Umarex Hammer .50 Cal Big Bore PCP Airgun Review


Testers: Doug Wall, Stephen Archer

Caliber: 0.50 nominal (0.510 actual)

Model Number: 2102635

Test Date: Oct 2, 2021

Serial Numbers: H1U000461

Source of Supply: Supplied by Umarex USA

Condition: New

We Like

Regulated action

We Don't Like

Very ammo sensitive
Less powerful than claim
Air blast on firing


  • Value for Money
  • Speed and Accuracy
  • Trigger and Cocking Effort
  • Comparison to Makers Claims:
  • Consistency
  • Noise Level
  • Sights
  • Shootability
  • Appearance and Finish
  • Buying and Owning



The Umarex Hammer .50 Cal was a long time coming. But now it’s here and working in this HAM test review.

Overall, the Hammer can’t be beaten in terms of power for price. The gun tested by HAM was definitely hunting-grade accurate with Umarex SLA 320 Gram slugs and performed consistently. We saw 560+ Ft/Lbs of Muzzle Energy. That’s huge, although well below the 700 Ft/Lbs that’s the headline claim.

With no less than three safeties, this is a complicated airgun to use. So it’s mandatory to read the Owner’s Manual before operating. But once you understand the workings, it’s not so difficult to shoot and handles surprisingly well.

If you’re in the market for an air rifle to hunt big game at the lowest price, the Hammer is the obvious choice. It’s a HAM Silver Award winner.


At a Street Price of $849.99, the Umarex Hammer .50 Cal has to be considered strong value for a big bore airgun. While it’s not absolutely the cheapest big bore, it certainly delivers the largest bang for the buck. By a long way!

As with any PCP the gun itself is only part of the cost. Naturally you’ll need a scope, but only Olympic-grade Triathletes are likely to relish trying to fill the Hammer’s HPA bottle to it’s full 4,500 PSI using a hand pump. For us mere mortals, a large HPA tank, plus compressor and possibly a Booster Pump will also be required.

Umarex Hammer .50 Cal Big Bore

So, although the headline price of the Hammer is attractive, you’ll need to budget for the charging and sighting infrastructure to go with it.

And then ammo is over $1.00 per round!

Umarex Hammer .50 Cal CP



For this test review, HAM specifically used the Umarex .50 caliber Solid Lead Ammo (SLA) that’s designed for use with this gun.

We found that accuracy was very good indeed. Given the design of the Hammer and its intended use solely as a hunting tool, we – exceptionally – fired only two-shot groups. At 50 Yards, accuracy was definitely of the order required for successful big game harvesting.

Umarex Hammer .50 Cal Big Bore

This was confirmed by a second target fired at 25 Yards. In this case, the two bullets went almost through the same hole. Great shooting by HAM Tester Doug Wall! (Note that we had left the scope set for 50-Yard shooting, so the impacts at 25 yards were high).

Umarex Hammer .50 Cal Big Bore

In this testing, the HAM Team recorded a maximum Muzzle Velocity of 889 FPS. With the 320 Grain slugs, this represents a Muzzle Energy of 561.7 Ft/Lbs.

We also determined the Ballistic Coefficient of the 320 Grain SLA slugs to be 0.174 when fired through the Hammer (using the G1 model).

Note that this review was updated in January 2022 by testing the Hammer with 550 Grain bullets that had not been available for the original test. Check out the results in this post.



The trigger of the Hammer tested by HAM had a light average pull weight of 2 Lbs 13 Oz. However the pull itself is long, “mushy” and rather “creepy”. There’s no external indication that it’s adjustable.

We’ve definitely used better triggers. However the Umarex Hammer .50 Cal is not intended to be a target rifle. It’s a hunting gun and the trigger is perfectly usable for this task. It certainly didn’t stop HAM Tester Doug Wall from achieving the excellent accuracy shown above!

The straight-pull bolt handle is easy to use. But it does need more force than might be expected for correct operation, as is covered below in the “Shootability” section of this review.



The Umarex Hammer .50 Cal was originally launched back at the 2017 SHOT Show. Back then is was marketed as the “World’s most powerful airgun” with 700 Ft/Lbs of Muzzle Energy, a category-busting price of $800, interchangeable HPA bottles and anticipated sabot ammunition.

Much changed between then and the product finally shipping to customers. The Street Price – understandably – crept up to $850, the HPA bottle is now not to be removed and the sabot ammunition was lost somewhere in development.

Now, using the recommended Umarex 320 Grain Solid Lead Ammunition, the Muzzle Energy achieved by HAM is actually around 560 Ft/Lbs. That’s still a huge amount of power, but it’s not exactly close to the original claim.

