Cylinder Throat Diameter & Hard Cast Bullets

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Carlitos

Carlitos

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Jan 16, 2020
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Hello All,
New member here who recently purchased a Redhawk 45 ACP/45 Colt. I have shot 150 rounds through it (50 rounds factory Remington 250 gn RNFP and 100 reloads a friend made up for me with Laser Cast 250 gn RNFP .452 dia and 8.0 grains Unique with CCI 350 primers that I have previously fired in my New Vaquero. Love the RH (it is my first one) and just got a 45 Colt conversion kit for my Dillon Square Deal B (I have reloaded 45 ACP for my 1911 for years). I already loaded some Berry’s 250 gn RNFP .452 dia at minimum 45 Colt reloading manual specs. I want to load some hard cast to see what this RH likes. I read on one online forum that the bullet should push through the cylinder throat with some hand pressure. A commercial hard cast manufacturer I spoke with said he had never heard of doing that. What say you? Thank you in advance.
 
Give Bruce at Montana Bullet Works a call. He recommends sizing to the cylinder throat, and their customer service is excellent. I've been very pleased with the various bullets I've bought from them. They may be more expensive than the mass produced coated lead bullets you can find, but my experience is they deliver better accuracy.
 
I read on one online forum that the bullet should push through the cylinder throat
with some hand pressure. A commercial hard cast manufacturer I spoke with said
he had never heard of doing that.
Click to expand...
Then I would offer that manufacturer doesn't shoot what he casts. :feet:
Bullets should sized to Groove+0.001", and those those be 'pushable' through the cylinder with a firm pencil eraser.


.
 
Thank you, MEHavey!
That is what I read on an online forum the name of which presently eludes me. Montana Bullet Works web site states: “The critical dimension in a revolver to match with a cast bullet is the cylinder throats. A bullet that snugly fits the cylinder throats shoots best. You get a better gas seal and better accuracy with a bullet sized to the cylinder throat dimensions in revolvers.” That’s triple confirmation!
 
Were you talking to the janitor for the bullet mfg.? I have seen that "hint" hundreds of times on line and it may work but I prefer to measure. Measure the cylinder throats of your gun (also slug the barrel to make sure the throats are larger than the groove diameter of the barrel). Size or purchase the bullets the same diameter as the throats. I did this to very revolver I own and have very, very little leading and I get the best accuracy with bullets that fit the gun...
 
I go for a bullet that can easy easily pushed into the cylinder but not fall through, to as large as can be chambered. Slightly over sized doesn’t seem to matter much unless the round won’t chamber. A bullet that just falls through the cylinder generally won’t be the most accurate option.
 
What is "hard cast"? Manufacturers like to be above BHN 15, and often above 18 because they can bundle pack bullets without marring in transit. 8.0 grs Unique and a 250 grs cast bullet is a SAAMI standard 45 Colt pressure load, so obturation with a BHN 15 + bullet is unlikely. Doesn't mean you can't use them, but it does necessitate very good bullet to groove fit. At the pressures for that load,a softer bullet will be more forgiving.

As mentioned above, measure throats and groove depth and try to match groove depth, but if using a hard - say linotype - bullet that may be difficult, unless the two measurements are very close.
 
Thanks to all for your replies! The information is very helpful. I have talked with a local gunsmith and will have the barrel slugged and cylinder throats measured with pin gauges. Theoretically, at what diameter should the cylinder throats be compared to grove diameter measurement of the bore (I know standard is .451 but we will see)? The gunsmith said he can ream the cylinder throats if needed. Thank you.
 
If you're looking at a modern 45 Colt, the proper throat reamer is (very) classically 0.4525"
https://www.brownells.com/gunsmith-...olver-cylinder-throating-reamer-prod7700.aspx
Bullets should be min 0.452-453"

Again, the cylinder should be made to match the desired groove application. (stomp, stomp, stomp)
Blindy matching bullet size to an undersize cylinder throat (Ruger is famous for undersize cylinders) outside of that measure will get you undersize bullets entering the barrel (bad juju ....duuuuh....)
 
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FYI every Ruger revolver I own has had to have at least one chamber if not all of them reamed to get accutate results and no leading using lead bullets. Also one 44 MAG had a restriction in the barrel where it was screwed into the fframe.I have had other brands with small cylinders as well but not always. YMMV
Jacketed bullets are less of a problem and shot well even with small chanbers.
 
Thank you, everyone!
Good information all around. I am glad I joined this forum! Seems like a great crew.
 
@MEHavey is spot on, Ruger is notorious for undersized cylinder throats, and if this is the case with your Ruger, they will need to he opened for acceptable accuracy with cast bullets. We can argue the proper diameter but I prefer .452"-.453".

35W
 
What is the ideal throat size relative to bullet size? I always heard 0.005" oversized +/- 0.001" was ideal, but another thread that complains of Ruger 44 special being 0.434" throats versus 0.429" bullet makes me second guess that.
 
The truth is you don't need or want bullet harder than 11 BHN. That's what Elmer Keith used in developing the .44 Mag.

Commercial cast bullets are designed for bulk packaging and shipping. The alloy is MUCH too hard and the lube is not ideal.

