pressure signs at min load?

[B.W.]

I appreciate all the great information you guys have given me. I think ill take your advice Andrew and go back to h4831sc or something little faster. See if I can find a good accuracy nod at the lower end.
Thanks for the info notaglockfanboy, that makes me feel lil better knowing someone else is seeing similar issues

 

[Andrew Leigh]

We still need to find out why you are over pressure thought.

 

[B.W.]

Andrew, ill get you the h20 capacity of fireformed case shortly

 

[B.W.]

Andrew, the average of 5 cases checked is 68.92gr

 

[murf]

maybe you should use that body die all the time.

murf

 

[Andrew Leigh]

Have I got all the inputs correct. Would be nice to have a measure barrel length from closed bolt face to muzzle but that will not affect the pressure.



There is something badly wrong of you are experiencing pressure signs. You got the right powder?

 

[B.W.]

Everything looks correct except the case length is 2.484 but I doubt that would make a big difference.
Its definitely the correct powder, and like I said it has shown these signs (ejector marks)with lighter loads using 3 different powders. You recommend a trip to gunsmith?

 

[Andrew Leigh]

Could you take a picture for me to see what the marks look like?

 

[B.W.]

I have never done it but I will see if I can figure it out

 

[Andrew Leigh]

E-mail me I will PM you my mail address.

 

[243winxb]

Mysteries And Misconceptions Of The All-Important Primer

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings —probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays.

http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/

 

[Andrew Leigh]

Hi,

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings —probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays

Thanks for the reference but a little too subjective for me. No meaningful facts or figures are quoted, neither is test method or control group nor the cartridge as they do make a big difference. Evidently you need to be an experience ballistician to detect it? A decent study would not have such subjectivity IMO.

 

[BigBore45]

http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings —probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays

Post # 16 that is what i was talking about and why i suggested mag primer. There are some good reads about it, i think from Richard Lee about pressures being higher until the use of mag primers or powder compression. Quickload can not help anymore than a reloading book. You are either getting secondary detonation or have an extremely tight chamber. A Crony would tell the tail and without one you will never know.

 

[notaglockfanboy]

Bw, are you seating the bullet close to the lands of your rifle?? I was having trouble with pressure signs while jumping the bullet 20 thousandths in lower powder loads, but when I increased the powder half a grain I didn't see the flattened primers or sticky bolt. The pressure signs started about midway through the workup between minimum load and max load, so I shot the next load which was half a grain more and the bolt didn't stick and the primer looked normal. I posted a question about it on this forum, but never got any resolve, although there were some interesting ideas. I moved the bullets back away from the lands and am no longer having the problem and am getting better accuracy. Hope it helps.

 

[murf]

either start using a mag primer with that slow powder, or switch to a faster powder. your load density is way too low, your bullet too light and your case capacity way to great to make this load work consistently with a slow powder like rl-22.

quickload is about as subjective as you can get.

murf

 

[243winxb]

From the link.

The op said

these loads are well under max in the book.

http://thefiringline.com/forums/showthread.php?p=4928827#post4928827

[/URL][/IMG] Combine slow powder, light neck tension, OAL to long, standard primer and you may make your own problems. Good luck.

 

[RugerOldArmy]

Could there be a brass doughnut in the neck causing this?

 

[RugerOldArmy]

Was this .25-06 brass formed from .30-06 or .270 Win?

 

[RugerOldArmy]

My bet is your brass has thick neck walls, and potentially a donut at the neck shoulder junction.

You could get this issue in one of a number of ways:

- Sizing down from .270 or .30-06 would result in thicker necks...the brass has to go somewhere. Components are scarce, forming .25-06 this way may have been attractive.

- Some brass flows forward with successive firings.

- Neck sizing, without an expander could push brass down toward the shoulder and form a donut over time.

In a rifle with a tight neck, or just thick enough neck walls in the cartridge, these can create an overpressure situation.

Anyway, that is my guess.

If that isn't it...I'd get a headspace check...try a no-go case gauge.

The more I consider this, the more I think a headspace check is necessary. Getting a no-go gauge would be cheap insurance here.