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SINCLAIR CONCENTRICITY GAUGE Reviews & Ratings

Sinclair Concentricity Gauge - Achieving Peak Ammunition Consistency

For precision shooters and dedicated reloaders, the difference between a hit and a near-miss often comes down to microscopic details. One of the most critical-and overlooked-factors in ammunition performance is concentricity. The Sinclair Concentricity Gauge is designed to give reloaders a clear, accurate measurement of both neck concentricity and bullet runout, allowing them to fine-tune their reloading process for maximum consistency and downrange accuracy.

The Role of Concentricity in Precision Shooting

Concentricity refers to how well the bullet is aligned with the cartridge case. Even slight misalignments can lead to uneven pressures, inconsistent velocities, and accuracy degradation-especially noticeable in long-range or competition shooting. By measuring and correcting concentricity issues, reloaders can reduce group sizes, improve shot-to-shot consistency, and extend the effective range of their ammunition.

The Sinclair Concentricity Gauge gives reloaders the ability to quickly identify alignment issues, whether caused during resizing, seating, or by inconsistent case preparation. It provides a way to spot these flaws before they impact performance on the firing line.

Design and Build Quality

The Sinclair Concentricity Gauge is built from anodized aluminum for a balance of lightweight handling and rigidity, with hardened steel roller bearings that support smooth, stable cartridge rotation during measurement. The rollers are mounted in milled V-blocks, ensuring that each round is held securely and spins without wobble. This stability is key for producing repeatable, trustworthy measurements.

The gauge’s base is long enough to accommodate everything from small varmint cartridges to large-caliber rounds like the .50 BMG. This wide compatibility makes it ideal for reloaders who work across multiple calibers.

Three versions are available:

Base-only model – For those who already own a compatible dial indicator.
Dial indicator model – Equipped with a precision analog indicator.
Digital indicator model – Offers high-resolution readings in a digital format.

All versions accept any indicator with a 0.375″ stem, giving reloaders flexibility in tool selection.

Ease of Use

One of the strengths of the Sinclair Concentricity Gauge is its straightforward setup and operation. Two adjustable roller blocks slide along the base to fit different cartridge lengths. The indicator tower offers both vertical and lateral adjustment so the probe can be perfectly aligned with the measurement point-whether you’re checking case neck runout or bullet alignment.

To use the tool, place the case or loaded cartridge on the rollers, position the indicator tip at the desired point, and slowly rotate the round. The difference between the high and low readings is the measured runout. Many reloaders aim for a reading under 0.002 inches for precision loads.

Real-World Shooter Feedback

Reloaders consistently praise the Sinclair Concentricity Gauge for its smooth operation, clear readings, and sturdy build quality. Users highlight its ability to reveal inconsistencies that other tools may miss, allowing them to troubleshoot problems in their sizing dies, seating dies, or case prep process.

Competitive shooters have reported measurable improvements in group size after using the gauge to weed out rounds with excessive runout. Others use it as a quality-control step in every batch, ensuring match-grade ammo before it leaves the bench.

Compared to budget gauges, the Sinclair is noted for its longevity-some owners have used the same unit for over a decade without loss of accuracy. The tool’s ability to handle a wide range of calibers also makes it a long-term investment that grows with a shooter’s needs.

How It Stands Against Similar Tools

When compared to alternatives like the Hornady Concentricity Tool, the Sinclair is often considered more precise and sturdier, though at a slightly higher price point. While other designs may require more setup time or only work well with certain case lengths, the Sinclair’s roller system provides universal support without the need for multiple adapters. This not only saves time but also reduces the risk of measurement errors from improper seating.

Another advantage is its non-marking, free-spinning support system, which prevents damage to cases while eliminating unnecessary friction that could influence readings. This is a key difference from clamping-style gauges that can introduce minor distortions during measurement.

Applications Beyond Competition

While the Sinclair Concentricity Gauge is a natural fit for competitive shooters and precision rifle reloaders, it also benefits hunters, varmint shooters, and anyone seeking better consistency from their handloads. Hunters who need guaranteed first-round accuracy can verify their loads before a big trip, while varmint shooters appreciate knowing that each round will track identically over extended shooting sessions.

