{"id":105,"date":"2022-08-28T06:41:40","date_gmt":"2022-08-28T06:41:40","guid":{"rendered":"https:\/\/americangunpeople.com\/?p=105"},"modified":"2022-08-28T06:41:40","modified_gmt":"2022-08-28T06:41:40","slug":"measure-that-bump-five-cool-tools-to-measure-shoulder-bump-daily-bulletin","status":"publish","type":"post","link":"https:\/\/americangunpeople.com\/?p=105","title":{"rendered":"Measure That Bump \u2014 Five Cool Tools to Measure Shoulder Bump \u00ab Daily Bulletin"},"content":{"rendered":"


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August 28th, 2022<\/span><\/p>\n

Measure That Bump \u2014 Five Cool Tools to Measure Shoulder Bump<\/h2>\n

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The Tactical Rifle Shooters<\/a> Facebook Group recently showcased tools used to measure case headspace before and after \u201cbumping\u201d the shoulder. After a case is fired, hand-loaders who full-length size their cases will typically bump the shoulders back anywhere from .001\u2033 to .0035\u2033, depending on the rifle and application. With our 6mmBR and Dasher cases we like about .0015\u2033 bump.<\/p>\n

You want the amount of case sizing and bump to be the same for all your brass. To ensure uniformity, it makes sense to measure your cases before and after the FL sizing process. When we have time, we check every case. Other folks will simply check the first 3-4 cases coming out of the FL sizing die to ensure the FL die setting is correct and delivering desired headspace\/bump.<\/p>\n

1. Whidden Gunworks Shoulder Bump Gauge<\/h2>\n

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There are a variety of tools that can be used to measure shoulder bump. Our favorite is a special cartridge-specific bushing made by Whidden Gunworks<\/a>. The Whidden Shoulder Bump Gauge<\/a> enables you to adjust your sizing die to the desired measurement. The bump gauge is attached to your calipers with a set screw and determines the measurement from the base to the shoulder of the case. The photo below, from Tactical Rifle Shooters, shows the Whidden Bump Gauge<\/a> for the .375 CheyTac cartridge.<\/p>\n

2. Dave Manson Vertical Comparator with Dial Read-Out<\/h2>\n

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Background image courtesy Tactical Rifle Shooters<\/a>; inset photo from Manson Precision Reamers<\/a>.<\/i><\/p>\n

Dave Manson states: \u201cThis tool was designed to make life easier for the advanced shooter and re-loader by allowing precise measurement of ammunition, case, and chamber headspace. With this information, the re-loader will be able to fine-tune clearances and fits between his ammunition and chamber, with resultant improvements in accuracy and case life.\u201d The functions of the Manson Comparator<\/a> are:<\/p>\n

1. Measure headspace of factory or reloaded ammunition
2. Quantify chamber headspace by measuring headspace of a fired case
3. Ensure minimal shoulder set-back when setting up re-loading dies
4. Compare base-to-ogive length to ensure consistent bullet-to-rifling relationship.<\/p>\n

In addition to the Dial Indicator and Stand, the $130.00 Vertical Comparator is supplied with multiple Datum Blocks of precise length and inside diameter (.3300\u2033\/.3750\u2033\/.4000\u2033\/.4375\u2033). MORE INFO HERE \u2014 Catalog page 20<\/a>.<\/p>\n

3. Hornady L-N-L Headspace Comparator System<\/h2>\n

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Hornady\u2019s Lock-N-Load Headspace Comparator<\/a> system is easy-to-use and handy. You can get a kit with Red bushing-holder body and 5 bushings for $43.43<\/a> at Midsouth. Hornady explains: \u201cThe Lock-N-Load\u00ae Headspace Comparator\u2026 gauge measures variations in brass before and after firing or re-sizing. It allows for headspace comparison between fire-formed brass and re-sized brass.\u201d IMPORTANT: Hornady states: \u201cTo determine the proper bushing diameter for your cartridge, simply add the neck diameter and the shoulder diameter and divide that number by two. Use the bushing closest to that number.\u201d Hornady offers five: .330\u2033, .350\u2033, .375\u2033, .400\u2033, and .420\u2033.<\/p>\n