10MM Primer Showdown: Federal Gold Medal Match:Velocity and Gel Test

| December 4, 2022 | 4 Comments

10MM has come a long way from the days of the Bren Ten. I would even say the past 5 years or so it has seen a strong resurgence. Almost every firearms manufacture is making a 10MM firearm now in 2022. 10MM is my second most favorite cartridge, it can serve a wide spectrum of use cases and for the reloader be loaded from mild to wild.

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Why Are They Messing With Perfection?

In a recent trend we have seen ammo manufacturers developing new cartridges which is very exciting. On the flip side of the coin they are also starting to tinker with existing cartridges. With the development of clean cartridges the first to be neutered was the 45ACP switching from large pistol primer to small pistol primer. What has not been explained at least within my research is what exactly makes small pistol primers cleaner. It is my understanding it is the same mixture of materials. Is it just as simple as there is LESS of it in a small pistol primer than there is a large pistol primer? Leave a comment below and let me know your take on this, but I digress. 45ACP was not enough for the first time I started hearing about small pistol primers in 10MM also. I literally convinced myself that this was not true and that I was going to ignore UNTIL. I walked into the local shop and found Federal American Eagle loaded with small pistol primers. Interesting enough nothing on the box indicated these were classified as “clean loads”. I quickly put those boxes back on the shelf as if it were vudoo in a can or a live rattle snake. So quick that the gentlemen next to me asked if everything was ok and I found myself in a 40minute conversation explaining why I was purchasing the Remington Green and White box 10MM. By the way I know many would say this factory ammo is high end 40S&W loaded ammo anyway. True though I am always looking out for 10MM ammo when the cash is right to add to my 10MM Load Depot the largest 10MM database on the internet.


Change Is Not Always Bad “The Test”

If there is one thing I know, change is the only constant and you must adapt and overcome. Hmmm I wonder where I got that from Oh-Rah Devil Dogs. So I decided to test with my own handloads, is there a difference in velocity between large pistol primer and small pistol primer loads. The fairest test to me would be one where I would sort brass and use the exact same components for both loads.


FC Cases loaded with LPP and SPP

To try and be as conclusive as these test can be I used the highest quality components available to reloaders. Federal Gold Medal Match primers in both large and small. Federal cases were used for consistency but mainly because I was able to get meet up with Josh who really is the sponsor of this article to get some FC small pistol 10MM cases from him. Thank you Josh. I would also use two different 10MM firearms to see if the same results were had in both.


Colt Delta Elite 5in Barrel
My Favorite 10MM Revolver Cimarron Badboy 8in Barrel


This data is not intended to replace the appropriate reloading manuals data and should not be used without verifying and double checking the loads between two different official published reference points — IE reloading manuals. If you elect to utilize any of this data it is at your own risk, you take full ownership and responsibility for your ammunition.

BE-86 9gr of Powder, 165grain Montana Gold JHP – C.O.A.L 1.256 Federal Gold Medal Small Pistol Primer – Alliant Says DO NOT GO OVER 8.7gr

BE-86 9gr of Powder, 165grain Montana Gold JHP – C.O.A.L 1.256 Federal Gold Medal Large Pistol Primer – Alliant Says DO NOT GO OVER 8.7gr

I did not intentionally go over the recommendation. These loads are set with the powder measure set for 8.7gr. My process is to weigh the first 6 and go with the highest load and label my boxes that way. In this case it was 8.7, 8.7, 8.7, 8.9, 9.0, 8.7. Satisfied with this I set forth reloading these rounds on my lee classic turret which has been reserved for quick small batch runs.



The velocity was taken with a Competition Electronics Pro Chrono DLX 6 Yards back from the chronograph. The manual actually states 3 yards is best but I have seen after years of testing that unburned powder in some loads can fly across the chronograph and produce inaccurate readings.


The velocity results prove to be full power loads in the Colt Delta Elite generating between 610 to 668ftlbs of energy. In the Cimarron the 10MM comes alive like an Alaskan Grizzly from hibernation generating 728 to 777FTLBS OF energy.


This 10MM recipe proved to be a great 2 legged predator load with the right penetration and expansion. Though I would look for a tougher bullet/freedom pill for woods carry or protection from those things with large teeth. Watch the video and see the freedom pill results below

The expansion was substantial and penetration of 14 to 15inches is satisfactory for me. I am very well aware of the FBI test with denim to simulate heavy clothing. Of equal importance is shot placement and quick follow up shots if needed. Though the test for me is the curiosity of my mind to collect data like this as my always first reaction in a bad situation is to be very attentive to your surroundings and AVOID any confrontation.

By the results lower velocity equaled less penetration while higher velocity equals greater penetration and expansion. Though with the Montana Gold Freedom Pills the greater penetration causes them to fragment therefor less weight being maintained. But I also noticed that the Large Pistol Primer produces by the numbers more consistent ammo, less extreme spread and less standard deviation. Maybe this means more consistent burn of powder?


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4 Comments on "10MM Primer Showdown: Federal Gold Medal Match:Velocity and Gel Test"

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  1. I found Federal ammo .45 ACP to be the first offender to vex me with small primers in order to be “green” where they are normally large pistol primers. Therefore, I purged my .45 supplies of all Federal brass. What do you suppose would happen if a stray environmentally friendly piece of brass with a small primer pocket got mixed in with the normal brass and my press was set up with large primers? I prefer to let someone else try that experiment.

  2. Patrick says:

    I’m new to 10mm, and an amateur reloader. Before I buy ammo I research it and I was confused by the different primer cup sizes in 10mm brass. This reminded me of 9mm brass in that some have a very small flash hole (norma used to the number one example) and some have the normal size one. All it meant was that your decapping pin would break. I didn’t know what the different primer cup sizes would mean.

    Thanks for taking the time to post your results. Greatly appreciated from a newbie enthusiast!

  3. Maz2331 says:

    All else being equal, the small primer pocketed cases will have a bit more strength in the head and resist pocket expansion better, allowing hotter loads if the case is properly supported in the chamber. And as the SPP works great in billions of .40 S&W, .38 Special, .357 Mag, etc cartridges for about a century, it will work just fine in the .45 ACP and 10mm as well.

  4. I understand the logic but disagree. I think it is a trade off as like with many things. I was so curious about the outcome of this test that I have performed it 2 additional times, with different powders/loads and observed the exact same results. Large pistol primer delivers more velocity and has less extreme spread even when using a revolver. By the numbers across the chronograph with more consistent velocities as long as you do your part the LPP loads in every testing scenario should be more accurate. In 20 years of reloading 10MM I have yet to throw away a piece of brass for loose primer pockets, I have thrown away those with split necks for sure. Though I do agree with the strength comments above anyone reading this has to ask themselves the question on which is more important to you strength in primer pockets or more consistent ignition leading to better accuracy. Great comment Maz.

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