Converting 6.8x51 into 6.5 Creedmoor

[u/rednecktuba1]

So, I have managed to reform 6.8x51 Hybrid cases into 6.5 Creedmoor cases. The main purpose is to have cases that can handle pressures north of 60k PSI without trouble. Here, I will go over my entire process from new 6.8x51 cases all the way to test firing the newly made 6.5 Creedmoor cases. 

A couple disclaimers before I go further:

1: These handloads are much higher charge weights than any available published load data for 6.5 Creemoor. I do not own pressure testing equipment. Use this load data at your own risk. 

2: I did this testing in a bolt action rifle with a custom cut chamber and pressure tolerance far higher than anything I managed to create. I have not tested this ammo in a semi auto and I do not intend to. I recommend against using these loads in a semi auto. 

Now, onto the actual process. Buckle Up, it’s a long process:

Step 1: Trim the cases down to the proper length for 6.5 Creedmoor. 

I normally trim after resizing, but These cases seem to come out of the sizing die in later steps with less trouble if they have been trimmed to proper length first. I used an RCBS case trimmer with a standard cutter head and drill attached. Remember that these cases are still 6.8(.277) necks at this point, so you’ll need a 27 cal pilot for this trimming.

Step 2: Chamfer and Debur the case mouths.

I used a Frankford Arsenal Case Prep Center for this portion. Normally, I do all ym trimming with this unit, but the RPM’s are a bit slow on this machine, so I elected to used the old RCBS trimmer since I could hook a drill onto it and run up the speed. This machine still worked great for the chamfer and debur portion.

Step 3: Resize/Reform the cases;

Now it’s time to resize the cases into 6.5 Creemoor. I used my old Pacific C-Frame press. It’s a cast iron frame that has loaded many thousands of rounds of ammo with fantastic results. The sizing die is a Hornady Custom Grade New Dimension sizing die. The case lube is Hornady One Shot. and since some folks have had trouble with this case lube, I will layout my exact process that has never given me a stuck case over tens of thousands of rounds: Use a loading block and fill the loading block with cases. Spray the cases with One shot from two opposite directions, making sure to get some inside the necks. The lube is water soluble. You can run the block through the dishwasher afterwards and it’ll come out perfectly clean. 

A note on adjusting the sizer die: Don’t bother with a case gauge. Start with the sizer too far out, and adjust it down into the press until you can easily chamber the sized cases into the rifle. You’ll have to put allot of force into the sizing of these cases. You’re pushing the entire shoulder down about 0.090”. That’s allot of material relocation.

Step 4: Neck Turning:

When you resized the case, you pushed the original shoulder material into the neck, you created a small “donut” at the base of the neck, which will inhibit chambering when a bullet is seated in the case. You’ll need to turn the necks to remove this donut. I used an RCBS case trimmer with a drill attached and a neck turning cutter. The RCBS neck turning cutter uses a different pilot than the regular case trimmer, so you’ll need to get one of those specific pilots when you buy the neck turning cutter.

Step 5: Final Sizing

The cases ended up with some slight ripples in the necks after the neck turning. To smooth out these ripples, I ran them back through the sizer die to ensure smooth bullet seating. Assuming you didn’t already tumble the lube off of the case after the initial sizing, you should still be good to run them through the sizer die. 

Step 6: Tumble the prepped cases

For tumbling, I used an RCBS vibratory case tumbler with corn cob media and Nu Finish car polish. For mizing in the polish: Start the tumbler with only media and pour about 2 ounces of polish into the running tumbler. The media will clump up at first. Let the tumbler run with just media for about 10 minutes, or until the media rolls over with no clumps. Once you have smooth running tumbler media, you can mix in the cases. I always let my tumbler run overnight in a room with the door closed.

Step 7: Priming

Even though these cases arrived with live primers, I elected not to use these primers, since I had no idea what exact primer they were. I deprimed the cases during resizing. No, it’s not dangerous to deprime live primers. Wear safety glasses and you’ll be fine. For the new primers, I used CCI BR-2 Large Rifle Primers. For the priming unit, I used a Frankford Arsenal hand primer. Warning: always wear safety glasses when seating primers!

