choosing 44 mag jacketed bullet diameter

O

oley55

New member
I have a Rossi R92 (lever gun), SS, 44 mag, 24" barrel. The bore in this rifle is fairly large (.4330", .4330", .4326"). I tried to measure the lands from a slug, but couldn't get a reliable measurement. I do however have some minus pin gauges and the .426" pin fits loosely in the barrel, while the .427" will not quite enter (no surprise with the .0004" squish).

I did run #20, BTB #320 grit lapped bullets through it, but certainly failed to eliminate all of the unevenness felt when pushing a slug through. As large as this bore already is, I am reluctant to fire lap further (at least for the time being).

And so to the question. I found a source for 240 gr, .431" JSP bullets. Can I run these bullets through this barrel without worrying that there isn't enough room for the bullet to obturate without creating a blockage?

edited to correct my pin measurements.
 
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You should be fine with .430s or larger.
Marlin and H&R .444 Marlins, for example, have an average groove diameter of 0.432" or just slightly smaller. Yet Remington's factory ammunition (the preferred choice of most owners) uses 0.429" bullets; and Hornady's factory ammo and component bullets come in at 0.430".
In some rifles where the bore diameter is also quite large (say 0.4285"), some bullets do tend to skid on the rifling through at least part of the barrel, due to the tiny amount of engagement. But, you're also typically dealing with 'Micro-Groove' rifling, 50,000 psi, and 2,300 fps -- not something the R92 will be seeing with .44 Mag.



If you try lead bullets, I'd definitely step up to 0.434" or better. ...As long as they'll chamber. Taurus barrels tend to be massively oversized, but the chambers are generally much closer to SAAMI spec. So, you often can't actually chamber a cartridge containing a bullet large enough to fill the oversized groove diameter.
 
Oley55,

When metal is squeezed down it has to flow somewhere. That can go into length or into filling out the grooves. If a bullet is undersized, you can figure about half goes each way. For this reason, SAAMI has a groove-minus-0.003" bullet diameter lower limit for the 44 Magnum. With cast bullets you run into problems with gas cutting occurring before the bullet fully fills the grooves if you do this without a paper patch or a gas check. But with enough pressure it will bump up and, despite some leading in the bore, shoot to minute of paper plate. With jacketed bullets, if they are within 0.003" of the groove diameter they can shoot OK. If they are within 0.001" they may do as well as full diameter bullets.

I do not understand how you got your pin gauges to avoid jamming into the lands of the rifling, as the dimensions you show suggest they would.
 
FrankenMauser

If you try lead bullets, I'd definitely step up to 0.434" or better. ...As long as they'll chamber. Taurus barrels tend to be massively oversized, but the chambers are generally much closer to SAAMI spec. So, you often can't actually chamber a cartridge containing a bullet large enough to fill the oversized groove diameter.
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Unsized .432-.433" lapping bullets chambered easily so I suspect .434" would chamber OK. I do not cast yet and was considering .433" cast bullets available from Montana Bullet Works, but the barrel doesn't feel or look right. When I push a slug (or a tight patch) I feel a loose spot at the forearm dovetail (where I would have expected a tight spot. Also with a light film of KROIL in the bore I think I can see a slight dimple under the front sight dovetail, and possibly at the forearm dovetail (but that could be my imagination since it is so far down the barrel).

With these anomalies I have doubts I'll ever be able to successfully push cast bullets through it. Which is why I was looking at these .431" jacketed bullets. But then again, I am too ignorant about cast bullet science to know anything. Just guesses and supposition on my part.
 
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OK. If you look at SAAMI 44 Rem Mag rifle cartridge specs, they do have diameters wider than the handgun specs call for. For handguns, the SAAMI 44 RM standard is 0.417" bore with 0.006" tall lands, to arrive at a 0.429" groove diameter with a tolerance of -0.000 and +0.004". So a middle tolerance gun would have a 0.419" bore with 0.431" groove. For rifle, the SAAMI standard is 0.424" groove with 0.0035" tall lands to arrive at a 0.431" groove diameter. Again, the standard tolerance is a unilateral +0.004", so a mid-tolerance range barrel would have a 0.426" bore and a 0.433" groove diameter. It sounds like yours is close to that.

Hornady makes 0.430 .44 cal rifle bullets. If you give them full peak pressure, I would expect them to fill those grooves fairly well. I'll have to call SAAMI at some point and find out why they have the different rifle dimensional standard. I wonder if they were afraid of light loads sticking in a long barrel with its greater expansion ratio. I just don't know. A custom mold for cast bullets could be made, of course, but I would make a chamber cast or measure the neck portion to be sure how fat I could load before the bullets jammed.
 
