Choked Mt. Rifle?

[JonnyReb3]

I recently received my first CVA Mt Rifle, a late model .50, with a Spain marked barrel. The rifle was unfired, excellent condition and has what appears to be very deep cut rifling. It'll make a great rb rifle i'm sure but when cleaning the barrel i noticed a constriction for the first inch or so at the muzzle. Seems like the barrel is choked. As i read lots of online stuff about the model, i saw a few other references to this as well. Were these barrels purposely choked or was this just a manufacturing issue? Does this cause any issues with accuracy? (only fired it once, subsonic velocities with rb's, seemed ok) Thanks in advance for any replies, J.R.

 

[nkbj]

If it's helpful data, I have a .58 that is bore (not groove) choked for one inch at the muzzle. It shoots very well.

 

[zimmerstutzen]

Never heard of them(CVA) being intentionally choked. I understand it is something that can happen with some rifling equipment.

A muzzle loader barrel company called H&H made choked bore rifle barrels 35 years ago. Their barrels are worth their weight in gold. Darn good shooting. a NOS H&H barrel sold for over $600 on ebay about a year and a half ago.

 

[BrownBear]

Green River Rifle Works barrels were choked, too. Mine is my most accurate rifle by quite a margin.

Never run across any CVA's that were choked, though I've only been around a few. Good shooters, but not choked.

 

[JonnyReb3]

Hey thanks for the info guys, i'll be interested to see how accuracy is affected as i move torward deer loads, i know my airguns with chocked barrels are more accurate than most of the unchoked ones but supposedly only under the speed of sound. High velocity, i've heard,negates a chokes usefullness.
Musta just been the way the machining bored the barrel. J

 

[BrownBear]

Musta just been the way the machining bored the barrel. J

I'm acquainted with the GRRW smith that built my rifle, and that's what he told me. It wasn't their aim when they set up for boring, but was an unanticipated "byproduct" of their chosen methods. Wish I could remember the explanation, but that's neither here nor there. He did tell me that in the last couple of years the GRRW rifles and the really scarce barrels have exploded in price.

 

[swathdiver]

Soft steel clamped down and squished at both ends for the cutters to do their work?

 

[BrownBear]

Soft steel clamped down and squished at both ends for the cutters to do their work?

Nah. It had to do with the way the cutters go through the bore. It's a long taper rather than a squish.

 

[JonnyReb3]

Starting to sound like a good thing :thumbsup:

 

[zimmerstutzen]

Most definitely a good thing.

The Alexander Henry rifling in martini Henry rifles made at enfield had two chokes. One just ahead of the chamber throat and another a few inches from the muzzle

 

[rafterob]

They are intentionally rifled that way, I read a CVA quip one time advertising it. The barrels are rifled from the breach end and they leave the muzzle a tad tighter with the theory that the ball having been deformed by ramming and firing will tightly engage the rifling upon leaving the barrel. Seems to work, my Mtn. rifle is mucho accurate.

 

[George T.]

I had one for several years that sure loaded tough! The barrel had tool marks end to end but shot very well. Geo. T.

 

[JonnyReb3]

Hey Ghettogun, thats some interesting information thanks! I wonder if other CVA's had such barrels or if, as it seems, the Mountain Rifle was designed from the start to be CVA's most accurate rifle. I've read the rifles designer put a lot of heart and soul into the original build. I've read that after the initial douglas barrel(s) Don Kammerer went to Spain to show them how to build barrels to his spec. I read this here on this forum in some fantastic posts by longball58. I guess its still up in the air whether or not Douglas made barrels and if so the number but the posts about Don stated he was a great fan of fine Douglas barrels and it stands to reason he might have designated a choke to go along with the slow twist and deep cut rifling. Also would be interesting if those with Deer Creek barrels note a choke as supposedly that equipment was from Douglas when they closed down 30+ years ago.

On a slightly off topic, wouldn't all the deer creek barrels be made in America or was it spanish barrels just being bored and rifled here? Geez i love mulling this stuff over..

