We make rifle specific adapters for a very long list of airguns, but there will always be rifles that are new, rare or modified enough that a dedicated adapter does not exist yet. That is where our universal adapters come in. In this Field Notes post I want to explain each universal option, how to measure for it, and introduce the new adapter we just released for the Air Venturi Alpha.
The DonnyFL Slide-On Adapter with 1/2 x 20 UNF threads.
Quick Summary
- Unshrouded barrels: Slide-On Adapter, 10, 11, 12, 14, 15 and 16mm barrels, .177 to .25.
- Female muzzle threads: A21 1/2 x 20 Double Male Adapter, also for the Air Arms S510.
- Quick detach: QD Barrel Adapter in 1/2 x 20 or M14x1.25, 7075 aluminum.
- New this month: the Air Venturi Alpha Adapter, short and long versions.
The Slide-On Adapter
The DonnyFL Slide-On Adapter with 1/2 x 20 UNF is designed for airguns without a shroud. It fits barrel sizes of 10mm, 11mm, 12mm, 14mm, 15mm and 16mm and suits .177 through .25 caliber. It is CNC machined from 6061 T6 aluminum, with the A56 version made of steel, and it uses M4 set screws with a standard 2mm Allen key.
Measuring for a slide-on adapter
Measure the outer diameter of your barrel at the muzzle with a quality caliper, and measure in more than one spot, since coatings and small variations can change the reading. Choose the size that matches, and seat the adapter fully and evenly before tightening the set screws, so the bore stays centered through the moderator. If you are using a slide-on adapter on a powerful rifle, drilling shallow divots for the set screws gives a more secure hold.
The Double Male Adapter
Some rifles have female 1/2 x 20 UNF threads at the muzzle, and the 1/2 x 20 Double Male Adapter solves that. It has 1/2 x 20 threads on both ends, a knurled cap on one side for hand tightening, a through hole for tightening with a tool, and a compact 0.79 inch, or 20mm, outer diameter. It is ideal for Air Arms rifles with female 1/2 x 20 threads at the muzzle, though it does not fit Air Arms S510 or S410 models with a factory moderator.
The A21 has 1/2 x 20 male threads on both ends and a 20mm OD.
The QD Barrel Adapter
If you run one of our QD moderators across more than one rifle, the Quick Disconnect Barrel Adapter lets you add the QD interface to another rifle. It is 7075 aluminum, anodized, available in 1/2 x 20 or M14x1.25, and it includes a set screw and wrench. Please note it is the barrel adapter only, and the moderator rear cap is not included.
The QD Barrel Adapter adds the DonnyFL QD interface to another rifle.
New: The Air Venturi Alpha Adapter
Earlier this month we released the DonnyFL Air Venturi Alpha Adapter, designed specifically for the Air Venturi Alpha .22 PCP. It provides a 1/2 x 20 UNF male thread for mounting DonnyFL moderators, with a knurled exterior and a matching knurled thread protector in black anodize.
Short or long version
The Alpha comes with either a traditional air tube or a larger bottle, so we developed two lengths. The short version is for tube equipped Alpha models and creates just enough clearance to add a moderator of any size while still accessing the fill probe hole without removing the moderator. The long version is for the bottle equipped Compact Alpha and moves the moderator mounting point forward so the moderator body clears the larger bottle.
Our pairing
Our team likes the .22/.25 Sumo with 1/2 x 20 threads on the standard Alpha, and the .22/.25 Shogun with 1/2 x 20 threads on the Compact Alpha. Our Shogun Field Notes explains that moderator in depth.
The new Alpha adapter comes in short and long versions for tube and bottle rifles.
Shop the Air Venturi Alpha Adapter
Universal Adapter Checklist
Check whether your rifle has a dedicated DonnyFL adapter first.
Measure the barrel OD or confirm the muzzle threads.
Choose a moderator one caliber size up on shrouded or slide-on setups.
Seat the adapter fully and evenly.
Re-zero after installation.
Frequently Asked Questions
What barrel sizes does the slide-on adapter fit?
It fits 10mm, 11mm, 12mm, 14mm, 15mm and 16mm barrels, for .177 to .25 caliber.
Which rifles use the DonnyFL double male adapter?
Rifles with female 1/2 x 20 threads at the muzzle, such as many Air Arms rifles. It does not fit S510 or S410 models with a factory moderator.
Does the QD barrel adapter include the moderator rear cap?
No, it is the barrel adapter only, in 1/2 x 20 or M14x1.25, and includes a set screw and wrench.
Which Alpha adapter do I need?
The short version is for tube equipped Alpha models, and the long version is for the bottle equipped Compact Alpha.
What moderator pairs with the Air Venturi Alpha?
Our team likes the .22/.25 Sumo on the standard Alpha and the .22/.25 Shogun on the Compact Alpha, both with 1/2 x 20 threads.
Final Thoughts
A rifle without a dedicated adapter is rarely a dead end. Measure carefully, choose the universal option that fits, and if you are not sure, reach out to us before you order so we can help you get it right.
