300 PRC Custom Build Overview

It’s taken a lot of planning and preparation, but now it’s time! It’s time for the most in-depth rifle build I’ve ever taken on: my 300 PRC full-custom. This will be a rifle that I can reach further with, and every detail will be exactly what I want for maximum precision and accuracy. So in this article I’ll go over all of the components and gear that I’ll use for this build. This is going to be GOOD!

Heart of the Rifle: Kelbly’s Atlas Tactical Action

I got to know the guys at Kelbly’s through a mutual acquaintance: Gordy Gritters of Gordy’s Precision and the “Extreme Accuracy Institute”. If Gordy endorses something, I pay close attention, and trust what he sayeth! During a phone call with Ian Kelbly, I outlined the goals for the PRC project and specifically the 300 PRC full-custom build. We decided that Kelbly’s Atlas Tactical action would be ideal for this rifle build. The Kelbly’s Atlas Tactical is a Remington 700 Semi-Clone- this means that it employs the Remington 700 footprint, but has a lot of custom features not found on Remington 700 actions.

From the Kelbly’s product page:

The Atlas Tactical action is a Remington semi-clone action, featuring a side bolt release and trigger hanger. There is little modification necessary to use a Remington 700/40x stock or chassis. We made the most rugged action possible for practical, tactical, or hunting. We use a Black Nitride finish from H&M Metal Processing. This allows you to use this action “dry” or without lubrication for extreme environments. As always it is best to use lubrication in normal day to day shooting. In addition to the Black Nitride process we use a fluted bolt, to help move dirt into the flutes allowing better function of the action. We cut the magazine well to use the Accuracy International single stack magazines. One of the key features of this action is the TG ejector, it is a mechanical ejector that does not put any chamber pressure on the round. It is also a “never fail” setup, meaning that there are no springs to get gummed up and stop working. We offer an Extreme Duty Bolt Stop, that bolts to the side of the action via a 6/48 screw. It is truly the most reliable bolt stop upgrade on the market! We finish it all off with a pinned 20 MOA Picatinny 1913 MIL-SPEC rail, a dual pin recoil lug, and a tactical bolt knob.

    • Specifications
    • Weight: 29.5 oz.
    • Length: 7.860 in.
    • Diameter: 1.355 in.
    • Bolt Faces: .223, .308, Mag (.532)
    • Bolt Head: Coned, Flat
    • Right Bolt – Right Port OR Left Bolt – Left Port ONLY
    • Head-Space: .692 in.

The action I got from Kelbly’s is a long-action version with flat bolt head/nose, here’s a picture:

I really like the quality of this action- it’s top notch! Some other things I like about it:

  • It’s slick- the Nitrided finish is AWESOME
  • An oversized pinned recoil lug will handle magnum-level recoil AND make barrel installation easy
  • The bolt stop / bolt release is a big upgrade from Remington 700 factory actions
  • A pinned 20 MOA rail is optimal for long-range applications
  • The TG ejector will make headspace checks EASY (on the lathe, and off the lathe)
  • The trigger hanger is a more convenient way to install a trigger, can’t wait to try it!

Benchmark Barrel Blank: As Good as it Gets

Benchmark Barrels is a craft barrel shop out of Arlington Washington. I personally believe that a quality barrel is the most important investment you can make in a rifle, and every rifle I’ve built with a Benchmark Barrel has shot about 1/3 MOA or better. For this build, I wanted to compare and contrast two different twist rates:

  • 1:8.5 – recommended by Hornady for 300 PRC
  • 1:9.5 – preference from Benchmark for heavy 30 caliber rifles

I ran this idea by the benchmark crew and they replied: “let’s do it!”. So for this full-custom build, I’ll use the following barrel specifications:

  • 26″ length
  • 1:9.5″ twist
  • MTU profile
  • 416R stainless, hand-lapped

I do have another 300 PRC build planned: my budget-oriented Remington 700 Long-Range 300 PRC re-barrel. And for that build we’ll use the same exact barrel blank specification, except it will have a 1:8.5″ twist instead of 1:9.5″. It will be interesting to compare and contrast 300 PRC performance with different bullet weights and profiles using these two rifles!

Dave Manson Reamer and Gauges

I’ve had nothing but great results with Dave Manson reamers- Dave’s 22-250 reamer did a great job on my Winchester Model 70 build a while back! So I reached out to Dave to discuss my 300 PRC builds and my 6.5 PRC build- and he was interested in collaborating. For the 300 PRC builds, I’ll be using the following from Dave Manson Precision Reamers:

These tools will be demonstrated in-depth in my barrel work story, stay tuned!

MDT ACC Chassis: King of Flexibility and Features

OK, this has been on my list for a long time! I’ve seen the MDT ACC Chassis system in use at PRS matches, and have really wanted to try one for myself. Now is the time! This chassis system meets all of my requirements and then some! From the MDT product page:

Adjustable Core Competition chassis system is designed for the competition world: the ACC is primarily suited for the PRS & NRL shooting style, although it can be used in other disciplines. The ACC chassis system is the result of endless testing and collaborating with competition shooters, implementing the most crucial and results driven features, while ensuring accuracy and precision remain unparalleled.

