Bergara B-14 R tips, tricks, mods, and photos
- Thread starter Johnny Boom
- Start date
I don't want to derail the thread any further, but I wonder if it is something that can fixed or reduced.
Fair enough, interested to see if any one else is experiencing this. Mine seems to be behaving, but now I'm going to pay more attention to the first shot. I'm at the same torque.
And now for something completely different. Burrs!
This is the worse one, new.
The same one around 360 rds.
After 800 rds.
This is the same burr in all the photos, each land has one, but this one is probably the worse one. Will they finally wear off? Are they detrimental to accuracy? Should I have bought a Vudoo? Stay tuned...
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It's possible the burrs will wear away after more rounds, but it doesn't appear significantly diminished after 800 rounds.
Bill Calfee the noted and often controversial gunsmith relates that often some top quality factory rifles that are accurate, such as 52 Winchesters, 37 and 40X Remingtons, 54 Anschutz, and Walthers that didn't shoot well at first did so after a few thousand rounds. He thought the problem was an "unseasoned" (his word) chamber and leade. What he was referring to was a rough chamber and leade, often with machine marks and burrs. When these were worn down, the rifles would begin to shoot.
He explains this in his book, The Art of Rimfire Accuracy. Calfee's own words in blue below from his Chapter "Chamber Seasoning". Images from the book.
If you fired a bullet in the reamed chamber I show in FIG. 1, with its roughness and the corner of the rifling and groove with the burr filling it, here is what happens: the bullet passes through the leade and being rough, the leade removes lead from the bullet which is bad enough, but that little burr in the corner of the rifling removes some extra lead from the bullet. As soon as the driving band passes completely through the leade, and gets to the bore proper, all of a sudden each rifling mark on...[sentence incomplete in Kindle version of the book]
In FIG. 2, I try to show what a perfectly finished leade looks like. Smooth, no ridges and the corner is “clean” clear to the bottom of the groove. If you note in FIG. 2, the leade actually cuts into the chamber slightly, depending on the outside diameter of the reamer and the diameter of the grooves of the barrel.
[a word or more appear to be missing here in the Kindle version] the bullet is wider, because of the burr, than the rifling in the rest of the barrel. So the bullet, driven by pressure, picks up the driving side of each rifling, but because the rifling marks on the bullet have been enlarged, there is a little opening at each rifling where gas pressure can escape past the bullet. Of course, a barrel can’t be accurate like this. Now, does this make sense at all? A lead bullet must completely fill the bore and grooves to be accurate. The condition caused by that little burr deforming the bullet is no different than the bullet just being too small to fit the grooves properly. Either way, a good seal is not provided between the bullet and bore so, bad accuracy results.
In this little drawing [shown above] I am trying to show a slug in a rifle bore that has passed through the leade, as reamed, with the little burr left in the corner of each rifling… the little burrs have made the rifling cuts in the bullet wider than the lands so once the bullet gets into the barrel proper, a gap exists at each groove, allowing gas to escape and therefore, bad accuracy. This burr must be removed, either by lapping or several thousands of rounds through the barrel.
@Grauhanen, I was hoping you were going to weigh in. I was reading Calfee's book over the Christmas break and I recall these observations. I also found it was interesting that he used a "hob" to finish his chambers, although this seems to be controversial, like many of Calfee's methods.
I'll try to shoot baseline groups periodically now that I have a case lot of good ammo. Interesting to see if the accuracy will improve with chamber wear.
However, for a factory barrelled 700 footprint action that takes AICS form factor magazines for around $1000 CAD, I think the current accuracy should be acceptable for my intended uses as a trainer and in CRPS/Rimfire PRS competition.
Do you have any insight on the cold bore issue?
I'll try to shoot baseline groups periodically now that I have a case lot of good ammo. Interesting to see if the accuracy will improve with chamber wear.
However, for a factory barrelled 700 footprint action that takes AICS form factor magazines for around $1000 CAD, I think the current accuracy should be acceptable for my intended uses as a trainer and in CRPS/Rimfire PRS competition.
Do you have any insight on the cold bore issue?
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You know, I'm not sure it was such a good idea to get one... And you don't have to call me Jesus, although it's been over a year since I had my hair cut.
Not sure it's worth the hassle on a factory barrel, as it seems to be shooting OK. However, it can be done, but for the same expense, I'm going to gently hone the leade by shooting a lot of ammo through it.
IBI apparently has replacement barrels in the works, but if I wanted a custom barrel and the increased costs I would have gone Vudoo or RimX in the first place. That being said, it could use a pound or two more weight in the front.
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I have a CZ 452, scoping it showed some bad burrs as shown above. A buddy that does a lot of BR rifles and is now doing RF BR smithing, hand reamed it with a sharp reamer and took all the burrs off, rifle is very consistent now.
I put my B-14 into an MDT XRS stock, with a TT Diamond trigger. I'm just waiting on an IBI barrel to put on that one and then spend the summer plinking steel in the yard.
