Pressure Signs Early/Well before MAX *AND W/Factory Ammunition*

[CouesPursuit]

I'm seeking advice on pressure signs at the very beginning of 2 different ladder tests shooting 160gr Accubonds in my factory Savage 7mm Rem Mag.

 

Here are 2 factory loads shot before and after the ladders.

 

 

Ladder RL23-

Starting at 61gr, published MAX is 65.1 for a 160 BTSP. Both 61 and 61.5 had pressure signs of sticky bolt, ejector marks, and cratered primers. Needless to say, I stopped. Velocity was 2960 FPS, 3001 is published for MAX.

 

Ladder H1000-

The only published data I could find for 160gr was for the Partition at 63 MIN and 66 MAX. Tons of guys out there claim to be loading 70+gr of H1000 for the 160AB as the AB and Partition have vast differences in pressure tolerances. I started with 64 grains and both 64 amd 64.5gr had the same pressure signs. Velocities were 3002 amd 3022. Frustrated and concerned, I quit there.

 

 

Answers to a few anticipated questions and additional info:

 

These are loaded 0.01" off the lands. I am neck sizing only and this is twice-three times fired brass. I do not anneal. The brass is properly trimmed and lightly chamfered. All lube has been removed after sizing via tumbling, and I'm not lubing case necks or bullets prior to seating. The rifle was recently cleaned, the chamber dried, and the barrel fouled.

 

In my previous, successful loads with this rifle, I used WLRM primers. "New" to my method and components is using Fed 215m primers and I changed to a 160gr Nosler Accubond.

 

At this point I plan on pulling the bullets and full length resizing and examining all my brass.

 

Thick skin on and ready if anyone can help straighten out my ways, thanks.

[452b264]

That is most likely a head space issue. I saw a brand new M 700 at the range with severe head space from the factory. I have seen guys beating their bolt open with a brand new gun. I have head space gauges for a magnum, but I dont have the wenches to loosen and re-torque the action and barrel nut.

[CouesPursuit]

FWIW, the gun has 700 rounds down the pipe and this is the first set of pressure signs I've seen other than a bit of sticky bolt on my prior load.

[lancetkenyon]

I agree this could be an issue with new brass, or FL sized brass. But twice fired and only neck sized if fired in your chamber should not do this.

 

Check headspace of your loaded, and fired brass.

 

Another possible culprit would be brass content of the Hornady vs. What the book uses. If there is less case capacity with the Hornady due to more brass content, then pressures will spike earlier. Seeing as how your velocity is much higher than what the book shows, leads me to think this could be a big part of your problem.

 

Also, jumping from LR to magnum primers greatly changes pressure too. Like 1-2 grains of powder difference at times.

 

Different lots of powders can cause this effect, as well as temperature swings, but H1000 is very temp stable, and RL23 is very good as well. RL22 would definitely show temp swing velocity changes however.

 

Bullet bearing surface and friction will also add or reduce pressure. That is a main reason why Partitions suggest less powder usage. Loading a bullet that is different than what a book calls out is not exact. There will be a difference.

 

You could also have a slight carbon ring right at the throat with 700 rounds down the tube. I doubt the barrel is shot out, but higher pressure and velocity is sometimes a sign of that.

[300RUM]

Do you have a reference weight for your scale? If not put one of those 160 gr bullets on your scale and see if the scale thinks it weighs 160 gr. If your scale is somehow off you could be loading a larger amount of powder than you think you are.

[CouesPursuit]

On 9/24/2017 at 2:56 PM, lancetkenyon said:

Check headspace of your loaded, and fired brass.

 

How do you check yours? Thank you for the feedback Lance.

[CouesPursuit]

Do you have a reference weight for your scale? If not put one of those 160 gr bullets on your scale and see if the scale thinks it weighs 160 gr. If your scale is somehow off you could be loading a larger amount of powder than you think you are.

 

Thanks 300RUM, I calibrate it often and check known random objects on the scale throughout each loading session. I understand my Hornady scale is not the best, but when it gives me the numbers I'm expecting..

