Want an Open Cylinder 410: any way to safely remove the choke

[cpileri]

I would like to fire some "full bore' (410 cal) slugs and maybe even round ball through a 410bore shotgun. My barrel, like most, is full choke from the factory- mikes out to .397.
is there any way to remove the choke, so that a 410 slug (*) does not have to swage down to .397 as it hits the muzzle?

i was thinking about a brake honing tool, but not sure if they are accurate enough to measure in the thousandths. Also, i woudl want to remove the choke symmetrically with the bore; not leaving any choke remaining (creating a lip or ledge in the barrel) but also not un-choking it beyond 410, or maybe .408-9. So it would need to be long enough to remove the whole constriction.

Also, the barrel has a fixed front sight, so i do not want to just cut off the last inch or 2 of muzzle.

Or, am i off base, and any lead bullet will swage down without causing barrel-splitting pressure problems?

Many thanks,
C-

(*) the bullet is a 410 cal hollow base wadcutter, facing backwards so the hollow base is at the powder. The lead portion, while note over 1/2oz in weight, is still thick enough to make me thing that swageing it down might cause pressure spikes. I have no evidence for this occurring, only my educated guess. The proposed 410 slug fits snugly but without shoving inside a 410 hull, both plastic and RMC brass.

[Bullshop]

I have a .412" pull through reamer. I got it to open the cylinder throats on a Ruger BH 41 mag.
Used once, well actualy 6 times. I think it would work for your job with the short pull rod because your only using it to cut the last couple inches of barrel. You could drop the reamer in from the breach and hold it near the muzzle with a dowel then thread the pull rod in from muzzle and go to work. Might do it.

[cpileri]

Dear Mr. Bullshop,
Can I order this reamer from your website?
It does sound like it might work.
C-

[gunoholic]

A 13/32 reamer should get you 0.4063 then a polish with a fine brake hone or wet and dry on a split dowel.
you need some way to align the reamer with the bore, like a bush that fits the barrel or better yet a lathe.
or you could just hack the last few inches of the barrel off with a disc cutter!!!!:shock:

[The Kid]

An adjustable reamer from the SnapOn truck will give you what you need. I think the last one I bought was about 30$. I would slide it into the muzzle and then expand it until it touches the wall. Remove it and make an electrical tape bushing that fits the unchoked section of the bore snugly by winding tape around the shaft. Push the reamer down the bore from the chamber end with a cleaning rod, the bushing should be a slip fit not tight. Grab the end that sticks out the muzzle with a tap handle or brace and bit (minus the bit obviously), and crank on it while putting a slight amount of pressure on the reamer. Clean the chips out often and use plenty of oil, you should be able to ream it to whatever diameter you want. Use a brake or flex home flooded with oil to polish machine marks out after you are reamed to within .002" of your target diameter.

Of course this is the home shop down and dirty method, but it does work. I have even installed choke tubes with nothing more than a brace, before I learned to do it in a lathe. Just take your time and go slow, if you botch it you can always cut 2" off the muzzle :).

[W.R.Buchanan]

Here's a little tidbit.

At the SHOT show last year I was talking to the Brenneke guy, actually his son, and he told me the reason for the fins on a shotgun slug.

I was under the impression that they were there to spin the slug. WRONG!

They are there to be squeezed down when the slug goes thru the choke on a shotgun barrel.

The areas between the lands provide a place for the lead to get displaced into, similar to the function of the areas between the driving bands on a rifle boolit.

Randy

[KCSO]

IF you use a snap on reamer you need to either make a pilot if you have to work from the muzzle or you need a long shaft if you drive it through the bore. Start slow and don't try and hog it out and for the finish cuts less than 1/2 a thou at a time.

[cpileri]

Sirs and/or Ma'ams,
Thanks for all the advice. I will look into the snap-on and 13/32 reamer and polishing hone. I cant cut the muzzle, as stated above, otherwise i'd be done already. :) The long shaft will be the problem, i think. Aligning it to the bore will be technical, but doable.
These are the bullets: http://www.mattsbullets.com/index.php?main_page=product_info&cPath=83&products_id=282&zenid=u9d9reajhn9t4sjqjdsgrkdf42 , so if they swage down without unsafe pressures maybe i dont have to go through all this at all. But I want to be safe.
My other plan was to fire bullets from .397 on up in .001" increments to .409 with valve grinding compound pressed into the bullet: only a few hundred shots at each diameter should do it (that was a joke, BTW).

[Tokarev]

Few considerations:
is your bore chrome plated?
do you know the length of your choke?
is it very difficult/costly to re-barrel?
You aware that adjustable reamers are not self-centering (have no pilots and their front edge of the blades is cut at close to square) so they will have a leeway in going sideways? If you could make a pilot to screw onto bottom thread of an adjustable reamer, that could do the trick and center it in the bore.

[cpileri]

Sorry I have been away from this thread and your kind replies:
No, not chrome plated.
Not sure. i can get an approx measure, though.
Relatively costly, its a savage 22/410 o/u, so have 2 barrels stuck together to consider.
Yes, centering the reamer is what is holding me back.
I did find both 13/32 and and adjustabel reamer, butits more of a hone; so cutting is a slow process. it did work well to get a burr from the forcing cone, but i am leery of taking it to the muzzle.
C-

[Tokarev]

Oh, it's O/U... I doubt it can be successfully opened with a variable hand reamer. Your money probably would be better spent on a single shot or bolt action 410 where even if choked, you could just chop the barrel if choke was not too long.

[Willbird]

Probably not a lot of help but my dad used to jug choke double barrel muzzle loaders by holding the barrel on the Bridgeport table in a vee block with the barrel hanging over the side of the table, same setup here only we would not be boring a jug choke we would just bore the choke out then hone for a nice finish.

[Willbird]

You could also twiddle around and set the barrels up on the cross slide of a lathe and mount the boring head in the headstock......the setup is the tough part :-) but with patience it can be done.