Primers for .357 Rifle loads

[ColinR]

I load 14 grains of N110 behind a 158 grain jacketed bullet in .357 magnum brass for use in a 1894SS Marlin. These loads use rifle data rather than pistol data and are specific to the Marlin. My question is can I use small rifle primers in place of the small pistol primers I currently use - I have a full carton of Federal small rifle primers that I am unlikely to use. What is the likely effect on pressure using a rifle primer in place of a pistol primer?

I understand that rifle primers are usually harder than the pistol type, but this won't be a problem with the Marlin I am sure.

[DavidRees]

Yes, you can. I've done this, in my .357 Marlin, also with Fed 205 primers. Absolutely no issues.

[ColinR]

Yes, you can. I've done this, in my .357 Marlin, also with Fed 205 primers. Absolutely no issues.

Hi David thanks for the confirmation. What load were you using with the rifle primers?

[DavidRees]

What load were you using with the rifle primers?

A light target load, as it happens--pushing the GM 180gr lead truncated cone bullet to about 700fps. Approx. 188ft-lbs. I used the Fed205 small rifle primers to finish them up, but noticed absolutely no difference between them and my then normal Fed100 (small pistol) load with the same weight of powder.

If one has a really high load, where any increase in pressure could result in an unsafe round, then any change in component should result in dropping powder charge by 10%, and working up slowly. But your stated load of 14.0gr N110 is approx. 8% below the recommended starting charge of N110 for a 158gr jacketed bullet in the 13th edition of the Viht reloading manual, so I would personally be comfortable with the idea of changing primers without reducing the powder load in this instance.

[ColinR]

What load were you using with the rifle primers?

A light target load, as it happens--pushing the GM 180gr lead truncated cone bullet to about 700fps. Approx. 188ft-lbs. I used the Fed205 small rifle primers to finish them up, but noticed absolutely no difference between them and my then normal Fed100 (small pistol) load with the same weight of powder.

If one has a really high load, where any increase in pressure could result in an unsafe round, then any change in component should result in dropping powder charge by 10%, and working up slowly. But your stated load of 14.0gr N110 is approx. 8% below the recommended starting charge of N110 for a 158gr jacketed bullet in the 13th edition of the Viht reloading manual, so I would personally be comfortable with the idea of changing primers without reducing the powder load in this instance.

Viht don't seem to differentiate between pistol and rifle loads for .357 magnum in their data and quote a 7" barrel as the test standard in their 13th Edition. In an old Speer reloading manual #12 (1994) they give data for both rifle and pistol. The rifle data uses the Marlin 1894. With Speer 158 grain jacketed bullets they give N110 as 13.5 - 15.0 grains, hence using 14.0 grains, so using this data I am above the minimum, but under the minimum given in the Viht data. I'm not sure how pressure changes between a 7" barrel and an 18" barrel.

[DavidRees]

I have no data to support it, but it is my view that peak pressure occurs relatively soon after the bullet enters the barrel. If this supposition is correct, then barrel length (at least for lengths useful to shooters) can be ignored when considering pressure levels. Of course, it almost all cases there is sufficient pressure remaining, even past the peak pressure point, to continue accelerating a bullet down the barrel, which explains why a given load has a higher velocity in a long barrel as opposed to a short one.

The majority of pistol calibre loads given in published tables relate to handguns, with barrel lengths (where given) usually below 8 inches. Any velocities given in such tables are likely to be considerable under-estimates as far as velocity (and hence energy levels) are concerned where barrels are considerably longer (as in a Marlin 1894).

If you know of a published source of loading data for pistol calibre rifles, please do post details -- it would be a very helpful resource.

[Laurie]

If you know of a published source of loading data for pistol calibre rifles, please do post details -- it would be a very helpful resource.

Most American loading manuals have specific 357 and 44 Magnum, sometimes .45 Colt too, rifle loads in the approriate section of the manual. Sierra for instance has loads quoting MVs from an 18.5-inch barrel Marlin 1894 for all of its jacketed 357 cal pistol bullets. The powders tend to be only a little different from those quoted for revolver loads in the manual's handgun loads section covering fast burners such as H. Titegroup through A. Unique to Viht N110 and W296/H110, but with A. Bullseye omitted. Some maximum charges vary a little, other hardly if at all.