Clay Shooting - April 2000

EQUIPMENT TEST

Putting replacement chokes under the microscope.

Over the last five years replacement chokes have become big sellers as shooters look for the extra few percentage points to stack the odds in their favour. With prices ranging from around ?15 to ?45 per choke tube they are not cheap, so would you be just as well off with the chokes supplied by the manufacturer? We have gathered together a comprehensive selection and put them to the test.

Even for the experienced shot the choice of chokes available now can be bewildering. Flush or extended? Plain or ported? Is a parallel section better than a continuous taper? Each manufacturer claims to give you the best and most consistent patterns - so how do you choose? We decided to bring all the main brands together on one day and test them. The results of those tests - the product of long hours counting pattern sheets - are compiled here, together with detailed measurements of each choke made with a bore gauge. The results make interesting reading.

The Test

We asked each distributor to supply us with an improved cylinder choke of each type they offer. Improved cylinder (quarter) is probably the most versatile choke for general sporting use and I would guess the most used along with modified (half choke). The test gun was the Editor's Browning B325 (the over-bored model) so all the chokes were supplied in Invector Plus fitting to suit. Bore sizes on all guns will vary a couple of thou or so from gun to gun, so choke makers have to decide on a nominal bore for each gun manufacturer. For Invector Plus most seem to have opted for .740" or .739" as their 'standard'. The test gun measures .740" in both barrels, or 11 thou over the nominal 12 bore measurement of .729". All the patterns were taken using the same cartridge (Rottweil Competition 28 gram, 71/2 shot) at the normal testing distance of 40 yards. We fired five cartridges through each choke before making the test pattern - to clear away any oil residues that might have affected performance.

We were looking in particular at the following aspects of each pattern:

Pellets within the 30 inch circle. The generally accepted figure for quarter choke at this range is 55%.

Pattern density. We were looking for even coverage with no obvious gaps or holes within the circle, especially in the centre area.

Edge density. What was the effective pattern spread for consistent kills?

Flyers. Many makers claim that their chokes reduce the number of 'flyers' - stray damaged pellets which do not contribute to the overall effectiveness of the pattern.

Clearly these results can give only a snapshot of each choke and ideally we would have taken an average of a large number of shots through each one. With ten chokes to cover however, we had insufficient time to go to such lengths for this test.

Back in the workshop each tube was carefully measured with a gunsmith's bore gauge to see if the marked constriction (where shown) matched the actual and to see how each maker had designed the profile. Some have a continuous taper from maximum to minimum bore dimension throughout the length of the tube. Others taper more quickly and then have a parallel section at the maximum constriction. Each maker has his own theories on the optimum profile. We also checked each choke for quality of materials and finish. This is an important factor, particularly in the bore itself, because surface irregularities on poorly machined tubes can have a detrimental effect on performance. In extreme cases plastic fouling from wads can build up until it is cleared by the next cartridge, resulting in sporadic poor patterns from each barrel. We saw this some years ago when testing one of the first replacement chokes on the market against a manufacturer's standard product. In a long run of patterns through the standard choke, results were very consistent until the nineteenth, which was almost unrecognisable. The only two likely causes were fouling build up or a dud cartridge. This kind of occurrence can be the reason for those cries of 'I can't believe I missed that - I was dead on it!' Finally, all the chokes were weighed so you can see the amount of extra weight you will have attached to the end of your barrels (if any). This can influence the handling of the gun. The standard choke weighs 28 grams and most of the replacements are 40-50% heavier. The Kicks is a massive 20 grams heavier, a total per set of 40 grams extra weight at the extreme end of the barrels. Only the Teague flush choke came in at the same weight as the standard Browning.

The Value of Porting

Does choke porting work? I confess I find the science behind the claimed benefits of ported chokes unconvincing and the practical measurement almost impossible. Of the three brands offering ported chokes, two - Rhino and Briley - also hedge their bets by selling plain tubes alongside them. The answer may lie within your head. If they work for you and give you confidence then they are probably worth it.

