In the Big Bertha OS irons there’s an all-new clubhead construction, called the Exo-Cage, which is an ultra-light yet strong.
It allows Callaway engineers to distribute more discretionary weight into strategic locations to promote more forgiveness.
In the Big Bertha OS hybrids, easy launch and more forgiveness is achieved through a deeper body and a larger faster face.
Callaway say they have improved ball speeds right across the clubface for improved performance on mis-hits.
A larger and more flexible face gives players more area to make contact with and the added flexibility pushes the COR (energy return/trampoline effect) closer to the USGA limit, promoting faster ball speed for more distance.
Refinements to the head design include a longer heel-to-toe length that allows for a larger and more forgiving face.
Callaway Steelhead XR vs. Big Bertha OS – The results
Both these sets of irons and hybrids are really good fun because they are easy to hit and go a long way. They do exactly what they are supposed to do.

Both irons were carrying a little bit further than what I’d expect from a 7-iron. There wasn’t a lot to spit the numbers really.
With the hybrids they were again carrying a bit further that what I would expect from a 19˚ hybrid. From what I’m currently used to, I’d expect more like a carry of 190 and a total of 200.
With these I was regularly carrying it over 200 yards which was really pleasing for me.

Callaway Steelhead XR vs. Big Bertha OS – NCG verdict
I’d slightly favour the Steelhead XR irons over the Bertha OS because I prefer the looks sound and feel. They were both very easy to hit and forgiving – I really couldn’t split the performance.
I did just prefer the overall looks of the Steelhead XR more than anything.
With the hybrids, the Bertha OS just seemed that little bit easier and more fun to hit and was carrying a little bit further.
This club was really good fun, it filled me with loads of confidence and just seemed to absolutely fly off the face.
The irons didn’t make me think like I desperately needed either of them in the bag. But the Bertha OS hybrid needs to go in because I feel like I’ll be able to rely on it for those long second shots on tough par-4s.
It will also be great for me off the tee on short par-4s and long par-3s.
I’d really look forward to any occasion where I could hit it out on the course.
Details
Steelhead XR irons (7 irons):
£649 (steel), £829 (graphite)
Hybrids: £199 each
Big Bertha OS irons
£799 (Steel), £999 (Graphite)
Hybrids: £229 each
More information can be found on the Callaway website.