Disclaimer: It is crucial to acknowledge that working with live ammunition and firearms is inherently dangerous and should be approached with the utmost caution and responsibility. The information provided in this article is for educational purposes only and does not substitute for professional guidance or expertise. See full disclaimer at bottom of article.
After taking a few weeks off from the 25 GT due to work and other obligations, I was finally able to make it to the range and finish up some load development. After talking with the winner of the Box Canyon Showdown, who won the match shooting a 25 GT, I wanted to play around with some Hodgdon Varget because at this point, I had only tried Hodgdon H4350.
Through research and discussion, I had decided I was going to start with 33.4 grains of Varget in order to ensure I started at a safe pressure, and then work my way up to 34.2. Although some have been able to go much higher than 34.2 grains, I do not intend to run this super-fast. I really want the ballistics to line up close to a 109 Berger Long Range Hybrid at 2820-2850, so it is similar to what I have been running in the Dasher for the last 4 years.
Having done load development hundreds of times over the years, I do not load a ton of rounds in the initial phase of the testing. I pretty much load 4 rounds per charge weight and pick a seat depth that I know shoots well at a similar speed. Having played around with H4350, I knew that 0.025 and 0.035 off the lands shot extremely well in this barrel, and with 0.035 being the best, I started there.
Here are the powder charges I decided to start with:
- Varget – 0.035 off unless indicated below
- 33.4
- 33.6
- 33.8
- 34.0 (0.025 off)
- 34.0
- 34.2
- H4350 – 0.035 off
- 36.6
- 36.8
I threw in two H4350 loads I have been wanting to play with. I was experiencing a little bit of pressure signs on my primers at 37 grains of H4350, but after taking some measurements, I am almost certain it is because the virgin 6 GT brass I am expanding has about 4-5 thousandths bump, which is a little more than I would like to have. You really want that to be in the 2-3 thousandths range, with 3 being max. In my experience, anything over that and you will start to get pressure signs.
Range Trip:
With everything loaded and ready to go, I headed out to the range to start this testing. Just for reference, the temperature that morning here in Kansas was about 46 degrees Fahrenheit, and the winds were extremely light at 2-3 MPH from the Southeast. This made for a very pleasant morning.
Setup:
- Load:
- Virgin Alpha 6 GT Brass necked up with a Sinclair Expanding Mandrel
- CCI450
- Berger 135 Long Range Hybrid
- Varget (33.4, 33.6, 33.8, 34, 34.2)
- H4350 (36.6, 36.8)
- Gear Used:
- Garmin Xero C1 Pro Chronograph
- Rifle: Impact Action, Foundation Stock, Leupold Mark 5, Hawkins Rings, ACE Brake, CRB Barrel, TriggerTech Diamond Trigger, Hawkins M5 Bottom Metal, MDT Mag, Harris Bipod.
- Plywood board at 600 Yards
- 2’ x 3’ white paper with an orange circle in the center (x2)
The Process:
I colored the bullets of the loaded Ammo with Sharpies:
- 33.4 Varget – No Color
- 33.6 Varget – Orange
- 33.8 Varget – Green
- 34.0 Varget – Red (0.035)
- 34.0 Varget – Green (0.025)
- 34.2 Varget – Blue
- 36.6 H4350 – Red
- 36.8 H4350 – Blue
You really want to get to the range in the morning or evening when the mirage and wind are the lowest. It is almost impossible to do this in the middle of the day when the mirage washes out your aiming point. Hang both pieces of paper on the plywood board at 600 yards. In this case, it was at 575 yards because that is where this range already has a board in place.
Shooting sequence one:
- Left Paper
- 33.4 (Varget)
- 33.6 (Varget)
- 33.8 (Varget)
- Right Paper
- 36.6 (H4350)
- 36.8 (H4350)
- 34.0 (Varget) (0.025)
After firing all the rounds from the above loads, I went downrange to verify and mark the holes in the paper. The Sharpie on the bullet will leave the color on the edge of the hole. If you shoot a load that is not colored with a Sharpie like I did with 33.4, it is easiest if you mark all the color ones first and then the leftover holes are the ones with no marks.