Unclenick;

A custom mold for cast bullets could be made, of course, but I would make a chamber cast or measure the neck portion to be sure how fat I could load before the bullets jammed.
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Do you suppose I could fill a 44spl case with hard alloy, chamber it, and then drive a soft lead slug on top of it to get an impression of the chamber. Much the same as Marshall Stanton recommends for getting an impression of the throat?
 
Yes. In fact, Veral Smith makes long lead slugs and you put one in a case, close the bolt on them and use a rod in the barrel and a mallet to expand it out to fill the throat and chamber neck. But in your case, since you seem to have a set of pin gauges, I bet it wouldn't take long to find out which one will and which one won't go all the way to the end of the chamber.
 
But in your case, since you seem to have a set of pin gauges, I bet it wouldn't take long to find out which one will and which one won't go all the way to the end of the chamber.
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now there's another one of those duh moments for me.
 
Nick,

per your recommendation I pin gauged the chamber at .460" (.4598"). Without knowing the wall thickness of the cases, how do I figure out if .434" bullets will fit?

My 44 mag brass is predominantly many times fired FC, with a number of others to play with (R-P, WW, Star, Norma, etc). I did notice when using the M-die the Norma brass seems to require a bit more pressure. Which could mean the walls are thicker(?).
 
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I went ahead and honed out a Lee sizing die to allow a .434" (.4338") pin to pass through it. Then I bumped a .431" 12 BHN bullet up and then sized it. The sized bullet is measuring .4347" I'm not sure how much bounce I should be getting or what is normal. I did screw up and severely over bump the bullet and spent a slot of time rolling it between a couple large files to get it small enough to size. The result was/is a perfect cylinder devoid of groves, dimples, or nose profile. So I'm guessing the .0009" bounce is the combination of normal bounce and sizing a solid slug.

At any rate, I seated the .4347" slug in a normally prepared case and it chambered with just some light little pinky pressure. The finished cartridge OD measures .457", giving me .0021" free space.

Due to lack of thought I had just grabbed a random case (an R-P) and didn't even think to look for one with thicker looking walls. So I suppose I will pull the slug, bump it lightly, resize, and then load in a thicker walled case just to make sure it will still chamber. If it does then a custom .434" bullet mold is in my future (some day).
 
It is theoretically possible you could find some brass thick enough to be too fat to fit your bullet diameter inside and still chamber. But the average neck wall should be 0.012" thick and that will let you load a 0.435" bullet and arrive at 0.459" OD. So I would just measure as I go and set aside lots of brass that work out to be too thick with your bullet diameter, assuming you ever find any. The custom rifle makers get away with as little as half a thousandth chamber clearance for the neck OD and this still lets go of the bullets well enough. For a rifle that's lever feeding, I wouldn't want it that tight, but you are probably OK up to about that 0.459 OD over the bullet.
 
Short of having a custom M-die machined, how does one avoid the bit of sizing the case does to the bullet when seated? I assume the bulging case is evidence that some sizing has occurred.

Or perhaps an over sized case die which does not size the case all the way back to SAAMI specs.
 
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just found this Lee collet style crimp die for 44 mag. It appears to be of the same design as their bottle neck rifle factory crimp die. Perhaps this is an the answer to my own question concerning bulged cases sizing down cast bullets. Assuming my fire formed cases will chamber with ease.

Regardless, I am happy to see Lee has listened and now makes these collet style crimp dies for straight walled 44/357 magnum cases.

even though the web address says carbide, this is not Lee's Carbide Factory Crimp Die.

http://leeprecision.com/44-magnum-custom-carbide-factory-crimp-die.html

the midway description of same item is different and even says there is a decapping unit which makes no sense, and that it neck sizes against a mandrel.

http://www.midwayusa.com/product/781382/lee-collet-style-crimp-die-44-special-44-remington-magnum
 
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Lee makes both the collet-type Factory Crimp Dies (there's a limit it how short they can make those work) and a collet-type neck sizing die for rifle cartridges. Your first description is of the former and second description is of the latter and is incorrectly copied and pasted into that product's description. I have made a comment to Midway to that effect.

Lee also makes what it calls the Carbide Factory Crimp Die, which is the one with a carbide ring to ensure SAAMI standard OD of the loaded round cannot be exceeded. You want to avoid that one in your case.

In general, a case neck is not strong enough to appreciably size down a bullet. It's yield point is reached first unless the bullet is very soft. So the bulge you see from a hard cast bullet is due to the bullet is stretching the brass from its resized diameter more than that the brass is squeezing the bullet. The carbide ring in the last type of crimp die I described can narrow a cast bullet, though.
 
I have Lee Carbide Crimp dies for 357/44mag, but only use them for jacketed bullets because of the sizing ring. Makes little sense to try and get larger cast bullets only to size them back down inside the case.

