Austin Custom Brass Backbores

(18 reviews) Write a Review
1.00 LBS
$3.00 (Fixed Shipping Cost)
  • ACB trumpet backbore blanks (from left to right: slug, heavy, heavy cut for sleeves, standard, standard cut for sleeves)
  • ACB cornet backbore blanks (from left to right: C1 heavy, C1 standard, C1s heavy, C1s standard)
  • Austin Custom Brass Backbores
  • Austin Custom Brass Backbores
  • Austin Custom Brass Backbores
  • Threaded backbore for Adams integrated receivers - special order only
"I own 4 different ACB backbores that the friendly staff at ACB helped me choose with specific tops as well. The quality is great and I have been in love with the ease and efficiency in my new equipment. I have better range now at age 45 then when I was playing all the time in my 20's. I love the flexibility that the backbores and tops offer me in different situations." -Derek Limback
Frequently bought together:


Austin Custom Brass Backbores

ACB backbores are now in stock!

All ACB tops and backbores utilize the now universally accepted "Warburton" threads, making them compatible with almost every other maker's modular components! Check out our mouthpiece sizing spreadsheet to see which backbores come standard with our various one-piece mouthpieces. If you want help choosing a backbore for your particular playing needs, please call our Mouthpiece Hotline at (781) 816-9664 and we'll be happy to assist you!

ACB backbores are designed to be as acoustically efficient as possible. Currently I have many different tapers available!

Standard backbores

Here are our standard backbores, from high compression commercial backbores to wide-open orchestral backbores:

  • KA3: Our newest commercial backbore and it is amazing! Feels almost like the throat is one size smaller due to the compression.
  • KA2: A very nice backbore with good zing.
  • KA1: More core than the A2 and a bit tighter as well.
  • A2: The A2 is a weapon!  Designed to be mated with compression mouthpieces. 
  • T (Tight): commercial backbore which provides the most resistance and "zing"  to your sound
  • MT (Medium Tight): Provides great resistance, especially for players who tend to "backup."
  • S (Standard): Provides the best balance between resistance and sound spread for most players. 
  • MO (Medium Open): A great slightly open symphonic shape produces a rich, warm tone but still gives ample resistance when needed.  
  • A1: This backbore is a very large, symphonic backbore that is in between the MO and O – a wonderful backbore suited for the classical player or jazz soloist wishing for a large sound!
  • O (Open): This is a very large, open backbore designed for the orchestral musician to provide the feel and sound spread that most orchestral players prefer
  • OO (Very Open): Huge backbore for enormous, rich sound (takes a lot of air)

Specialized backbores

We also have some specialized backbores that are different than the "standard" line:

  • AOS: Designed for C trumpet players looking for a large and warm sound, it's open and free-blowing. It provides a feel and sound spread that is perfect for orchestral playing and for chamber music.
  • KA1, KA2, and KA3: Based on the great customer response to our A2 backbore we decided to expand our commercial backbore line with the three new options in our KA Series!
  • VNT: a vintage trumpet shank backbore specially designed to work with pre-1930's classic trumpet shanks (King liberties, Holton Revelation, Martin Handcrafts, etc), available here.

Cornet Backbores

We also have two different cornet backbores available (one in standard length, and one in the short "British" length which works nicely with larger tops). 

Flugelhorn Backbores

Choose between our Large and Small taper flugelhorn backbores, available in our standard weight only.


All trumpet mouthpiece backbores can be ordered now to be cut for sleeves in the drop-down menu (the sleeves are not included in the purchase; backbores cut for sleeves will not work without the sleeves). 


Special Order Options Call (816) 410-0826

Throat sizing: All backbores will be made with a #27 (.144) throat. If you would like to change it to a custom size we can do almost any modern size. Let us know we'd be happy to help!

Gold plate: Gold plated backbores may be ordered over the phone. Gold plating will add $30 and an additional 3-4 weeks for delivery.

Threaded backbores for Adams integrated receivers: We can make backbores for the Adams A8 integrated mouthpiece receivers (requires a specialized mouthpiece top as well).


If you have additional questions send us an email

Prior to ordering please check our Shipping and Returns policy.

Also note weight indicated in the ad is shipping weight not actual weight of the item.