Geo t., my rifle too, is tough to load and all i had was .495 rb's ,i ended up shooting bareball. The rifle actually shot the balls with no patch pretty well.. J

 

[JonnyReb3]

Should have already made an observation that although late in the thread, i'll make. i've another Mt Rifle i shoulda checked, i've never fired it though and so never noticed a choke one way or another. Its a .50 also but was an earlier flintlock kit rifle that does not say where it was made, only the CVA logo\caliber. I checked its barrel and it has no choke whatsoever. Straight bore and very different from the rifle i first mentioned. I took a pic and the rifle on the left, the spanish barrelled rifle from apprx 1989, has the choke. If you look inside the bore you can also see stirations in the bore, counter cut\pressed to the bore about a 1\2" in. The constriction is felt about another 1/2" beyond this. The rifle on the right is from apprx 1978 or 9, no mention of make on the barrel, no proof marks, only CVA and serial #75xxx. Note the barrels bores are quite different in about all respects and were obviously made on different machines. Of course though, much changed between 79 and 89 in CVA. Of more interest probably to most would be the differences between the barrels made from the time of the first production rifle to the ones made with no place of manufacture marked. J

 

[longcruise]

Both Ned Roberts and Walter Cline describe the mountain smiths as very carefully chocking their barrels the last few inches at the muzzle. Also the later builders of the tack driving match rifles about 1840 and onward did the same thing.

Pedersoli LRML guns have an intentional taper choke as well.

 

[M. De Land]

Here is what happens with single point cut rifling. The bore is the bed for the rifling head and should be reamed and lapped before rifling to make it level. If you have seen a rifling head you will note that the window near the middle houses the hooked cutter or scraper and is raised with shims or a screw driven wedge.
The heads are introduced from the muzzle, pushed down the bore and the rifling head is raised before the cut traverse. As it inters the bore the head is supported only by one side of the cutting box until drawn into the bore past the cutter. Now it is supported on both side and cuts full depth. The grooves are always shallower in the breach end until the rifling head is fulling inside the bore and supported on both ends of the cutter box.
When it reaches the muzzle and clears the bore the cutting depth is again made shallower than when fully in the bore as the support on both ends is reduced on a taper as it is withdrawn from the muzzle.
When all the grooves are fully cut to maximum depth there will be a taper in the grooves and the bore will be level at both ends.
Many guns will shoot very well with only groove taper but Brockway and Warner used to lap in bore choke after rifling, commensurate with the groove choke already cut in. They would enlarge all the bore from breech to about the last three inches of the muzzle by reaming and lapping. The taper would be in the first 1.5 inches of the last three and the last 1.5 inch would be level again left from the original bore reaming and lapping. In this way they could ring out the last possible bit of accuracy potential of the barrels they made.
Pope tapered his bores the whole way by using a series of tapered plug gauges lapped until they fit there designed place in the bore. A thirty inch barrel required thirty, one inch long tapered plugs pre- machined and ground to where they should come to rest in the profiled bore. These were lapped into their predetermined positions according to Smith in his book "The Story of Popes barrels".
It is said that Pope tapered the groove bottoms as well but I don't believe he did. I think they were level except for the muzzle and the bore was a continual taper lapped in with a leather washer affair that did not go down into the grooves.
Brockway and Norman made them level with choke only at the muzzle. Neither could see any advantage to gain twist and both tested it thoroughly. Pope liked and used gain twist which means groove lapping with a lap slug is impossible.
I use these gun makers as my examples because I feel single point cut rifling reached it's
Zenith under there skilled hands.
The reason choke works is because it introduces resistance on the projectile just as it exits thus tensioning the barrel and dampening oscillation. That's the theory anyway. Mike D.

 

[rafterob]

I forgot to mention that my barrel is a Deer Creek aftermarket barrel, simply marked .50 cal. Bought about 5 years ago. But my Traditions Hawken has the same style of rifling.

 

[M. De Land]

Pedersoli broach cuts it's bores and I remember reading that Dick Gunn, (not knowing specifically Pedersoli's proprietary methods) speculated that they wrapped the barrels with a heating coil of a known resistance and increasing diameter which introduced a current which progressively heated the barrel from the exterior. It heated progressively one end to the other and when the correct temperature was reached the broaches were passed through and thus a taper was cut from the heat expansion differential along it's length.
When speaking of taper or choke we are talking only one or two ten thousands of an inch at the most. Mike D.

 

[BrownBear]

When speaking of taper or choke we are talking only one or two ten thousands of an inch at the most. Mike D.

Interesting. Not doubting you, rather I'd always assumed there was more choke in my GRRW bore.

Though it's "58 caliber" a .575 ball rests on the muzzle without dropping and if there's the least irregularity a .570 hangs up too. I have to use .562 balls, which virtually drop with the weight of the ramrod once you're about half way down the bore. If you go ahead and use a .570 and thin patch, it's likely to start dropping about 2/3 down the bore.

 

[M. De Land]

That could be. I was referring to lapped in choke or taper in the guns made by Pope, Brockway and Warner. There were a number of other very fine gun makers of the era but I'm most familiar with the work of these three.
Billinghurst, Shouyen, Gove, Ferris, Perry, James, Schaulk, Amsden and Reinhardt were all probably equally skilled rifle makers. Mike D,