.25-45 Sharps AR-15 Part 5: Precision Loads with the MEC Marksman

The quest for precision ammunition is something I never grow tired of. Well that is, if I’m dealing with a firearm of sufficient precision! If I’m not, I may resort to some gunsmithing because precision is just in my veins. So I’m excited to be working on precision loads for the .25-45 Sharps. I can’t wait to find out just how precise my .25-45 Sharps AR-15s will shoot. Will they shoot sub-MOA consistently? Will I find that “magic load” that shoots like a dream? It’s all part of the fun, and part of the journey.

Breaking Down the Precision Loads Process

Loading precision ammunition is not an “exact formula” that you can repeat each time you load for a rifle. There are a lot of factors to consider, and variables that will affect the steps and techniques you perform and use. Here’s a general breakdown of a typical precision loading workflow with notes for this loading session: (as demonstrated in the video above)

  1. Inspect and clean brass. (I started with new brass before forming, so did not apply here)
  2. Size and de-prime brass. (we handled this in the case forming part of this series)
  3. Measure brass and trim if needed. (this brass did not need trimming, I measured after forming/sizing)
  4. Chamfer case mouths. This was necessary here (see notes below), may also need to swage primer pockets if brass is once-fired military.
  5. Prime cases. Here I used the LEE Auto-Bench prime tool.
  6. Charge cases. I used the Hornady Lock-N-Load case-activated powder measure for this step.
  7. Seat bullets. I used a Redding Seater die for this, which gave outstanding results.
  8. Crimp bullets. (did not decide to crimp here)
  9. Inspect completed ammunition. Can include measuring bullet run-out which I did here.

There’s much more that you can do, including turning case necks, annealing, and other processes. These are the first precision loads I’m loading for my .25-45 Sharps AR-15s, so I though I’d “start simple” and see how things go. I’m still in the process of developing load data, so that’s where my primary focus is at this point. I had already formed my .25-45 Sharps brass which included sizing and checking with a case gage- so that part of the loading process wasn’t necessary here. But what I did discover was some slight/small “half moons” of brass: ever so falling out of the seating die when running some test loads through my workflow. Sure enough, when I inspected the brass I saw sharp case mouths- from the forming process. This told me I needed to chamfer the case mouths in order to avoid brass debris and bullet shaving from negatively affecting my precision loads.

Hornady Case Prep .25-45 Sharps case mouth-2000

For this task I decided to use the Hornady Case Prep center. You can do this kind of chamfering by hand or by machine, it’s all a matter of time, effort, and equipment on hand.

.25-45 Sharps formed 5.56 before after case mouth chamfer 2000

Above you can see the before (left) and after (right) for the case mouth chamfering process. Quite a difference! Chamfering you case mouths is usually a good idea, and typically only needs to be performed once. After performing this process, the results were *much* better. Smooth seating, no shaving, and no brass debris falling down!


As you saw in the video, the combination of the floating shellholder design on the MEC Marksman with the addition of the Hornady Lock-N-Load conversion kit gives you perhaps the best die-to-case alignment possible as evidenced by the bullet runout measurements I performed in the video.

Speer TNT 25 Caliber Bullets-2000

I’ve been loading Speer Hot-Cor 87 grain bullets with great results- this time I decided to try some Speer TNT 87 grain bullets. It will be interesting to see how the results (precision and ballistics) compare between these two bullets with the same underlying load data:

This data was taken directly from the Sharps Rifle Company 25-45 Sharps Load Data Sheet (PDF).

Use load data at your own risk. Ultimate Reloader is not responsible for errors in load data on this website. Always cross-reference load data with manufacturer’s published data.

These precision loads will help establish some “baseline results” for precision and ballistics that I can iterate on. The process is essentially the same as each successive set of loads are loaded and evaluated. By measuring groups, performing ladder testing, and mixing up components (bullets, primers, powder) as well as varying factors such as seating depth, the “ultimate” set of loads will emerge for the two .25-45 Sharps AR-15 rifles I own. It’s going to be a lot of work, but I’m going to enjoy every minute! And of course I’ll bring you all along for the journey. Make sure you’re subscribed here (click this link) as well as on YouTube!


8 thoughts on “.25-45 Sharps AR-15 Part 5: Precision Loads with the MEC Marksman”

  1. Gavin, I really enjoy your site and videos. Been reloading a long time, but you have taught me a lot.

  2. Gavin, thanks for your well written and informative articles. I am very interested in your journey with the 25-45 Sharps. I am trying to decide weather to invest in this cartridge or the 25 DTI and your journey will be key in helping me with my decision.

  3. Great Video.

    I have an interest in buying the new MEC Marksman Loader. My biggest concern that I have is using the Lee Precision Decapping Die. Due to the floating shell holder I am not sure that the decapping pin will line up with the primer hole on every stroke causing the decapping pin to break.

    I currently load all of my match and hunting rounds on a single stage press. I do shoot a lot of 556, 45, 9mm, 762×51 and many other plinking rounds on two 650s that are setup for small primer and large primer. All of my spent cases are deprimed on my single stage press prior to cleaning. This step is very important to me and if the MEC can not place the decapping pin into the primer hole on every stroke then it would not fit into my reloading procedures.

    Could you please test the MEC with several brands of Universal Decapping Dies. I have been known to deprime several K of brass in a day. Breaking decapping pins would not be good.

    I have found that your advice and opinions to be very helpful when looking for better equipment and reloading practices & procedures.

    Thank You and Have a Great Day!


  4. I currently reload 7mm Remington Mag and 357 Sig pistol cartridges. Can you recommend a deprimer only die for the 7 mm? I use a Hornady Single stage press. Just want to reload for a single bolt action rifle, thus not wanting to full resize each case when decapping.
    Thank you for any reply. And thanks for the info.

  5. I ordered a .25-45 conversion kit from SRC a week ago. Their website says it’ll take 4-6 weeks to arrive. In the meantime I have stocked up on powder, some bullets, and have reformed some cases. The cases are once-fired 5.56 LC ones I got from Everglades Ammunition and reloading. They have been resized, deprimed, swaged, and polished.

    It’s a mixed lot but I sorted out the LC cases and chose only the ones that weighed between 91.5 and 92.5 grains. The info I have says the LC brass is the lightest of all brass and has the greatest water capacity. Figuring this cartridge could use all the case capacity we can muster. I am interested in checking the new Starline brass when available to determine weight and capacity.

    Will start with Speer 87 gr. hot core and Barnes 80 gr. lead-free. I think the Speer bullets are softer than the Barnes.

  6. I just came upon your articles on this fine rifle build. I purchased a 20 inch barrel from Sharps and built a precision rifle. The basic AR does not contribute to accuracy as there is way too much looseness between parts. After reworking my rifle I was able to observe incremental improvements. I am now at the point where I can shoot a five-shot group inside of 1.5 inch at 300 yards. Sadly, that’s as far as I can shoot around here (New England). I have been using the Speer TNT for about a year. My cartridge is assembled with the TNT reaching out to within 0.025 inch of the lands (the sweet spot). I use H322 powder and CCI 400 primers. It is not uncommon for me to have five shots covered by a penny at 100 yards. I started shooting in 2011 and think I have learned a lot, but I am still learning. Oh yes, I use a Harris bi-pod, a SWFA SS 10×44 scope and a Timney trigger. The Sharps was my second rifle and my first build. My first AR was a Bushmaster with a 20 inch heavy barrel. I reload using a Lee Precision classic turret as my center piece. Thanks for your great coverage on this fun rifle. No, no deer as I don’t hunt.

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