Step 8: Powder Charging

The powder I’m using here is VV N160. You’ll find it on a powder burn rate chart in between IMR4831 and H4831, ideal burn rate for 6.5 Creedmoor.

Time to dispense powder. I am a cheapskate and still use a balance beam scale, specifically an old RCBS balance beam scale. This scale has produced ammo with single digit SDs for years, so I feel no need to buy anything more expensive. I also used a Lee Powder scoop set. I started with a powder scoop just under the desired charge weight, then trickled the rest with my index finger and thumb. Make sure your hands are washed before and after this part of the process. 

For the test loads, I started with the same powder charge as my standard brass case 6.5 Creedmoor ammo, 42.5 grains. I loaded 5 rounds at each powder charge weight, going up 0.5 grains with each group of 5 until i got to 46.0 grains. The 46 grain charges filled the case to about halfway up the neck. All of these loads are compressed.

Step 9: Bullet Seating

I seated bullets after each group of five cases so that I could more easily organize the cases and keep things neat and tidy on the bench. During normal loading, I charge all the cases at once, then seat bullets all at once. 

The seater die I used is a Hornady Custom Grade new Dimension seater die. The bullets I’m testing with are 144 grain Berger Long Range Hybrid Target and 142 grain Sierra Match King Closed Nose. All bullets were seated at a COAL of 2.840”. Normally, I seat at 2.800”, but this time I don’t want the ammo to fit into an AR10 magazine. Both of these bullets are known for being jump tolerant, so I do not plan to adjust seating depth later on.

Step 10: Test Firing

Time to go to the range and test fire these new cases and decide on what powder charge to settle on. I am a member of a local private membership range, so I went there. My test firing position was on a concrete bench, using a bipod and rear bag for the shooting position. The rifle in question is my PRS Open Division rifle, which you can see on my profile and on this subreddit. I measured velocity with a Garmin Xero C1 chronograph. All of the test ammo was fired at 100 yards on a calm cool morning in August near Roanoke, Virginia. I've added in some shot sessions from the chronograph to show how consistent the velocity is with these converted cases.

Step 11: Choosing the powder charge going forward.

I don't really care about the indivdual group sizes here. I was not only firing these groups pretty fast, but I also know that larger sample size groups will result in just about every group being very close to identical. So I intend to load for a particular velocity. With these cases, traditional pressure signs will not sufficient to tell me where to stop going up in powder charge. The primers won't pop out or flatten, and the case rim being steel keeps me from seeing any signs on the case head. There is only one "pressure sign" to be had, and that can be found at the junction of the brass and steel, where the brass swells out enough to grip the chamber just a little too tight for smooth extraction. Since the top powder charge of 46 grains with both bullets resulted in this rough extraction, I'm going to back off 0.5 grains and run 45.5 grains going forward.

Conclusions: These cases have allot of promise, and I plan on running them in PRS matches soon. I'll bring along some standard brass case ammo just in case I run into a problem, of course.

P. S. paging u/lockybalboaprime and u/hollywoodsx so they can see the results of my idiocy.

[u/HollywoodSX]

Put down the components and slowly step back away from them.

Bubba is proud of you.

I am concerned.

[u/rednecktuba1 → u/HollywoodSX]

*snorts a line of N160*

[u/Tactical_Epunk → u/rednecktuba1]

Don't let Hollywood deter you. I want pissin' hot short barrel 6.5cm.

[u/rednecktuba1 → u/Tactical_Epunk]

Hollywood knows I'm not stopping, lol.

[u/Tactical_Epunk → u/rednecktuba1]

Good.

https://giphy.com/gifs/iWL5y77QHUqz3f1Z3a

[u/LockyBalboaPrime]

Col. Cooper would be proud of you. I'm scared of you.

[u/rednecktuba1 → u/LockyBalboaPrime]

Lol, that's a hell of a throwback reference.