The manufacturer claims the Hammer will produce 700 ft lbs, with a 550-grain projectile, but we did not test with 550 grain rounds and hope to perform that test at a later date

There’s more detail on this in the “Buying and Owning” section of this review, below.

Finally, the manufacturer claims that three full-power shots are available from one 4,500 PSI fill of High Pressure Air. As the Umarex Hammer .50 Cal tested by HAM used 600 PSI per shot and the regulator is set to 3,000 PSI, it’s clear that – even when fully filled – the gun will give just two full-power shots per fill. The third will have – at most – 2,700 PSI to work with. As this is below the regulator set pressure, it will – therefore – generate a lower velocity.



The Umarex Hammer .50 Cal is currently unique as the only regulated big bore airgun. Most big bores are unregulated as these designs aim for the maximum possible Muzzle Energy. Whatever its other benefits, a regulator will always place a restriction on maximum power.

Yes, the Hammer tested by HAM gave just two really consistent full power shots per fill. However, two consistent shots is better than any other – unregulated – big bore out there, so this is a big benefit for the Hammer.

Another benefit for the Hammer due to the regulated action, is that those two FULL POWER shots are also available even when filled from a tank that only has 4,200 PSI inside. Unregulated big bores which would need to be tethered to a HPA tank to match this and obviously this is unrealistic in the field.

Tank Fill PressurePressure After Shot 1Pressure After Shot 2
4,500 PSI3,900 PSI3,300 PSI
4,400 PSI3,800 PSI3,200 PSI
4,300 PSI3,700 PSI3,100 PSI
4,200 PSI3,600 PSI3,000 PSI

In testing for this review, the HAM Team were able to achieve no less than 14 full power shots from a 550 Cu. Inch tank with a starting fill pressure of 4,500 PSI. That was before the tank pressure fell to 4,200 PSI. There’s no other big bore that can match this performance!

The maximum Muzzle Velocity recorded in HAM testing with the 320 Grain SLA slugs was 889 FPS. The average was 881.5 FPS. The Standard Deviation across a 10-shot string was 7.6 FPS, which is a fair figure for a PCP air rifle.

Trigger pull weight was also acceptably consistent. In HAM testing, we measured a low pull weight of 2 Lbs 8 Oz and a high of 3 Lbs 0 Oz. The average was 2 Lbs 13 Oz.



OK, there’s no getting away from this one. The Umarex Hammer .50 Cal is LOUD!!! Yes the barrel may be shrouded, but this is definitely not backyard-friendly in any way. There’s just no way to expel so much high pressure air from a barrel and it not be so…

Of course, for its’ intended use as a pure hunting airgun, that’s not likely to be an issue. The sort of large game that people will hunt with this gun is typically found well away from human habitation.

In fact, the Hammer is loud enough that the HAM Team recommends the use of ear defenders with this airgun.



For this test review, the HAM Team installed a Hawke Sidewinder 30 SF 4-16 x 50 scope using Hawke Tactical Ring Mounts. The scope mounted easily on the Hammer’s Picatinny scope rail and overall appeared quite small when compared to the bulk of the gun.

The Umarex Hammer .50 Cal has a significant recoil, but there was no question of this scope and its mounts not standing-up to the forces involved.

Overall, HAM Tester Doug Wall felt that he would prefer higher rings or a riser mount if this were his gun. But he still shot very well with the rig shown here!



There’s no way that any big bore air rifle is going to be dainty. The Umarex Hammer .50 Cal is therefore a big gun, although somewhat shorter than many of its competitors. It’s also heavy.

The test gun, loaded, scoped and ready to shoot, weighed-in at 11 Lbs 14 Oz. However the balance was good for offhand shooting.

Serious hunters will want to install a sling on their Hammer. There’s a threaded hole for a sling swivel at the rear underside of the buttstock. A front swivel can be effected by using an adapter in the the M-Lok slots of the forend.

The position of the Field Safety is fine for use by right-handers. However, it’s a pain for left-handed shooters as it’s located exactly where the cheek rests.

Doug Wall is left-handed, so he completely removed the screw for comfort when shooting. In doing so, he observed that there was a very limited number of rotations between the Field Safety being correctly disengaged and coming out completely. So the cautionary warning here is that it could be possible to loose this Field Safety in use if you are not careful.

During testing, we experienced a couple of misfires when shooting the Hammer. However this was traced to operator error. We were being too gentle with the bolt handle, Umarex explained.

Yes, it does say in the Hammer’s Owner’s Manual that the bolt handle must be pushed “ALL THE WAY FORWARD”. It fact, the bolt handle needs to be pushed all the way forward with a fair amount of force to ensure that it’s correctly engaged. Once we understood that, the gun worked correctly.

