BPS; Barrel Choke Question

[Pahoo]

First off, let me say that I just have a general knowledge of shotguns and trying to help out a friend to identify this shotgun.
Have a 12ga. Brownning BPS, that I cannot identify the choke and there is also a selector on the magazine tube that is marked "R" and "S". Figured out that this is for single shot and repeat but why is it there in the first place. The barrel is a fixed choke has a vent rib but not marked with what the choke is. There is an "NP" stamped on the bottom of the barrel. Here is the info stamped on the gun. Sure would appreciate your experties.

BPS, Special Steel, 12GA. 2-3/4 & 3", Feild Model - 30"
Browning Arms Company, Morgan Utah, Made in Japan

 

[Omaha-BeenGlockin]

Sounds like you have the Trap model.

Oopppss---read more----maybe not with a fixed choke.

The choke designation might be found if you remove the barrel.

NP=nitro proof---I think??

 

[BigJimP]

The Browning BPS was first introduced in the late 1970's as I recall. I have a couple of BPS's - but frankly, I may not have bought them until the mid 1980's ( don't remember ) but neither one of them have the selector on the mag tube ( or if they do, I've forgotten its there ...).

My hunch is that selector will shut off the mag from feeding into the receiver - so if you fired one shell - you could drop another shell into the receiver by hand - and still keep the shells in the magazine. In the field a gunner might load a # 6 in the chamber, and a couple of # 4's in the mag - and if you wanted to shoot a 2nd shell of 6's I suppose in principle, you could turn the mag selector - and eject the spent shell without dropping a shell into the receiver from the mag at the same time - turn the gun over and drop another shell into the receiver and cycle it into the chamber.

The "NP" has to be an old holdover from the proof mark days .......I'll have to check my guns tonite and see if they have it ( I think they still do have the mark ).

The choke on the barrel has to be marked - maybe some stars on the barrel - after you remove it from the receiver.

 

[classic095]

choke

See if a Dime slips down the barrel,, if not, its as full choke...Barely misses the insides of the barrel , Modified,, wobbles like crazy in there, Cylinder,,

 

[oletymer]

If you look on the right hand side of the barrel there is text like BPS special steel and so on. The line of text has astericks in front of it. One asterick is full choke, two is modified and so one. For get the dime idea as that is from a time when people did not realize that constriction in the choke compared to the bore of the barrel is what constitues actual choke.

 

[classic095]

choke

The DIME is good if you dont have the gauges to determine the actual choke on a shotgun.. I run across many shotguns at the skeet and trap range that I run that dont have choke markings on them,, the dime is very expedient in determining if its a full choke or not.. Other than that I use a digital micrometer to determine the actual constrictions..

 

[Pahoo]

WOW

Collectively you guys have given me the information I needed and it sure is appreciated. Yes, it must be a full and possibly an older trap gun. The year of manufacture, is 1978 as listed on another website. I bought it and plan on restoring it as the butt stock is cracked. Generaly the metal and bore, are in great shape. Again, I thank you very much. Be safe !!!

 

[skeeter1]

Get yourself some vernier calipers. Digital or old-fashioned dial calipers. Both work just fine. I got some dial calipers from from Grizzly for 12 bucks, ant ehy work just fine.

http://www.grizzlyimports.com/products/searchresults.aspx?q=caliper

Here's a chart (I hope this works) of what you can expect from chokes for a 12-gauge. I have no idea how this correlates to smaller gauges:

Table of shotgun chokes
for a 12 gauge shotgun using lead shot Constriction
(micrometres) Constriction
(inches) American Name percentage of shot
in a 76 cm (30 in) circle
at 37 m (40 yd) Total spread at 37 m
(cm) Total spread at 40 yds
(in) Effective range
(m) Effective range
(yd)
0 .000 Cylinder 40 150 59 18 20
127 .005 Skeet 45 132 52 21 23
254 .010 Improved Cylinder 50 124 49 23 25
381 .015 Light Modified
508 .020 Modified 60 117 46 32 35
635 .025 Improved Modified
762 .030 Light Full 109 43
889 .035 Full 70 37 40
1143 .045 Extra Full
1270 .050 Super Full

 

[Pahoo]

Great info and I thank you skeeter1