It’s also a powerful diagnostic tool. If your groups suddenly open up, checking concentricity can quickly reveal whether your reloading process or component consistency has shifted.

Technical Specifications

Feature	Detail
Material	Anodized aluminum base, hardened steel rollers
Max Cartridge Size	Up to .50 BMG
Adjustability	Sliding roller blocks, vertical and lateral indicator adjustments
Indicator Mount	Accepts 0.375″ stem
Available Models	Base-only, dial indicator, digital indicator
Measurements	Neck concentricity, bullet runout
Accuracy Goal	≤0.002″ runout for match-grade loads
Weight	Approx. 2 lbs depending on configuration

Why the Sinclair Concentricity Gauge Is Worth Owning

In precision shooting, small details make big differences. The Sinclair Concentricity Gauge offers a rare combination of accuracy, durability, and versatility that earns it a place on any serious reloader’s bench. Its solid construction ensures long-term reliability, while its ease of use encourages reloaders to incorporate concentricity checks into every loading session.

By catching misaligned rounds before they make it to the range-or worse, the match-the gauge not only helps improve accuracy but also builds confidence in your ammunition. Whether you load a few dozen rounds a month or thousands a year, this tool can help you get the very best performance from your rifle.

If your goal is to produce ammunition that shoots as consistently as possible, the Sinclair Concentricity Gauge is a wise and lasting investment.

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Reviews Summary

The SINCLAIR CONCENTRICITY GAUGE is appreciated for its solid construction and ease of use, enabling precise measurements for reloading. While many users found it effective for improving accuracy, some expressed concerns about its setup complexity and inconsistency due to design flaws, particularly with the included dial indicator. Overall, it offers good value for serious reloaders.

What Reviewers Are Saying

Ease of Use

75%

Many reviewers highlight the Sinclair gauge's straightforward design, making it easy to understand and operate, even for those new to reloading. This ease of use contributes significantly to user satisfaction, with around 75% mentioning it as a key advantage.

Construction Quality

65%

The durability and solid build of the gauge is frequently praised, with reviewers noting it is well-constructed and should last a long time. About 65% of users emphasize the overall quality, which enhances their confidence in its precision.

Accuracy

55%

While many users report increased accuracy in their reloading process thanks to the gauge, some express frustration with its inconsistent measurements. Approximately 55% of users mention the effectiveness of the gauge in identifying runout issues, though some experienced varied results.

Included Dial Indicator

50%

The included dial indicator receives mixed reviews; some users consider it adequate, while others criticize its quality and performance. Roughly 50% of reviewers mention the indicator, with several opting to replace it for better results.

Setup Complexity

45%

A notable number of users discuss the learning curve associated with getting consistent readings from the gauge. About 45% express that while the tool serves its purpose, mastering its use requires practice and familiarity.

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NIce gauge at a reasonable price

I bought this gauge w/o the dial micrometer since that was all that was in stock. Then separately purchased a Fowler 52-520-109-0, which fits and functions perfectly with it. I really like this system and am divided as to whether to give it 4 stars or five. I am settling on four stars because it takes some care and practice to get consistent readings. The only real issues that I have encountered are with cases from ARs get dented on ejection. Even a tiny dent will throw off a reading significantly. Often the problem can be avoided by adjusting the locator slides so that the dented area is well away from the steel balls that the case rolls over.

by George Pontis on November 20, 2023

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useful tool

wish dial was made in america..works great.. back roller has a stop bar and it would be great if it was adjustable to allow you to move it back or forth where you want it

High Quality

The pieces I received were very high quality. Unfortunately my item was missing one of the roller blocks. I spoke with a few of the pro shooters in my circle and did my research before I bought this and the Sinclair Concentricity gauge was the most highly recommended. As soon as I receive the rest of my parts I will update to a five star for sure!!!

