Muzzle coning
1 - 20 of 26 Posts
Joined
·
6,979 Posts
I just finished coning one. I was cutting a patch at the muzzle now and then. Polishing the crown didn't help. Neither did changing patch material or lube.BenJr said:
I've tested it at 25 yards. All patches look perfect and the accuracy is unchanged and more consistent. I really need to get it to the range and test it at longer distances for a better assessment. At this point, I couldn't be more pleased.
Joined
·
12,388 Posts
accuracy is very relative. For as accurate as scientifically possible, you need a perfectly square muzzle. However, that is found only on guns with false muzzles. Coning a barrel needs to be done with some precision or it destroys accuracy. For a hunting gun, it's ok.
however if the gun was ever capable of 150 yd accurracy, it will not keep that group after coning.
however if the gun was ever capable of 150 yd accurracy, it will not keep that group after coning.
Joined
·
241 Posts
I strongly advise against coning any barrel based on my experience in dealing with barrels that had been coned. Even if it's done correctly, the mechanics of the barrel cannot overcome the mechanics of the consumables when shooting. When the patch/ball combo enters the cone on the way out, the most common problem is caused by the high pressure gas leaking past the patch. Even if the gas leakage is concentric (same all the way around the patch), the gas is moving at a considerably higher velocity than the projectile causing considerable disruption of the surrounding air, that disruption more often than not results in disruption of the flight path and/or stability of the projectile. A small amount of excess patch hanging on one side of the ball can get pushed around the front of the ball causing the ball to be deflected. Excentric gas blow-by (more on one side than the other) is all too common with a coned muzzle and results in the ball being pushed away from the area of gas leakage. Any one or combinations of those conditions result in loss of accuracy and because the conditions can vary greatly from shot to shot, obviously one can not maintain any reasonable expectation of consistency.
The three most common coned muzzle complaints clients come into my shop with are:
1- Occasional fliers.
2- Loss of accuracy at longer ranges.
3- Reduction in maximum load capability.
As stated above, inconsistencies created as the projectile passes through the cone on the way out of the bore often result in the occasional flier which can be way off the POA (point of aim) even at short ranges. Minor inconsistencie result in larger groups as range increases. The maximum load capability is often reduced as well because the higher the pressure the load is running at, the more effect even small amounts of excentric gas leakage will have on the projo. For example; a .50 or .54 rifle that would shoot good groups at 75yds with say a 90gr main chanrge will often top-out with a much lower main charge such as 6-gr.
The three most common coned muzzle complaints clients come into my shop with are:
1- Occasional fliers.
2- Loss of accuracy at longer ranges.
3- Reduction in maximum load capability.
As stated above, inconsistencies created as the projectile passes through the cone on the way out of the bore often result in the occasional flier which can be way off the POA (point of aim) even at short ranges. Minor inconsistencie result in larger groups as range increases. The maximum load capability is often reduced as well because the higher the pressure the load is running at, the more effect even small amounts of excentric gas leakage will have on the projo. For example; a .50 or .54 rifle that would shoot good groups at 75yds with say a 90gr main chanrge will often top-out with a much lower main charge such as 6-gr.
Joined
·
6,979 Posts
Tested my coning job at 50 yards and 100 yards...bench. Grouping shifted to the left and opened up a bit at 50, but was easily resolved using a tighter patch which the cone helps facilitate loading the tighter ball/patch combo. Could still load without short starter.
With teflon...At 100 yards..benched, all 5 shots were in the black on a NMLRA 100 bull with 1 x. Best group I've ever gotten with this gun at 100. That was with .395 ball, .015 teflon and 60 gr FFF.
I can't start teflon without the aid of a tapping hammer and short starter. But it was alot easier with the cone than it ever was with the crown.
With teflon...At 100 yards..benched, all 5 shots were in the black on a NMLRA 100 bull with 1 x. Best group I've ever gotten with this gun at 100. That was with .395 ball, .015 teflon and 60 gr FFF.
I can't start teflon without the aid of a tapping hammer and short starter. But it was alot easier with the cone than it ever was with the crown.
