doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Choke opening process?

I think I need to open up the chokes on the R13 Darne I have worked on. After putting the stock back on I was able to shoot it more extensively this week. I have used both RST best loads and WR gameshot that pattern tight, (the barrels are well regulated and the stock fits me well). The shot was #7 and #7.5
After removing the pits from the bore, both barrels showed an increase in diameter from .669 to .674 thus increasing the overly thight chokes that I started with. Now, RB is choked .030 and LB is.037. It seems that this is outrageously tight for a 16 ga.
I will have to do more patterning as well to better define the chokes on the board and not base my desision on the choke measurements.
What I would like to use the gun for is upland hunting, pheasants and grouse.
First question, is it reasonable to have more open chokes, somewhere in the IC/M range?
Second question, I would love to do it myself. I would use a Brownell's choke adjustable reamer with access from the breech, going slowly and checking patterns on the patterning board. The reamer should have a bore guide and a chamber guide. Any problems with that?

No, do it.

Well yes, Sliver, there are several problems with that. Where to start? First off the reamer. I don't imagine you intend to get a set of reamers made up to your exact requirements so that leaves an adjustable one. A lot of 'em are pure crap. Lets suppose you get a good one, you then have to make up a shaft with appropriate size guides to hold said reamer securely. I know that you had to straighten the barrels of your gun but are they perfectly straight? Just sliding your reamer and shaft down the bore can leave scars that you will then have to polish out. Ask me how I know. Do you have access to a lathe? I'm not saying you won't be able to do it. I am saying that this job can turn into a disaster real quick. When you add up the cost of tooling required, stuff you may never use again, and compare that to the cost of sending the barrels to Mike Orlen there's no contest. He has the gear and experience. Opening chokes is a very simple process for someone with a long bed lathe and the knowhow but even with the knowhow but without the lathe can be something you'll wish you'd never gotten into.
npm

Just opened the choke tubes on a set of Kolar tubes, The Brownells reamers did a very good job on the Stainless chokes so I am sure they will cut Darne tubes. Go slow , I used lard oil for my cutting oil. My industrial former life indicated it(lard oil)provided the best finish.
bill

I have done it many times using adjustable reamers and tools to hold them that I made myself. I am not a machinist, just a lifelong tinkerer with a good set of brains. If you will really only do this one set, having a reasonably priced 'smith like our good friend Mike Orlen do it is economically sound. However, Mikey just told a friend of mine that stock bending was the only thing he wanted to do, now. If that's not correct, I hope Mike will 'splain what I heard.

I would be interested in reading more about the correct method and tools to properly open chokes. I'll never do it myself, but would like to learn more about the methodology.

The above comments about a lathe are interesting, but I don't understand the purpose, nor can I easily visualize. Any photo's?

Also, how does an adjustable reamer function?

Are chokes reamed from the muzzle, or from the chamber to provide more support?

How does the operator know he is not altering the point of impact? Or does he?

Any explanation will be appreciated...

Nials,

The piloted reamer system Silvers mentioned works very well. If you had trouble with it, you tried to take too big a cut. I take out about .002 every cut. I think that is 2 flats on the adjustment.


Silvers,

The piloted reamer from Brownells is easy to use and there is no doubt that you can do it, If I can do it, it's not hard. It does not have a chamber guide. The pilots on mine are brass rings that come in different sizes to match your bore, You can make them out of brass bushings if you like, and guide the reamer from 2 points. It is cheaper to have it done for one gun. I've probably opened up 8 or 10 guns with mine. I just lube mine with oil, It ain't rocket science.

Call me if you have questions, Dick

"It ain't rocket science." I have done several from the muzzle, no guides, nothing fancy, just a adjustable reamer. The best advice is take very light cuts, pattern between every cut. I have actually fixed a gun that had bad POI by ever so lightly 'leaning' on the reamer. Some people are just afraid of their shadow, if you have average or better mechanical ability you can do this.

Friends,

Thank you for your encouragement. You don't know how much it matters to me. However, I am trying to be reserved in my optimism because I know I don't know.
Every new step I go through is a new territory that I have to explore cautiously. If I make it alright, there is great reward to be cherished. Sending it out would be the easiest thing to do and most cost efficient. But I would be missing the excitement of the discovery. I obviously am an adrenaline junkie.
Nial brings an important point. My barrels were bent up and I straighten them to the best I could. I know they are not perfectly straight, just by looking at the light reflection. Here is the problem. One wants to ream the chokes from the chamber with a guided reamer so that the chokes do not come out of alignment. If the barrels are not perfectly straight, the reamer may be misguided and the choke cut out of POI.
I might do better with a nonguided wooden dowel and emery cloth to allow a selfcentering tool to do the job?
The other option is to go very slowly and pattern after each cut to catch on an early changed POI which I am going to anyway.
The third option is to use a concentric guide close to the muzzle and see if the shaft would need an eccentric guide at the chamber, assuming that the last third of the barrel preserved its straight path.
Maybe I am complicating things too much. After all it's a shotgun, not a rifle.
Again, thank you for your support.

Sliver, I went the wooden dowel/emery cloth way with my sons 16 bore Simson.
It worked out quite well. Took my time and used a wet t-shirt to wrap the muzzle
to avoid excessive heat while polishing away. Patterns great. JMTC.

JC