Dangerous 6.5 Grendel loads?

[Jester]

I'm getting back into reloading, and even though I reviewed a lot of material before working up my latest loads, I believe I was missing the pressure signs. I'm used to feeling a sticky bolt and seeing primers with sharper corners when loaded too hot. This rifle is a Howa Mini in 6.5 Grendel, and the bolt lift is stiff with factory Wolf (steel cased) ammo. My brass loads were easy to extract across all tests. I started at the recommended minimum and worked up to just under max using 0.5gr increments. The load I decided on was 0.6gr under the listed max.

After testing various charges, I decided on:
Brass: New Hornady 6.5 Grendel
Primer: CCI #400
Powder: Accurate 2460 27.0gr (the only book-listed powder available locally)
Bullet: Hornady 123gr ELD-Match


My primers had a bit of cratering, but nothing too extreme I thought. The corners are still radiused. Here is a typical example:



There is some ejector swipe, but not a circular indentation. (The flash hole looks damaged here but it's just the lighting):



The bottom of the primer pocket is ugly, but the sides were clean and no primers were loose:



What concerns me is that I'm seeing banding on the cases that looks like incipient case head separation, but when I run a bent wire along the inside of the case I don't feel a groove. All of the brass did stretch one to two thousandths beyond the max trim length when fire forming, though. The banding is seemingly random, in multiple places on some cases, and not present on all cases:



One other concern I have is that I ordered a LabRadar chrono and noticed that my velocity was 2400ft/s, which is the stated max for this load in the Hornady manual. I cut my barrel to 16.5" so I shouldn't be getting max velocity. I'm using ball powder and it has been 106 degrees lately, so I'm assuming the load was quite energetic and I need to back off quite a bit, but I'm not sure if I'm reading the pressure signs correctly. Even if these aren't dangerous loads, I want my brass to last because components are stupid expensive these days.

So my questions to you experienced reloaders are:
1) Are these loads dangerous?
2) Did I potentially damage my rifle? (I assume the Howa Mini action is weaker than a short action)

 

[mattri]

Watching with interest.

 

[Kracken McGraw]

I’ve never seen brass flow like that in the primer pocket before.

 

[Mark611]

My experience with 2460 even in my 6.5GRR That powder for 1 will not produce the velocities for this cartridge! AR Comp is the powder you need! I mainly shoot the 6.5 GRR in an AR plat forum, and have tried several different powders, for the is caliber like Tac, A2520, A2495, 2460, SWMR, H322 H4895, and probably a few more, these powders were shot from an 18'' 1&8 twist barrels, I have discovered most of these powders showed pressure signs way before reaching max powder charges, But I have not had any pressures like I see in your pix of your brass or primers, AR Comp loads I run are 27.1gns, from my 18'' those loads run 2495fps with a 120gn SMK, out of my 24'' 1&8 2545fps SD are 7 out of both barrels, These other powders I have mentioned do not produce the velocities or accuracy for the 6.5Grr, IMO they also don't have the correct power curve for this cartridge either, I know my charge weights are right because I use and analytical scale that measures down to the 4th decimal point and backed with 2 tuned beam scales! bullets are seated to mag length, Now another example loading A2460 in my 308win, I loaded 41gns under a 175gn SMK's this charge weight was way too much! 2700fps not for me! 39.5gns gave me 2560FPS to 2590fps which is where I like it! That's where 41gns of A2495 runs, just giving you an idea YMMV!

 

[NZ_Fclass]

You load is a gnat's over the max. (26.8 in Winchester brass -Hodgdon's) and I would expect that, being a ball powder, the pressure is your problem. I do have some Hornady brass for Grendel, but I am unsure how it compares to the Winchester. I always use Lapua for targets and and Hornady for varmints = with different loads/bullets.

I suggest that you try Benchmark, IMR8208 or Power Pro Varmint - which have proven to be the best in my Howa mini - or reduce you load a couple of grains, and work up slowly

 

[HandgunHTR]

Some barrels are fast, some are slow. Some reloading manuals are close to what you have, some are not.

For example, Hodgdon lists 26.8 grains as the max load for that bullet with 2460.

I would like to see pictures that are not super close-ups. Just like a borescope, pictures that are too close will accentuate things to the point where they look bad, but actually aren't.

Did you start in the middle and work your way up, or did you just go to 27 grains and try the one load?

In regards to the rings, how clean was your chamber? I assume you cleaned the gun prior to shooting it. Did you use a bore guide? Did you dry out the chamber good before shooting? Those look like soot rings to me.

 

[mattri]

Did you start in the middle and work your way up, or did you just go to 27 grains and try the one load?

I started at the recommended minimum and worked up to just under max using 0.5gr increments.

