Need help way way over pressure on near minimum powder

[AZlongrangehunting]

Hey guys... I'm looking for some help or ideas as to what is causing a massive over pressure in my new loads... 7mmRM
Symptoms brass into extractor flow
Head of the brass stamp reddish tinge and scoring from bolt face when lifting bolt
Obviously extremely difficult to remove from chamber
Oh...... And primers were blasted out of the pocket completely on all 3

To start this is virgin norma brass all I did was use a flash hole uniformer brass was perfect all around so I did nothing else to it.
Powder which is new to me is H1000
Bullet new to me is 175.00 gr weight sorted
All of my data shows about 61-61.5gr h1000 to 64.5 do not exceed.
I did the jam method for new brass as I didnt have any fired for modified aka using the brass expanded inserted a bullet and chambered it to get my approximate max ogive length
My goal was to reach at least .020" off the lands for new brass

My starting gr was 2 cartridges @62gr... and I pulled one from a second batch that i did this morning same 62gr all the same symptoms all the same everything depth etc.

I re checked my charge master lite scale with a known bullet of 175.0gr and it was dead on

I removed ALL kernels from previous powder and even if that were the case the second batch (25 charges later) would have been absolutely cleared.....
I took one of the fired cases and made a modified case to attempt to check max ogive... and it showed I was .042" off the lands... I dont trust this entirely as the brass is likely over stretched... but even then if so the .042 should account for extra brass stretch?

My first thought was I must have seated them too long but i didnt notice them jamming or feel it into the lands at all
So i checked another that was unfired to see if i had land marks on the bullet seated at that depth using a marker and I think faintly I am seated into the lands I'm pretty sure my suspicion is right here... also I have modified cases for hornady federal Winchester and rem... some are the same max ogive and nearly all the same so I'm assuming this is definitely my problem

This is a factory action and barrel savage 111

Fortunately or unfortunately the results were good... I just hope it performs like this with safe pressures

 

[Ckleeves]

Have you fired this rifle with other loads before? Not a new barrel or anything like that?

 

[fmuguira]

First thought was bullet jam but you re on that.

Did you double check your charge weight?

Have you used that lot of powder in any other applications? Possibly a fast lot? Any chance wrong powder in container ?

62 grs of H1000 in a 7 RM with a 175 gr bullet sounds very mild... we usually work up to 67-68 gr range with 180 s.

Let us know what you find!! Trying that lot of powder in another gun with a known H1000 receipe might be an idea too!

 

[MarkA]

Be sure to check barrel groove diameter. I got a .277 barrel on what was supposed to be a .284 barrel once long ago on a Savage.

Also check that a new bullet will drop very freely thru a fired neck. If it does not or has any snug feel the neck was reamed too tight and will cause this too.

 

[AZlongrangehunting]

First thought was bullet jam but you re on that.

Did you double check your charge weight?

Have you used that lot of powder in any other applications? Possibly a fast lot? Any chance wrong powder in container ?

62 grs of H1000 in a 7 RM with a 175 gr bullet sounds very mild... we usually work up to 67-68 gr range with 180 s.

Let us know what you find!! Trying that lot of powder in another gun with a known H1000 receipe might be an idea too!

Guarentee its seated too long... I'll find out in a few hours at the range today

 

[Rick Richard]

Guarentee its seated too long... I'll find out in a few hours at the range today

I doubt with that load and even jammed into the lands that it would blow primers. Something else going on.

 

[AZlongrangehunting]

I doubt with that load and even jammed into the lands that it would blow primers. Something else going on.

Definitely not the seating depth same symptoms but a little less in signs of pressure (still way over) at this point I think I'm getting a compressed charge.... are my options just drop it down in grains far below spec data...

 

[MarkA]

Definitely not the seating depth same symptoms but a little less in signs of pressure (still way over) at this point I think I'm getting a compressed charge.... are my options just drop it down in grains far below spec data...

Something serious is wrong in the gun.

 

[ar10ar15man]

what is the case volume of the unfired and fired cases ?
what bbl length
what actual COAL
( 300 WIN MAG CASE's VOLUME VARY A TON BY MAKER)

 

[AZlongrangehunting]

Something serious is wrong in the gun.

I don't know what would be wrong with it but just a little background my previous load data for a horady ELDX 162 grain with IMR7828 started showing signs of pressure halfway through the suggested grain capacity but they were very minor just extractor marks on the head and at 65gr it was definitely apparent
Factory loaded hormady precision hunter ELDX 162 grains were way over pressure as well extreme extreme bolt lift They were 150 to 200' fps faster than my loads so I accounted it to my gun did not like that cartridge from the factory I do not see any of these signs with factory loaded Winchester super X Remington core locked or federal in the 150 grain bullets

 

[fmuguira]

I d taken some measurements of fired case expansion , neck diameter, length, etc.

Then look at bore diameter as previously mentioned.

If nothing jumps out I personally would try a different powder or at least a different lot of H1000 at a minimum charge. Issues after that would lead me to a gunsmith.

Make sure you re wearing eye protection on any firing / testing.

 

[Rick Richard]

I think I would bore scope the bore to see if there is anything that a gunsmith might determine is an issue such as a severe carbon ring in the throat area. Otherwise, if you continue on loading without investigation you run a significant risk in harming yourself...STOP and proceed with caution.

 

[AZlongrangehunting]

Be sure to check barrel groove diameter. I got a .277 barrel on what was supposed to be a .284 barrel once long ago on a Savage.

Also check that a new bullet will drop very freely thru a fired neck. If it does not or has any snug feel the neck was reamed too tight and will cause this too.

As addition to this... I noticed that the hornady bullets measured .2835" at the thickest a couple smaller and the noslers are .2838" all of them... the necks were turned using the eldx bullets to .0125" and my measure using a needle bore gauge was about factory for the neck chamber... I believe

 

[ar10ar15man]

take a new and a fired sized case, seat a fired inverted primer.
weigh and log each weight
fill each with water at aprox 70-75 degree water, tap case to remove bubbles,
use a tissue to wipe dry, use corner of tissue to reduce bubble of water to be aprox flat with case mouth.
re weigh, do the math, difference is aprox case volume