Are BM59E Barrels Usable on Regular BM59?

Are BM59E Barrels Usable on Regular BM59? The Beretta BM59 is a classic military rifle with a fascinating history, beloved by collectors, shooters, and firearm historians. Over its production life, the BM59 appeared in several variants, including the BM59E—a version adapted from converted M1 Garands.

Because of its interchangeable-looking parts and shared lineage, a common question arises among owners and builders: Are BM59E barrels usable on a regular BM59?

The short answer: Not directly—while BM59E barrels share similarities with standard BM59 barrels, they are not perfectly interchangeable without modifications. The differences come down to manufacturing origins, specifications, and how each rifle was configured.

1. Understanding the BM59 and BM59E

The Regular BM59

• Developed by Beretta in the late 1950s.
• Chambered in 7.62×51mm NATO.
• Designed as a modernization of the M1 Garand, with a detachable box magazine, a shorter barrel, and selective-fire capability in military configurations.
• Featured a proprietary barrel and gas system optimized for the BM59 platform.

The BM59E Variant

• Created primarily for countries that already had large stocks of M1 Garands.
• Essentially a conversion of an M1 Garand to BM59 specifications.
• Retained more Garand-like features in its receiver and stock fitting.
• Barrel profile and threading sometimes differed slightly from standard BM59 barrels, since many were adapted from existing M1 barrels.

2. Physical Similarities Between BM59 and BM59E Barrels

From the outside, a BM59E barrel may appear nearly identical to a standard BM59 barrel:

• Both are chambered for 7.62×51mm NATO.
• Both have a similar external length (generally around 19.3 inches for military versions).
• Both can mount BM59-pattern muzzle devices, such as combination flash hiders and grenade launchers—if properly machined.
• Gas port placement is generally similar, aligning with the BM59’s short-stroke piston system.

3. Key Differences That Affect Interchangeability

Although they look similar, several differences can prevent a BM59E barrel from dropping into a regular BM59 without adjustment:

1. Barrel Shoulder and Indexing
   • On many BM59E conversions, the barrel shoulder (the point that indexes against the receiver) may be cut slightly differently to fit a modified M1 Garand receiver.
   • A standard BM59 receiver may require precise re-machining to ensure proper headspace and timing.
2. Gas System Fitting
   • The BM59E’s gas cylinder and front sight assembly may be positioned based on Garand dimensions.
   • The regular BM59 has its own gas system alignment, meaning an E barrel might require gas block repositioning or port re-drilling for proper cycling.
3. Muzzle Device Threads
   • Some BM59E barrels retain Garand-style muzzle ends without the correct BM59 threading.
   • A standard BM59 barrel is usually cut and threaded for the BM59’s unique tri-compensator or grenade launcher device.
4. Markings and Proofs
   • BM59E barrels may have different Beretta markings, arsenal stamps, or even U.S. Springfield Armory proofs if they started life as M1 barrels.
5. Material and Wear
   • Many BM59E barrels were conversions of used M1 Garand barrels, meaning their lifespan and bore condition vary widely.
   • Regular BM59 barrels were generally purpose-made for 7.62 NATO from the start.

4. Can You Make a BM59E Barrel Fit a Regular BM59?

Yes, but with gunsmithing. A qualified armorer or gunsmith can:

• Re-cut the barrel shoulder for proper indexing.
• Adjust the gas port size and placement.
• Thread the muzzle for BM59-specific devices.
• Verify and correct headspace for safe operation.

Important: This kind of work requires proper tooling, chamber gauges, and knowledge of both M1 Garand and BM59 systems. Improper fitting can result in unsafe pressure levels or cycling issues.

5. Why Owners Consider BM59E Barrels

There are a few reasons enthusiasts might want to use a BM59E barrel in a standard BM59 build:

• Availability – Original BM59 barrels can be scarce, while BM59E barrels sometimes appear more frequently on the surplus market.
• Cost – E barrels may be less expensive than original BM59 barrels.
• Historical interest – Some builders enjoy mixing parts from different BM59 variants to create unique custom rifles.

6. Downsides of Using a BM59E Barrel in a BM59

• Extra work required – Rarely a direct fit, often needing machining.
• Potential mismatch – Even after fitting, it might not perfectly match other BM59 parts in contour or finish.
• Collector value – Altering an original BM59E barrel for a BM59 build may reduce its historical or collector appeal.

7. Best Practices for Barrel Swaps

If you plan to attempt this swap:

1. Inspect the barrel – Check rifling, chamber, and muzzle condition.
2. Confirm measurements – Use proper gauges to check indexing and headspace.
3. Work with a professional – A gunsmith experienced with M1 Garands and BM59s is ideal.
4. Document the modification – Keep notes and photos for historical and safety records.

8. Conclusion

While BM59E barrels and regular BM59 barrels share many characteristics, they are not fully interchangeable without modification. The BM59E’s origins as a Garand conversion mean its barrel dimensions, gas system alignment, and muzzle threading can differ from a standard BM59’s requirements.

For collectors, keeping each variant correct may be the priority. For builders and shooters, fitting an E barrel into a BM59 is possible, but only with proper machining and safety checks. Always approach such modifications with caution and the help of a knowledgeable gunsmith.

FAQs – BM59E vs. BM59 Barrels

Q1: Are BM59E barrels the same as BM59 barrels?
No. While they share caliber and general profile, BM59E barrels were often adapted from M1 Garand barrels and have small dimensional differences.

Q2: Can I install a BM59E barrel on my BM59 without modification?
In most cases, no—you’ll need to re-cut the shoulder, adjust the gas system, and possibly re-thread the muzzle.

Q3: Is it safe to swap these barrels without a gunsmith?
No. Improper fitting can cause unsafe pressures, poor cycling, or damage to the rifle.

Q4: Are BM59E barrels cheaper than BM59 barrels?
Often, yes. This is one reason some owners consider the swap.

Q5: Will using a BM59E barrel affect the value of my BM59?
For a collector-grade BM59, using a non-original barrel could lower value. For a shooter-grade build, it may be acceptable if fitted correctly.

Q6: Do BM59E barrels have different markings?
Yes. Many have Garand or arsenal markings distinct from purpose-made BM59 barrels.

Q7: Why not just buy a regular BM59 barrel?
Original BM59 barrels can be scarce and expensive, making BM59E barrels an attractive alternative if modification is possible.