BRILEY

Briley have four types of replacement choke: Flush, X2, X2 Ported and Spectrum. We tested all three extended models. X2 This is a plain extended choke, with 3/4" (18mm) showing beyond the muzzle. The whole of theextension is neatly milled to give excellent grip whenchanging tubes. The size is clearly printed on the side for easy identification in situ.All screw-in chokes start wider than the nominal bore so as not to form an obstruction on the transition from barrel to choke tube. On the X2 this measures .745". Maximum constriction measured .729", reached some inch (25mm) or so from the muzzle end. This last section is then parallel. Finish quality is excellent. Weight: 40g. The X2 delivered the highest pattern percentage of all the chokes tested at 71% - a full choke pattern.

It was very centre dense and the effective pattern would be 24", with the outer ring patchy. Inside that the results would be puffs of smoke. A great pattern but not necessarily what you would expect or want from a choke marked Improved Cylinder. Out of curiosity we repeated the test with this choke at 30 yards where it gave an astonishing 86% pattern, but still with that dense centre and sparse outer ring.

X2 Ported Identical to the X2 except for the addition of three rows of porting slots which run horizontally (when the tube is viewed in the upright position). The profile is the same but the maximum constriction is .730". Again the finish is excellent. Weight: 40g. This choke delivered a 60% pattern with much less density in the centre and no real 'hot spots', although one or two edge areas were very thin. In practical terms however you would not be expecting much help from the edge of a quarter choke pattern at 40 yards range. In the natural ranges for this constriction of 30 yards and below, this would give good results.

Spectrum In this range only a narrow band of the extension is milled, with the rest given a smart coloured finish, each constriction being a different colour. This is presumably for those too short-sighted to see the large letters IC also printed on the tube! The entrance to this choke measured exactly .740", giving no margin for error on a bore larger than this size. Maximum constriction was .729" and the design is identical to the others in the range. Weight: 40g.
At 55% this was the lowest figure from the aftermarket brands, although you could argue that it delivered exactly what a quarter choke should! The distribution left something to be desired though with significant gaps and no more than an 18" circle with which you could have full confidence. A bit disappointing.

 

BROWNING

This is the standard choke that comes with the gun. The tube is finished in black with rim notches to identify the different constrictions. The entry dimension is .752" and the choke tapers down steadily to a maximum .736".This is only four thou less than the bore dimension not the expected ten. In fact this is consistent across the range of Invector Plus chokes. All of them we measured came out some 5-6 thou less than the expected figure for the markings. Remember though that the only true measure of a choke is how it performs not what is stamped on the tube or the precise measurement.

The finish is rather ordinary and does not inspire confidence. They look and feel a mass produced item. Weight: 28g.The Browning gave the lowest percentage on the test at 52%. Big holes everywhere, with an effective area of little more than 12 inches. Lots of stray flyers were in evidence and large areas of the edges of the circle devoid of pellets. Not a great result.

Price: Supplied with gun. Extra chokes approx ?12.
Distributor: Browning Sports

KICKS

Definitely the most radical choke you can buy! The ported extension measures a massive 11/2" (40mm) beyond the muzzle so you will not be missed when using these. The actual constriction is engraved on the barrel - in this case .728" and proved spot on. The maximum constriction is reached at the start of the extended area which then runs parallel through the ported section. The ports run vertically in alternate rows of three and two which is either deeply meaningful or just looks pretty! Presentation is very good and the machining excellent. Weight: 48g.It gave a 68% pattern, which is three-quarter choke performance, but the pellets showed a greater tendency to be clustered in groups. The central area would stop anything but the outer parts of the circle would not be reliably effective. Like the Briley X2 it would probably perform more like a full choke at normal quarter range.

 

 

RHINO

One of the first brands to make a mark and many people's first sight of ported chokes, Rhino also market plain extended versions.

Rhino Plain Slightly longer than Briley tubes with an extension of 7/8" (23mm). The tube has a knurled rim for gripping and the constriction is identified by black rings. The barrel is marked .730" but measures slightly less at .729" The taper runs from .752" reaching the maximum about an inch back from the muzzle and then running parallel. Nicely made and the bore is very smooth. Weight: 42g. Another centre dense pattern giving 65% in the circle. Several hot spots, so you would get some impressive kills if you put that part of the pattern on the target. Others gave better distribution however.

