Can we talk slug chambering?

[vmaxpro]

Ive chambered a few barrels for slugs now but would like to hear some others opinions.

Do slugs like a good run at the lands?

Do slugs like a light jam into the lands?

1* included lead or 4*?

chamber size, a tenth or two under? 

Whats your guys experiences? Light slugs have little bearing surface and are tough to start straight. Heavy slugs have a long surface but a lot of drag and depending on your chamber a very heavy jam into the lands and seems to kill velocity.

 

[Motorhead]

Caliber, barrels groove depth makes this a very loose question ?



What caliber, what barrel ?

 

[vmaxpro]

Thinking of building another .30 so lets say tj .294/.300

Im going to grind a chamber reamer for nsa 65.5 slugs and wanted to try something different.

 

[Motorhead]

In a .30 because of the surface area based off the diameter, seating the slug INTO the rifling will be very difficult. While .003" engagement is not a lot, the friction is still pretty high and your likely to need just a bit of JUMP to get a good low ES. The free bore needs to be at the slugs actual diameter so it can't YAW and entering leade ramp is square and true.

Would think you need no more than .100" jump .. tho that makes longer slugs closer and lighter further away.



Ideally in the tuning process ... start the leade ramp so slug is touching it or even just denting lead. see what the ES is doing & if wide move the leade ramp forward a bit being as you do this it should be very telling if your getting a more consistent launch.



Full bore contact SLUGS are like a Cork In a Bottle so getting them to break loose and move correctly timed with the pressure peak can be tricky. Or they get stuck due to cork effect being too great.

 

[vmaxpro]

Thank you motorhead! Whats considered a standard practice, cut your reamer to the longest slug and see what shoots the best? Or shallow ream and keep going deeper and testing?

 

[Motorhead]

Thank you motorhead! Whats considered a standard practice, cut your reamer to the longest slug and see what shoots the best? Or shallow ream and keep going deeper and testing?

Machining 101 .... Once gone there's no putting it back !!

Start shallow and able to chamber w/o forcing cocking handle .... see if the gun can fire the slug and how consistent it does so ... increase depth if needed.

 

[mercado]

Thanks for the info...now for example I have a .223 tj barrel 1-12 ...how I decide what reamer to purchase for the barrel...do I slug the barrel first n then go .002 over with the reamer..or just go to the guys that rent them for a few days...I would prefer to just buy the reamer..the barrel shoots awesome but it really needs a better made chamber....I recently purchased a 257 texan that needs the chamber a little more deep because a 85g bullet sticks out more than 3/4 where could I purchase the reamer for that to...thanks 

 

[vmaxpro]

Now were gettin somewhere! Jamming the nsa 61.5 with basically a zero freebore came in at 860fps. .050 jump with a 3* included leade came in at 904fps. I used my uragan to test it but It will be for a different gun. The tj barrel and chamber for the uragan is so perfect with 49.5 im not touching it. A quick 3 shot accuracy test at 900-905 fps first try was under .500” at 85 yards. Pretty happy with that. I mic’d the 61.5 at .3003 so I cut the reamer at .3000 and it seems perfect. 

 

[Motorhead]

Hell yea !!

 

[vmaxpro]

Thanks for the help motorhead! Im gonna toss this info in too for anyone else learning slugs. If they dont start straight, no tuning will help. Digging through my dirt pile I noticed a slug or two with uneven rifling engagement. Bet money they were the unexplained fliers. I started looking over my uragan and noticed the bolt probe is very sloppy in the guide. I made a new one so ill have to test it more on friday. The original was .4153, the bore is .4330. Doesnt seem like much, but when its extended out it moves ALOT. I made the new one at .432. Glides like butter with a little moly too.