Custom Remington 700 .308 Build - Load Development - Inside MDT - Part 3

Editor's Note: This is a Three Part Article. Part 1 and Part 2 can be found here.

The best part of building a semi-custom rifle is seeing the results. In part 2 of the series, we left off with a completed sniper-inspired rifle, which you can read about here.

Since then, I have put roughly 350 rounds through the rifle, including break-in, load development, factory ammo testing, and shooting out to medium ranges (300-600 yards).

More: Is the 308 Winchester Still Relevant?

Here we will be primarily discussing load development. Before we head there, there were a few small changes I made to the rifle that I would like to discuss. We replaced the factory Remington trigger, which had roughly a 5 lb. pull, with a Walker M40/M24 adjustable single-stage trigger, set to a very crisp 1 lb 8 oz. While swapping the triggers, I had a whoopsie and lost the bolt-release spring. That led to me ordering Holland's Deluxe Trigger Spring kit. Once I got it all together, I decided to swap out the firing pin spring for no other reason than that it was there.

While the stock Remington trigger is a very good factory trigger, the heavy break leaves much to be desired in terms of repeatable, precise trigger presses. The Walker fixes that problem, and it fits in perfectly with the inspiration of the overall inspiration of the build. The firing pin spring, on the other hand, I have yet to experience any changes from it. The claim is that the stronger spring prevents light primer strikes, leads to lower SDs, and improves accuracy. We will see about that in time. Before we get to the load development process, we need to take care of some housekeeping notes:

Disclaimer: This article is for informational purposes only; all load data is for my rifle specifically. Before loading your ammo, reference published load data from bullet and powder manufacturers.

Handloading Equipment Used:

• Press: Forster Co-Ax
• Dies: Forster Micrometer Seater, LE Wilson Bushing Resizer
• Powder Measurer: Fx120i with AutoTrickler v. 4
• Primer: Lee Bench Primer
• Brass Prep Station: RCBS Prep Station
• Annealer: Annealeez
• Tumbler: Frankford Arsenal Quick N EZ Tumbler w/ Lyman corn cob media

Components:

• Brass: Lapua .308 LRP
• Bullets: Berger 175 Grain OTM
• Powder: Varget
• Primers: Federal 210 Gold Medal Match

In case you haven't read the build article, the rifle used is a Remington action with a 20" International Barrels 1:10" twist .308 barrel with an M40 contour sitting in an MDT ESS with a deadline compatibility kit. All shooting was done from the prone using an MDT CKYE POD and a rear bag.

MDT ESS Chassis System. Schmidt and Bender Scope.

THE PROCESS

This time, I decided to use the optimal charge weight method or OCW. For the uninitiated, that's where you load up a certain amount of rounds for a certain amount of charge weights, shoot the groups and analyze the velocity data and group sizes to choose your optimal charge weight. In this case, it is 5 charge weights of 5 rounds.

Anecdotally, with 175 grain Sierra MatchKings, 44.2 grains of Hodgdon's Varget is the golden ticket for consistency and precision in .308. Since we're dealing with the same bullet weight, albeit a slightly different bullet shape, we decided to use that as the base charge weight with two more above and below it in 0.3-grain increments. That leaves us with 43.6, 43.9, 44.2, 44.5, and 44.8. All ammunition was loaded to a 2.820" cartridge overall length, or COAL.

Tip: the more precise option would be to measure from cartridge base to ogive. Typically speaking, the bullet tip, known as the meplat, of open-tip and hollow-point bullets can be very inconsistent.

ANALYZING THE DATA

What do we do with this information? Typically speaking, you want the best group size to standard deviation ratio. While picking the smallest group is sexy, the velocity consistency becomes far more important when you shoot out to distance.

Considering the "flier" in the 3rd group was called a poor trigger press, I decided to go with the gold standard charge weight of 44.2 gr.

In my experience, ¾ MOA groups and sub 10 fps standard deviation is outstanding for .308. It could be better, but as long as that stays consistent moving forward, I'm very happy.

Speaking of which, that leads me to the next step.

VERIFICATION

We loaded up 20 rounds to verify the load for the next range trip. Two 10-round groups were shot on the same chronograph string. The first 10-round group was 1.239" with a cold bore. Not very good. However, if you ignore the first 2 shots, the 80% group measured in at 0.782". The second 10-round group measured in at 0.800". The velocity numbers for all 20 rounds clocked in at an average of 2618 fps, with an SD of 9.7 fps and an ES of 37. That is plenty acceptable.

How did it do at a distance? The rifle made easy work of a 2/3 size IPSC at 600 yards. The firing solution for 500 and 600 yards was 3.1 mils and 4.1 mils, respectively.

CLOSING THOUGHTS

I am very pleased with the results of this rifle. The testing period is over. Time to continue to push the rifle out to distance. Everyone should have a .308. Thanks for reading!!

BUILD RESOURCES FROM MDT

• Upgrading the Bergara B14
• Building a Custom Bergara B14 for Competition
• Building a 308 Tikka Rifle
• Building A Training Rifle - Part1 and Part 2
• Building a General Purpose 300 Win Mag Rifle
• Building a 6mm GT for Competition
• Re-building a 308 Winchester from a Remington 700 SPS Tactical
• Building a Custom Remington 700 in .308 - Part 1 and Part 2.

ABOUT THE AUTHOR

William Maxwell served in the United States Army. After returning from his first deployment in 2015, he started building firearms and focused heavily on pistol and carbine training. In 2018 he fell into the rabbit hole of precision rifle shooting. He spends his free time competing, reloading, editing digital content and writing. He can be reached via Instagram @maddmaxxguns.