Products
2,548 Brands 529 Categories All Departments
Sightmark OPMOD™ G.U.M.B. 1.0 Limited Edition Green Universal Boresight OP39025 w/ Free S&H
$74.99 $95.99 Save 22%
Browse by Rating
(15 reviews)
Share your Thoughts! Write a Review
Most Helpful Positive Review Good idea
For what it was designed for, it is what it says. "It helps get you sighte...
Read More...
Most Helpful Negative Review Very good boreaighter
I love this product.But I hate glock please whatever you do do not buy a gl...
Read More...
Sort by
Show
Page
Back
Next

Good idea - needs better execution

by Cat Herdr, from United States, GA Written on April 10, 2015
Received with the switch in the "on" position, so the battery was dead. I live in a rural area, so had to make a trip to a big-box electronic store 35 miles away to find the correct lithium battery. The flat magnet that attaches to the barrel has painted on rings to aid in centering to the bore, but after it attaches to the barrel, it is hard to tell if the laser is concentric with the bore. If it is not centered on the bore, then you can't align the scope with the bore center-line. You CAN get close.

I have used up another battery, apparently by switching the laser on while it was in it's nylon case in the box. The switch is more positive in operation than the screw-on type my other laser bore sights use, but is prone to turning on in routine handling. Not the best idea with a laser capable of causing eye damage. A retractable centering cone on the base and a more robust switch would go a long way to making this the perfect laser boresight....
Would recommend: Yes
0 of 0 found the following review helpful.
Was it helpful to you? Yes / No

Great Tool

by George, from United States, FL Written on March 3, 2015
Excellent tool for pistols and rifles. Laser light could be seen indoor and outdoors out to 50 yards. It is one boresight for pistols and rifles. Easy to use with Laser sights.

Used to boresight 308, 556, and pistols from 45acp to 9mm....
Pros:
  • Use on all calibers, rifle or pistol
  • Seen up to 50 yards out
Cons:
  • Barrel connection is not percise as it attaches to end of barrel.
Would recommend: Yes
0 of 0 found the following review helpful.
Was it helpful to you? Yes / No

Very good boreaighter

by I hate glock pistols, from Albania, reproach Written on February 20, 2015
I love this product.But I hate glock please whatever you do do not buy a glock.The guns are not American made!guns are junk ! Do not I repeat do not buy Austrian made garbage!Please don't buy any glock for the reliability bull....
Would recommend: Yes
2 of 10 found the following review helpful.
Was it helpful to you? Yes / No

awesome boresighter!

by glockssuck, from United States, AA Written on February 18, 2015
Highly recommend! Greatboresighter is very close on sighting in at 100 yards! Please dont buy glock hangun...they are unamerican pieces of garbage! I just think glocks are so overrated guns!If you even think about glocks than im done!...
Would recommend: Yes
1 of 4 found the following review helpful.
Was it helpful to you? Yes / No

It gets you on the paper

by hdgypsyman, from United States, MN Written on January 26, 2015
I have used this on several guns since I bought it to do the initial set up of a scope or red dot. It seems to work good enough to get you where you need to be On the paper) so you can finish dialing it in on the range....
Pros:
  • Adapts to many calibers
Cons:
  • Tough to get centered on the bore
Best Used for:
  • Initial set up
Would recommend: Yes
2 of 2 found the following review helpful.
Was it helpful to you? Yes / No

Gets you close

by Hman, from United States, OK Written on December 5, 2014
This laser magnetically attaches to the end of the weapon's barrel. Very easy to see when changing the weapons windage and elevation. Only thing left to do then is fine tune on a range with live ammo....
Would recommend: Yes
1 of 1 found the following review helpful.
Was it helpful to you? Yes / No

Great Product

by Rick, from United States, WA Written on December 4, 2014
This is a great aide as a quick bore sight. I own and shoot many different types of handguns. I use it as a quick sight test when going from one pistol to the next. Green dot shows up easily at 40yds. Have not tested it beyond the 40yds. Well worth the money and a nice tool to have....
Pros:
  • Very easy to setup and use
  • Very strong magnet
Cons:
  • None
Best Used for:
  • Quick bore sighting
Would recommend: Yes
0 of 1 found the following review helpful.
Was it helpful to you? Yes / No

easy to use

by bobbybeegood, from United States, FL Written on December 4, 2014
Easy to use. Snaps easily on the end of the barrel via magnet. The laser could be a bit brighter. Difficult to see in the bright sunlight. It gets you on the paper but you have to walk in the zero. I spun the Boresight in a circle on the end of the barrel & the dot never moved from the same spot. For what it is; it does very well....
Pros:
  • Easy to use. Attach to muzzle and go!
  • Keeps zero.
Cons:
  • None
Best Used for:
  • Boresighting
Would recommend: Yes
1 of 1 found the following review helpful.
Was it helpful to you? Yes / No

Breakthrough in Bore-sight Technology

by Doc Sparks, from United States, OH Written on November 18, 2014
I own and have experimented with, a lot of gadgets to help align sights and point of impact for long rifles, carbines and handguns. The Sightmark G.U.M.B is truly in a league by itself. It works on the simple premise that the muzzle of your gun is exactly perpendicular to the bore of the rifle ... a pretty good assumption for new or well treated guns. Prior to this my go-to bore sight was one that was fitted into the barrel at the breech. They used a ruby laser to shine down through the barrel and an project an alignment mark on a target. You then dialed-in iron sights, red-dots or scopes. Works well, but each caliber requires a separate laser bore sight and the ruby laser doesn't project all that far. The Sightmark G.U.M.B. changes the game. It simply attaches to the muzzle with a very strong magnet and projects a green laser beam visible up to 50 yards! I had just acquired a new scope for my Henry Golden Boy and used the Sightmark bore sight to zero the scope. Ata range of 50 yards the first shot was well low of the crosshairs (.22LRs drop about 4" at that distance) but the windage was within 1/2" of the bullseyeI I could hardly believe it. Two more shots and I was sighted in!! This thing will pay for itself in ammo cost especially on hunting rifles. I tried it on my 30-30 Winchester. At 100 yards the first shot was 1.5" left of the crosshairs and 4" low. Again the scope was aligned in three shots. I am very very happy with this product. Well worth the money. However, i...
Read More...
Would recommend: Yes
4 of 4 found the following review helpful.
Was it helpful to you? Yes / No

Why wouldn't you save ammo by using this?

by Jesse Tischauser, from United States, OK Written on October 2, 2014
This is the first laser bore sighter I have ever used. I love it! I build 10-15 new AR15 type rifles a year. Why I didn't have one of these in the past to site these new guns in I don't know.

The only complaint is the battery compartment is a little flimsy....
Would recommend: Yes
1 of 2 found the following review helpful.
Was it helpful to you? Yes / No
Page
Back
Next

Comments on 15 User Reviews of Sightmark OPMOD™ G.U.M.B. 1.0 Limited Edition Green Universal Boresight OP39025 w/ Free S&H