[Autolite]

I don't know nothin' bout scatterguns so I'm hoping y'all can give me a clue.
I am looking at a Valmet H1950 over/under 12 gauge. I would like to know whether it is a full choke, modified, or cylinder. On each barrel, near the breeches, there is a stamp that reads 'F18.4'. Can anyone tell me what this signifies. Also, there is a stamp that indicates that the gun is a '12/70'. What does this indicate. Any help would be most sincerely appreciated. Thanks ...

[SDC]

The "12/70" just means that that firearm is chambered for 12 gauge shells that are 70mm (2 3/4") long when fired; as for what it's choked, the only REAL way to tell is by patterning it. You can take two "identical" shotguns off the rack, and one will pattern to one side of what it's marked, and the other will do the exact opposite. "F18.4" is a measurement of the interior constriction of the bore at a specific distance from the breech, but I don't have any idea what it translates to in North American usage. HTH.

[Spinner]

I'm also interested in the interpretations of the 'F 18.4' designation.

I have a Bettinsoli O/U with one barrel marked 18.4 and the other marked 18.3. Being Italian I figured it probably related to a metric measurement of choke. Near as I can figure 18.4 mm equates to 0.724409" and 18.3 mm equates to 0.720472".

What's the nominal size of a 12 gauge bore - somewhere around 0.7" isn't it?

I haven't been too worried what it meant as my crude attempts at patterning so far have suggested its choked about 1/2 and full. I've now made up a pattern board and I'm planning to get a bit more scientific about the whole patterning thing. Still .... it'd be interesting to know what patterns its supposed to be throwing.

Spinner

[Dave McCracken]

The 18.4 is a bore diameter. While the 12 gauge is supposed to be .729, Italian bores have typically run tighter, down to about.720" or so.Pattern to find out the chokes, like SDC said.


Those Valmets have a following that's almost a cult. Some models have hangers like the Kolars that can adjust one barrels' POI. A durable gun too.

HTH...

[Autolite]

I think you're on to something here. I have a Rem 870 12 gauge with a 'cylinder' barrel and I have just measured the muzzle bore. The measurement is just a hair over 18 millimetres (0.710 inches). Converting the inches to metric gives us 18.034 millimetres. Starting to make sence. But what does the 'F' stand for? Does anyone know what the word 'barrel' or 'bore' is in Italian? Maybe this Valmet has Italian barrels???

[SDC]

The Italian word for "barrel" is "canna", but I don't think that helps. If it's Finnish, it should have standard Finnish proofs on it (something like a lion's head from the side, wearing a crown and sticking his tongue out).

[Spinner]

Well, just to confuse I had another look at my Bettinsoli and the barrels have stars stamped on them as well as the 18.3 and 18.4.

I found this reference among Chuck Hawks pages

http://www.chuckhawks.com/shotgun_chokes_exp.htm

My bottom barrel is marked with 3 stars, the top with one. According to the table given by Mr Hawks that makes them 1/2 and full or pattern percentages of 60% and 70% respectively. This ties in with my limited attempts at patterning.

So .... maybe the 18.3 and 18.4 doesn't have anything to do with nominal choke. Check to see if there are any stars stamped on them barrels.

Spinner

[Traveler]

The numbers (18.4 et al) are nominal bore diameter. The stars are the choke designation. As noted one star is full, three is mod. The Valmet should have the chokes marked in a similar manner, but usually by the ejectors. I cannot remember ever running across one that did not have the choke maked in some manner (exception being those with removable chokes).

[Autolite]

Traveler, Spinner, SDC, Dave McKracken, for your posts. They were of tremendous help. I was particularily happy to read Traveler's last post as it verified what I was beginning to suspect. It was very important that I solve this choke question. This shot gun was used to fire slugs and "bird fright" that is not supposed to be fired through a choked shotgun. The '18.4' stamp indicates a dimension of .724", very close to our nominal reference 12 gauge bore of .729'. Just today, I decided to check the bore at the muzzle with calipers. Lo and behold, both muzzles measured .680".
Then it occured to me that the '18.4' figure just might be the nominal barrel bore. Again, thanks to all for the help, it is much appreciated...

PS: As for additional markings, this Valmet has three individually "boxed-sevens" stamped around the '18.4' stamp...

[Spinner]

That bore measurement you made (0.680") gives it a 0.044" constriction from the nominal 0.724" (18.4 mm) bore. I'm picking you'll find that gun shoots full choke patterns, but the only way to be sure is to set up a pattern board and try it.

BTW the stars stamped on my barrels aren't particularly obvious .... they're there but they don't leap out at you .... and if its full choke you're looking for only one star.

Now that we've sorted out the 18.4 and 18.3 stamped on my Bettinsoli and the nominal chokes, I just have to work out what the other stampings mean. The bottom barrel has CAM 70 stamped on it (I'm picking that's a reference to a 70 mm or 2 3/4" chamber) and the top barrel has KG1 550 stamped on it (its not a metric version of barrel length). Oh well, guess I'll just shoot it anyway ;)

Spinner