emblem_red_solid

What is roller-delayed blowback?

Click here for a video introduction to the system.


I have a problem with my firearm. What should I do?

Please reference your owner’s manual. If your question is not answered there, e-mail info@zenithfirearms.com with your concern. If you do not have access to your owner’s manual, select “Manuals” from the drop-down list in the Products top menu or click here: https://zenithfirearms.com/manuals/ to download it.


Can I use +P ammunition in my Zenith roller-delayed firearm?

Yes. These are military-grade firearms designed to withstand and operate with +P ammunition. However, we do not recommend the use of +P+ ammunition.


What kind of ammunition should I use in my Zenith roller-delayed firearm?

During the break-in period for your new firearm, we recommend you use NATO-spec or +P ammunition having a bullet weight of 123-124 grains. Following the break-in period, we still recommend you use NATO-spec or +P ammunition, but the grain weight is no longer as important, and 115 grain ammunition should work just as well. Having said all that, in our testing and experience we’ve also found that steel-cased ammunition cycles just fine. Of course, it is of critical importance that you ensure you are using the correct caliber of ammunition for your firearm.


What is the recommended break-in period for a Zenith roller-delayed firearm?

We recommend a 500-round break-in period, during which a high-quality firearm lubricant should be frequently and liberally applied to bearing surfaces of the bolt carrier assembly and receiver, and occasionally, sparingly applied to moving parts in the trigger pack assembly.


Are Zenith roller-delayed firearms compatible with parts from H&K?

Our firearms are compatible with most H&K parts. However, please consult your local gunsmith before purchasing or installing any aftermarket parts or accessories.


Can Zenith remove the full-auto bolt carrier block from my privately owned Zenith roller-delayed blowback firearm?

In 2018, Zenith formally inquired of BATFE about the legality of performing that modification. In an August 15, 2018 letter to FTISB Chief Michael Curtis, we set forth the following argument:

If under its U.S. manufacturer license Zenith Firearms were to remove the full-auto carrier blocks from its upper receivers, after importation, and then sell those upper receivers either as stand-alone parts or as components of partially or fully assembled firearms, provided their metal shelves were still in-tact, Zenith Firearms would not have sold any machine gun receivers, just as other U.S. manufacturers that sell roller-delayed blowback firearms without full-auto carrier blocks but with metal shelves are not considered by BATFE to be selling machine gun receivers.

On May 17, 2019, Mr. Curtis sent BATFE’s formal reply, several excerpts from which are reprinted here (bold and underline are BATFE’s emphasis):

Previously, importers requested ATF allow a forward pin-hole in semiautomatic firearms, in order to give their firearms a more authentic appearance. These semiautomatic firearms continued to incorporate a “blocking shelf” in order to prevent the installation of an unmodified machinegun trigger pack. However, this “blocking shelf” was smaller than the original full shelf; therefore, a secondary blocking feature was required to prevent a semiautomatic firearm from being easily converted into a machinegun.

ATF has permitted semiautomatic receivers to include a forward pin-hole only if the receivers contain both:

  • A smaller blocking shelf, still preventing actual attachment of an unmodified machinegun trigger assembly; and
  • An internal blocking feature which prevents the installation of an unmodified machinegun bolt assembly.

Any HK-type receiver that contains a “blocking shelf” that is insufficient to prevent the installation a machinegun trigger assembly, constitutes a machinegun receiver, and will be classified as a “machinegun.”

Zenith semiautomatic firearms also incorporate a blocking bar in the rear of the receiver, which prevents the installation of an unmodified machinegun bolt carrier. This is consistent with other semiautomatic HK-type receivers, where the presence of a forward pin-hole and the smaller “blocking shelf” require a second blocking feature.

In your correspondence, you request permission to remove the secondary blocking feature in order to install unmodified machinegun bolt carriers. FTISB cannot approve this request because the Zenith Firearms without the necessary blocking features is a “machinegun” receiver.

Accordingly, it is clear that Zenith cannot lawfully remove the full-auto bolt carrier blocks from privately owned Zenith roller-delayed blowback firearms. Neither can it do so from its firearms that have yet to be sold but are destined for private ownership. And the reason is because Zenith roller-delayed blowback firearms incorporate in their design a forward pin-hole and “blocking shelf,” the BATFE approval of which was always, and continues to be, conditional upon Zenith firearms also incorporating in their design a full-auto bolt carrier block. Hence unambiguously, in BATFE’s judgment, removal of the full-auto bolt carrier block from a Zenith firearm would constitute manufacturing a machinegun.


My charging handle is stiff. What can I do to make it easier to operate?