Like some other Umarex PCPs, the Umarex Hammer .50 Cal uses a Ninja Paintball regulator and pressure gauge. In the HAM Team’s opinion, this gauge is extremely difficult to read accurately. The graduated angle on the gauge plate is too small, the maximum indication (6,000 PSI) is too high and there’s no red warning section to advise that the HPA bottle is being overfilled.

In addition, the Hammer Owner’s Manual indicates (with a rare degree of honesty) that the gauge has an accuracy of +/- 10%. That’s a full 450 PSI either way at the full 4,500 PSI fill pressure!

So HAM agrees wholeheartedly with the Owner’s Manual. When filling the Hammer, do not rely on this built-in gauge but consult the (hopefully more accurate and larger) gauge on the HPA tank or compressor being used to fill the gun.

One additional shootability issue with the Umarex Hammer .50 Cal is also covered well in the Owner’s Manual. This is the considerable blast of air that emerges from around the magazine well when the gun is fired.

With the Hammer, you really do need to RTFM!!!

Because the Hammer fires slugs directly from the magazine (this is covered below in more detail), they need to “jump” across to the barrel at the moment of firing. The magazine is a close fit in the magazine well, but there are no seals, so air escapes from all around the magazine when the gun is fired. As a surprisingly large amount of air at 3,000 PSI is expelled in this way when the gun is fired, you definitely do not want your hand or face in the way – or even to be next to the gun!

Once you know and understand this air blast issue, it’s manageable. Even though it’s not what you would expect to find in an airgun.

Recoil is fairly stout, however it feels like a sort of “slow recoil”. It’s more like the recoil of a black powder gun rather than a centerfire powderburner.



The Umarex Hammer .50 Cal is an attractively-styled bullpup with a two tone green/black color scheme. To the HAM Team, the Hammer manages to look smaller than it actually is

The finish of the visible metal and synthetic parts is high. There’s a Magpul AR-style pistol grip, so that could easily be replaced with an alternative if required by the owner.

Umarex Hammer .50 Cal Big Bore



Due to Umarex USA’s massive distribution reach, the Hammer is available online, at some big box sporting goods stores and gun shops. For a big bore airgun, it’s pretty easy to buy.

However, shooting with a big bore air rifle like the Umarex Hammer .50 Cal is a VERY different experience from shooting a “normal, conventional caliber airgun”.

First there’s the HUGE air consumption! Even sighting-in the gun requires significant amounts of air when you’re topping-up the Hammer’s 24 cubic inch bottle after every two shots. This is why the Extreme Booster Pump is generally such a benefit when shooting Big Bores. The Booster Pump allows you to achieve a full fill of the gun’s HPA bottle, even when your tank pressure has fallen.

Secondly, it needs to be re-stated that the Umarex Hammer .50 Cal has no conventional bolt. Slugs are fired directly from the Hammer’s magazine. They are not first forced into battery in the rear of the barrel by closing a bolt – as is the case with a conventional airgun.

This means that fit of the slug (or bullet) in the magazine is extremely critical. Too loose and the slug can fall out of the magazine. Too tight and it will not load fully into the magazine. Importantly, the difference between “too tight” and “too loose” is very small.

The diameters of the chambers in the magazines for the Hammer tested by HAM measured 0.507 Inches. So, .510 caliber Umarex SLA ammo is – in theory – 3 Thou oversize. This allows the slug to be pushed into the magazine without too much force, yet there’s enough swaging effect of the ammo for the slug to be an appropriately-tight fit into the magazine.

In fact, HAM measured the base of the SLA slugs at a consistent .509 Inches diameter. They inserted perfectly into the magazine – all except one which measured .511 Inches. That did not. The additional 2 Thou made all the difference!

Also we found that longer (and therefore heavier) slugs would not push into the magazines of our gun – even if their outside diameters were also exactly .509 Inches. We attributed this to either the increased friction caused by the longer parallel bearing surfaces of the slugs – or possibly the hardness of the lead. Either way, the friction was too much for the effort that we were able to apply by thumb when pushing the ammo into the magazine.

And yet the slugs must be a “fairly tight” fit in the magazines in order to avoid air blowing past the projectile and loosing power when fired. There’s a very fine balance here between ammo that works and that which doesn’t!

We installed an UTG TBNR bipod to the review Hammer using a UTG M-Lok adapter. This proved an effective and useful support for firing the Hammer from the prone position.

As usual with Umarex products, the Hammer is supplied with a comprehensive and useful Owner’s Manual. It’s in English, French and Spanish and you REALLY need to read this one before operating the gun! (Did we mention this before???).

There’s a 3-year warranty with support through the Umarex facility in Fort Smith, AR. This is where the Hammer is manufactured.

Umarex Hammer .50 Cal CP

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