Question for Longshot

[Adam604]

Hi Longshot,

In reading through the old posts here in casting for shotguns, it seems that you may have access to machine tools.

Look for a extended style of screw in rifled choke tube, that is a choke tube that extends past the tip of the barrel

If you do and are going to try using a rifled choke tube to shoot round ball, check your choke before using it for:

Where does the rifling start? If the rifling starts inside the the threaded portion or the thin portion of the of the screw in choke you should try machining it. I think the rifling should not start until the choke is at full thickness. On the Browning choke I have the rifling started in the threaded portion of the choke and the choke tube is not strong enough in this thinner area to withstand the round ball.

I will have to try to work on my choke tube with the hand tools that I own to try to lap it open with a lead lap and aggressive buffing compound. I expect it to take a good deal of time.

Adam

[longbow]

Adam604:

I have been thinking about putting together a screw in choke system similar to what I had many years ago and wish I still had.

I bought a Pachmyr (I'm pretty sure it had the Pachmyr name anyway) barrel adapter and 3 or 4 screw in chokes. It was supposed to come with a muzzle brake as well but that was missing so I got a deal on this stuff and made a muzzle brake out of stainless steel.

Basically it is similar to the Cutts compensator. A threaded barrel adapter is soldered to the barrel, the muzzle brake screws onto the barrel adpater then the choke screws into the muzzle brake leaving a small (?) gap between the choke tube and muzzle ~ if memory serves the gap was about 1/8". The threads are at the muzzle end of the choke unlike the current Cutts compensator here:

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=7958&title=CUTTS%20COMPENSATOR

I like that arrangement better than the modern style screw in chokes because everything can be bigger ~ threads, shoulder, wall thickness. Plus the muzzle brake can't hurt (no pun intended) when shooting slugs from the bench!

Looking at the Cutts compensator at Brownells, it does look beefier than typical screw in chokes though so may be okay.

If I get ambitious I may just make a short rifling bench and make my own choke tube with appropriate round ball twist.

By the way, I wouldn't use too aggressive a lapping compound until you test it. You don't want to overdo it. Take it slow and easy.

Longbow

[Adam604]

Longbow,

I really need to get more specific in my initial postings....

I am planing to work on the portion of my choke that is in the area of the threads and turned area. I am planing on just removing some of the material from the lands of the rifling to provide a more gradual transition to the parallel section of the rifling.


I'm also planning to work on the exterior of the choke a bit to make it easier to install and remove.

When I mentioned that it was hard to remove after shooting round ball I believe most of the problem was because of the distortion to the choke tube over the lands of the rifling. (.002") after about 20 rounds of hard cast WW .735 round ball.

I've seen no change in the choke tube after 50 more round ball loads and over 100 7/8 oz slug loads

The rifled choke does really improve the groups I have shot with slugs and round ball.

Do you have a chronograph?

Adam

[longbow]

Adam:

If you have access to a lathe it may be easier to use a boring bar to skim a few thou out of the choke to make a bit of a forcing cone. A gunsmith might not even charge much as it would be a pretty easy job just centering then skimming the lands down in a gentle taper.

Do you think the distortion is due the impact of the ball into the choke or from the torqueing of the choke tube tightening up the threads so much?

If I ever get to making the Cutts type muzzle brake and choke tube I would be putting threads at the muzzle end where the knurl or wrench flats are so not only would the ball be engraved before it got there, that would be the thickest part of the tube too.

Yes, I have a chronograph but so far haven't chronographed the slug loads. I am a little worried about wad damage to the chrony so want to make a shield first.

I will be loading up some of my AQ clones today with the intent of going to the range tomorrow.

Longbow