W748 Primer

1. Use what the load manual recommends. I see my data shows standard large rifle primers (Hodgdon website, Hornady manual) for all listed charges of 748.

2. Yes, Lake City brass is known to have a slightly smaller case capacity than most others. Most manuals will have a note about charge reduction for this brass. You can always measure the capacity in grains of water and compare to the listed capacities for various brands of brass.

I have never seen any need for a magnum primer with 748 in any chambering. Some day that may change, but so far so good. 748 is my go to for .223/5.56 and .308/7.62 loads.

It matters not if you brass is smaller or larger internally. Sort by case headstamp and load from a starting load and work till you get what you want. Change components and start again (this is if you are loading near maximums).

I seldom load near 'hot' but keep my brass seperate just for consistency, that give me better accuracy.

Am consistently getting better accuracy with mag primers, usually use CCI 34's for semi-autos.

Reducing the charge depends on what case/primer the data source you are looking at used. it takes less powder in a smaller volume case to get same velocity as a case with more volume.

And 308 cases can vary significantly in weight and volume.

I would use the magnum primer, because the loads with ball powder I have chronographed gave consistently lower velocity spreads and deviations. So I tend to use them as a rule with any ball powders. That doesn't mean you need to by any means, or even that they are the best choice - only my choice based on my own experiences.

I agree with Ifishsum regarding mag primers with ball powder, but my only experience is with .223. One of our resident experts once posted that it's best to start ignition of a full case gently and this may explain why mag primers need to be formulated differently. Tests done for an article in the 2015 Hodgdon annual reloading manual suggest that regular primers are actually hotter and thus more suitable for the courser stick powders. At least this is what I took away from the data, others may have perceived it differently.

Winchester 748 being a ball powder I am going with the magnum primer. Will a standard primer ignite the powder? Yes, it will. I want the magnum primer to assure better uniform ignition, it's all about uniformity for me. So I am in that group for those reasons.

When I load GI brass I really don't worry much about any difference in case capacity since I start with minimums. I would not run a maximum load for starters in GI brass. Then too if you are really curious compare some case volumes of what you have. You may find the results to be interesting.

Ron

JO JO said:

that is way I asked on opinions on this as I have read the manuals and some
manual's say mag primer with 748 and some don't.

Click to expand...

Yeah, I can give you examples of exactly that. Hornady 9th Edition for example for 308 Winchester calls out a Federal 210 (not a magnum primer like the Federal 215) and for .308 Winchester Service Rifle they call out the Winchester WLR (not the WLRM Magnum primer). My Speer #12 manual calls out using CCI primers and does specify the use of the magnum primers with the use of Winchester 748 powders. The Sierra 50th Anniversary calls out a Remington 9 1/2 for all loads. The Remington 9 1/2 comes in standard and magnum and neither is spelled out.

Me? I have always been in the habit of using magnum primers with ball powders. How much does it really matter? I really don't know but what I have been doing has served me well for around 45 years of hand loading and when something works I try not to screw with it. I have done some experiments loading the same charges over several brands of standard and magnum primers and run them over the chronograph and really saw much of any velocity difference to get excited about.

I guess you can decide for yourself which primers to use or you will never go wrong using what is called out in the manual you happen to be working to.

Ron

Using 748 for 223, 30-30, 300 Savage, 307 Winchester and 308. For all but the 30-30, have better accuracy with mag primers. Rem 7 1/2 (mag strength)in 223, usually CCI 34 for 308 in bolts, lever and semi's.

In the 30-30, got significantly better accuracy with standard Fed 210 primer. Doesn't mean there may be different results using other brands of primers, never tried em all.

Also live in colder region, liking 748 for efficiency/commonality in loading.

There is no "best", only what works for your purpose.