contending that the difference in velocity causes this. I still don’t see what a short vs. long chamber or a short vs. long case would have to do with it.

Again, just trying to understand your logic.

My response to you was that shooting a 44mag and 44spl from the same chamber is not the same as shooting a 45Colt from a 45 Colt chamber and 45acp in an 45acp chamber in the same revolver. Apples and oranges.

I most certainly believe velocity is a factor, however my FA delivered the same POI with both 45ACP and 454Casul at 20 yards. Ergo, there are additional contributing factors above and beyond only velocity.

I’m sure if you duplicated you 44spl load in 44mag brass you’d get a more consistent result. That’s been my experience with 357/38s.

 

[Saleen322]

We have a 9mm-357 convertible. I cannot speak to factory ammo but we have loads that deliver same POI @ 25 yards with 9mm, 38 Special, and 357 Mag.

 

[Tallball]

I have a 9mm/357 Blackhawk and a 45acp/45colt Blackhawk.

With normal loads, the POI with the different calibers isn't noticeable at 15 yards with my mediocre shooting skills.

 

[GarrettJ]

I’m sure if you duplicated you 44spl load in 44mag brass you’d get a more consistent result. That’s been my experience with 357/38s.

So it’s a nice sunny day, and I don’t really need too much of an excuse to go shooting. So I loaded up some fast & slow loads in both .44 Spl & Mag cases as well as in .45 ACP & Colt cases. I shot the .44s through the Contender, and the .45s through the Blackhawk Convertible.

At the end of all of it, I’d say we were both right to some extent. You moreso about how the revolver behaved and me for the single-shot.

So I loaded up some 225 gr. FTX bullets in .45 cases. For my slow loads, I used a starting load of AA#5 in .45 Colt cases, and I found where someone had used Titegroup with these bullets in .45 ACP. My fast loads I used H110 with a near top-end load from the "Ruger Only" section of the Hornady 10th ed.

Average velocities were:
.45 Colt: 1268 fps.
.45 Colt: 719 fps.
.45 ACP: 696 fps.




In .44, I used a 240 gr. Zero JSP. Slow loads used Trail Boss for both Spl. and Mag brass. Fast loads were with a near-max load of AA#9.

Average velocities were:
.44 Mag: 1690 fps.
.44 Mag: 427 fps.
.44 Spl: 565 fps.




I shot at 25 yards from a rest for everything. The .45s on the left target and the .44s on the right. I fired 10 rounds of each load. The .45s generally all grouped in the same area, just a bit above point of aim. Shooting either fast or slow bullets from .45 Colt cases was a little more accurate than from ACP. I have found each cylinder with this revolver to have very bullet-specific preferences. Apparently neither cylinder likes this particular bullet. That gun generally groups better, but I usually load 250 and 300 gr. bullets. I just didn't think they would be as appropriate for the ACP case, and the FTX are rated for the full range of what the .45 ACP or Colt are capable of. I also didn't want to introduce another variable by using a different style/weight of bullet.

The full-velocity .44 Mag shot a couple inches below point of aim. And the much slower bullets fired from either Colt or ACP cases all hit about 10" higher. The length of the cartridge does not effect the POI, as I had noted previously.



I suppose the next thing to try would be to shoot both .44 Mag & Spl from a revolver with both fast & slow bullets to see if the case length makes a difference there. The test should also be valid shooting .45 Colt & .45 Schofield. But since I don't have any of the shorter cases, I likely won't get any just for this experiment.

It's been instructive, and good dialogue.

Hopefully this also answers some of the questions relating to shooting different cartridges/cylinders in the same revolver. Ultimately, the best answer is to shoot your gun(s) with the different cartridge/cylinder combinations and see how they perform.

 

[GarrettJ]

As a follow-up, I had tried shooting different weight bullets out of both .45 Colt and ACP cylinders a few years ago. I just had to figure out what I’d done with the pictures. These were all shot from a rest at 25 yards.

In this one I had been attempting to load each bullet to the same velocity from each type of casing. I’ll have to dig some more to find what the actual velocities were. If memory serves, some bullets were pretty close and one (250 gr. from the ACP case I think) was a couple hundred fps slow.

In my mind, the same bullet at the same velocity should hit at the same POI, regardless of which case it was fired from. Obviously I’m not always right.

And this also shows what I was saying about each cylinder having a preference for what bullet/load it likes.