We have mouthpieces equivalent to the Laskey 84D, Warbuton 2D, Laskey 84B, Warbuton 2MD, Laskey 84C, Warbuton 2MC, Hickman GW, Bach 1X, Monette B1-1, 30's Bach NY1, Vincent Bach 1 mouthpiece, Laskey 80B, Haefer, Yamaha 16C4, Schilke 16C4, Bach Mount Vernon 1 1/4C, Curry 1.25BC, Bach 1 1/4C, Bach 1/4 C, Tilz 1 1/4CE, Monette B2, Monette B2S3, ACB 1.25C, MV 1-1/4C, Monette B2LD, Tilze 1 1/2E, Bach 1 1/2B, Monette B3, Curry 1.5BC, Warbuton 3MD, Bach 1.5C, Monette B3, Curry 1.5C, Warbuton 3MC, Bach 1.5C, Monette B3, GR 67, Monette B3L, Bach 1.5D, Mount Vernon 3C, GR 66.5, Mount Vernon 3B, BH3, Monette B4, Bach Mt. Vernon 3, Monette B4S, Bach Mt. Vernon 3D, Monette B4L, Bach 2 1/2C, Bach 3D/E, Curry 3DE., Monette B5L, Bach 3, Bach 3B, Monette B5, Bach 3, Warbuton 4MC, Schilke 14B, Monette B6s1, GR 65M, Pickett 5D, Monette BLM, GR 65M/S, Monette BL, GR 65S, Pickett 5E, New York Bach 5B, Pickett 5B, GR 74.7 MX, Bach 5B, Pickett 5C, Curry 5C, Monette B6, Giardinelli 7M, Bach 7D, Monette B7, Bach 7E, GR 64S, Giardinelli 7S, New York Bach 7, New York Bach 7B, Giardinelli 10M, M Shew 2, New York Bach 10 1/2C, Shew Yamaha Lead, Marcinkiewicz Shew 1, Giardinelli 10S, Schilke 14a4a, Monette B4L, Bach MV 3D, Marcinkiewicz Shew 1.75, Vintage Gustat Heim trumpet mouthpiece, Al Cass 1-27, Cat Anderson trumpet mouthpiece

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18 Reviews

  • 5
    MO backbore

    Posted by Gregory H Haubrich on 2nd Feb 2022

    just right for my horn, and very precisely machined.

  • 4
    Backbore ACS/27

    Posted by Caviezel Juerg on 21st Sep 2021

    The Mouthpiece (Head and Backbore) is about 4mm shorter than my Conn 4 by design.

  • 5
    AOS (Heavier Blank) = Awesome!

    Posted by Chris on 8th Sep 2021

    This backbore is actually incredible. Intonation is good, and the slotting feels very stable and locked in (possibly the heavier blank). The sound is clarion, centered and projecting and holds together and remains clear at soft dynamics. When pushed, the sound stays clear and full, but it turns into a cannon. As a result, this backbore seems outstanding on both tricky things like Tomasi but also would have no issue ringing out with gusto on the Zarathustra Trumpet Calls etc. Also, it is one of the only backbores with a 27 throat that I like on my C trumpet... Usually I have to open them to a 24 or 22 but this one is so great as-is that for once, I'm actually scared of ruining it by opening the throat!

  • 4
    ACB KA2 heavyweight backbore

    Posted by Gary G Wada on 19th Feb 2021

    Great sound in the upper register.

  • 5
    Love it!

    Posted by J on 13th Sep 2020

    Loving the commercial backbores ACB makes! They are bright and PROJECT but they don't feel tight at all

  • 5

    Posted by David on 25th Jul 2020

    Top of the line! Great manufacturing, awesome look, soulful response and sound! Thanks ACB!

  • 5
    MTH backbore review

    Posted by Ron Jimison on 30th Apr 2020

    I have a TA-3 top that did not match any of my (symphonic) backbores. I discussed with Josh what I thought I needed. He asked about my playing and my setup (Schilke B1-LB). He advised this MTH backbore. I will not know for the next month (or five?) when we can play gigs again how it works in a bi room, but here in my home studio it does just what I hoped. As always, the quality is perfect, and in spite of the current situation, shipping was very fast! Thanks to all at ACB!

  • 5
    Great Backbores!

    Posted by derek limback on 12th Nov 2019

    I own 4 different ACB backbores that the friendly staff at ACB helped me choose with specific tops as well. The quality is great and I have been in love with the ease and efficiency in my new equipment. I have better range now at age 45 then when I was playing all the time in my 20's. I love the flexibility that the backbores and tops offer me in different situations.

  • 5
    heavy backbores

    Posted by J on 8th Feb 2019

    are fantastic! Love the response and the sound. Bought the S, O, MO, and MT and use them regularly!

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