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Large rifle primers vs. magnum primers?

TNSleeper99

Sergeant of the Hide
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Aug 4, 2019
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AM PRS shooter and reloader here. So far I have developed loads I am happy with but have only used FGGM primers (small and large). I have seen large rifle magnum primers in stock a few places local to me. Can I use large rifle magnum primers as a substitute? What can I expect? I would expect to drop down on powder charge and work back up to my current velocity?
 
They say drop down and redevelop. I've never noticed a difference in velocity, but I don't run near max either. I will say group size was 2x as large when I shot magnums in my regular load, so be prepared to essentially start from scratch.

Below photos were shot running a pressure test . Big group is fed 215m, small gryis fed 210m
 

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If for long range stuff I'd hold out. When I played with this, velocity was all over the place.

Let us know how it goes.
 
I tried the same using 210M v's 215M. I couldn't get a stable group over different days using the 215M's. Not like I could with 210M's. I just used the 215M's for my plinking 308 stuff out of the M1A and looked harder for 210M's.

That is just a small sample size though. I have no idea of CCI or others will act the same.
 
So far, it seems like a waste of powder and time......
 
Like many others all I use is small rifle magnum primers for everything from 223 to 308win.
For large primer applications I have BR2, 200, 210M and 215M and wouldn't hesitate to work up a new load with any of them.
As was allready said you are pretty much starting over if jumping to a LRM primer to find the node unless you just luck out.
 
I find it rather interesting how so many guys run Magnum SRPs in their rifles, but it's almost unheard of to run Magnum LRPs.

Edit:. I'm talking about precision rifle shooting/prs events and have no experience in ELR type shooting or benchrest.

I'm curious to see how this plays out if you do choose to run them.
 
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I actually did a test with my 140 ELD Match load over H4350 out of my 6.5 creedmoor with fed 210’s, cci 200, cci 250 and BR2’s. All produced a little different results. Group sizes were a little smaller with some. BR4’s ended up working the best for me. I can upload a picture of the target later. If you do end up switching I wouldn’t worry about it, just rework your load up and you should be good to go. Before the test I used CCI 250’s only with good results.
 
Right now I’m getting .2-.25 MOA results out of my 6mm CM, but like I said I’m on a limited supply of 210M primers and I seem to be able to find magnum primers more often. I’m trying to prepare for a few years of shortages. Just in case.
 
The LRM primers are designed to have hotter and longer burning flames, to ignite large amounts of slow burning powers like IMR-7977, or IMR-8133 just to name a couple, in cases like 7MM Rem Mag or 300 Win Mag, just to name a couple .They are also used When hunting in very cold conditions, when slow burning powders are even harder to ignite.
 
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I am a Noob to reloading for precision rifle and getting started at this time is not a good time. I will be reloading in 6.5 CM and I lucked into a good supply of CCI Magnum Small Rifle Primers. That is what I will be working up my loads with. I have 2 powders, 4350 and 6.5 Stabal. I plan on working up to loads with both. In your guys experience will the 4350 be better than the Stabal with the magnum primers? The Stabal being a ball powder seems like it may be suboptimal with magnum primers which appear to be favored for stick powder. Anyone tried this combo?
 
CCI450s

Virgin brass and once fired, same load. 6 Creed Starline brass 105 Hornady HPBT h4350, 21" barrel. The slower one was the virgin and also a new barrel.
 

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CCI450s

Virgin brass and once fired, same load. 6 Creed Starline brass 105 Hornady HPBT h4350, 21" barrel. The slower one was the virgin and also a new barrel.
What was accuracy like? That's what really matters
 
The assumption that a lot of people seem to make is that they can simply swap in/out one primer for another into an existing/tested combination and then judge that magum/non magnum primers are good/suck based on that one action alone.

Folks need to work up a load all over again.

You may find that specific primers dont work well with a specific powder....but that doesnt mean that the primer sucks or results in less accurate ammunition because of the primer.....its a combination of different variables that typically stacks up to produce a poor/sub optimal combination

Personally, I find that 4831sc with a magnum primer in 6.5 creed is a very accurate combination IN MY RIFLE

In my experience #34's and CCI LRM's are interchangeable wrt accuracy (both are magnums)

4831 is a slower burning powder than 4350 (and most others for that matter) that are commonly used in 6.5 loads.

Its extremely insensitive to temperature being one of hodgdons "extreme" powders and I see almost no variation whether its below freezing temps are a warm sunny day.

YMMV
 
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Well considering the BR primers are just higher QC/QA magnum primers, there is zero reason to use anything but mag primers.

The thicker cups will resit piereced primers and help contain pressure better.