[lancetkenyon]

Hornady comparators and headspace insert.

 

1st a fired case

 

 

Resized and bump shoulder back .002"

 

[lancetkenyon]

Here is some 7RM brass.

 

New Nosler brass

 

 

Fired brass (grew .010")

 

 

Bump shoulder back .002" during FL resizing

 

[CouesPursuit]

Looking into my reloads further, it seemed as though I wasn't as far off the lands as I thought. I had actually jammed a bullet while loading and when it didn't feel right, I extracted the case (with some effort) and the bullet remained. I figured this could explain the pressure spike so I decided to shoot some factory rounds after work this week that I had laying around. The results are interesting.

 

Last week, and shown above, I shot Hornady 140 BTSP and Nosler 168 LRAB, with no pressure.

 

This week,

Remington Corelokt 150 grains, shot great, no pressure.

Remington Corelokt 175 grains, shot great, no pressure.

Winchester Super X 175, no pressure.

Winchester Super X 150, no pressure, and a bonus 1.25" group at 200.

 

 

 

Then, the kicker. I shot one 160 Nosler Accubond FACTORY round that was nowhere near the lands and it shot 4" higher than anything else at 200. Similar pressure signs as the 160 AB reloads at MIN (again both RL23 and H1000) with a very sticky bolt.

 

 

My previous reload, a 168 LRAB with no pressure, loaded to 68 gr of H1000, only shot MOA with an occasional flier so I moved on. Now I can't get 64 gr of H1000 to not give pressure on the 160 AB, and a once fired factory case looks like this? No way can a bullet itself have that impact? Is it gunsmith time? Thanks.

 

I have a comparator on the way.

[300RUM]

You have a really unusual problem. It is possible the bullet could do it. If you have a box of bullets that were somehow manufactured oversized in diameter and made it past QC. An oversize bullet would be harder to force through the bore and increase pressure. Measure the accubond's diameter to rule that one out.

[300RUM]

Dump out some of your H1000 on a tray and take a real good look at it. Is it possible it's been contaminated by mixing in a faster burning powder on accident? That would give you pressure problems. You wouldn't be the first guy to do that one and you would be somewhere in line behind me.

[300RUM]

The factory accubond load being hot is interesting. It still seems like there has to be a problem somewhere in the reloads. How are you measuring COAL to lands? I have a Sinclair tool that measures from the base of a bullet seated at the lands then from the base of a fired case in the chamber. Subtract B from A, add the length of the bullet and you have a figure that's based off the actual bullet against the lands and the cartridge in the chamber. If you want to try it that way shoot me a message. I'm in Chandler.

[CouesPursuit]

Thanks for replies, Lee.

 

Not the bullet.

 

 

As to the powder, it is from the same 8 lb jug that was running the 168 LRAB, and I haven't used another powder since. I'm confident it is not contaminated. I also have the same issues with the RL23 that was just purchased for this load.

 

 

Neither of these 2 things explain the pressure sign on the factory round, but I should mention -

 

The reload bullet that just pulled from the case has some scraping on the jacket. Is that enough increase in neck tension to cause problems?

 

 

Or what about my primer pockets getting larger. Some cases were seating primers easier than others, I trashed anything that I could pop out.

[CouesPursuit]

On 9/30/2017 at 10:43 AM, 300RUM said:

The factory accubond load being hot is interesting. It still seems like there has to be a problem somewhere in the reloads. How are you measuring COAL to lands? I have a Sinclair tool that measures from the base of a bullet seated at the lands then from the base of a fired case in the chamber. Subtract B from A, add the length of the bullet and you have a figure that's based off the actual bullet against the lands and the cartridge in the chamber. If you want to try it that way shoot me a message. I'm in Chandler.

I have been seating a bullet inside a pinched, once fired case into the rifle 3 times and taking an average COAL, then seating down 0.01" from there.

 

I just got my comparator so I'm looking forward to using CBTO from here on out.

 

Thank you for the offer! I will check out the Sinclair tool and let you know if I want to try yours first.