Throat lapping a Buffalo Classic .45-70...

Finally some time with Buffalo Classic; Slugging the barrel and especially the throat which appeared to be very non-existent when looked through the chamber with flash light. That was pretty much right, not too much throat in this rifle. Groove dia is .4555" and bore .4515"; almost can't believe that groove diameter. "Throat" style you'll see from the pic:

http://pyssymiehet.com/gunstuff/bc_throat.jpg

My .459" Marlin boolits with tapered front band were literally engraving, lands were cutting chips when forced in to the rifling... Some work ahead I guess.

That bore is way undersize....are you sure?? Iwould not fire .458 J-boolits through that tight of a bore. The pressures would go through the roof along with parts of the gun. A friend of mine has on of those and the bore is the usual .458

If that is cerrosafe that you used in the chamber/ throat area , it has to cure for an hour or two to give an accurate measurement.

That is tight but I think it is still in specs for H+R...... .457+or- .002 IIRC
I have one of these with a groove diameter of .4575" it shoots very well. One thing to remember with this rifle is to close it firmly every time.....lockup will change the point of impact if you do not close it consistently.
Stomp:drinks:

Oh yeah, pretty sure; it's impact slug (high impact I must say and I made several) of pure lead in the pic and the groove dia is the one that I'm most certain of. I already lapped the thing just to smooth out the start of the rifling, bottom one is the original and top one is after modification. At least it's not shaving lead rings any more:

http://pyssymiehet.com/gunstuff/lapped.jpg

I think you should consider your self fortunate. That is what I believe to be an ideal throat and bore diameter for smokeless equivalent of BP levels around.

You can use virtually any factory mold without diameter worries. You can use real soft lead and fill the chamber with bullet so that you get a good chamber seal and let that cone do the work. Just seat out until you lightly touch it. No bullet pulling issues to deal with. No crimp issues or case neck tension issues. Bullet takes up unnecessary case volume so filler use is minimized. Or you can shoot light weight bullets like a champ. Then just see what your rifling height limits you to in the way of velocity.

If you wanted a BP reproducer with smokeless, you got about the king of setups. If you wanted a HV 45 rig, you're probably screwed unless you pp. Then you WILL need to modify the throat. :grin:

added: Oooops. I see you were already working the throat. I should have read on first.

nice job on the lapping. How did you do it?

David

I have to ask if you just pounded the lead slug in or if you put a brass rod in from the muzzle and upset the lead against the brass rod. You will get different readings between the two methods.

Slugs were pounded out using long M10 threaded rod; cushioned heavily with plastic tape. Slugs were tight so they received pretty good pounding from both ends. I don't have brass or copper rods, I know I should have. I hammered slugs in using wood dowel and few of the latest ones were driven in with cushioned M10 bolt. Slugs were like in the first pic; fattened with hammer and anvil and they entered freely only half way to the chamber:

http://pyssymiehet.com/gunstuff/fatslug.jpg

Lapping rod is almost chamber dia steel rod turned down to gently sloping taper in lathe. First pic shows it with masking tape cushion in the narrow end; tape is for centering the rod to the bore for hand turning. Gray ring on the fatter end is from previous use with my friends gun. I don't remember if it was me or my friend who suggested this kind of lap, but it seems to work pretty well. Shiny ring on the gray area is from my BC, first feeler without any lapping compound:

http://pyssymiehet.com/gunstuff/beforelap.jpg

I lapped using NECO pastes (any silicon carbide mixed with grease will do) from 220 grit to 400...800...1200. Not really necessary to use finest ones but no harm either. I used cordless drill at first, but because this kind of lap needs only light touch and frequent relieves (to keep the compound between the surfaces) it's not necessary and it also jams very easily because compound gets out of the worked surfaces. Hand turning is safer and works fine and is very effective also. Here's the lapping rod after the work, notice how the gray area is increased:

http://pyssymiehet.com/gunstuff/afterlap.jpg

Finn45;
I have a Handirifle, barrel is .4500-.4565".
I can shoot anything, plain base, gas check or jacketed and do not have to worry about small molds.
What you have is much better than some of the .459-.460 groove barrels I have heard about, most of those require special molds or very soft lead bullets for any sort of accuracy.

Yep, I'm pretty confident it will do what I'm expecting. Really like to try BP in it, perhaps boosted some by duplexing with smokeless. No real need for extra power, but need to reach some weird energy levels if I'm walking this one to moose hunt. Thanks for the replies.

..................As usual Finn, nice sharp photo's and clearly explained. Uh, have you shot it yet? :-)

.................Buckshot

HAR! At that time no, but now, yep...

Finn: I shoot the Buffalo Classic only with BP reloads using:
Lyman 457123
Lyman 457124
Lyman 457125
Lyman 457661 - bore rider
Victory PGT - bore rider (designed for Pedersoli 1874 Sharps)
Lee 500 3R
and 2 custom BP mold bullets in 400 and 500grs

All reloads will shoot with accuracy to 600yds using a Pedersoli Creedmore sight except the Lyman 457124 and 125 from my rifle

Last summer, with the custom 500gr BP 'Big Lube' over 57gr of H777 at 600yds:
5 shot group that measured 7.25" (no not 7 MOA). Three holes were grouped just over 2" Average groups at 600yds are 12 -16" when my eyes are working good.

Last week, using the Lee 500 at 600yds, a 20 shot group was 15"

I've found that the rifle likes reloads with the lands just lightly engraving the nose. The Lyman 457123 shoots best 0.05 off the leade

For $400US ... not a bad deal

Nice job lapping. A hint for the impact slugs. Use a rod small enough to slide inside a 38 or 357 case. That will prevent the end of the steel rod from damaging the bore, and the rim on the case is just the right size to prevent any "blowby" of the lead.

Ian

I bought a troating reamer for my BC and 2 reguler Handi rifles. Cost $50, well
worth it. I lengthened the throats about 1/4 inch on all 3. Very easy to do. I think
a deeper throat is needed for BP. It also may be needed for full load smokeless rifle powder with a heavy bullet.

Thanks for the insights, much obliged. I have two other BP designs that I haven't tried yet; NEI 535 grains Gunn modified and NEI 610 grains, don't recall the cherry designations right now. Both sleek looking designs sharing similar long and free hanging nose section. I tried Gunn boolit in Marlin once just to see that about 1500fps from 16.5" barrel with smokeless threw perfect key holes. I had terrible problems casting with both, so I opened the sprue holes but haven't had chance to cast any after that.

Good tip on using case as a rod end stopper. Week ago my friend asked for old .357 cases to use for blunt arrow heads in order to make some new wooden arrows for his daughter, he said those are perfect arrow heads for home made arrows, good balance and no wounds if something unexpected happens. Very versatile caliber :lol:.

Throating reamer would be ideal but just for now this will do. Before that I would get one of those hand operated crowning cutters that Brownell's is selling, Marlin has a smith made "crown" and I see many advantages to give it a whirl with one of those. Brownell's just have had too many mishaps shipping here that I've been holding my needs for that.

john boy i to shoot the 500r in my buff classic i did a bit of an exsperiment and fited a gascheck to the 500r and shot this group at 400 meters of crosed sticks. it was a little windy but was very happy with the size of the group not bad for 57 year old eye's 6and 7/8 by 3and5/8. the target was on a two foot white backing paper fixed to a six foot by six foot black plywood pannel . my sights are lyman .404 globe front with lee shaver insert and a smith buckhorn lader sight with peep hole slider. that load is dooing 1690 fps and no leading.
bernie:-D




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