I’ve recently gotten set up to reload and have a question. I’ll be loading for 6 Creedmoor and due to the obvious supply issues, the only primers I’ve been able to find are CCI 450 small rifle magnum. Other than starting at published min charges and watching for pressure signs is there anything else I need to be aware of? Will magnum primers in cartridges such as mine create pressure issues at max charges?

This is just me speaking but I interchange small rifle with small rifle magnums all the time. Both chrono and visual inspection yield hardly any changes in CCI, Federal, Remington or Winchester primers.  If you were going to start loads up near max, then I might back off a little, otherwise, I personally would not worry about it.

Thanks guys!

CCI-450 primers are excellent

CCI 400s are really for moderate to low pressure rifle cases -- like 6mm PPC, 6 Benchrest, and M1 Carbine.

400's work well with 223, they are not to relegated to low pressure rounds like the Rem. 6.5.
It is a disservice for people to profess such inaccurate information

Until you get up near or at 556 pressures. It's easy to get cratering and then pierced primers on a hot day in the sun.

Just that spreading INACCURATE information is complete disservice.  
Apples and oranges 223 Rem VS 5.56.
Follow the reloading data and people should have no problems.
Simply put the cci 400 works just fine.  
Go look at SPEER web site, and their data SURE SEEMS TO SHOW it used with multiple bullets along with Fed 205.
Their 5.56 does say CCI 41 on some.

Small rifle magnums should help; some have had hangfires with less powerful SRP.   Either of them are significantly less powerful than an LRP, so I would think that could affect powder charges.

howdy

There is a thread with a Primer on Primers I read somewhere on this website that is really informative.
I would urge the OP to check with that.
I have a related question.
loading for .338 Lapua Magnum my Hornady manual calls for Federal 215
Its basically unobtanium to find anywhere.
I have CCI 200, and Federal 210M (both of these are Large Rifle non-magnum)
either of those be an acceptable substitute? Maybe wait until I can find the 215 or 215M.

If I were loading .338 Lapua I would definitely use a magnum primer. The primers you have will probably work fine provided you load on the lower end of your reloading data. Federal 210M are considerably warmer than CCI-200's which are one of the mildest primers available.

Don't try to load full power loads and you should be fine until you can located some magnum primers.

Primers can often be interchanged - except when you're near the hot end of a particular load.

It's also important to understand that the term "magnum" when applied to primers does NOT have a set definition.  Some makers' magnum primers burn "hotter," others longer, while others' flame extends farther out of the primer.

When loading with certain powders, a "magnum" primer is needed to ensure proper ignition.  These are often thought of as "magnum" powders, and they need more spark to ignite.  If the manual says to use a magnum primer with a given powder, use that magnum primer.

On the other hand, except for some "benchrest" primers, most mid-range, NOT hot loads won't show you much difference in velocity or pressure no matter what primer you use.  Accuracy, on the other hand, may be all over the place...it kind of depends on, well, everything involved in that load.

So my take is to at least test your load if you change primers.  Some people will say that doing an entire new work up for a different primer wastes components.  But you won't know what, if any, effect changing primers may have unless you test it and see for yourself.

I interchange with magnum primers in both rifle and pistol as needed and haven't seen any issues with middle of the road loads.   I've used magnums a lot in 9mm when primers are hard to find.  I've never seen any notable difference in FPS numbers.  I do think you could see pressure signs a little earlier as you start to push pressures.  As long as you are working up your loads responsibly, you should be fine.

I load for 300rum(slightly more case capacity than 338LM) I have loaded with standard non magnum rifle primers, for use in warm weather..If they are going to be shot in cold weather, you could have hangfires with them...To be safe, I would load a small test set working up to your original load and watching for velocity and pressure signs...

I use CCI450s exclusively in my 6.5CM loads with Lapua SRP brass.