Thread: Advice please

Originally Posted by Hunterdave

In regards to case sizing, was I right to size brass to bump shoulder back .002” allowing for a bolt fall with no resistance or should I have left longer so bolt closes with minimum pressure while not pushing shoulder back?

Two schools of thought on that, when neck sizing was all the rage I used to leave it at just a bit of tension on closing the bolt.
Accepted theory then being the case neck and hence bullet had to be perfectly centered in the bore.
Now the pro shooters are full lenght sizing everytime as it is more consistent, so might as well save the wear and possibility of galling up your bolt lugs and give it 1 or 2 thou of headspace.
Its good enough for the professional shooters so thats what I do now.

I am wondering if, this being the first time the brass was annealed and therefore softer than in the past, might the brass have stretched a little more than it might have done when harder?... just a thought as this seems to be the only real change.

when deer in standing on edge of toitoi clearing 40 yards away and you cannot for life of you get bolt closed on a neck sized round,you will from that day forth be a fan of always either full length resize or partial length resizing.. 34 years ago now but I can still see the big red bitch laughing at us before turning and walking away. we didnt see many deer back then which made it all the harder to take.

Originally Posted by Magnetite

Some rough numbers from GRT:
Maximum pressure: 63,817psi

Your Load: : ~66,300psi
162gr ELD-M, 3.113", 2820fps, 20", 21°C

Very sorry I was wrong it a 22” barrel, what someone mind running the numbers again with longer barrel

Updated rough numbers from GRT:
Maximum pressure: 63,817psi

Your Load: : ~61,860psi
162gr ELD-M, 3.113", 2820fps, 22", 21°C

Originally Posted by Magnetite

Updated rough numbers from GRT:
Maximum pressure: 63,817psi

Your Load: : ~61,860psi
162gr ELD-M, 3.113", 2820fps, 22", 21°C

So please explain how 2 inches of extra barrel drops the pressure by almost 5,000 PSI? It should be exactly the same.
Grandpamac.

Originally Posted by grandpamac

So please explain how 2 inches of extra barrel drops the pressure by almost 5,000 PSI? It should be exactly the same.
Grandpamac.

I’m leaving muzzle velocity constant in GRT. The longer barrel will produce the same velocity with less pressure requirement due to longer acceleration time.

Normally the pressure would be the same for the same charge. This is all a rough estimate.

Originally Posted by Magnetite

I’m leaving muzzle velocity constant in GRT. The longer barrel will produce the same velocity with less pressure requirement due to longer acceleration time.

Normally the pressure would be the same for the same charge. This is all a rough estimate.

Thanks Magnetite that makes sense. Out of interest what was the load of AR2209 powder used for the revised barrel length? I assume GRT will show this.
Regards Grandpamac.

I used 53.0gr for both 20”, and 22” barrels.