Shooting Sequence two:
- Left Paper:
- 34.0 (Varget) (0.035)
- 34.2 (Varget)
- Shooting Process Complete
Note: During the shooting process, you need to monitor your barrel temperature. When you go out on a morning like I did when it is in the 40s, barrel heat is not going to be a major issue.
The Results:
Okay, the part everyone is looking for. Once I completed this process, I loaded everything up and headed back to the house. It is much easier to use a computer and layout the targets on a big table at home than trying to do all of this at the range. What I was looking for at 575 yards was the loads with the least amount of vertical dispersion. I am not worried about the wind or left and right of the aiming point. Once I got home, I was able to measure the difference in vertical from all the rounds fired across all the powder charges.
Here are the results:
Analysis of the results shows that just about any one of these loads will shoot well enough to win a PRS match. I will also add that I have not done much seat depth testing with any of these powder charges other than the 37 grain H4350 that I started with. The next step in the process would be to conduct a seat depth test at 575 yards with whichever powder charge I go with. In this case, I am going to go with the 34 grain Varget.
One note I would like to add is as the morning went on, the mirage picked up quickly. This can impact your aiming point and cause bigger groups.
Overall, in my barrel, Varget seems to produce the best SDs and ESs. I did load up about 40 of each of the loads below and took it to the range. On the day I took it, the temps had climbed to 75-80 degrees, and the barrel now had about 70 rounds on it. The barrel was completely clean with about 20 rounds of fouling before running this 575-yard test.
Here are the last 10 rounds of the 40:
My final load:
Right now, I am sitting at around 330 rounds on this Custom Rifle Barrel (CRB), and unless something changes in the next 750-1,000 rounds, I am going to run the following load in practice and the next few matches.
Final 25 GT Load Data:
- Powder: 34g Varget
- Bullet: Berger 135 Long Range Hybrid
- Jumped at 0.035 from the lands
- This is 2.069 OAL using a 3-24 insert on a Hornady Comparator Tool
- Primer: CCI 450
- Avg FPS: 2725
This probably ends my major exploration with load development for the 25 GT. If my groups start to open up at this point, I will probably just play around in the areas I know it shoots well.
If you have read my first article about the 25 GT in which I talk about how much I enjoy shooting this cartridge, just for the record, that has not changed. I really enjoy shooting the 25 GT and will probably finish out the year shooting it at club matches.
As age sets in on my eyes, it is becoming harder to see the impact points on target with the smaller 6MM bullets, which is what sparked my interest in 25 caliber bullets a few years ago when I played around with the 25 Creedmoor. Keeping the ballistics the same as the 109 Berger by reducing the speed helps with the transition. Also, the recoil is very manageable, and in the 330 rounds I have sent down range so far, I do not feel like I have missed a single impact due to recoil.
Thanks for reading and Enjoy the Precision Rifle Process!
Disclaimer: It is crucial to acknowledge that working with live ammunition and firearms is inherently dangerous and should be approached with the utmost caution and responsibility. The information provided in this article is for educational purposes only and does not substitute for professional guidance or expertise. Loading ammunition requires in-depth knowledge, experience, and adherence to established safety protocols. It is essential to consult with a qualified professional, such as a certified firearms instructor, experienced reloader, or ballistics expert, before attempting to develop or modify ammunition loads. Improperly loaded ammunition can lead to catastrophic consequences, including injury or death. Any experimentation with ammunition should be conducted within the parameters specified by reputable reloading manuals and manufacturers’ recommendations. Additionally, local laws and regulations regarding firearms and ammunition must be strictly followed. It is the responsibility of the individual to ensure compliance with all applicable legal requirements. The authors and publishers do not assume any liability for the use or misuse of the information provided in this article. Readers are solely responsible for their actions and should exercise caution, seek professional guidance, and prioritize safety above all else when working with firearms and live ammunition. Always prioritize safety, seek appropriate training, and consult with professionals before engaging in any activities related to firearms, ammunition, and reloading.