Rhino Ported With the same dimensions as the plain version but a much thicker extended section with three rows of vertical slots. The keen-eyed will have noticed that Rhino machine their ports the other way up to Kicks. On the face of it the Kicks way looks more logical because it presents a surface for the escaping gases to bear upon. If anyone can throw more light on the subject I would be delighted to hear it. On this tube the marked and measured constrictions agreed at .730" and the profile is the same as the plain version. One downside of this particular choke is that there is no way of identifying them once they are installed in the barrel which can be a bit of a pain. Weight: 44g.Similar results at 64%, but a more even distribution without the tight clusters evident on the other Rhino. It wouldn't be the automatic choice for a target at this distance of course, but at thirty yards you should have a very effective choke with usable pellet density right out to the edges.

 

SEMINOLE

Another American brand, Seminole's selling point for their extended (non-ported) chokes is the colour coded rubber insert which identifies each choke. The extension is 18mm with a generous knurled section.

The entry dimension is .745" and maximum constriction .729", reached about 25mm back from the muzzle and running parallel from there.

Another very high quality piece of machining. There really is very little to choose between the brands in this respect. Weight: 40g.One of the higher scorers at 67% and very solid distribution in the centre 20 inches or so. (This is incidentally no surprise - all shotgun patterns are denser in the centre; it is a mathematical certainty based on the standard bell-shaped distribution curve. The objective is to get a bell which is short and wide, not tall and spiky. For an example of the latter fire a full choke barrel at the pattern plate from 15 yards and see how dense the centre area is.)

There are plenty of pellets around the 30 inch circle indicating very few flyers. A good result.

 

TEAGUE

Britain's answer to the American invasion, Nigel Teague's replacement chokes complement his established work in choke conversions. Two types are currently offered, flush mounted and extended.

Flush
Along with the Briley flush chokes, this is the least obtrusive way to upgrade from the factory chokes. Precision engineered to match the quality of the American products, the biggest drawback is a complete lack of identification marks on both this and the extended version, so you have to take them out to check what is installed. The profile is one long continuous taper from .750" down to .729" at the muzzle. Weight: 28g. A 65% pattern with good spread and very few flyers. The outer ring is a bit patchy but the centre 24 inch circle would do a very solid job.

Being flush mounted like the originals, these are the ones for all you shy types who do not like lots of shiny bits sticking out of your barrels. They will also not change the handling characteristics of the gun. Would I continue to use the standard manufacturers' choke when these are available for ?15-21 each? No I would not.

Extended
A modest extension of some 1/2" (12mm) with the whole area knurled for easy gripping. Again it is a continuous taper design down to .729", but with a more gradual taper thanks to the extra length. Weight: 36g.A slightly better performance in terms of percentage at 69%, although the extra pellets are probably just adding to the centre of the pattern. As with the Briley X2, you can admire the quality of the pattern but question whether it is in fact delivering quarter choke performance.

 

 

 

 

Conclusions:

Whenever we go to the pattern plate we come away with food for thought. If nothing else it shows that you should take nothing for granted with your gun and you should test it with your favourite cartridge so that you know just how it is performing. If nothing else you will probably surprise yourself just by accurately measuring 40 yards out on the ground.

This test has shown that the boom in replacement chokes is not just a fad. All the chokes featured here outperformed the standard Browning product. I have often wondered why some of the gun makers pay so little attention to chokes when they have such an impact on the performance of the gun, yet are a relatively small part of the overall cost. It is a bit like putting cheap remould tyres on a sports car. All of them delivered higher pattern percentages than the nominal 55%. This supports the claim that pellet damage is reduced, putting more to effective use, especially with a good quality cartridge using hard shot. None of the brands did badly, although we were surprised by the difference in performance between the two non-ported Briley products. However as we said earlier it is unwise to read too much into the detail of the result without a bigger sample of patterns. From our brief test, any one selected from the Briley X2 Ported, Rhinos or Seminole would give good results and the choice may well come down to a preference for the appearance of one over another. Alternatively you could take appearance out of the equation altogether and go down the flush mounted route. This - and the relatively low price - makes the Teague flush fitting chokes our 'Best Buy' this time around.

 

Produced by Brunton Business Publications Ltd.
email:info@clubclayshooting.com

 

 

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