Showing signs of excess pressure/what next?

[goose]

I loaded some rounds a few days before hunting season with my 300WSM, and things went fine. I had no time to spend in load development, so I used the 3 loads recomended in the manual with IMR 4064 shooting 150gr bst nosler bullets. They were 56.5 58.5 and 60.5 grains. None showed signs of pressure at that time and I went with 58.5 for hunting.

I now have time to experiment more with these loads and loaded 6 loads starting at 56.7 up to the max moving up in smaller incriments. I had just cleaned my rifle so I shot a fouling group of 3 with the 58.5 grain loads I hunted with. Then on to the optimum charge weight procedure as has been described here.

first shot 56.7 shot fine
second 57.6 shot fine
third 58.9 Bolt hard to open and ejector mark on face of case

I inspected the rifle, took a walk to the target and returned a few min later.
Things looked fine and a I fired another 56.7 which was fine. I fired a 57.6 and that also was hard to open. I stopped there and went in.

I'm using once fired brass, full length sized winchester WRL primers. All of the rounds chambered easily. I'm wondering why I had no problems the first time around up to 60.5 grains, and now having problems with lighter loads. All of the components and procedures were the same, the only change really was cleaning the rifle and Tepmerature which was less than 10 degrees warmer the first time.

Any ideas?

 

[KQguy]

How close are the bullets seated to the lands?Maybe the ones that showed pressure signs were seated out further,and into the lands,wich could have caused more pressure.Other than that,I would check to make sure your powder dispenser is throwing accurate charges.

 

[Michael Eichele]

It can be several things. One possibility is your brass. As the necks get fired and resized the brass becomes work hardened. When this happens, you can get very inconcistent pressures AND velocities. When doing development you NEED a chrony and you NEED to fire EVERY round over a chrony so you KNOW what is going on. You may need new brass or to anneal your necks.

Have you changed to a new lot of powder?

Have you changed to a new lot of bullets?

Have you changed to a new lot of primers?

You stated that all components were the same but are they from the same lot?

Are your cases matched by weight or volume? Some will argue that it doesnt matter but I personally have found that volume matters. Heavier/thicker brass will increase pressure over brass that is thinner due to less case volume. Have you matched your cases?

Also, how old is your barrel?

 

[kraky2]

Just checking your loads against quickload there shouldn't be a problem. The 60 grain load is guessed to be doing 3112 at 60k pressure and the 57.5 grain load is really mild at 53k and 3002 velocity.
Has this batch of 4064 performed normally in other guns/cartridges??
Are you absolutely sure they are 150 grain bullets (sorry to sound dumb)
Are you sure your scale is working perfectly?
Have factory loads ever done this in this gun?
One last thought....is there a chance you are ovesizing your brass leaving lots of headspace??
This can sometimes show ejector marks etc at lower pressure.

I can't think of anything else offhand but getting to a chronograph is definately going to be a next step.

 

[goose]

Investing in some equipment paid off. I bought a bullet puller die today and checked the loads. I had set the scale incorrectly and 5grains heavier than indended.
One thing that was suggested I would like to know more about, how would I know if I was "oversizing" my brass? What is the correct procedure for setting my die if full length sizing?

 

[Michael Eichele]

Investing in some equipment paid off. I bought a bullet puller die today and checked the loads. I had set the scale incorrectly and 5grains heavier than indended.
One thing that was suggested I would like to know more about, how would I know if I was "oversizing" my brass? What is the correct procedure for setting my die if full length sizing?

My method may be unorthodox but works.

I take a fire formed peice of brass and measure the shoulder from the base using a custom neck trimmer that uses the shoulder to stop the trimming. This trimmer rests on the shoulder. Then I use a micrometer between the trimmer and base of the case. Then I size a case and measure. If the die set the shoulder back more than .0005 to .002" then IMHO it is set back too much. Adjust your die and start over.

I had one barrel in particular that if I set it more than .0005 back, I had trouble extracting cases. Actually I think it was a poorly cut chamber. In any event, it didnt like to be set back much at all.

With my current chamber (which is WAY more forgiving, I just set them back to factory which is about .001 back. It is a fairly tight chamber.

BTW, I am glad you figured it out. Your next purchase WILL be a chornograph, right?

 

[AJ Peacock]

Investing in some equipment paid off. I bought a bullet puller die today and checked the loads. I had set the scale incorrectly and 5grains heavier than indended.
One thing that was suggested I would like to know more about, how would I know if I was "oversizing" my brass? What is the correct procedure for setting my die if full length sizing?

The tool that is designed specifically for this task is the Hornady Headspace gage / comparator kit.

MidwayUSA - Hornady Lock-N-Load Headspace Gage 5 Bushing Set with Comparator

You simply attach it to your calipers and it measures from the base of the brass to a datum point on the shoulder (different calibers use different datum radius and these are included in the kit).

This is doing essentially the same thing that Meichele is describing.

They also make a kit for measuring from the base of a loaded round to a point on the ogive that has a radius equal to your caliber. The following kit includes 6 calibers (.22,6mm/243, 25, 270, 7mm, 30) other inserts are sold separately. I use this kit to measure my loaded rounds, as measuring to the tip of most bullets is much less accurate.

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=231904


I use both kits all the time.

AJ

 

[goose]

BTW, I am glad you figured it out. Your next purchase WILL be a chornograph, right?[/quote]


Got a chronograph and tumbler with some gift money from christmas.