Why a custom modified case is more accurate
You use a modified case to measure the distance to the lands, in other words the point where the bullet touches the rifling. That measurement is the basis for setting the right cartridge overall length in precision shooting and precision reloading. The better the case fits your chamber, the more reliable the measurement.
Because we machine your own fired cases, the case is already formed to the chamber of your rifle. That is the big advantage over a standard modified case, which is made to an average dimension. You measure with a case that was literally formed in your chamber, which gives a more precise and more repeatable result.
How we make your modified case
Your fired cases are clamped and centered on a lathe. We then drill and tap the case neatly through the center, so the thread runs true and fits the Hornady OAL Gauge perfectly. This method gives a clean, centered thread and a modified case you can rely on for years.
Send two cases, receive one ready to use
You send us two fired cases. We machine your case and return one ready to use modified case. We ask for two cases so we have a spare on hand, in case something goes wrong during machining. That way no case ever has to travel back and forth again, and you have the certainty of receiving a good case.
Fired cases only, do not resize
Important, send your cases exactly as they come out of your rifle. So fired, and not resized or de-primed. It is that fired shape that gives the best fit in your chamber and therefore the most accurate modified case.
Where to send your cases
You can simply send the cases in a letterbox envelope or small parcel to:
Cool Things B.V.
Rooseindsestraat 31
5705 BP Helmond
The Netherlands
Add your name, address and if possible your order number, and we will return your modified case to you quickly after machining.
Which calibers
This service exists precisely for the calibers where a standard modified case is hard to get. Think of less common calibers, calibers that are temporarily out of stock and wildcats that are not part of the regular range at all. As long as you can supply fired cases, we can in most cases make a matching modified case from them. If you are unsure whether your caliber is possible, feel free to get in touch with us.
Calculating your jump and setting seating depth
The jump, also called the freebore jump, is the distance the bullet travels before it touches the rifling. That distance has a direct effect on your accuracy, and with your modified case and the Hornady OAL Gauge you can work it out easily.
Step by step
Thread your custom modified case onto the OAL Gauge and push the bullet forward until it just touches the lands. Measure with light, even pressure and repeat the measurement a few times, so you get a reliable average touch length. When you measure, use a bullet comparator on your calipers and measure on the ogive rather than on the tip of the bullet, because tips vary too much from one to the next.
From that touch length you then subtract your desired jump. A common starting point is 0.010 to 0.020 inch, roughly 0.25 to 0.50 mm, off the lands. The result is the cartridge length, measured to the ogive, at which you seat the bullet. If you prefer to work in COAL, keep in mind that bullet tips vary and that measuring to the ogive is more accurate.
Fine tuning
The ideal jump differs per bullet and per rifle. Some bullets perform best close to the lands, others prefer a bit more jump. So test in small steps of, for example, 0.003 to 0.005 inch and watch your groups to find the sweet spot for your combination. Finally, always check that the cartridge still feeds smoothly from your magazine.
Who it is for
This custom modified case is intended for the precision shooter and reloader who takes cartridge length and jump to the lands seriously. For long range shooting, benchrest, F-class and other precision disciplines, an accurate measurement of the lands is crucial. With a modified case tuned to your own chamber, you lay a reliable foundation for that.
Key benefits
Tuned to your rifle: made from your own fired case, so formed to your chamber.
More precise measuring: a more accurate and repeatable measurement of the distance to the lands.
Also for tricky calibers: ideal when the modified case is unavailable or does not exist, wildcats included.
Craftsmanship on the lathe: centered in the chuck, drilled and tapped through the center for a true thread.
Always a good one back: you send in two and receive one ready to use modified case.
Easy to send: by letterbox envelope or small parcel to Cool Things B.V. in Helmond.
Frequently asked questions
How many cases do I need to send?
Two fired cases of the same caliber. We machine your case and return one ready to use modified case. The second one is our spare, so you always receive a good case.
Why can I not resize the cases first?
A fired case has taken on the shape of your chamber. It is that shape that gives the best fit and the most accurate measurement. Sized or de-primed brass loses that dimension, so send your cases exactly as they come out of your rifle.
Which OAL gauge does the modified case fit?
The Hornady Lock-N-Load OAL Gauge, formerly known as the Stoney Point gauge. Both the straight and the curved version.
Does this also work for wildcats or unusual calibers?
In most cases yes. As long as you can supply fired cases, we can make a matching modified case from them. If you are unsure about your specific caliber, get in touch before you send anything in.
What exactly do I get back?
A ready to use, custom machined modified case, made from your own brass and ready to thread onto your OAL Gauge.
Specifications
Type: custom modified case, made from your own fired case
Compatibility: Hornady Lock-N-Load OAL Gauge (formerly Stoney Point)
To supply: 2 fired cases, not resized and not de-primed
You receive: 1 ready to use modified case
Machining: centered in the lathe chuck, drilled and tapped through the center
Suitable for: common calibers, hard to source calibers and wildcats
Application: measuring the distance to the lands and setting cartridge overall length
Send to: Cool Things B.V., Rooseindsestraat 31, 5705 BP Helmond, The Netherlands
Shipping: letterbox envelope or small parcel, including your details and order number
Carried out by: Cool Things B.V. / hop.nl