Hard cast USED to refer to lead with tin added. Then it was antimony and/or arsenic. Hard cast was considered 10-12 BHN, as opposed to pure lead at 5-6 BHN. Now many people think the harder the bullet the better. In truth the harder the bullet the higher chances of leading.

http://www.lasc.us/Fryxell_Book_Chapter_12_KeithSWC.htm
http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.htm
http://www.lasc.us/Fryxell_Book_Chapter_6_ThroatGroove.htm

Read those three chapters at a minimum.

https://missouribullet.com/details.php?prodId=216&category=5&secondary=17 These bullets would be a good choice.
 
Thank you, 35 Whelen (Great cartridge!)
I was curious about the widely accepted cylinder throat diameter range but understand that .4525 is often used. I’ve also read online that throats need to be .001 -.003 above groove diameter of the bore for best accuracy and least leading using cast bullets. I am certain opinions vary on the precise spec. Thank you all for sharing on this post!
 
welcome to thr, carlitos. your barrel groove diameter should be .451" give or take a thou. suggest you slug your barrel to make sure before you open up the throats on that cylinder.

suggest you use cci 300 primers with your unique load. magnum primers are not needed and will most likely increase chamber pressures, increase extreme velocity spread and decrease accuracy.

luck,

murf
 
Carlitos said:
The critical dimension in a revolver to match with a cast bullet is the cylinder throats.
Click to expand...

That works, but only if the throats are .001-.002" larger than the barrel diameter.
And it only works if all of the throats are the same size.

In the end, it's the barrel & bullet match.
If the cylinder throats are smaller than the barrel, you likely will have accuracy issues.
And bullet hardness matters too.
If you're making light loads a BHN of 10-12 works fine, but if you're trying to let 'em fly, then a higher BHN is needed.
Missouri Bullet Co offers .452" with a BHN of 12 or ,the higher, 18

PS: BHN = Brinell Hardness Number

You may also want to "Slug the Barrel"
There's plenty of videos on YouTube showing you how.

Welcome to the addic .. Oh I mean hobby
Ya hobby, that's the ticket. :eek:
 
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I've been casting for almost 20 years now. I was taught by someone that produced cast bullets for a living. He told me the first thing before spending time slugging a bore and measuring the forcing cone was to make sure the bullet does not fall through the cylinder. If it does it will never shoot accurately. You should be able to drop the cast bullet in the cylinder and give it a push with a pencil to get it out.
 
FWIW, two observations:
- If the bullet is Groove plus-a-thou and still drops freely through cylinder -- maybe trouble.
- My S&W #3 in 45 Colt drops through a .453" and is very accurate. It also shoots handloaded 45 Schofield cases (same bullet) just as well.
- My New Vaquero -- cylinders reamed .452" -- shoots that same 45 Colt load exceptionally well. It hates the shorter Schofield loads.

Go figure.....
 
WrongHanded said:
Give Bruce at Montana Bullet Works a call. He recommends sizing to the cylinder throat, and their customer service is excellent. I've been very pleased with the various bullets I've bought from them. They may be more expensive than the mass produced coated lead bullets you can find, but my experience is they deliver better accuracy.
Click to expand...

Hello WrongHanded,
Thank you again for your answer to my post. I wanted to let you know that I spoke with Bruce at Montana Bullet Works on Friday, 1/17. What a great and knowledgeable guy! He talked with me at length, shared his recommendations and offered additional help if I wanted it. I really appreciate you pointing me in his direction. His bullets look like they may be worth the higher cost. I will definitely buy some once my bore is slugged and cylinder throats are measured.
 
murf said:
welcome to thr, carlitos. your barrel groove diameter should be .451" give or take a thou. suggest you slug your barrel to make sure before you open up the throats on that cylinder.

suggest you use cci 300 primers with your unique load. magnum primers are not needed and will most likely increase chamber pressures, increase extreme velocity spread and decrease accuracy.

luck,

murf
Click to expand...

Thanks for the welcome and the sound advice, muff!
 
Assuming the throats are .452 or larger, size/buy bullets to fit the throats and shoot some. No leading? Your golden and the groove to throat relationship is fine. Get leading? Time to slug the bore and measure throats.
 
Hondo 60 said:
That works, but only if the throats are .001-.002" larger than the barrel diameter.
And it only works if all of the throats are the same size.

In the end, it's the barrel & bullet match.
If the cylinder throats are smaller than the barrel, you likely will have accuracy issues.
And bullet hardness matters too.
If you're making light loads a BHN of 10-12 works fine, but if you're trying to let 'em fly, then a higher BHN is needed.
Missouri Bullet Co offers .452" with a BHN of 12 or ,the higher, 18

PS: BHN = Brinell Hardness Number

You may also want to "Slug the Barrel"
There's plenty of videos on YouTube showing you how.

Welcome to the addic .. Oh I mean hobby
Ya hobby, that's the ticket. :eek:
Click to expand...

Hello Hondo 60,
Thank you for your post and sound advice! You hit the bullseye with your comment about my latest adic..., I mean hobby! Lol
 
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