Operation of the charging handle in a roller-delayed firearm compresses the recoil spring, which is often stiff in a new firearm. After tolerating this stiffness through the recommended break-in period, your firearm should become easier to charge.


What are the advantages of a roller-delayed blowback firearm in comparison to a gas-operated firearm?

Several tangible advantages are worth noting: 1) The engineering of the roller-delayed blowback system is very simple and reliable. While gas-operated systems can also be engineered to a high standard of reliability, the roller-delayed blowback system is at least their equal and arguably superior. 2) Roller-delayed firearms tend to run cleaner than direct impingement gas-operated firearms, since there is no recirculation of gas by which debris can be introduced into the chamber area during the cycle of operation. 3) Especially when firing suppressed, the far-forward position of the roller-delayed system’s charging handle will limit or eliminate the blowing of gas directly into the user’s face. 4) Due to the lack of requirement for a buffer tube, roller-delayed blowback firearms can be made more compact in pistol form than their gas-operated counterparts (e.g., a Z-5P, K, or even RS pistol, with their receiver end caps, vs. an AR-15 pistol with its required pistol buffer tube). For further information about the roller-delayed blowback operating system, click here for a video introduction.


How do I become a dealer?

Select “Become a Dealer” from the drop-down list in the Dealers top menu or click here: https://zenithfirearms.com/dealers/become-a-dealer/ and input and submit the requested information. You can also sign up with your current distributor of Zenith Firearms products. You will be required to provide a current FFL.


How do I become a distributor?

Please contact info@zenithfirearms.com.


How do I submit a warranty claim?

Select “Warranty” under Quick Links at the bottom of our website or click here: https://zenithfirearms.com/warranty-form/ to complete and submit our online warranty return form with as much detailed information as you can provide. Following your submission of this online form, we will contact you within 48-72 hours with further instructions.


Can I use a suppressor with my Zenith roller-delayed firearm?

Provided you own a Zenith roller-delayed firearm capable of receiving a suppressor, you can use a suppressor with your firearm once you have completed the legally required paperwork and are in possession of the resulting approvals (tax stamp, trust, etc.)


My suppressor either will not mount or mounts too tightly on my barrel’s 3-lug device. Is that normal?

Yes, that is sometimes the case due to the coating on many of our 3-lug devices. However, the problem is easily remedied as follows:

If you’re unable to mount your suppressor on your barrel’s 3-lug device, or if you’re able to mount it but the fit is too tight, use steel wool or acetone to remove up to 1 mm of paint from the circumference of the barrel immediately forward of the 3-lugs and up until the start of the thread protector, as indicated in the photo above.

Once you remove this extra paint, while some suppressors will still be very tight when they’re new, after a short break-in period you should have no problem mounting your suppressor.


If I purchase a firearm online, can I ship it to my house?

No. All firearms purchased online or otherwise must be shipped to a properly licensed FFL where an ATF E-Form 4473 and background check must be completed. Please verify with your local FFL dealer that you are eligible to purchase a firearm.


How do I properly unload my roller-delayed firearm?

Verify that your firearm is on “Safe” and pointed in a safe direction, and that your finger is not touching the trigger. Detach the magazine, and then pull the charging handle rearward and to its upright and locked position (lock the bolt in its open position). A chambered round may eject. Verify that your firearm is now empty by looking through the ejection port. Insert a chamber flag if necessary. Please consult your owner’s manual regarding proper and safe handling of a firearm.


Where can I find a Zenith Firearms product catalog?

Our catalog is available for download as a PDF at the bottom of our website’s About page. You can find that page here: https://zenithfirearms.com/about/, by clicking the word “About” on the top menu, or by selecting “About” under Quick Links at the bottom of our website.


I just ordered a firearm online. When will it ship?

Verify that the firearm you ordered is in stock and not on backorder. Provided it is in stock, you can expect to receive tracking information for your shipment within 48-72 hours. Following receipt of that information, your order will ship on the very next of our weekly shipping days, which are Monday through Wednesday. Backorders will be processed and shipped in the order they were received and can take several weeks or more, as they are often subject to circumstances beyond our control.


Can I order a firearm and pick it up from Zenith Firearms?

No. Zenith Firearms does not currently operate as a brick and mortar retail outlet.


Can I ship my firearm to Zenith Firearms for repair?

Yes. However, not without first receiving an invitation from Zenith’s warranty/technical team to do so. If you would like for Zenith to repair your firearm, please contact warranty@zenithfirearms.com to explain the problem, and then await our reply with specific instructions. Whether or not a needed repair service is covered under warranty, we do not accept unexpected shipments of firearms.


What kinds of services can the Zenith Custom Shop provide?

For more information see our Zenith Custom Shop section.


Zenith FirearmsFAQs