Should there be any difference in loads for 158 gr. SWC and 158-160 gr. RNFP bullets, given the same or nearly so Brinnel hardness?

I will be ordering commercial cast bullets of that weight range.

As I understand it, reasoning for adopting the SWC shape rather than round nose was the SWC was more "effective" on flesh and bone targets.

Are the current RNFP shapes more "effective" than round nosed bullets, or will I be better served by sticking with the old standard SWC shape?

I use RNFP's in 45 handgun and 45-70. These are my loads for plinking, and SASS competition. They don't have much expansion, but a hunk of lead the size of your thumb shouldn't need much expansion! This design feeds well in almost every gun there is, Yet is safe to use in guns with tubular magazines.

Full and semi wadcutters were developed with shooting paper in mind, and they give crisp round holes. Regular RN bullets just give a tear to the paper and are hard to measurer for dispute resolution. RNFP won't have sharp edges to the holes in paper.

The formula for muzzel energy is:

Weight in grains X velocity in FPS X velocity in FPS, divided by 450240, Equals Energy in Foot Pounds (E=MC squared)

The Taylor Knock Down factor is Weight in grains X Velocity in FPS X Diameter in inches (.000)

These are just 2 of the many ways to judge the mechanical function of ammunition.

Bullet design influences the damage a bullet can deliver, in theory!

IN THEORY, THERE IS NO DIFFERENCE BETWEEN THEORY AND REALITY!
In reality there always is a difference!

Ivan

As stated, wadcutter and semi-wadcutter bullets were develop[ed to cut clean holes in paper. They also, however, cut large wounds channels for hunting. Generally, the Larger the meplat, the better for hunting, outside expanding bullets.

Full wadcutters tend to lose stability fairly soon, making semi-wadcutters a better choice for game.

My revolver business load is the Buffalo Bore 45 Auto Rim 255 grain LRNFP. Not worried it will be inadequate.

Shot placement and adequate penetration are MUCH MORE important than bullet shape. Once you get down to bullet shape of the choices listed the RN will be the least effective antipersonnel round all other things being equal, the RNFP will be somewhat better and the SWC better still.

Given the same bullet fit to the throats and like hardness the difference in pressure and therefore load data, theoretically since you don’t have pressure measuring equipment, will be based on case capacity.

The bullet design having more of the bullet weight outside the case will produce less pressure due to having more case capacity. Part of the reason Elmer Keith and Veral Smith designed bullets with a large proportion of the bullet outside the case when crimped in the groove. Think of a 158 RN with approximately half the bullet outside the case compared to a 158 full wadcutter with 90 percent of the bullet seated inside the case. The same powder charge is confined into effectively half the case capacity, therefore the same powder charged will produce more pressure.

The difference between commercially available bullets likely won’t make enough difference to matter in your case as far as load data is concerned.

As far as effectiveness is concerned the larger the meplat or flat on the nose is going to be more effective as a general rule. Given like meplat sizes it will be hard to tell a difference at 38 special speeds. The solid full power wadcutter shouldn’t be overlooked as a viable SD bullet, you get the biggest possible meplat at the expense of accuracy out past 50 yards or so.

Load data should be the same so long as the distance from the crimping groove to the base of the bullet is the same, meaning the seating depth of the bullet within the cartridge case not changing the internal volume available for the powder.

As for terminal effectiveness, the semi-wadcutter is likely to cut closer to a full diameter hole than a truncated cone or round nose flat point. The advantage of the round nose flat point is in the speed of reloading, as it does not have a sharp shoulder of the semi-wadcutter which can snag on the edge of the chamber.

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VCDL, GOA, NRA

I always shot SWC bullets, then I got interested in action pistol competition and much prefer plated RNFP. The reason being all my competition revolvers are cut for moonclips and RNFP are much faster on the reload then SWC. I shoot light to moderate loads almost exclusively so I don't have to worry too much about being over pressure.

The RNFP was developed by Veral Smith who claimed that since there was more weight outside of the case, it provided more case capacity for powder.
If you choose to load them differently, I would only do so minimally as there is a ton of data for the swc's.

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Front sight and squeeze

I'd use either.
A flat point delivers energy to the target.

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it just needs more voltage

I interchange RNFP and SWC 200 grain with no issues. Load data is the same and in my 1911’s the RNFP feeds perfectly.

For years I shot the lead RN bullets, since they were lower in cost and
they also went into my revolver cylinder, easier, than the swc design.

Today I use the 158 lead swc design, since the holes in my paper targets
are a lot easier to measure , see and score, if needed.

The 148 HB or BB design is also very good for scoring and seeing a hole at 25 yards
vs a LRN, if used.

However, I learned that a very slow 148 BBwc out of a M49 38 special snub nose
with a minimum load of Trail Boss, Red Dot, w231 etc. will tear a paper target, without any backing, making for a por grade target result.

I'll remember this. I have a 10mm 1911A2, and it is a woods pistol in bear/cougar/moose country. I realize it just might anger the moose as he tramples me......

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NRA RSO

Shoot a few of each in your gun and use the bullets it likes best .
I like the wadcutter for under 25 yard target loads .
The SWC for general all-around use ... because I was brought reading the works of Elmer Keith and Skeeter Skelton .
The RF shows it worth when you want fast easy reloading and for loads in Lever Action rifles ... they feed quite smootly .

To me the old RN design is the least effective on targets , the flat spot (Meplat) adds to a bullets hitting power and the more flat spot ... the harder the hit .
The RN design tends to "slip through" flesh .
The RN can be accurate , but it leaves a ragged hole for scoring
but a lot of game and bad guys have succumbed to round nosed bullets .

Try them all ... every shape has it's purpose !
Gary

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Certified Cajun
NRA Member