H&R Topper 12 questions

[cofi]

hello i have a 1970(i think serial starts with AG) H&R Topper 158 i had a couple of questions about it

1.What is the barrel OD?the barrel was cut to 18.5" and  i would like to have choke tubes installed and the barrel has to be at least .805" OD

2. would it be safe to use one of these http://www.gearupcenter.com/products/10-x-caliber-shotgun-gauge-adapter-system-pre-order.html i know my reciver is cast or something it looks like its case hardened

3. is it ok to shoot steel shot

other then having the choke tubes installed a bead installed and the forcing cone lengthened are there any other must do modifications?

[quickdtoo]

Welcome! All the low pressure adapters would be fine, but the .223 / 7.62x39 / 308 adapters would be too much for the cast iron receiver. Steel shot is fine in modern H&R guns, but I doubt it would be good for the vintage M158's fixed choke, but the aftermarket tube should handle it. If you have the barrel, measure it, you can get a cheap caliper for less the $10 or take it to the gunsmith that's going to install the tubes to have it measured.

Tim

[cofi]

thanks.....is it safe to shoot buckshot and slugs through?

[quickdtoo]

I believe those work best thru chokes less constrictive than a full choke.

Tim

[cofi]

there is no choke as the barrel was chopped to 18.5 just want to make sure that the recivers not gonna blow up in my face

[quickdtoo]

Yes, but you mentioned having removable tubes fitted, that's why I mentioned that.  All shotgun chamberings are low pressure, even 3½" 12ga only runs 14kpsi MAP, shy of a blocked barrel there would be no issue with the frame, just the constriction at the choke if there is one, by the time the shot/slug gets to the muzzle, the pressure is reduced significantly.
 
Tim

http://www.leverguns.com/articles/saami_pressures.htm

[cofi]

wow thats so odd i woulda thought 12ga hunting loads carried huge pressures because they kick so damn hard

last question

to drive the pins out can i get away with using a brass hammer and punch or am i going to need a press?

[quickdtoo]

They kick(recoil) because of the weight of the shot and powder and how light the gun is.

http://www.handloads.com/calc/recoil.asp

Any hammer, will work, but a brass punch or cupped tip steel punch(nail set) works best, see the trigger hone info in the FAQs for detailed help, the pins need to be drifted out the left side of the frame due to the splined heads on the left side, a slave pin and hammer wedge are extremely useful for reassemble.

Tim