 

[Mark611]

I will say this again A2460 is not the powder for the 6.5Grr! nor are the other powders I have listed that I have used other than AR Comp! I have heard Levelution, CFE223, and a few others work as well, I have no experience with these powers! and from what I have read It takes a lot more of these powders to equal what my loads of Comp do JMO

 

[Jester]

My experience with 2460 even in my 6.5GRR That powder for 1 will not produce the velocities for this cartridge! AR Comp is the powder you need! I mainly shoot the 6.5 GRR in an AR plat forum, and have tried several different powders, for the is caliber like Tac, A2520, A2495, 2460, SWMR, H322 H4895, and probably a few more, these powders were shot from an 18'' 1&8 twist barrels, I have discovered most of these powders showed pressure signs way before reaching max powder charges, But I have not had any pressures like I see in your pix of your brass or primers, AR Comp loads I run are 27.1gns, from my 18'' those loads run 2495fps with a 120gn SMK, out of my 24'' 1&8 2545fps SD are 7 out of both barrels, These other powders I have mentioned do not produce the velocities or accuracy for the 6.5Grr, IMO they also don't have the correct power curve for this cartridge either, I know my charge weights are right because I use and analytical scale that measures down to the 4th decimal point and backed with 2 tuned beam scales! bullets are seated to mag length, Now another example loading A2460 in my 308win, I loaded 41gns under a 175gn SMK's this charge weight was way too much! 2700fps not for me! 39.5gns gave me 2560FPS to 2590fps which is where I like it! That's where 41gns of A2495 runs, just giving you an idea YMMV!

Thanks for the information. I'm having trouble finding the recommended powders locally, so I may have to special order some. I've heard good things about AR Comp and CFE 223.

 

[Jester]

You load is a gnat's over the max. (26.8 in Winchester brass -Hodgdon's) and I would expect that, being a ball powder, the pressure is your problem. I do have some Hornady brass for Grendel, but I am unsure how it compares to the Winchester. I always use Lapua for targets and and Hornady for varmints = with different loads/bullets.

I suggest that you try Benchmark, IMR8208 or Power Pro Varmint - which have proven to be the best in my Howa mini - or reduce you load a couple of grains, and work up slowly

Interesting, thanks for the information. Hornady shows the starting load at 24.2 and max at 27.6 with Hornady brass, but I'm not convinced it can handle it. I did start at 24.0gr and work up to 27.5, but I didn't notice the rings until I cleaned the brass afterwards. I will reduce the charge and pay closer attention if I can't find a different powder to try in the meantime.

 

[Jester]

Some barrels are fast, some are slow. Some reloading manuals are close to what you have, some are not.

For example, Hodgdon lists 26.8 grains as the max load for that bullet with 2460.

I would like to see pictures that are not super close-ups. Just like a borescope, pictures that are too close will accentuate things to the point where they look bad, but actually aren't.

Did you start in the middle and work your way up, or did you just go to 27 grains and try the one load?

In regards to the rings, how clean was your chamber? I assume you cleaned the gun prior to shooting it. Did you use a bore guide? Did you dry out the chamber good before shooting? Those look like soot rings to me.

I started at 24.0gr and worked up to 27.5. The Hornady manual recommends 24.2 to 27.6gr. I wasn't watching for rings because I'm not used to seeing anything like that until the brass has been fired several times. I did clean the rifle but did not use a bore guide. I ran patches through until they came out dry but it's certainly possible that I may have missed something. This brass has been in the ultrasonic cleaner twice since being fired; would the soot rings still be present after that?

Unfortunately, I have already pressed out the primers and cleaned the brass or I would take some pictures that aren't so close. If I test fire more I will be sure to take a picture.

 

[JLT]

Thanks for the information. I'm having trouble finding the recommended powders locally, so I may have to special order some. I've heard good things about AR Comp and CFE 223.

IMR 8208 is my preferred powder in the Grendel. Yeah, I know. It is available nowhere. AA 2520 has shown me that it will work with the 120-123 class bullets, although it is very sensitive to temperature. Not optimal, but it works. CFE-223 is another that works with the 120-123s and RL-15 is worth a look, although it is on the slow side for the case capacity.

Your extraction difficulties are most likely a function of the case material, not pressure. The lacquered steel cases don't behave like brass - that's why they're known as the bane of extractors in ARs. Lastly, I've measured some steel cased Grendel factory loads and found them to be quite short. This can lead to flattened primers in an otherwise safe load, pressure-wise. I would put a lot more trust in what I see with reloaded brass cases that better fit the chamber.

 

[Mark611]

Again, IMO the stick powders work well over the ball Powders, from my experience! I try to keep my load for all my guns at +- 400hundreths of a grain, habit! sorry, I have also noticed loading stick powder 27 to 28gns is a pretty good case fill! for the 6.5Grr!

 

[mattri]

 

[mattri]

Just for reference.

 

[Mark611]

Now you see why AR Comp shines!

 

[Mark611]

The rest of those other powders don't even come close to AR Comp!

 

[JLT]

The rest of those other powders don't even come close to AR Comp!

In what respect? I get stellar precision at good velocities with IMR 8208. There's more to it than velocity.

 

[Mark611]

Last thing I will say is the primers you are using are too soft! you need the CCI #450 or the CCI #41 primers

 

[Mark611]

My brother also likes the XBR 8208 powder, the problem is it's not as available as most powders, into days world, even at that it takes more of the 8208 to do what AR Comp does, I can also add a few tenths of a grain and get a tic more velocity if I so decide to do so, but it's not necessary for my needs, I target shoot only, don't hunt, to me accuracy is more important than velocity! YMMV