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SINCLAIR BUMP GAGE INSERT Reviews & Ratings

SINCLAIR BUMP GAGE INSERTS

Sinclair Bump Gage Inserts are used to measure the amount of shoulder bump when setting up full length sizing dies. Our Bump Gages install in either of our comparator bodies and are machined to fit particular shoulder angles of cartridges. Rather than measuring to the datum line, these gages indicate off of the shoulder of the case to get a better, more easily assessable measurement of how much you are actually sizing your cases. We usually recommend between .001" to .002" bump for bolt action rifles and between .003" and .005" for AR-15 type rifles. Also a useful tool for keeping your brass and loaded ammunition separated if you have multiple rifles chambered for the same cartridge and checking loaded ammunition.

17 - 25-06 Remington, 270 Winchester, 280 Remington, 30-06 Springfield, 7.62 x 39 mm

20 - 243 Winchester, 260 Remington, 7 mm - 08 Remington, 7 x 64 mm Brenneke, 307 Winchester, 308 Marlin Express, 308 Winchester

20A - 338 Federal, 338 Lapua Mag

21 - 220 Swift

23 - 17 Remington, 221 Remington Fireball, 222 Remington, 222 Remington Mag, 223 Remington, 5.56 mm NATO

23A - 6.8 mm Remington SPC

25 - 264 Winchester Magnum, 225 Winchester, 6.5 x 55 mm Swedish Mauser, 7 mm Remington Magnum, 7 mm STW, 30 Remington AR, 300 Winchester Magnum, 8 mm Remington Mag, 338 Winchester Magnum

26 - 6 mm Remington

28 - 22-250 Remington, 223 WSSM (Winchester Super Short Mag), 243 WSSM (Winchester Super Short Mag)

30 - 20 Nosler, 6 mm BRX, 20 BR (Benchrest), 20 PPC, 20 Tactical, 20 Vartarg, 204 Ruger, 22 BR (Benchrest) Remington, 22 BRX, 22 PPC, 22 Nosler, 224 Valkyrie, 6 mm BR, 6 PPC, 6 mm XC, 6mm Creedmoor

30A - 300 Remington SAUM, 25 WSSM (Winchester Super Short Mag), 6.5 mm BR, 6.5 Grendel, 6.5 Creedmoor, 30 BR (Benchrest), 30 Thompson Center, 300 Ruger Compact Magnum, 300 Savage, 338 Ruger Compact Magnum

35 - 27 Nosler, 26 Nosler, 270 WSM (Winchester Short Mag), 284 Winchester, 7 mm WSM (Winchester Short Magnum), 30 Nosler, 300 WSM (Winchester Short Mag), 33 Nosler, 325 WSM (Winchester Short Mag)

40 - 22-250 Ackley Improved, 22-6mm Remington Ackley Improved, 22/30-30 Ackley Improved, 220 Ackley Improved, 223 Ackley Improved, 228 Ackley Magnum, 243 Winchester Ackley Improved, 6mm Ackley Improved, 6mm/30-30 Ackley Improved

40A - 25 Ackley Krag Short Improved, 25-3000 Ackley Improved, 257 Roberts +P Ackley Improved, 257 Roberts Ackley Improved, 338-06 Ackley Improved, 257 Ackley, 260 Ackley Improved, 280 Ackley Improved, 30-30 Ackley

45A – 45 Degree Shoulder up to 30 Caliber

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5 Stars

59%

4 Stars

3 Stars

2 Stars

1 Stars

38%

Reviews Summary

The SINCLAIR BUMP GAGE INSERT is praised for its quality and durability, particularly its stainless steel construction that promises longevity and precision. However, some users encounter issues with inconsistent measurements and a lack of fit for certain calibers, impacting their overall satisfaction. Customer support is noted as responsive and helpful.

What Reviewers Are Saying

Product Quality

60%

Many reviewers highlight the excellent build quality of the SINCLAIR BUMP GAGE INSERT. Its stainless steel material is perceived as superior to aluminum alternatives, ensuring durability and offering consistent, accurate measurements over time. This theme is mentioned by 60% of reviewers.

Calibration and Measurement Accuracy

45%

Several reviews point out that while the gage works well for some calibers, users experience issues with inaccurate readings for others. The design does not consistently produce accurate measurements, causing frustration, particularly for those with specific needs. This concern is raised by 45% of reviewers.

Compatibility and Fit

35%

Compatibility with various calibers is a common theme, where users mention that some inserts do not fit certain cases well, leading to issues like poor measurement contact or complications during use. This inconsistency in fit is noted by 35% of reviewers.

Customer Support

25%

The responsiveness and assistance offered by customer support is frequently praised, with users reporting positive experiences when resolving issues related to order entry or product inquiries. This positive note comes up for 25% of reviewers.

Ease of Use

40%

Many reviews appreciate the ease of using the gage, particularly its compatibility with other tools like Hornady's equipment. The design's focus on matching shoulder angles is also highlighted as a beneficial feature for accurate measurement. This aspect is mentioned by 40% of reviewers.

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Wont fit 30BR case

The 30A is advertised to fit 30BR. A .328 neck wont even come close to fitting in my 30A insert.

Inaccurate Results

This tool is convenient, but be cautious. I full length sized a 223 REM round with a 0.002” shoulder bump. I verified this by successfully chambering the case and then trying to chamber the same case with the addition of a 0.002” piece of scotch tape. That case would not chamber. The 0.002” setback was correct but the Shoulder Bump indicator showed a 0.013” set back. In looking at the construction, the gauge sits on the case well below the mid-neck datum, which I think is problematic.

by MICHAELL V. on December 10, 2025

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Does not work for 6.5CM

The neck hole is too tight for fired 6.5 brass so can't measure fireformed shoulder datum. Useless product.

by 30 W. on November 24, 2025

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Do not buy

I was very excited to use the 35 comparator on my new 30 Nosler rifle. I loaded up some rounds to break in the rifle. Then when I went reload and get the head spacing measurements, the numbers were all over the place and I spent the next several hours trying to figure out what was going on with the conflicting measurements. So, I picked up my tried and true Hornady gauge, and there weren’t any more issues. Perhaps the angle on the comparator was off?

by Taylor on August 12, 2024

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Shoulder bump gauge

Doesn't read the shoulder to my expectations

by MICHAEL M. on November 10, 2023

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Doesn't work for .338 Lapua Mag

The whole gage prep is too large for .338 lapua Magnum Case Shoulder completely goes inside of the gauge therefore you cannot accurately measure proper bump.

Not for a 6.5 Creedmoor

This gauge is trying to fit too many different calibers. One size does not fit all. For the 6.5CM the gauge only touches the lower 25% of the shoulder near the body. So you are not getting good contact between the gauge and the brass shoulder at all. Not enough to get a good measurement anyway. My other Sinclair bump gauges touch almost the entire shoulder and work well. This one does not. Plus the case neck hole is so large that the 6.5CM neck can move around too much to give repeatable measurements. PS. the #30 won't work either. The neck hole is too small for the 6.5CM. Bad design. Don't waste your money.

Does not work for 6.5 Creedmoor

Bought this 30A to check bumping the shoulders of my 6.5 Creedmoor brass. Had been using a Wilson Case gage to do the job and it works well I thought this may be faster. I bumped and bumped no reading beyond the initial cal of 1.501 on the digital calipers. Each bump i got a new reading on the Wilson Case Gage. Highly disappointed with the purchase.

Poor / Inaccurate Description

Does NOT fit 300 Blackout without modification.

Incorrect fitment

The details on this part say this fits 300 Blackout. Turns out it doesn't unless you modify it does not explain that anywhere in the description.