Throat erosion 284

[swampshooter]

I carefully measured my throat erosion last night after 577 rds. fired. I had .005" of throat erosion. I used the same bullet and case to measure that I took the original measurements with. The load I am shooting is 53 gr./ H4831sc/ 180 smk/ cci 200 primer/ lapua brass/ seated to a .003-.005" crush. According to my calculations I should get 2500+ rds. from this barrel, maybe 3,000. Bartlein 5r stainless on a savage 12 action. I'm getting just a little over 2800 fps.

 

[dannyjbiggs]

I carefully measured my throat erosion last night after 577 rds. fired. I had .005" of throat erosion. I used the same bullet and case to measure that I took the original measurements with. The load I am shooting is 53 gr./ H4831sc/ 180 smk/ cci 200 primer/ lapua brass/ seated to a .003-.005" crush. According to my calculations I should get 2500+ rds. from this barrel, maybe 3,000. Bartlein 5r stainless on a savage 12 action. I'm getting just a little over 2800 fps.

More than likely around 3,000 rounds with that light load? For my last straight Win .284 barrel chambered with a .284 Whitley reamer, using 52.00 grains of H4350 (the equivalent of using about 55 grains of H4832SC), I got a little over 2,600 rounds in F-Open competition. In it's waning days, the barrel velocity came down to around 2,875 fps from the initial 2,920 fps.

Good luck,

Danny Biggs

 

[PRECISIONWELDING01]

Look up listen to this guy he has wore out more barrels then we could get ahold of

 

[falconpilot]

Interesting..unless I'm measuring wrong, I'm getting about .002 growth every 100 rounds or so with my 7 Walker. I'm running 53.5 grs of H4350 at 2940, but am jumping the bullets slightly. Makes me wonder if jump verse jam has any effect on throat erosions, besides from the obvious difference of 1.5 grs more powder. I started with a .212 freebore.

 

[Keith Glasscock]

Are you measuring throat errosion by checking the just touching length or the full jam length, or something else?

My straight 284 has had a mix of H4831SC (400 rounds ranging from 2750 to 2970 fps with HBN) and H4350 (200 with HBN at 2820) through it. At 600 rounds, I have only .005" of throat growth measured from the point of just touching.

 

[corning]

A gentleman I know shooting a .284 in F-open told me he will start looking to replace his barrel at 1500 rounds as he sees performance dropping off at that point or earlier.

Danny Biggs' comments are very credible.

 

[falconpilot]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

 

[Erik Cortina]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

Jim, you will find that if you lube the bullet ogive with die wax and open the bolt fast you will get more repeatable measurements.

 

[Keith Glasscock]

Just for giggles, I'll take and record that for my barrel.

 

[Immike]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

Jim, you will find that if you lube the bullet ogive with die wax and open the bolt fast you will get more repeatable measurements.

I keep closing the bolt on a soft seated moly coated with rotation each time until it is it's shortest length with good consistency. Erik, are you lubing so it doesn't pull on the bare bullet when opened?

Edited to repair a spelling mistake with Erik's name.

 

[Erik Cortina]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

Jim, you will find that if you lube the bullet ogive with die wax and open the bolt fast you will get more repeatable measurements.

I keep closing the bolt on a soft seated moly coated with rotation each time until it is it's shortest length with good consistency. Erik, are you lubing so it doesn't pull on the bare bullet when opened?

Yes Mike, that's the reason for the lube.

 

[Immike]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

Jim, you will find that if you lube the bullet ogive with die wax and open the bolt fast you will get more repeatable measurements.

I keep closing the bolt on a soft seated moly coated with rotation each time until it is it's shortest length with good consistency. Erik, are you lubing so it doesn't pull on the bare bullet when opened?

Yes Mike, that's the reason for the lube.

One more question Erik, why open the bolt fast?

 

[Erik Cortina]

Checking by soft searing a bullet long, bolting down and repeating 3-5 times, taking an averagw

Jim, you will find that if you lube the bullet ogive with die wax and open the bolt fast you will get more repeatable measurements.

I keep closing the bolt on a soft seated moly coated with rotation each time until it is it's shortest length with good consistency. Erik, are you lubing so it doesn't pull on the bare bullet when opened?

Yes Mike, that's the reason for the lube.

One more question Erik, why open the bolt fast?

It also keeps the bullet from sticking. If I open the bolt fast, I find that even with lube the bullet wants to stick.

I mean lift bolt handle fast, not open bolt fast.

 

[swampshooter]

Busdriver, I'm measuring by solidly touching the lands with the same bullet that I initially used to get my initial throat measurements. I'm using Hornady LNL OAL gauge set and their LNL Bullet Comparator. I also lube my bullet for measurements.