Manipulating choke performance

I found a fantastic antique 16b percussion double that I just have to adopt. Only concern is the choke. The seller says its FULL/FULL. Just for details, this has 26 3/4" barrels (marked in mm), and they're damascus. It is a very high-end English gun. Just shy of 6-pounds weight and it seems to fit me okay. So - I would use this for upland game and in particular, woodcock and quail with an occasional pheasant. I don't really want to alter the physical choke. What are your ways to open the pattern? One thought was to put an over-powder card than then take two cards and cut slits. Make an "X" out of them and push them down slowly. Then pour the shot and put over-shot card. The four compartments with the shot are said to spread the shot. One guy uses a thick fiber wad and actually uses a drill to make multiple holes not quite all the way through. The shot finds its way into those holes and supposedly spreads when the wad leaves the muzzle. I don't know. I kind of wish this gun was choked cylinder or no more than IC for what I want to do with it. Any manipulation of the components will be tedious and slow, and generally a pain, however I don't want to mess with the metal if I can help it. What do you think?

Just put more powder to shot ratio. Simples.

You may also find some shot sizes create a larger spread of shot than other sizes.

Shoot it at a patterning board before you get to worked up over it.

A full choke in a muzzleloader with no shot cups and other pattern tightening modern "enhancements" might not shoot as tight as you fear.
Slightly more powder should open the pattern a bit. Larger size shot will give you less shot in the pattern, thus less shot to pick out of your game....

I have a super tight unmentionable that I shoot really well with and it's chokes are not a hinderence at all. Some cartridges shot mod choke patterns.
Don't turn it down due to choking.

Re the metric markings. Sounds like of European manufacturing than of English but it don't matter none. Probably better in that it may have brazed barrels over softer soldering.

Not to sound like a wise guy, why not just wait a litlle longer before you shoot? That way the bird will be further away and your pattern will open up more.

Spark, there used to be a company the made plastic "X" inserts for modern shotguns, not sure if the still make them. Another company made a plastic disc to press into the shot before crimping, never cared for the pattern they threw, but you could probably replicate with a hard fiber wad over the shot. But realistically, i dont think you can wide patterns from that gun you are hoping for like you would from a cylinder choke.

erhunter said:

Not to sound like a wise guy, why not just wait a litlle longer before you shoot? That way the bird will be further away and your pattern will open up more.

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Never found that to work well somehow.

The gun is made by a high end British firm, but the Seller has listed the bbl length in mm. There’s no actual length on the barrels. While the locks and barrel are properly marked with maker and address, they are a weird length for a British gun, but show no sign of being shortened. London proof marks. Also, the Seller is saying it’s full/full because that is what the measurement would be in a modern cartridge 16b. I have dozens of photos but the detailed info is what the Seller says. I may buy it and carefully go over it during the 7-day inspection. Seller also said they (the company) haven’t shot it. However they recommend separating the shot in 1/3 or 1/4 portions by adding a thin card wad. In other words, stack the shot/card. This company is well known as “experts” in antique guns. Take that with a grain of salt. I’d not heard if separating shot like that.

Here are some photos…

Lovely gun.

My apologies for mistaking the metric thing and assuming.

I have heard of stacking the shot in compartments but what a pain.

Personally, I would worry more that it fitted me and then shot where I was looking.
Best wishes.

No way I could take that beautiful gun hunting Woodcock hunting. One season and I'd have it full of nicks and scratches.

Spreader loads used to be a standard offering from Rem. and Win. for smokeless breachloaders. The paper cruciform inserts shot lousy pattern in my experience but they worked. I don't know why you couldn't pre-assemble plastic shot cups with shot and spreader X's and an inverted shot cup to hold it all together. Would make field loading easier. Beautiful Manton double!!

TrophyGuy said:

Spreader loads used to be a standard offering from Rem. and Win. for smokeless breachloaders. The paper cruciform inserts shot lousy pattern in my experience but they worked. I don't know why you couldn't pre-assemble plastic shot cups with shot and spreader X's and an inverted shot cup to hold it all together. Would make field loading easier. Beautiful Manton double!!

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What....and load all that past a full choke!

Britsmoothy said:

What....and load all that past a full choke!

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I would. There is no telling what the actual constriction is. Many shot sleeves are pretty squishy, and Ballistic Products has quite a variety. If that Manton were mine I would do some load development and patterning before whittling on 175 year old pattern welded (Damascus) barrels that are very likely quite thin walled on an ultra high quality British best gun like this. There's only one shop in the world that I would trust to ream them and they might not take the job for liability reasons. Of course the owner can do as he wishes, but a split barrel on this piece is an un-recoverable situation. You could sleeve the barrels with fluid steel tubes, but much value would be lost and it would be shockingly expensive.

You can take a post wad that is made to spread shot then cut off the shot cup and base just leaving the part with the post and base at its bottom and it should go past chock easily and it will spread the shot

Opening patterns : higher muzzle velocities , smaller shot sizes , softer lead ( no antinomy ) , all open patterns up , The full choke is often more of an indication of muzzle size than pattern ,Spreader wads in the shot do work but are a real handful in a muzzle loader . Id suggest you do some patterning before trying to open things up . Manton made great quality firearms , the hammers are unusual and interesting

I've got a fowler with the Colerain turkey choke, which is extra full full. If I load it with an over powder card/wad, shot, over shot card, it will hold a super tight pattern past 30 yards. I found if I use wasp nest over powder, shot, then wasp nest over shot that the pattern opens up similar to a modified choke at 30 yards.

Someone needs to verify that the barrels are actually choked as stated. A measurement of the bores ahead of the chokes needs to be determined. They might tight bores without chokes at all.

Well mine is definitely a choked 20 gauge and is choked down to .569 at the muzzle. It would be tough to get a .570 bare ball in the muzzle, although I wouldn't even try. Colerain says "Shot Only" tight constriction does not allow anything other than shot.