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A little too much pressure?

TN-MadDog

TN-MadDog

Full Member
Full Member
Minuteman
Feb 6, 2009
136
7
Ooltewah, TN
#1
I'm just getting into reloading for precision rifles. I have loaded off and on for a long time for rifle and pistol but have been out of it for several years. I am trying to work up loads for my GAP Crusader.

Once fired Lapua brass neck sized only.
175gr SMKs
Loaded .005 off the lands
Varget
Loaded 11 increments of four rounds each starting at 40grs and ending with 44grs.

44grs is above book max (Sierra and Hornady) but many loads listed on this site go that high and higher.

I had no pressure signs until the last group with 44grs. I detected no bolt lift difference but two of the four rounds showed some signs as you will see in the pictures.

Since I really have no need to max out velocity, how much would you recommend backing off as a max load for this rifle?

I would appreciate some input since I really don't have anyone locally to go to for advice.

Thanks,

Joe

GAPloadprimers.jpg


GAPloadprimer2s.jpg
 
#2
Re: A little too much pressure?

In this case steel was stronger than the brass case. Speed is not always king. Some of my more accurate loads have been "middle of the road" charges. Of the loads you fired which was more accurate? That's the load I would go with.
 
#3
Re: A little too much pressure?

I only loaded four rounds each so that was not much of a sample size. Of course, that last load was the best with all in pretty much one hole. There were two loads (42.5grns and 42.8grns) that looked pretty good so I will back down and work in that range more.

Based on the pressure signs at 44.0, do you think that I will be safe and reasonable backing down 1 to 1.5 grains?

Thanks,

Joe

Here are groups from those mid-range loads (numbers 6 and 7)

GAPloadtargets2-1.jpg
 
#5
Re: A little too much pressure?

I load hotter until the primer pierces or the primer pocket gets loose.
Then I back off a safety margin.
Then I have a useful load.

Most people should just use a load book.
 
#6
Re: A little too much pressure?

I had some with another powder show signs like that. Adjusted QuickLOAD's burn rates to match my velocity, and I had to go fully 2 grains less powder before the mathematical models said I was back to being safe.

What are your velocities with those three loads?

IF your aimpoints were all the horizontal lines below the bulk of the groups, I'd consider splitting the difference between #6 and #7 as the promising mid-point for OCW purposes.

Barrel length and velocities? OAL at .005 off the lands?

My case capacity in QuickLOAD says 44.0 is almost 4,000 PSI overpressure. However, my barrel is also shooting faster than it "should" with every handload and has shown pressure with some published loads. 42.8 Varget "by the book" predicts safe pressure 1,040 PSI under max, and a 24-inch velocity of 2665 fps. AFIC, anything over 2600 with a 175 is fast enough.

If you're getting over 2675 out of a 24-inch barrel with 175 SMKs, you are probably over pressure.
 
#7
Re: A little too much pressure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">Adjusted QuickLOAD's burn rates to match my velocity, and I had to go fully 2 grains less powder before the mathematical models said I was back to being safe.

What are your velocities with those three loads?

IF your aimpoints were all the horizontal lines below the bulk of the groups, I'd consider splitting the difference between #6 and #7 as the promising mid-point for OCW purposes.

Barrel length and velocities? OAL at .005 off the lands?

</div></div>

I recently purchased QuickLOAD but haven't really had time to sit down and learn how to use it. I work on that before I go any further.

Barrel length is 22". I did chronograph all the rounds but hesitate to rely on those numbers. The sun was at a bad angle with variable clouds and I had problems getting good readings. I had several errors that day which is unusual. My plan now is to go back and make up some loads that start just below 6 and go just above 7 and see if I can get better data. I am going to try to run all this through QuickLOAD first to see what it says.

Thanks to everyone who has replied.

Joe
 
#8
Re: A little too much pressure?

With a rifle as well crafted as the Crusader-why not back away from the lands. My GAP 308's all shoot outstanding right at 2.800 coal. 168smk,175smk,190smk and the 155Scenar all tolerate a jump. That is a HOT load in my GAP TIS. I don't mind a little primer cratering,but when the ejector marks the case its time to back down.

With Quickload,be certain to carefully measure your resized case volume-AND case length. Using the default values will result in incorrect calculations.

You might also have a "faster" lot of Varget too.
 
#10
Re: A little too much pressure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lt. Arclight</div><div class="ubbcode-body">With a rifle as well crafted as the Crusader-why not back away from the lands. My GAP 308's all shoot outstanding right at 2.800 coal. 168smk,175smk,190smk and the 155Scenar all tolerate a jump. That is a HOT load in my GAP TIS. I don't mind a little primer cratering,but when the ejector marks the case its time to back down.

With Quickload,be certain to carefully measure your resized case volume-AND case length. Using the default values will result in incorrect calculations.

You might also have a "faster" lot of Varget too. </div></div>

I'm definitely going to back down. Started working with QuickLOAD today. I can see that it is going to take some time to get that all figured out.
 
#12
Re: A little too much pressure?

TN-BD: I've had exactly the same issue with my Lapua brass. I've been running 44.4 gr Varget behind a 175SMK. Some of my brass show the same ejector marks as yours do. I shot a comp once where at the end I started to get stiff bolt lift and deep ejector marks and the primer pockets got loose, but most of the time it's just a light mark that is barely feelable with a fingernail. I still wonder though.

I'm shooting a 308 with a 25" barrel (Bartlein) and my chrono reads around 2760fps with this load. I worked up from 44.0 gr Varget up to 44.6 gr. The 44.4 gr load was the most accurate with SD's around 8 fps. I'm planning on backing down and working back up from 43 gr to see if I can find an accuracy node a little lower.

ETA: I don't think that is true primer cratering from over-pressure. It seems to me that most Remington actions I have shot will cause a bit of this "cratering" due to a larger hole in the bolt face for the firing pin. Others please feel free to correct me on this if I'm wrong.
 
#13
Re: A little too much pressure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: a-hull</div><div class="ubbcode-body">reminds me of working in the shop with my dad,
he used to say tighten it down til it breaks, then back it off a half a turn. </div></div>

My mother, while teaching me to drive, deadpanned, "Just back up until you hear glass crash."

dscf0032bulletpinch308brass243chambercroppedtwice.jpg

These three rounds all were the same load.
After the third, I decided to quit for the day and go home.
 
#17
Re: A little too much pressure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Clark</div><div class="ubbcode-body">I load hotter until the primer pierces or the primer pocket gets loose.
Then I back off a safety margin.
Then I have a useful load.
</div></div>

This is what I do as well, I generally find that .3-.5 underneath my "max" are where my best loads are.
 
#20
Re: A little too much pressure?

You guys are a bunch of pussies!
Now is the time to be UPPING the charge weight.
46.0 grains + and jammed deep into the lands.
If you want more speed, switch to a faster powder too.

I load until the primer falls out on its own, then I save tons of time depriming.

















Seriously though, I'd consider 42.5 grains of that lot a place to look for an accuracy node.
I'd also give the bullet a little more of a running start going into the lands to keep the engraving forces low.
 
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