Pressure signs...now what

[Bigeclipse]

I just started working a load for my 300wsm using 200gr accubonds and h4350. Book max is 62.5grains for imr4350. Hodgdon website says 62gr for max with a 200gr bullet so I followed that. I first wanted to determine my rifles max load. I loaded a 60,60.5,61,61.5,62. The 60, 60.5 and 61gr loads all shot fine. Then I hit 61.5. I noticed a nice mark from the extractor on the case bottom and was told this is a sign of excess pressure so I did not fire the 62gr. Now what do I do?

 

[Bigeclipse]

Do I back off a grain...down to 60.5...more...less...thanks!

 

[highridge1]

Chronograph it at 60- 61 grs and see where your velocity is at .Then shoot some groups to see if you are happy with accuracy. If things don't line up where you want them too switch powders like RL17 or RL19.

 

[Barrelnut]

Usually I back off 1 gr and start accuracy testing and seating depth adjustments from there. That would put it at 60.5 gr. That happens to be the most accurate load tested by Nosler for IMR4350 and the 200 gr Accubond. So maybe you are close to a sweet spot.

 

[Bigeclipse]

Chronograph it at 60- 61 grs and see where your velocity is at .Then shoot some groups to see if you are happy with accuracy. If things don't line up where you want them too switch powders like RL17 or RL19.

Usually I back off 1 gr and start accuracy testing and seating depth adjustments from there. That would put it at 60.5 gr. That happens to be the most accurate load tested by Nosler for IMR4350 and the 200 gr Accubond. So maybe you are close to a sweet spot.

I got about 2700fps at 60.5gr which is definitely not top end for velocity but will be fine for the purpose of this load. 300yard deer/elk load.

 

[Barrelnut]

Nosler manual states 2775 for the 60.5 gr load. They tested in a 26 inch barrel. If you are shooting a 24 inch barrel, seems 2700 would be about right.

Highridge 1 is right. R17 will make it scream.

 

[Unofficial Gun Addict (UGA)]

Usually I back off 1 gr and start accuracy testing and seating depth adjustments from there. That would put it at 60.5 gr. That happens to be the most accurate load tested by Nosler for IMR4350 and the 200 gr Accubond. So maybe you are close to a sweet spot.

+1. This is what I'd do.

 

[Bigeclipse]

Nosler manual states 2775 for the 60.5 gr load. They tested in a 26 inch barrel. If you are shooting a 24 inch barrel, seems 2700 would be about right.

Highridge 1 is right. R17 will make it scream.

Chronograph it at 60- 61 grs and see where your velocity is at .Then shoot some groups to see if you are happy with accuracy. If things don't line up where you want them too switch powders like RL17 or RL19.

Just a note...it is actually a 23in barrel so yeah, the velocity is right where I was expecting it to be.
One reason I was going with imr/H4350 is because it was one of the few loads with 200 grain accubonds that was not compressed. What is the general thought on compressed loads and safety?

 

[Unofficial Gun Addict (UGA)]

Lots of reloaders compress their loads, but I generally attempt to stay in the 96-98% range.

 

[Lefty7mmstw]

You can have issues with too compressed of a load, like bullet creep or case bulging, but stay away from extremely compressed combinations and all is well.

 

[Bigeclipse]

You can have issues with too compressed of a load, like bullet creep or case bulging, but stay away from extremely compressed combinations and all is well.

I forget what the nosler manual said but I know a bunch of the loads listed said like 108% for case volume and such. What do you consider extreme compressed?

 

[Lefty7mmstw]

I forget what the nosler manual said but I know a bunch of the loads listed said like 108% for case volume and such. What do you consider extreme compressed?

if you seat your bullets, then come back to measure them the next day and they've crept at all, the load is extremely compressed and you need to either alter your loading technique (like using a drop tube for better fill) or change either your powder or charge to get your compression down.

 

[FearNoWind]

P { margin-bottom: 0.08in; } If you have a 200 grain bullet running downrange at 2700 fps you've got all the knock down power you need. I frankly prefer H4350 (IMR4350) to RL17 because RL17 tends to be temperature sensitive and my hunting and competition environments can cover a pretty wide range of ambient temperatures depending on time of day or season of the year. The competition range temperatures sometimes vary 40 degrees over an 8 hour period.

If you're looking for higher MV - which I don't believe you need - try 180 grain bullet. That's enough for any big game on the North American continent. If you're going to work the loads at the higher end just remember that a change of .006 in seating depth can make a huge difference in chamber pressures.

... What is the general thought on compressed loads and safety?

I can't speak to the "general thought" but IMO compressing loads serves no useful purpose. If you can't get what you want out of a moderate load, find a bigger gun. You can push a .17HMR past it's limits and walk around with the rifle's bolt sticking our of your forehead but it'll never knock down an elk.

 

[Kennibear]

I chronograph everything because in my experience the velocity increase flattens out (quits increasing velocity) at max pressure. The velocity increase is linear with increasing powder weight until you approach max where it drops pretty fast. That is why so many old time reloaders have no problem cutting back on powder charges as the velocity loss is minimal.
I like slightly compressed charges as the powder position in the case is not a factor then. But Lefty is correct as to heavily compressed charges altering the load length. My difficulty with extreme compression is the bullet punch dings up the bullet nose from the excess bullet seating pressure.
KB