Why factory ammo for barrel break in?

[General RE LEE]

Breaking in my 6.5 PRC, I'm shooting factory ammo to break in bore and collect the once fired Hornady brass. I'm at 80 shots now but got two more boxes to go. I'll have a bunch brass.

 

[Frank in the Laurels]

Just make sure you feed the newborn H-4350, the "mother's milk " of all short mags....

 

[Mike Matteson]

Longwalker,
The old rule of thimb was use mag primers at 70gr charge and above. The case geometry of the new short mags has shown that this is not always the case today.
In older, longer (taller) cases this is still pretty typical. (Like Win Mags) In the newer short/fat cases, you can sometimes pressure out prematurely. Try both types of primers. You may find you can burn more powder/get more speed with a more gradual burn/pressure curve. Your rifle and chrony will tell you what's best

I have felt that under 75 gr a mag primer wasn't needed. Now I don't have anything cartridges, that gets into the 80gr + areas either. I have tried M primers over the years. Found no gain either. Barrel heated up quicker was my feeling too.
It's my understanding that WSM brass and factory loads are hard to come by presently. My brother has a friend that has one or getting WSM rifle and is looking for ammo for it.
Anymore it seem like you need to figure out what you need and start looking for the items a year ahead of that. Now I have updated my reloading equipment this pass year, and it has taken me that to achieve that too. Still waiting on some items. Component are still hard to come by. Being a day late hasn't help much either.
I never found that factory ammo was cheaper than reloading. If acquiring brass then that's a different story. I feel no gain there either. Better off to getting something like Lapua or Petersons brass. There others out there, that are good brass too.
Do your fireforming and break-in at the same time. Use 2nd for bullets, easy to get powders. Don't use your good powder nor bullets, if you have any to start with. I generally only use a few powders to reload with, and don't change much either. I do explore with powder, primer, bullets to find what I am looking for. I hunt in weather from 100+ to -20.
In 1962 I could load a box of 20 for a 300 H & H mag for a $1.60. Store was somewhere around $5.00.

 

[Mike Matteson]

Just make sure you feed the newborn H-4350, the "mother's milk " of all short mags....

I don't know much about Short Mag, but the H-4350 is one of my go to powders. Because of temperature changes.

 

[LongWalker]

I have felt that under 75 gr a mag primer wasn't needed. Now I don't have anything cartridges, that gets into the 80gr + areas either. I have tried M primers over the years. Found no gain either. Barrel heated up quicker was my feeling too.
It's my understanding that WSM brass and factory loads are hard to come by presently. My brother has a friend that has one or getting WSM rifle and is looking for ammo for it.
Anymore it seem like you need to figure out what you need and start looking for the items a year ahead of that. Now I have updated my reloading equipment this pass year, and it has taken me that to achieve that too. Still waiting on some items. Component are still hard to come by. Being a day late hasn't help much either.
I never found that factory ammo was cheaper than reloading. If acquiring brass then that's a different story. I feel no gain there either. Better off to getting something like Lapua or Petersons brass. There others out there, that are good brass too.
Do your fireforming and break-in at the same time. Use 2nd for bullets, easy to get powders. Don't use your good powder nor bullets, if you have any to start with. I generally only use a few powders to reload with, and don't change much either. I do explore with powder, primer, bullets to find what I am looking for. I hunt in weather from 100+ to -20.
In 1962 I could load a box of 20 for a 300 H & H mag for a $1.60. Store was somewhere around $5.00.

You're right and why I asked about the primers as magnum primers as they are the only component I'm lacking at the moment other than the rifle. If I can't find any before the rifle gets here, I'll start with the standard and see what kind of performance I get. Even with the 180s I don't see a load at or above 75gr. I got lucky on the quick with brass (Norma) and Berger 205s which is why I finally pulled the trigger on the build. I already had a good supply of three powders that should work well for the cartridge.