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Swapping your rifle scope

The ability to swap scopes between rifles is not a new concept and has its benefits as well as its negative points.

If the calibre is correct, a swift change of optics means the same rifle can become both a long-range fox gun, hill rifle or close-quarter woodsman, negating the need to carry two types of rifle.

If damage is incurred on a stalking trip, a spare scope can easily be replaced with a pre-zeroed substitute, or, as a precautionary measure while travelling, the scope can safely be stowed away, free from knocks and scratches.

To achieve interchangeability, however, the scope rings and mounts have to be very well made to ensure an absolute non-shifting zero when they are removed and remounted.

Fortunately, GMK recently lent me a pair of Leupold quick-detach (QD) mounts to test. I was impressed by their quality, but rather than test them alone I got two sets of QD Warne mounts from the Sportsman Gun Centre. These are the major players, and both are readily available.

Sticking to your guns
I wanted to devise a system that would test:
1. Whether two differing scopes with pre-zeroed reticules would return to zero on the same rifle.

2. Whether the same scope would maintain zero after being removed from and reattached to the same rifle.

3. Whether the scope would maintain zero when used with different bases.

4. The QD capabilities of rifle-specific mounts, i.e. Tikka only.

Through the use of computerised machining techniques, close tolerances in manufacture and relative low cost, both Warne and Leupold are able to produce first-class products.

Not only do they work well, but also have a good finish and positive operating lever.Both share a common mounting system, generically called a ‘Weaver’ base.

This allows the scope rings to fit not only their own bases, but also most other Weaver-type systems. At the base of each ring set is a cross-bolt configuration that slots precisely into the base unit attached to the rifle, thus helping to ensure a more uniform alignment.

Warne mounts
I had two sets of these US-made mounts to test: one, a Weaver-style base connection unit with QD facility and 30mm ring sizes, priced £69.99; the other, Warne Maxima rings, for Tikka, attached directly to the rifle’s integral scope rail and is priced between £49.99 and £94.99, depending on height and ring size.

In both cases, the Warne rings are distinct from the Leupold in that they are split vertically rather than on the more conventional horizontal. There are aluminium or steel ring sets. I prefer steel for full-bore use and aluminium for rimfires.

The bases come in two pieces, meaning they mount fore and aft of the receiver, and are not one continuous length. Screws used for both the rings and bases are of the Torx style, with a star-shaped head rather than a hexagonal Allen key arrangement.

A Torx wrench is supplied, claiming to offer 25 per cent more secure grip. A QD attachment lever is sited to the right of the mount and it is this that securely clamps the rings to the base units.

To mount the scope, simply remove all the Torx screws from the ring set, thus separating the two halves, then place the scope with its saddle at approximately the correct eye relief or position. Rejoin the two halves, making sure the cross-bolt is aligned, and tighten the bottom screws fully.

Now place the scope plus rings on to the bases attached to your rifle, making sure the cross-bolt is pushed forward to contact with the front of the cross slot machined in the base.

Tighten the side-lever and repeat for the other ring. As the top screws are loose, you will now be able to manipulate the scope on the rifle to the most comfortable position for your style of shooting. Once you’ve done this, tighten the top screws.

Because the two top screws and bottom screws act independently of the attachment lever, you can loosen and tighten the scope from the rifle without it becoming loose with the rings.

The Tikka mounts that go directly on to the rifle’s scope grooves are the same, but there is no cross-bolt location, only a QD lever operation. Common to both is that, once tightened, the QD lever may finish in different positions and thus look a tad untidy, but simply pulling on the lever allows it to move outwards, then on return it freely rotates, utilising a battery sprung-loaded system, so that both sets can be aligned and keep a good-looking appearance.

Leupold mounts
The second set of rings and bases on test came from US scope-maker Leupold. Known as QRW mounts, they were priced at £59 for rings and £43 for a two-base set. These also had Torx screw fittings for both rings and bases, and were available both in 1in and 30mm ring sizes and many differing height configurations, like the Warne mounts.

The bases and rings are both constructed from steel and the bases are two-piece units that accurately screw to the rifle’s receiver using the Torx screw system. The rings are split on the traditional horizontal axis and have four Torx screws apiece, and a similar QD lever-securing attachment. By loosening these levers with two or three turns counterclockwise, both bottom halves of the rings can be secured to the bases on the rifle. Again, make sure the cross-bolt is snug up against the corresponding slot in the base.

Place the tops to the rings on the scope and, once the correct eye relief and vertical reticule alignment is achieved, rejoin the two ring halves using the Torx screws. As with the Warne scope removal is easily achieved by loosening the side QD lever and lifting the scope off the rifle.

Both systems had little to choose between them with regard quality of build, which was excellent, but what I was really interested in testing was how they fared in the field.

Field trials
I chose two rifles to test the mounts in order to cover two shooting styles. One was a Steve Bowers Custom RPA switch-barrel foxing outfit in .17 Rem and .20 Satan, and the other a Remington .260 stalking rifle.

The first test was to check the accuracy of maintaining zero when removing and reattaching the same scope to the rifle many times. I used a Swarovski scope for testing with both the Warne and Leupold rings.I zeroed the Bowers Custom at 100 yards with the Leupold mounts first and achieved consistent 0.75in groups centrally placed on the target.

I then removed the scope and replaced it, keeping a slight forward pressure on the mounts as the QD lever was tightened. I shot a second group using the same ammunition, range and, as far as possible, wind conditions.

The group did not deviate from the first group by more than 0.25in. This was repeated for 15 rounds (five three-shot groups), allowing time for the barrel to cool down, and the same results were achieved once again.

I then cleaned the rifle and attached the Warne bases and ring set, and shot exactly the same regime. Results were identical and proved that both systems and manufacturers could guarantee that their products return to zero.

This was repeated with the .17 Rem calibre RPA rifle, with the same accurate, unerring results. The next test was the switching of two scopes to achieve a fox-cum-deer rifle on demand. I used the Remington .260 rifle, coupled with a Leupold 1.25-5×20 compact scope for woodland deer use and a Kahles Multi Zero for longer range deer or fox use.

I zeroed each independently to point of aim at 100 yards using Remington 120-grain factory ammunition.

The same regime as the first test was used and, despite the weight difference and balance issues from the two very differing scopes, here again was only a minimum shift of 0.5in or less between each group – perfect.

Finally, I switched the mounts between each base, i.e. put Leupold rings on Warne bases. I found no obvious signs of deviation, which were all good; the only slight zero change came when I used some aluminium Weaver-style bases on the .260 rifle and then mounted the steel rings from both manufacturers.

Because the tolerance was different, there was a measurable shift in zero, by approximately 1in in some cases, which proved interesting. For best results, I conclude you should use bases and rings from the same manufacturer, or at least do not mix steel rings with aluminium bases where you can help it.

The QD 30mm Maxima rings on the Tikka also proved accurate at returning to zero after removal and reattachment of the scope: there was less than 0.5in to 0.75in maximum deviation between groups shot.

Because these rings fit directly to the rifle’s own receiver, to achieve maximum accuracy it is important to position the scope and mounts in the same place or positive stop each time. In addition, keep the grooves or dovetails clean of debris between scope-mounting, otherwise this will interfere with your zero.

As a convenient way to store, change roles or clean your rifle, the QD scope mount system from both manufacturers certainly sold the idea to me and makes for a confidence-inspiring and versatile shooting arrangement I intend to use in the future.

Leupold – GMK, tel (01489) 579999;

Warne – Sportsman, tel (01803) 558142;

Remington ammunition – Edgar Brothers, tel (01625) 613177

Steve Bowers custom rifles, tel (01242) 863005.