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Why factory ammo for barrel break in?

I recently bought a 300 WSM rifle and went through this myself. Norma brass is among the best brass for 300 WSM and it also turns out that at this time Normas 300 WSM ammo can be among the more affordable ammo as well and after shooting it you're rewarded with the fire-formed brass. I was lucky enough to find some Norma 150 BT ammo at my local gun store for ~$32/box, so it was cheaper than buying brass alone. Chances are you won't find ammo that cheap but consider the cost of the other 3 components and your time and enjoyment when doing the math. I personally also find it comforting to send a few quality factory cartridges through the rifle first thing and check the brass dimensions/condition when making sure a new rifle is properly setup: this just eliminates a couple more variables.

Whatever you do, don't mix and match brass, even with the same brand: get as many rounds/cases as you'll expect to use for a while so they're all from the same lot.
 
When I bought my 300wsm-- I found factory bondstrike ammo for less than new norma cases -- so I bought the factory ammo just for the brass ( no it wasn't very accurate or consistant)

Broke in the barrel and got ised to the gun and trigger worh the factory ammo and then I get good 1x fired brass from my gun for reloads

It depends on pricing and availability of components for me on what I do

On semi- auto guns I do test function with factory ammo before going to reloads to make sure the gun cycles reliably
This is the only reason to buy factory ammo....for the brass....if itnis good brass. But buy enough (5 boxes of the same lot) to get your 100pcs of brass you will be using.
 
I learned a valuable lesson with my 280AI build that factory brass from ammo is not necessarily the same as their component brass.

At least for Nosler.
 
I bought 10- just for the brass-- all same lot
genius.gif
 
Number one I'm not being a smart alec.
With that said how will a barrel tell the difference between a factory round and a reload?
How about.....consistency?

Have you ever pulled apart a box of 20 factory loads and actually measure everything? I have seen 3 full grains of powder charge variation, and .045" of seating depth differences in a single box, with ES up to 180fps. Let alone up to 20+gr of brass weight difference. There are some that are much better, like Berger ammo, Sierra ammo, and.... (choking on my words here), Hornady Match ammo.

Plus, you get to pick choice of way higher quality of brass, bullet selection, powder selection, primer selection, seating depth, neck tension, runout.

I have a buddy who bought 4 types of factory .280AI ammo for his CA Ridgeline. Best he got was 1.5", with the other 3 at 2"-3.5" @ 100 yards. ESs were from 30 to 150fps. And I shot some too, so it wasn't the shooter. I had my personal .280AI out there with my handloads tailored for my rifle. Told him to shoot 3 rounds.....under 1/2" with an ES of 9. Shot out of my rifle, they are in the .2-.3s.

That is what good handloads will do over 90% of factory ammo. Because it sure doesn't save money.
 
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 loaded light loads for 458 Win Mag (45-70 loads) and didn't use magnum primers. I got a lot of unburned powder, burning powder blasting out of the barrel and charred powder residue in the barrel.

The savings on primers wasn't worth the wasted powder & the mess I had to clean up.
 
I have never used factory ammo to break in an barrel, why spend the money when you don't need to? You should be able to find some Hornady Interlok or something like that for 25 cents each-ish and load those. I use the lowest cost cup and core bullets I can find. Depending on the barrel and how accurate you are trying to get you may need to shoot 100 or more to get the barrel fully broken in, only your chronograph and cleaning patches can tell you when it's done. Plus you will have 100 pieces of brass fire formed in your chamber to start the real load development. Win win in my book.
Exactly....
 
It's one of my Rules!!!
Always use factory ammo when breaking in a new gun, rifle/pistol which ever. If things go wrong, not as expected, then your reloading experience/ techniques are not at question in determining responsibility.
Example: a local man, ex-Marine, a very, very experienced reloader, bought a new at that time S&W Model 29-3 in 44mag. He used his reloads for the first firing. Gun seized up. I'm not sure of the details exactly, it was a real long time ago, but he wasn't hurt. He notified Smith & Wesson who investigated and upon the results of their investigation, contested his claim and refused responsibility because it was reloads and thus the possibility of a mistake made during the assembly of the reloading components and or calculation of resulting pressure.
It's definitely a hard thing to do these days, finding factory ammo!! But it is a safety factor.
There's always a possibility to have the custom maker or seller provide a box of ammo for break-in.
 
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