I have many different approaches to load development. In fact, I tend to change my process just about every time I develop a load. The specific method and process I’ll use is based based on the tools, components I have on hand, and my needs/requirements for the ammunition I’m developing. In this article, I’ll outline my 6mm Creedmoor load development process and equipment that I’m using for an upcoming PRS type match.
The rifle I’m developing loads for is my HOWA 1500 that I recently rebuilt to address some accuracy issues. I’m now able to attain approximately 1/4 MOA performance when things (including my shooting) are “dialed in”.
Here are some of the stories related to this rifle published so far:
- HOWA 1500 Barreled Actions from Brownells: 6mm Creedmoor Build Kick-Off
- KRG Bravo Upgrades and Mystic Precision MPOD Install: HOWA 1500 6mm Creedmoor
- Re-Barrel at 300? Diagnosing a HOWA 1500 6mm Creedmoor That Won’t Shoot
- 6 CREED UR: Rebuilding a HOWA 1500 for Accuracy
- Timney HOWA 1500 Trigger Upgrade: Install, TriggerScan, Shooting
Even with factory ammunition, this rifle is now a tack driver!
But for this match, I’ll need to satisfy the following requirements:
- Sub 1/2 MOA performance
- Sub 10 FPS Standard Deviation for velocity
- Ability to load on progressive press
The factory ammunition shoots great groups, but the SD was high (20+ FPS, not tuned for my rifle). So it was time for some load development!
For this PRS match load, I’ve settled on the following components:
- New Starline 6mm Creedmoor cases (large rifle primer, small rifle primer 6mm Creedmoor also available)
- Berger 6mm 105 grain Hybrid Target bullets
- Hodgdon H-4350 Powder
- CCI BR2 benchrest primers
The Equipment and Gear
For this loading, I used gear that would roughly simulate a progressive loader (stay tuned for the follow-up on that!), and gear that was not in use for other projects. So I used the following:
- MEC Marksman press
- RCBS 6mm Creedmoor full-length sizer die
- LEE Auto Bench Prime bench priming tool
- Hornady Lock-N-Load bench powder measure
- L.E. Wilson 6mm Creedmoor chamber-type micrometer seater die
- K&M Precision Arbor press (for bullet seating)
Before rebarreling the HOWA 1500, I had put quite a bit of effort into load development while working through the accuracy issues. Rather than throw all that work out the window, I decided to take some of the “promising” loads from that effort, and work with those. This worked out quite well! I started with the Hornady 108 grain ELD-M bullet since I had worked mostly with that bullet during my testing. I decided to focus on two charge weights: 40.6 grains H-4350, and 43.0 grains H-4350 (OVER MAX- don’t use this load, I worked up to this charge weight in my rifle looking for pressure signs). I found that both accuracy AND velocity SD were better with the 40.6 grain load, so I decided to focus there. The velocity averages were consistent with the Federal Premium ammunition that shot so well during break-in, so I felt I was on the right path! I found slightly better accuracy when I tried Berger 6mm 105 grain Hybrid Target bullets – so I switched over to those in the process.
While the 40.6 grain load shot well, the SD wasn’t quite where I wanted it to be:
I decided to up the powder charge 0.2 grains up to 40.8 grains, and right away I saw an improvement in SD on velocity. Here’s some chronograph data captured with my Caldwell G2 Chronograph:
Now we’re talking! Sub-10-fps SD on velocity. But what about accuracy? That worked out well with this load too!
The above shots were fired almost rapid fire, so I’m confident there’s further room to tighten up groups shot with this load.
Let’s go over my checklist:
- Sub-1/2 MOA? CHECK!
- Sup-10-fps SD? CHECK!
- Loadable on progressive CHECK! (powder was thrown without trickling)
Things have really fallen into place with this PRS match load development and prep. The next thing to do is to load some of the ammo on a progressive, stay tuned for that! I’ve VERY happy with how the Starline brass and Berger 105 Hybrid Target bullets are shooting. Now to practice, practice, practice!
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