I hadn't seen the collet dies for 357/44 mag previously, so I think they are fairly new. I had read an article by Marshall Stanton on the BTB site about modifying 44-40 collet dies for 44 mags, and his questioning why Lee hadn't started making them available for straight walled pistol. Don't recall the date he wrote that article.

edited: article was posted 2013-08-01. http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/66
 
I was just curious as to how standard size .429 or .430 jacketed bullets shoot in this gun. Is it really that bad?
 
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I approached my .44 Puma shooting much differently than you, I shot first and if there was a problem I asked questions. I shot a few factory rounds through it (Magtech 240 JSP, and Remington 240 JHP. both .429" bullets)) and accuracy was acceptable to me for a new gun. When I went to cast bullets I slugged the bore and found it to be .432"+ (and nope, not completely smooth from muzzle to chamber) and found a Ranch Dog mold (Lee) that dropped 265 gr. RNFP @ .433"-.434" (and sometimes a bit bigger depending on alloy). I customized a Lee push through die to .433" and have fired a few hundred of these bullets through the Puma (.433"), with no problems and very little, if any leading. Accuracy is OK for me, best groups run about 3" @ 50 yards, but I ain't the best shot in town. Plus the Puma levergun ain't exactly a bench rest quality rifle.

K.I.S.S. and use a plain old roll crimp die, or a Redding profile Die. There should be no need for a "post seating sizing die" especially for a .44 Magnum.

The only thing I don't like about my Puma shooting cast bullets it that SWCs don't feed reliably (unless I use .44 Special brass or seat the bullet much deeper than normal)...
 
TimSr I was just curious as to how standard size .429 or .430 jacketed bullets shoot in this gun. Is it really that bad?
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I have fired #50 .429" 240 gr JSP and #30 .429" 180 gr JHP through it before my shoulder crapped out completely. It did ok but not great. Overall about 6-8" groups at 100yds. Admittedly the loads fired were not developed for this rifle and I was getting used to the Skinner peep sight.

Barrel cleanup took two days. Day one for the copper and carbon, and day two to finally get all of the carbon. That is when I decided for certain I would do a little fire lapping. Have not fired since my 6 hour fire lapping trip. Also I do not have any .430" jacketed bullets on hand.

My thought on the larger .431" jacketed bullets was a hope of better performance/accuracy due to less gas blowing by or escaping along side the smaller .429" bullets as they exit the barrel. I also expect over time to see some noticeable gas cutting to the throat grooves from all the gas squeezing by the undersized bullets.

You should see the gas cutting grooves in the throat of my ole 80's Redhawk. And that Ruger SS is the hardest SS known to the gun industry.

mikld: I approached my .44 Puma shooting much differently than you, I shot first and if there was a problem I asked questions.
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To be fair, I can't argue with that logic, and I am known for getting myself wrapped around the axle on "what if's". However, I think you and I may have different chicken n egg situations. You seem to have bullet casting experience and equipment. I have neither.

I do have some prior experience with a 24" .357 mag Rossi which after some effort is pretty close to a tack driver. When I bought this 44 mag, I had the same expectations and am again willing to expend considerable efforts to make it so.

For me ordering and then waiting months for .433 bullets, only to find out I don't have the right tools/dies, or ordering a custom mold to try out seems backackwards.

I am to a fault, hung up on the 7 P's of life; "Proper prior planning prevents pi** poor performance".
 
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I have fired #50 .429" 240 gr JSP and #30 .429" 180 gr JHP through it before my shoulder crapped out completely. It did ok but not great. Overall about 6-8" groups at 100yds. Admittedly the loads fired were not developed for this rifle and I was getting used to the Skinner peep sight.
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I only ask because I really think you could greatly improve accuracy by focusing on the bigger picture, and some of the other factors that could be affecting accuracy as much or more than just the bullet fit aspect. People are getting much better accuracy than you from the same model gun with some factory ammo. You've not given any specifics about the loads you are shooting, and are narrowly focused on bullet fit.

Most jacketed bullets have a very soft core, and obturate very well when loaded to the right pressure for the bullet. If they don't seal when fired, even with an oversize bore, it often means they are under loaded. If you are loading 44mag jacketed bullets at full 44 mag pressures, they should obturate and seal just fine.

Some bullet designs are more accurate than others. At 100yards from a Redhawk, my ranking for bullet accuracy is

1. Hornady 240gr JTC-SIL,
2. Tied between 240XTP, and Missouri 240gr SWC BRN 18
3. 240gr JSP (semi-jacketed)
4. 240 gr JHP (semi-jacketed)
5. 180gr JHP (semi-jacketed)

I think if you went to 240gr XTP (.430) and loaded it up as a real magnum, your group would close immensely.

If you are looking for oversize bullets, cast is the easiest way to go, with a 240gr SWC oversize to fit your bore, and BRN18 only if your doing full power magnums, otherwise get a BRN od about 12.
 
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