The ACC (keyword A for Adjustable) was created with an integrated weight management system, allowing shooters to fine tune their chassis’ weight and balance point. The adjustability comes from a series of weights that can be added to either the buttstock, interior forend or exterior forend m-lok. It’s original weight of 5.9 lbs transforms into a maximum of 12.3 lbs (chassis only – add on your action, barrel, scope and accessories and most shooters are pushing 25-30 lbs in the ACC).

All of this modularity and adjustment can be achieved without taking your barreled action out of the chassis system: internal forend weights can be inserted from the front of the forend and screwed in place, while external weights were designed to be M-LOK compatible and easily attached on either side of the forend. This ACC weight management system allows shooters to rapidly adjust the feel and recoil characteristics of their system, even while at the range.

Along with other features like the full 17” ARCA/RRS forend, flared magazine well, extended barricade stop, widened thumb shelf, adjustable cheek riser and length of pull – the Adjustable Core Competition chassis is nothing short of excellence for the competition shooting world.

The ACC chassis is designed to accept an ESS compatible buttstock, with a few modifications to provide extra weight and solid lockup of adjustments, whilst still being tooless. The MDT Vertical Grip was designed at the same time as this chassis and is built for the competitive shooter.

The ACC chassis accepts AICS-pattern external box magazines, and supports installation of M-Lok patterned accessories along the forend. The full length Arca/RRS standard dovetail allows shooters to mount a wide variety of accessories with infinite adjustment, which is now a standard among the competitive community.


    • CNC Machined from 6061 Aluminum
    • Chassis, buttstock and grip weight: 5.9lb – 13.3lb, depending on the rifle model and number of weights added to the system
    • Cerakote finish in Tactical Grey
    • 17″ of available ARCA/RRS dovetail, with retention screw so that accessories don’t fall off mid-stage
    • M-LOK pattern attachment system on all 3 faces of the forend
    • Accepts most AR-15 pistol grips, but designed with the MDT Vertical Grip in mind
    • Wider, ergonimic thumb shelves than previous chassis systems
    • Mag latch limiter to prevent over camming and pinching of magaines
    • Uses our proprietary ESS buttstock interface
    • Free floating barrel channel with removable end cap for interior weight installation and adjustment
    • Trigger adjustment slot of R700 single stage triggers
    • Will accomodate barrels up to 1.350″ diameter
    • Compatible with AICS style magazines

I had some discussions with MDT about how to configure this chassis and set it up for 300 PRC. My goal was to make this rifle as pleasant to shoot as possible, and to minimize the effect that recoil has on accuracy as well. We put together a killer package:

  • MDT ACC Core chassis for remington 700 Long-Action
  • Full weight kit (~9lb of extra weight!)
  • 3.850″ capacity single-stack AICS style magazines
  • Bag rider for buttstock

When you get the chassis out of the box, it’s amazing to look at! (click/tap to enlarge)

And the skeletonized buttstock is like a piece of artwork to look at:

I can’t wait to get this chassis system and rifle put together. I can only imagine what it will be like to shoot the completed rifle…

TriggerTech Diamond: Scalpel-Like Precision

I’ve had really good luck with TriggerTech so far- I used their Remington 700 Special for my 224 Valkyrie Remington 700 Build, and have used the AR Diamond with multiple ARs in my lineup. So the TriggerTech Diamond for Remington 700 was a logical choice for this full-custom Remington 700 build! I’ll detail the install and performance of this trigger later on in this series!

Next up: barrel work! Don’t miss out on Ultimate Reloader updates, make sure you’re subscribed!


7 thoughts on “300 PRC Custom Build Overview”

  1. Sounds like you may end up with one of the best rifle build collections one could have. I just read of the 300 RUM and you’re already doing the PRC. And it was only a couple of weeks ago I watched your video on another build. Can’t remember if it was a 6.5 CM. Enjoy your addiction- you only live once. Shoot well.

  2. Hi Gavin, enjoying all your you tube offerings. I also have recently had a custom 300 PRC made . I had them grind the reamer for a .340 neck. It will take factory ammo but gets rid of a bit of some slop. Mine is based on a 85 Sako long action which already has a magazine with a lot of space in it. It has a reverse taper Walter special SS barrel and a muzzle break. It is mostly for hunting and I wanted the three position safety so the bolt will stay locked while going thru brush etc. It is very accurate. Made by Accuflite. I also have a wildcat 338-375 Ruger, straight neck down, in a MDT chassis. Please keep up the 300 PRC posts. As a suggestion for future posts may I suggest one on reamers/chamber dimensions/ freebore/ neck/ setting up for using LONG bullets seated properly in the neck ,not stuffed down in the case.

  3. First off great work on the shop and the rifle builds and the you tube channel! Now how much does that beast actually weigh? How long is it? What’s the height over bore with those tall rings? Have you tried shooting it off a pack or pack frame or PRS style barricades?

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