I put my B-14 into an MDT XRS stock, with a TT Diamond trigger. I'm just waiting on an IBI barrel to put on that one and then spend the summer plinking steel in the yard.
First shot fliers from a clean bore are not unusual, and they are said to be caused by the increased friction from the clean, unlubricated bore causing an increase in pressure behind the bullet, ultimately resulting in a higher MV. This explains why these shots are typically high. At the same time, a few shooters have reported a low first shot from a clean bore. In any case, shooters fire a few fouling shots to alleviate the problem.
More significantly here, some shooters find that, even with a fouled bore, the first shot will be off POA after the rifle has been sitting in the rack for a time .
Although it doesn't appear to happen with all rifles, this problem seems to be the one described in this thread. I'm not sure, however, what causes it.
There may be several related things that happen that might be linked to an explanation. The one that comes to mind is that if the shooting is interrupted for a time, the moisture that results from the combustion process may have enough time to change the characteristics of the fouling and lubrication on the walls of the bore. If the change is sufficient, the POI is affected. As a result the first shot that follows the "cooling off" period is a flier. Some shooters will try to shoot some foulers if their rifle sits for a time.
Ill second you on this HAHA. I seem to recall someone else, oh yeah the first fellow to make the 1/4" club, challenge him and the air suddenly went out of the sails!!! When the gate drops the BS stops.
It's possible the burrs will wear away after more rounds, but it doesn't appear significantly diminished after 800 rounds.
Bill Calfee the noted and often controversial gunsmith relates that often some top quality factory rifles that are accurate, such as 52 Winchesters, 37 and 40X Remingtons, 54 Anschutz, and Walthers that didn't shoot well at first did so after a few thousand rounds. He thought the problem was an "unseasoned" (his word) chamber and leade. What he was referring to was a rough chamber and leade, often with machine marks and burrs. When these were worn down, the rifles would begin to shoot.
He explains this in his book, The Art of Rimfire Accuracy. Calfee's own words in blue below from his Chapter "Chamber Seasoning". Images from the book.
If you fired a bullet in the reamed chamber I show in FIG. 1, with its roughness and the corner of the rifling and groove with the burr filling it, here is what happens: the bullet passes through the leade and being rough, the leade removes lead from the bullet which is bad enough, but that little burr in the corner of the rifling removes some extra lead from the bullet. As soon as the driving band passes completely through the leade, and gets to the bore proper, all of a sudden each rifling mark on...[sentence incomplete in Kindle version of the book]
In FIG. 2, I try to show what a perfectly finished leade looks like. Smooth, no ridges and the corner is “clean” clear to the bottom of the groove. If you note in FIG. 2, the leade actually cuts into the chamber slightly, depending on the outside diameter of the reamer and the diameter of the grooves of the barrel.
[a word or more appear to be missing here in the Kindle version] the bullet is wider, because of the burr, than the rifling in the rest of the barrel. So the bullet, driven by pressure, picks up the driving side of each rifling, but because the rifling marks on the bullet have been enlarged, there is a little opening at each rifling where gas pressure can escape past the bullet. Of course, a barrel can’t be accurate like this. Now, does this make sense at all? A lead bullet must completely fill the bore and grooves to be accurate. The condition caused by that little burr deforming the bullet is no different than the bullet just being too small to fit the grooves properly. Either way, a good seal is not provided between the bullet and bore so, bad accuracy results.
In this little drawing [shown above] I am trying to show a slug in a rifle bore that has passed through the leade, as reamed, with the little burr left in the corner of each rifling… the little burrs have made the rifling cuts in the bullet wider than the lands so once the bullet gets into the barrel proper, a gap exists at each groove, allowing gas to escape and therefore, bad accuracy. This burr must be removed, either by lapping or several thousands of rounds through the barrel.
I can not see shooting soft lead over a burr like that doing much. MAYBE after 10’s of thousands of rounds might affect it. That looks like some thing you would have to remove.
Perhaps not. But Bill Calfee, who has a bit of experience with .22LR gunsmithing, thought that with a few thousand rounds similar imperfections might be reduced sufficiently to turn a previously poorly shooting rifle (good quality ones such as those listed above) into good ones.
How would you go about removing such flaws in the leade area?
This is the same burr in all the photos, each land has one, but this one is probably the worse one. Will they finally wear off? Are they detrimental to accuracy? Should I have bought a Vudoo? Stay tuned...
Light "flake" type burrs would eventually wear off, those however appear a tad too thick. I had the same in my CZ 455 Full Stock (actually all 3 of my CZ factory barrels had them), they definitely hurt accuracy. I was fairly successful lapping out the burrs in one of the barrels, went from shooting 1"+ groups at 50 yards to averaging 0.4xx"-0.6xx" groups and even did a 1/2" challenge target.
Might is the Key word. What is the Rockwell of the interior the barrel where the burr is? That is a factor. Sending soft lead that is coated to slide easier down a metal barrel my round the burr but a burr that size I would have serious doubt.
How I would fix it. Easy .
1) get or make an aftermarket barrel.
2 make a cutter to take the burr out of the barrel.
