Park in Cronins Yard V83665 87340 A where there is pay parking (2€ per day) and room for 50 cars.
There is also a seasonal Tea room and toilets.Walk through the gate passing a wall of plaques to your left , follow the track through another gate and over a stream. The path becomes loose pebbles, turn left just before the first bridge crossing to a stile at V83070 86411 B. Follow the stream edge from here before turning off to the left aiming for a noticable line of rocks that descend from Lough Cummeenapeasta. Follow this line up to the Lough.
Ascend eastwards over large rocks, it is easier to use these to step on rather than picking your way around them on the scant loose soil.
The summit of Cruach Mhor is marked by a large grotto with a brass statue of the Virgin and Child.
From Cruach Mhor though it looks daunting start by following the ridge crest then following the faint track down and along under the northside of the ridge by-passing the first 2 rock outcrops.
Where the path divides to an upper and lower track take take the lower one. Start to ascend at V84039 84575 C where the track to the col with Knocknapeasta is steep but obvious.
From this col the ascent to the summit of the Big Gun is a matter of heading back along the crest of the ridge and not nearly as difficult as a direct assault from the east.
This place is not for the faint-hearted however but it is special. Linkback: https://mountainviews.ie/summit/10/comment/4770/

Early morning start on Friday 27th May. I followed the route described in Adrian Hendroff's The Dingle, Iveragh & Beara Peninsulas Book. A bit of a trudge up to Lough Cummeenapeasta but from there almost constant stunning views and interesting terrain. While resting on Cruach Mhor the ridge across to The Big Gun looked daunting but following the detailed directions in Hendroff's book I bypassed the majority of the difficulties. I scrambled the last section up a lockstep, which he describes, this isn't difficult but has a very "airy" quality to it. Clouds back by the time I got to the summit but finding the correct arête towards Cnoc na Peiste wasn't difficult. I followed the intermittent path on the Lough Googh side which brings you right up to the summit of Cnoc na Peiste, continued on to Maolan Bui and down The Bone. This is a spectacular walk/scramble for good weather and a reasonable head for heights. Linkback: https://mountainviews.ie/summit/10/comment/23524/

I started at 6.30am from the parking lot on the west side of the Gaddagh River (i.e. the parking area due west of Cronin's yard, typically used for the Shea's Gulley route to climb Carrauntoohil). From there, I followed the path to Lough Callee, and from there headed in a south easterly direction, ascending the Bone to the summit of Maolan Bui. This part was the most physically demanding part of the trip, as it's a pretty continuous climb, and I had not picked up the trail, so it was a mix of walking on a grassy slope and scrambling on rocks. The ridge from Maolan Bui to Knocknapeasta is a pretty straightforward walk, but things get a lot more interesting from there. From Knocknapeasta to the Big gun, the ridge is nothing short of spectacular. The views are fantastic, and the exposure on both sides will certainly test your head for heights. The only exposure that I have experienced in Ireland that comes close is on a short section of Sliabh League in Donegal. I stayed on the skyline as much as possible, which meant a few interesting downclimbs to deal with. The ascent up the southern slope to the top of the Big Gun is fairly straightforward, and from there had a short steep descent to the ridge heading over towards Cruach Mor. This ridge does not have as much exposure as the section between Knocknapeasta and Big Gun, as it is a broader ridge, with a flatter top, however if you stick to the skyline, it is more interesting (and challenging) due to 3-4 sections where you have to downclimb approx 10 ft drops - does not sound like much, but a fall could mean you tumble a long way before stopping! After the summit of Cruach Mor, there is a long slog back to the starting point. Descending the ridge in a northeasterly direction from Cruach Mor, a fence marks the spot where you turn north, and begin the descent back towards home. When you reach the point where this slope starts to flatten out, turn north west for a squishy walk (or run!) through bog to the point where the Cronin's yard trail crosses the Gaddagh river. From there, cross the river, and pick up the trail that brings you back to the parking lot. This was a great loop to do on an early weekday morning. I was the only person up there, and got back to my car by 10.15am, just in time to make breakfast (barely!) back at the B&B in Beaufort.

See the following link for a route map (under the "map type" drop-down, best to view as "satellite map"):
http://www.mapmyrun.com/hike/ireland/killarney/559125146044060028 Linkback: https://mountainviews.ie/summit/10/comment/4058/

A view of the Big Gun, Cnoc na Péiste and the southern ridge of the Reeks taken after a light fall of snow in late January 2017 Linkback: https://mountainviews.ie/summit/10/comment/18840/

The Big Gun taken from the col under Cruach Mhor with Cnoc na Peiste in the background on the right. If you've got the nerve go over the top or as close to it as you can manage (which will be scrambling rather than hill-walking)-really the only other option is to drop down about 150 meters on the north side and try to find the track across to the col before Cnoc na Peiste, you will have to go down below the blocks of rock sweeping down the sides.We could see no other obvious route across. The Big Gun is absolutely the most challenging climb I have done in Ireland - we crossed in calm weather during a dry August afternoon - if you were to attempt it in more difficult weather/wind I think harnesses/ropes etc. would be needed. When ever you attempt it a good head for heights and good route finding skills will be needed. - Linkback: https://mountainviews.ie/summit/10/comment/1149/

The second summit on our traverse of the Eastern Reeks, and probably the most frightening mountain I've ever done. Looking at the ridge over to The Big Gun as we ascended Cruach Mhor, it seemed impossible. All our concentration was required for the last part of Cruach Mhor from Lough Cummeenapeasta, but that ridge was lurking in the back of our minds. Thankfully, when we actually set off we were able to see a way ahead, below the ridge, on the northern side. We dropped down a good way to avoid the steeper parts, actually by-passing the summit, before ascending to a point south west of the top. So far it had been easier than it had looked, and had never felt dangerous (apart from the danger of precariously poised rocks above us). Doubling back to reach the top was probably the scariest experience I've ever had on a mountain however, and I really wouldn't want to attempt anything worse or similar. The rocks were wet and slippery, it was windy, the ridge was narrow,steep and exposed, and visibilty was poor. I'm glad I bagged the Big Gun on this attempt as it would take perfect weather to make me consider it again! Don't let me put you off though: I'm a walker not a climber, not cut out for peaks like this, and there are people who just find it exciting. No photos from the top as it lashed with rain from Cruach Mhor all the way to Knocknapeasta, and I couldn't take the camera out without it being ruined. The clearest view we had was just before leaving Cruach Mhor. Linkback: https://mountainviews.ie/summit/10/comment/18189/