I know its a stupid question and I have been hunting both internet and local alike but does anyone know where I can get my hand on some 450 magnum primers?

Depending on the powder you are using, you may be able to get away with using SRPs.  Some ball powders are difficult to ignite, so magnum primers are all but necessary.  Military SRP are actually pretty close to magnum to ensure ignition of ball powders.   However, if you are using stick powder, it's quite possible that a "hot" SRP is all you will need.  The difference in pressure should not be an issue unless you are loading over max spec, and may have some effect on accuracy.

Some SRP and LRP burn hot, close enough to magnum primer specs.  You will have to do some homework,  maybe @Bully @Longranger @10X or one of our other resident experts can shed some light on this, but I do believe you can find a workable  substitute.

If all you have are standard small rifle primers, I'd say load up some rounds and test them.  The powder will ignite!  From what I've read (but not independently confirmed) you will probably lose a little velocity, and see a little more shot-to-shot variability in muzzle velocity by using a standard primer where the reloading manuals recommend a magnum primer.

Over the years, I've moved away from using powders that recommend magnum primers, just so that I don't have to keep magnum and standard primers in stock.  It has made my life simpler to buy and use standard primers for everything, or almost everything...I've still got a few magnum large rifle primers that I use to reload the big honkin' rifle cases, but I shoot those so infrequently that I don't need to keep many of those primers around.

Unless you want large pistol, I haven't seen shit anywhere. 

hit up google and look up primer cup thickness for what you are looking for vs. what you have. Assuming you have something. If the cup thickness is the same, there should be no issue trying non magnum primers as stated above. Just make sure you have a rod to clear a squib worst case. 

On 11/13/2020 at 8:58 AM, Scorpio64 said:

 maybe @Bully or one of our other resident experts can shed some light on this, but I do believe you can find a workable  substitute.

Heh.  Far from an expert.  With reloading I just follow the recipes.  

That said, I've not had issues with lighting off stick or ball powder with standard primers.