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.
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.