Joined
·
12,388 Posts
A good target gun with a standard crown can easily do a 49 or 50-3x on that target. I've done it with open sights. I don't use a hammer to start it either. 445 ball and a cotton flannel patch over 65 grains of 3fg. Instead of coning, I have a choked bore the last three inches. Darn H&H made a good barrel.
Joined
·
6,979 Posts
That's nice shooting Zim. Sure have me beat. I surrender.zimmerstutzen said:
If it's the same as used in match 175 (100 yard flintlock bench) at the NMLRA June 2010 shoot, a 49xxx won it at the last National shoot. 50 xxxx is the record set for that match back in 1960.
Joined
·
12,388 Posts
Ever see that six bull target Chuck Dixon shot? He had it framed in the shop. There are alot of guys who never go to friendship that are great precision shots. Now, I will say that my target was shot with a percussion side lock. An unfinished Italian hawken kit stock, a TC percussion lock, Italian DST's, and an H&H barrel I breeched the barrel, even cut the dovetails and mounted the sights myself. A proper choked bore makes a heck of a difference down range.
Joined
·
6,979 Posts
From my one time experiment with coning. I agree it does affect accuracy. The point of impact and the group size was affected. Both were corrected with a heavier patch with the same size ball and powder charge. When I tried a heavier patch I was hoping to tighten the new group and if so, move the rear sight. Instead the entire grouping went back on center. With the tighter patch I could still load without a short starter.
The only patch material I couldn't load without short starting was the teflon. Teflon did improve the group tighness even more. The coning made it much easier to start than with the original crown. But, the bore needs to be swabbed between each shot.
Given that short starters don't show up in history until about the time conical types were emerging (crowning), all those old originals must have been coned. They did OK with them.
The only patch material I couldn't load without short starting was the teflon. Teflon did improve the group tighness even more. The coning made it much easier to start than with the original crown. But, the bore needs to be swabbed between each shot.
Given that short starters don't show up in history until about the time conical types were emerging (crowning), all those old originals must have been coned. They did OK with them.
Joined
·
12,388 Posts
I don't know about originals being coned. I have two percussion originals and they are definitely not coned. The only flint original I have is a middle eastern club butt and it is not coned either. I have two other originals but they are smooth bores.
Joined
·
6,979 Posts
I've had the opportunity to test this same rifle both crowned and coned. Whereas I was cutting patches regularly at the muzzle, I was getting flyers beyond what I get now. What I'm getting now is the best it will ever get in that the barrel is coned. That best, isn't best for someone into serious target shooting. Coning IMO affects accuracy toward the negative side of precision.brewyak said:
The game won't know the barrel is coned. Targets tattletail.
Joined
·
1,363 Posts
I have a rifle with a Getz barrel that I ordered and I got the coned muzzle option, which Getz offered. Works great with round balls. The rifle shoots more accurately that I can.
Joined
·
12,388 Posts
Part of the problem is examing your objective in coning. If you wish to skip the need for a short starter for a quick second shot, that is of course an option. For some one for whom a 5 shot 6 inch group is fine under hunting conditions at 100 yards is acceptable. Hey go for it. With a standard crown I have never needed a mallet, hammer, or arbor press to seat a ball. A light tap with a short starter did the trick. MY short starter is fastened to the strap of my possible bag right in front about the height of my solar plexus. easy to use. I can just about thumb start my PRB's anyway.
To really know if there is an undesirable affect on accuracy, one would have to shoot the barrel many times before coning and then afterward. WHEN I say many times, we are talking development of the best load, maybe 100 to 200 shots. Then sighting in and developing a load all over again after coning. I can't for the life of me figure out how coning does not affect accuracy.
To really know if there is an undesirable affect on accuracy, one would have to shoot the barrel many times before coning and then afterward. WHEN I say many times, we are talking development of the best load, maybe 100 to 200 shots. Then sighting in and developing a load all over again after coning. I can't for the life of me figure out how coning does not affect accuracy.
1 - 20 of 26 Posts
Join the discussion
Join now to ask and comment!