If the goal for your reloads is precision without a compromise in function, the Bushing Bump Die from Forster is worth a look! Normally you’d have to choose between full-length sizing and neck-only sizing with the drawbacks inherent in each type of sizing. With the Forster Bushing Bump Die you get precise control over neck tension with familiar bushings *and* the ability to bump the shoulder without disrupting the fire-formed case body. Interested? Check out this video!
Setting up the Bushing Bump Die
There are two major factors that will affect die setup with the Forster Bushing Bump Die: Die height for shoulder bump, and bushing diameter for neck tension. The first thing to do is measure bullet diameter and case neck thickness to determine the optimal bushing diameter. I would suggest using a micrometer for bullet diameter (or use published bullet diameter), and to use a ball micrometer (like the RCBS unit) for case neck thickness.
Once you have these numbers, it’s easy to calculate optimal bushing size, which is a factor of:
- Bushing diameter (inches, as calculated) = BD
- Bullet diameter (inches, as measured) = D
- Average case neck thickness (inches, as measured) = T
- Bullet tension press fit = BT = 0.001″
- Brass spring back factor = SBF = 0.001″
The formula is: BD = D + 2 x T – BT – SBF
Simplified, this becomes: BD = D + 2 x T – 0.002″
When I measured my case neck thickness, I came up with 0.014″, and bullet diameter was measured at 0.264″ as expected for the 6.5mm caliber. Here’s my “working out of the math”:
So we have 0.264″+ 0.028″ -0.002″ = 0.290″ bushing. That wasn’t too hard! The pre-selected bushings that came with my 6.5 Creedmoor die were 0.288″, 0.290″, and 0.292″ – so this selection was *perfect* – I can go up or down by 0.002″ as factors change without needing to order additional bushings- awesome.
iGaging EZ Data Micrometer showing bullet diameter
Installing the bushing is simple:
- Remove the decapping spindle
- Remove bushing (if installed)
- Drop in bushing chamfered end first
- Tighten decapping spindle until it bottoms out against bushing
- Back decapping spindle out 1/8 turn
- Tighten spindle lock ring
You can then install the die in your press, and lower the die until it contacts the shell holder. Lube the case neck of a case, then size it- now you’re ready to measure the shoulder bump. I use the Hornady headspace gauge kit which work quite well for these types of measurements. If your shoulder bump (0.001″ – 0.002″ for a precision bolt gun) is not where you want it to be, you can raise and lower the die slightly to “fine-tune” the value you are looking for.
iGaging Origincal 0-6″ digital caliper with Hornady Headspace Guage kit
The Forster Bushing Bump Die is a great tool to have for precision reloading. Combined with a full-length die, you can adapt to most common loading scenarios for a precision rifle. And that’s what reloading is about isn’t it? Saving money, having fun, and getting the results *you* want with your firearms. If you need precision and flexibility, check it out! You can find the Forster Bushing Bump Die at Midsouth Shooters Supply HERE.
4 thoughts on “Forster Bushing Bump Die in 6.5 Creedmoor: Overview and Setup”
I have heard that neck turning is necessary before using one of these dies, any truth to that?
No, it’s not necessary to turn necks *unless* you have a lot of neck thickness variation (from piece to piece, or around the case mouth of a single piece).
I use Lapua brass (6.5 Creedmoor). Necks are not turned. I have a Redding full size bushing die and a Forster full size die. The concentricity on once fired brass spins at >.001. After sizing it, the Redding die spins at .002-.003 out. I tried the Redding die with and without the mandrel. The Forster is out .001 or less.
Have you ever tried checking concentricity before and after with this die on unturned necks? I have talked to people that use the Redding full size bushing die with turned necks on Lapua brass and they claim it stays true.
Excellent how to article. Every step was clear and concise.