New rifle load development

[thaught]

You know what they say about opinions right? Well here's mine.

Big cartridge and you probably aren't going to be shooting many hundreds of rounds for hunting. Proof barrels are good barrels and hand lapped so you don't really need a break in per say. They are cut rifled and take forever to settle in on my comp guns. For that reason I have favored button rifled lately in this component shortage. The only part that will break in is the lead where the reamed cut 90° to the lapped barrel. That will only take a few rounds. Shoot a few and clean and repeat should be sufficient IMO. The Proofs I've used have always had nice machine work.

You can do a Saterlee type ladder to go up and find pressure. The test itself hasn't been very impressive in my experience. I can repeat the test three times on three different days and get three different results. There are sometimes trends, but not always. To me the most useful part of it is finding pressure and what the speed is associated with that pressure. YMMV

I think if you use quality brass and sound reloading practices and a powder that isn't real temperature sensitive you will find an acceptable load pretty quickly whether that be Saterlee, OCW or whatever you choose. Are you going to use a muzzle brake?

Yes, 419 muzzle brake

 

[MLN1963]

That will help, I bet that bad boy is going to have some bite to it?

 

[thaught]

That will help, I bet that bad boy is going to have some bite to it?

I have one already and it's recoil is about that of a .243. Not bad at all

 

[SSgt G Cody]

Good advice! And good gun and caliber choice! I would also suggest you clean bore thoroughly after each 10 rounds of break-in, followed by a lightly oiled swab. Usually bullet honing is mostly complete within the first 40-50 shots. At this point I would consider a moly treatment of the bore, but just one time! The next 40-50 shots will afford you load development and fit-up info, as the load performance homes-in. For a hunting rifle, this should be sufficient, and you'll have your first 100 sized cases for serious reloading!

 

[BrentM]

So recall I said that velocity usually increases when a barrel breaks in or settles in and the node still remains the same or similar?

I decided to document every shot on this new barrel with my lab. I installed a new x caliber carbon barrel last week and ran 30 rounds through it. Didn't doing any break in cleaning. Got it home, cleaned carbon, zero copper. It shot an avg of 2855, sd 6, bug hole zero groups and .5 or better to 800. Didn't shoot past 800. Yesterday I shot another 50, so total of 80. Around 60 the barrel sped up from 2855 avg and settled in to 2895, rounds 70-80 had an sd of 7. 700, 800, 880 targets were showing solid groups in the .5 moa range. Didn't measure just eye balled, its close enough and good enough for me (off tripod, sitting, and little windy).

 

[CoachChris]

I just built a new 308Win.
Initial load development for fire forming brass had me at 43.2gr of IMR 4166 at an avg velocity of 2644fps.

Right around 100rds I had a major POI shift. Avg velocity increased to 2689fps.

I tested again and found a node at 42.9gr. at an avg velocity of 2665fps.

Now I have all my brass fire formed. Testing begins again with a few different bullets.