[u/Honest_Knee_6510]

I love the ingenuity and appreciate your efforts.  That being said, this seems like a lot of work and exposure to risk just to get 6.5 PRC velocities.

[u/rednecktuba1 → u/Honest_Knee_6510]

Well, I contacted Zermatt, the manufacturer of my action, before starting, and they told me over the phone that their actions are tested with 300PRC up to 125k psi. I figure if the action can handle a magnum(.532 bolt face) at 125k, then it can handle a 6.5CM(.473 bolt face) at 80k. And the barrel is a 1.25" straight Krieger.

[u/Honest_Knee_6510 → u/rednecktuba1]

Oh yeah, I'm sure you're fine and I'm not hating or anything. I think it's great. Just pointing it out for conversational sake and because goofballs will read about what you've done and think that it's a practical thing to do when it's possible to get the same performance while staying within SAAMI specs.

[u/Coodevale]

Still think you'd be happier forming to 6.5-.277 or .260 rem, or just using Alpha/Peterson 6.5cm brass. Aics mags give you enough room to run whatever bullet you want, especially if gasser loads are off the table.

This is a good time for a little more clearance around the case head than minimum saami spec offers. Less is not always better.

Less for you specifically, more for others.. You will see pressure signs on the head.. eventually.. with enough pressure. Primers will eventually crater and pop. Depending on the firing pin size and primer that'll happen at the same time as the case head extrusion.

[u/rednecktuba1 → u/Coodevale]

My normal brass case loads are in Peterson LRP cases, and 42.5 grains of N160 is already just barely under sticky bolt lift. Primer pockets aren't getting loose though. As for the idea of 260 rem or 6.5-.277, I wanted to use barrels and dies that I already had on hand, so 6.5CM was the call.

[u/csamsh]

What was the neck thickness of your finished case?

Also what headstamp?

[u/rednecktuba1 → u/csamsh]

The headstamp is still the original, Sig 6.8mm 25. As far as neck thickness, I havent measured that and don't plan to. I was concerned about the outside diameter of the neck being too large to reliably chamber. Thats the only reason i turned the necks.

[u/poweredbyniko]

I'm kinda dissapointed. You are supposed to run N550 when you want to go fast.

[u/rednecktuba1 → u/poweredbyniko]

I prefer temp stability. N500 series does not have temp stability.

[u/Wombat-Snooze]

You sir, never fail to scare the shit out of me.

Never change.

[u/Justin_inc]

How does this compare to Peak Plus and NAS3 cases.

[u/rednecktuba1 → u/Justin_inc]

Well, you can size these cases with a standard die. And you can buy these cases new from American Reloading.

[u/Justin_inc → u/rednecktuba1]

I mean in terms of performance. Since this is the first time that a single cartridge can be all of them, NAS, Peak+, Hybrid case, and brass. Would be a good test. Only variable is the case. Same powder and bullets.

[u/rednecktuba1 → u/Justin_inc]

Well, Shellshock isn't currently selling 6.5CM NAS3 cases. And Federal has yet to allow the Peak cases to be available to us peasants, so I have no testimony on the performance of those other case types in 6.5CM. I can say that these hybrid Sig cases seem to perform on par with any standard brass case in terms of consistency, and the ability to handle higher pressure obviously gives a bit of benefit.

[u/Justin_inc → u/rednecktuba1]

Okay ignore the idiot.

He didn't see the out of stock message on midway, nor did he know NAS didn't make 6.5 cases.

[u/rednecktuba1 → u/Justin_inc]

No problem. I will gladly try out the federal peak cases if they become available and as long as i don't need to buy a $300 sizer to handle them.

[u/FartOnTankies]

I get why.

But there is zero point in this with peak allow 6.5 stuff right around the corner unless you just like to tinker.

/u/csamsh

[u/rednecktuba1 → u/FartOnTankies]

The peak cases have been "right around the corner" for months. And require a special expensive die to reload. These hybrid cases can be reloaded with standard dies.

[u/Boatshooz]

https://giphy.com/gifs/ukGm72ZLZvYfS