Well made, not perfect design though

This gauge is well made, no complaints there. After using this for a couple weeks I see a flaw in the design that makes it quite a bit less accurate than the Hornady concentricity gauge. The Sinclair rolls the cartridge on two points on the side of the case and measures runout on the side of the bullet causing the measurement to be partly of the roundness of the case and about half of the bullet runout (depending on where the dial is resting on the bullet). Because of this design, a total runout number is difficult to achieve. The Hornady works around these problems by gripping the cartridge at base and the tip of the bullet, and measuring at the point where the bullet enters the case mouth giving you a total runout number

It was on sale

After many years of hand loading, I am ramping up to loading match ammo and I needed a concentricity gauge. Sinclair has a good rep and this one was on sale, so I took the plunge and ordered one. To be honest, at the price I paid, I expected the included dial indicator to be a piece of junk. It did not disappoint. Not China's finest work, but I spent some time working on it and it will do for now. I'll replace it with a good one later. The mount shaft on the indicator measured .375", which is standard. The two holes in the cross support fitting measure .377", so the indicator fits the support with very little slop, which is good for accuracy. The tool's vertical post, on the other hand, measured .371", which allows a lot of slop when the cross support is slid into place. This is NOT good for accuracy at all. I ended up wrapping the post with a layer of cellophane tape to increase the diameter. That eliminated most of the slop and made the tool usable. The four captured steel balls are polished nicely and allow brass cases to roll relatively freely. The down side is the balls do not provide a secure rest and a little clumsiness will roll the case right off the tool. Total attention is required to make sure the brass case is held on the tool correctly and rolled smoothly. Using both hands helps! With the repairs and improvements I made, and a little self training, I am able to get accurate readings....if I pay attention. My recommendation is to buy a better tool unless the price for this one is too attractive to pass up. If that is the case, buy this tool without the indicator and add your own quality one.

Disappointing Attention To Detail

Yes I knew it would come with a less than desirable Chinese Dial Indicator. Bent and rusted dial markers was worse than inticipated. Now I dont know what exactly this blue tinged dust which coated the base was, but I wiped everything down with KROIL. Then all the dings and scratches appeared. Is this the new Sinclair standard of excellence?

Tool could be much better!!!!!

This is a very well built product however, It is VERY difficult to use. I fought with it for about a box of reloaded .308 and gave up. You need at least 3 hands to use this tool. I never could get consistent measurements. The cartridge slips around on the bearings. And there are not instruction on how to remove the run out. I sold it on Gunbroker and bought a Hornady concentricity tool and I like it a lot. I must say I am disappointed in Sinclair for selling a marginal tool like this. .

Junk dial indicator

The included dial indicator hangs up on every revolution and looks like a very poor quality part. Sinclair would not exchange the dial indicator itself unless I sent back the whole concentricity gauge (which I am still using with a dial indicator borrowed from my machine shop). Unhappy with the whole deal.

Made in China

I was very disappointed that the dial indicator was made in China. The base unit itself seems rock solid though.

Not impressed

This is the first concentricity gauge Ive purchased in my 30 years of reloading. Honestly I was not impressed with how it sets up. A drive screw to lower the gauge on to the bullet would have made setup much easier. Now I had around 40 rounds loaded that shoot extremely well cams produce dime size 3 shot groups at 100 yds. All the rounds on this gauge was showing between 4 to 10 thousandths runout. I was appalled by these results wondering what is wrong with my 7mm08 dies or whats wrong with my RCBS Rock Chucker Press . I spoke to a friend whos been loading as long as I have who has a business selling reloaded ammo . He felt those numbers were way off unless I have a drastic problem. He removed his Hornady lock n load concentricity tool from his loading bench and suggested I correct the run out with his tool . I took his advice and brought the tool home . When I put those same rounds in the Hornady tool the highest runout I had with my rounds was 3 and a half thousandths with the majority being in the one and a half to two and a half thousandths of runout. I dont know if its just a bad guage or not . I will be returning the Sinclair guage for sure. A new guage and a drive screw to lower the guage and something to hold the loaded cartridge onto the rollers would be a real upgrade to current model.