Savage 10ML-II: On Primers and Heat

By Randy Wakeman

The question comes up from time to time about the "best" or "most accurate" 209 shotshell primers to use in a Savage 10ML-II, and also how to avoid frustration in 80 degree (or warmer) weather at the range. I'll try to briefly touch on these two areas in the hopes I can reduce or eliminate unnecessary frustration.


The Savage 10ML-II is unique in that the 209 shotshell primer is carried into and out from the breechplug via the patented, half moon primer holder that is integrated into the bolt. The primer cannot stick inside the breechplug as they can in other muzzleloaders, nor are plastic primer holders, decappers, or red plastic thingys required.

If you have reloaded over the years, you are likely aware that 209 shotshell primers vary in dimension by manufacturer. This shouldn't be surprising, as battery cup anvil primers were never designed for loose fit or slip fit use. They are designed to be press fit flush into the bottom of a shotshell hull. Respective manufacture's primers are designed to fit their own hulls: Remington STS primer fit well into their "STS" or "Nitro 27" hulls, Winchester 209s take a little more leverage on my MEC 9000G presses to seat. Federal 209A primers are larger yet, best suited to Federal's Reifenhauser style hulls.

The hierarchy of primer size runs from Remington having the smallest outside diameter, then Winchester 209s, with Federal 209A primers as the largest. All are considered "magnum strength primers," but Federals are the hottest, then Winchester, with Remington STS primers as the mildest of the three. All are very consistent in size from lot to lot. I have little experience with Fiocchi, Cheddite, or CCI primers in reloading or muzzleloader use, so I won't comment on them.

Winchester 209 primers tend to fit Savage 10ML-II breechplugs the best and are also perhaps the most readily available shotshell primers. That's what most Savage shooters are using, and most inline muzzleloaders for that matter. Savage Arms has long recommended Winchester 209s, and they are universally the best choice. I avoid Remington primers in muzzleloaders, as they have given me several misfires, where Winchester and Federal primers have not.

I prefer Federal 209A primers in all my frontloaders, as the hottest, most reliable ignition is what I want. Federals will also give you a slight velocity increase in the 10ML-II application, 20-25 fps depending on charge type and amount, but they make your bolt hard to close.

Using Winchesters is the fix; some have lightly reamed out the primer pocket to better accommodate Federals. I have detected no accuracy difference, regardless of primer used, in any muzzleloader. Winchester's W209 remains the most available and generally most suitable primer with Savage recommended powders.


Late summer is the time of the year when many folks are breaking out their Savage 10ML-II's for sighting-in and practice. It is still quite warm in many places, including right here in northern Illinois, and heat is the enemy of the sabots upon which we rely.

Heat quickly softens and weakens sabots. Today's latest MMP sabots are vastly superior to anything available just a few years ago, but they are still soft and will always need to be pliable enough so that they can be smoothly loaded from the muzzle.

Hold a cigarette lighter beneath a sabot: you will see the petals quickly wilt, melt, and catch fire. The sabot will continue to burn. Please extinguish and dispose of properly.

That little test is conducted with no induced barrel pressure, and cannot compare with the blast of 5000 degree-plus heat and pressure a sabot endures when being fired. The Savage 10ML-II is very easy to operate, with exceedingly clean burn propellants and no swabbing between shots required. So, it isn't hard to see how barrel heating can quickly become a sabot damaging issue. As we need not clean, spit patch, or introduce any solvents into the barrel at all during a range session, care must be taken to keep our barrel cool if we want accurate, confidence-inspiring results.

On hot days, if we can feel heat from the barrel on our hand (the hottest area will be by the rear ramp sight), our barrel is too hot. We may need to allow 10 to 15 minutes between shots. For best accuracy, never load powder or sabot until right before firing. Certainly this is no hunting issue, but it is a range issue in 80 degree and hotter weather.

There is more we can do to dramatically reduce barrel heating and likewise reduce the barrel cooling time required. Two things stand out: use 250 grain bullets instead of 300 grain bullets, and reduce the powder charge. Less powder burn, less pressure, and markedly less heat is the result of these simple steps.

Specifically, use 38 grains of Vihtavouri N110 or 40 grains of Accurate Arms 5744 pushing a .452", 250 grain Hornady XTP in the short black MMP sabot or a 250 grain Barnes MZ-Expander with its supplied MMP HPH-12 sabot. You will enjoy the lack of recoil and barrel heating will be dramatically reduced.

Don't be fooled by these pleasant, soft-shooting loads, though. That 38 grains of N110 is good for a MV of about 2150 fps. The 40 grains of Accurate Arms 5744 approximates the Lee 3.1cc plastic dipper scooped load. Either load will allow you (with a rifle sighted-in 3 inches high) to aim straight through the body of a whitetail out to about 185 yards, and will ruin the day of most any game animal in North America. They are great hunting loads year-round. Having a gun that is supremely lethal on one end but a delight to shoot at the other is no reason to feel guilty!

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Copyright 2005 by Randy Wakeman. All rights reserved.