Thompson/Center Omega Z5 Blued/Composite Muzzleloading Rifle

By Randy Wakeman

T/C Omega Z5
Illustration courtesy of Thompson/Center.

With the sales of scope-burning, pull-cock or plunger rifles quickly fading, Thompson looked at what they could do to stay competitive as their Black Diamond sales faded. The Omega Z5 is the result, essentially the regular Omega .50 caliber with a carbon steel barrel and a plastic stock. I was immediately surprised, pleasantly so, at what I found in this value edition of the popular Omega.

The Omega Z5 came supplied with a one-piece Weaver style base already installed, a much appreciated extra. I installed a Bushnell Elite 3200 3-9x40mm scope in a pair of Warne medium height, quick-release rings with no hassle. Unlike some economy rifles that come with the equivalent of “Popeil Pocket Fisherman” ramrods capable of landing a moderate sized bluegill, but incapable of proper bullet seating, the Omega Z5 ramrod is made from sturdy aluminum. The Omega features two metal ramrod ferrules to retain the ramrod, not the cheesy plastic ferrules we see on some economy models. The iron sights, while not as good as the original Omega and Encore versions, are still the popular and well-accepted Williams fiber optic set that worked well during my scopeless shooting.

I was also quite pleased with the Omega’s deep, rich barrel blue. A big notch up from the various paint or crude tool blackening attempts found on other economy rifles and far more attractive than the black wash used on the Knight Shadow I was simultaneously reviewing. I was also pleased with the Omega’s trigger, which broke at a crisp and repeatable 4 pounds, 2 ounces.

The Omega’s plastic stock was average for the type and the generic, almost properly fit, recoil pad was adequate. The stock appeared to me as the only noticeable concession compared to higher-priced models, but still was quite suitable, especially considering the price point of the Z5. It is remarkable only in the sense that the rest of the rifle is so good.

Scoped and ready to go, the Omega weighed just less than nine pounds. All of my shooting was with Western Industries “Blackhorn 209” propellant. I had no hang fires or ignition issues with the Omega, something that I cannot say for the Knight Shadow. Moreover, the breech area showed only light mung. I also appreciated the smaller, somewhat recessed hammer of the Omega that made it easy to cock with gloved hands. I had a good chance to test that, as my range work was done at 28 degrees F. with 20-30 mph winds.

Shooters do not seem to like the idea that “all rifles are individuals,” but that’s the way it is. Assuming a well-produced rifle, it is still necessary to find a sabot+bullet that gives an interference fit of .003 - .004 inch to load smoothly, yet with some resistance, and shoot accurately. If they load tight, they tend to shoot tight, all things being equal.

This is important enough to discuss in a bit more detail. I have compiled a list of assembled bullet sabot outside diameters. MMP refers to these as "loaded" diameters; what they mean is a sabot with a bullet loaded into it. Contingent on manufacturer, these dimensions are characterized as dressed diameters, loaded diameters and so forth. Assembled outside diameter seems to be the most appropriate way to cite these dimensions.

As a generalization, an assembled outside diameter exceeding the muzzleloader bore by .003 - .004 inch is about right, offering accuracy with reasonable ease in loading. In other words, a 3 to 4 thousandths interference fit has proven to be ideal. A few thousandths more and I hear complaints of “I can’t load my muzzleloader.” Less than the 3-4 thousandths, it is “my gun won’t shoot accurately.”

Here are the representative dimensions:

.452 XTP / short “MMP” sabot: .508 in.

.451 / .452 bullets with MMP HPH-12 sabot: .507 - .508 in.

.451 / .452 bullets with MMP HPH-24 sabot: .505 - .506 in.

.451 / .452 bullets with MMP 3P-EZ sabot: .502 - .504 in. (Note: This three petal sabot, black in color from MMP, is what Hornady sells as their red “Low Drag High Velocity” sabot.)

.451 / .452 bullets with Thompson “Superglide” two-petal sabots .504 - .506 in.

.458 bullets with MMP .458 / 50 Orange sabot: .507 in. outside diameter

There is, of course, a bit more to it than assembled bullet diameter only. A short, stubby bullet like an XTP has a comparatively short bearing surface compared to the longer Barnes MZ-Expander heat treated copper alloy bullets: the same goes for the 250 XTP vs. the 300 grain XTP’s. Where a 250 XTP may load tight but tolerable in an individual application, the 300 grain may be just enough of a difference in loading ramrod pressure to generate complaints. A further consideration is bore condition. My standard testing protocol was with Blackhorn 209 propellant that needs no swabbing between shots. If you use a higher residue propellant, the sabot you use must have a bit smaller loaded diameter to compensate, even with spit-patching.

The test article, the Omega, had the typical tight Thompson bore of about .501 inch land to land. Though not as unbearably tight as the previously tested T/C Triumph, it still needed a smaller outside diameter sabot. The Barnes T-EZ 250 grain and Barnes T-EZ 290 grain sabots have a loaded diameter of .505 inches and suited the Omega perfectly, giving me the .004 in. interference fit I sought. Despite cold and very windy range conditions, the Omega was able to average 1-1/4 inch groups at 75 yards, clearly out shooting the Knight Shadow I had along for comparison.

I sometimes get a few complaints about using “MSRP” in reviews, but we need to set a baseline. If the Manufacturer’s Suggested Retail Prices are meaningless, then we need to address that complaint with the specific manufacturers, as they are the ones that set them. In any case, to be topical, our survey of big box stores found the Omega Z5 at around $310 not including any rebates or other promotions. What the future pricing may be, of course, is both speculative and beyond my control.

Based on its trigger, accuracy, reliability, ease of use and overall build quality, the Thompson Omega Z5 richly deserves and gets a buy recommendation. It is an amazingly competent muzzleloader at an affordable price.

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Copyright 2009 by Randy Wakeman. All rights reserved.