How many is enough for load

[Bassfish1952]

Your 8 boxes of Ammo will likely provide all the brass you will need if your shooting practices remain remotely close to your past practices. Number of details I am un-clear on regarding your future intentions and the market availability going forward. Id anticipate a brass life of 8 reloads give or take 2 depending on how hot you load & how well you control head space.

Regarding your future intentions. If a factory 90 grain GMX load came out & if that load shot well in your rifle, Would you consider reloading yet? My impression is no. OK say the 90 gr GMX load came out & your rifle would not shoot those factory loads any better than a 3" group at 100 yards, Would you consider reloading your own ammo going forward?

My impression is you really do not wish to get into reloading & if that is so fine. On the other hand if you are inclined to reload then we can dig in with the rest.

If you do not wish to shoot more than you have then reloading is likely something you may be best avoiding IMHO. For me the more I reload the more I wish to shoot especially when I am working with a new to me gun. Your motivation to reload seems simply to be able to shoot a caliber where ammo & bullet options are currently scarce. keep in mind most of my components were purchased years ago at more favorable prices.

Going forward, say 2 or 3 years from now,  the scarce issue may be better or perhaps worse.

Thought that keeps on coming up for me is I feel you may be quite happy with a threaded barrel for the purpose of a barrel tuner. Why would I say that? With factory loads or reloads you could likely tune your barrel to your loads for accuracy as opposed to tuning your loads to your barrel.

Sorry to go off on a tangent.

Next question I may have is how far do you need to travel to test how your rifle is shooting which ever loads you may be working with?

Personally If I had expectations of shooting game out to distances of 300 yards Id insist on being able to shoot a 4" group or better at 300 yards from a bench with a proper rest. otherwise Id need to reassess my distance to be considered for shooting game. We have a lot of rabbit holes we would do well to consider here.

Back to the question at hand. 150 bullets to start with.

One pound each of powder would be my path to finding a load, emphasizing on Leverevolution & CFE 223 may be another good alternate propellant. Sometimes one powder won't tune in while another does considerably better. Leverevolution more often than not seems to be the go to powder for heavy bullets in the 6mm ARC. Keep in mind a load that shoots well on a 85 degree day may not shoot so well on a 40 degree day & vice versa. Not a uncommon concern with ball powders. Both CFE 223 & LVR are ball powders that happen to deliver top velocities.

If you want a more stable powder in a wide range of temps Varget is the go to. Good luck finding that at reasonable prices. H4895 may be another consideration. You will notice there will be a velocity sacrifice with the Varget & H4895.

Primers Id be hoping to purchase 300 Rem 7.5, CCI 450 or  or CCI Bench Rest,  Powder & primers have Hazmat shipping considerations if ordering on line. Thus Id  hope to purchase the powder & primers at an actual brick & mortar store.

You're right on a lot of it.
I should have just stuck with my CZ557 in 6.5 CM. My hobby in life is my Bass Fishing been doing it since I was 5 or 6. For a while I was #38 in the world for biggest Bass still in the top 100
BUT long ago I promised my grandson I'd take him hunting. This year we went and had a great time and as a bonus I have a freezer full of meat. I enjoyed my time with the grandson and we are planning a trip every year till I can't. My doctor thinks the deer meat is great for me, so it's a win-win. 

As for reloading , you're right I don't have a need to reload I have a need to have to round for hunting that I like to shoot and I think that may be either a 90gr CX or a GMX and if Hornady started making what I wanted I would probably give away the stuff I have bought and  just buy the factory ammo I need, But I don't think with things the way they are now that will happen anytime soon.
So I went ahead and bought the 150 GMX 90gr bullets I found and talked with a friend and a custom ammo guy close to me. I'll have the GMX's done up ,shoot them and find a good load for me and use them while I wait for more of the CX's
Also my grandson is into guns and shooting, what I learn from being on here provides us with something to talk about in planning next year and since he has a daughter now 1 month old we talk about her and the rifle I am building for her when she starts hunting with us, so again a win-win for me and who knows I am saving all my brass maybe the grandson or great granddaughter will be a reloader
I have an indoor range within 3 miles of me where I go to zero and sight in my rifle but can't do load development there (well I could but no chronograph in front of the firing line),not allowed for that I have to go 33 miles to an outdoor range with a 200yd range. So for me I have to work at it.
As for 300yds I picked that simply because the area we go to in Alabama gives us shots out o about that range and I feel comfortable to that range and 6ARC gives me a round that can do that .
In Alabama and Georgia some of the private schools do fund raising with deer hunts, you pay your money show up for the weekend , they treat you like family and allow you the use of private deer blinds on the parents property, feed you like kings and the kids in 4h or FFA skin and cutup your deer and for that I put extra in their pocket.

Now as far as shooting , my dad was a Marine, when I was a kid he taught us to shoot, I was Army, 8 years I am not the best shot in the world but at 300yds I can hit what I aim at, last years longest shot was around 260 . I used a range finder and checked different spots from the blind before shooting and my longest was just short of my 300yrd tree. That was from a tree stand 20' off the ground using a part of the tree as a rest.
I have a friend that reloads and there is a custom ammo guy within 30 miles of me that will do as Copper Creek does and work up a Load pack from the stuff I provide and then load up the remaining rounds in the load that shoots best in my rifle.
So you guys are helping me decide what to start with . I think it will be 150 90gr GMX bullets, a pound of Leverevolution and once fired or new if I can find it Hornady brass along with CCI 450 for primers. Once I get a load I like I'll have rest loaded up for hunting . 
My 90gr CX bullets I will save until I have more.

Thanks for answering my questions, you have given me a lot to talk over with my grandson and I have learned a lot from guys on here.

Oh PAC-NOR called today I will have my barreled action back in a couple of weeks , they are building the barrel this week and applying the Cerakote finish next week so I will have plenty of time to work up a load before our hunting trip in January 

Last thing , for me cost is not a real object because I am not doing thousands of rounds just enough to last my time. Turned 70 this year and hunt 2 times a year, if I am lucky enought to go till I'm 85 I will be amazed and that will be maybe 500 rounds max and leftovers will go to the grandson, he'll have to deal with it then.

Again thanks for the time