The effect of bearing length on accuracy

[Zero333]

Too many variables to predict anything until you test and believe the targets.

Once you're satisfied with the group size you can fine tune the ES/SD by many different methods.

In the Hand-loading world, there are always exceptions to the rules. It gives me a headache. Thus I just let the target speak for itself as long as it's consistent and repeatable.

 

[Homerange]

To bound the consideration a bit, lets assume a goal of .5 MOA as sufficient accuracy.

As is mine.

Is there a relationship between bearing length and accuracy?

I don't believe so and instead any particular rifle will like one bullet and not another.

FWIW
2 rifles, 222 Sako L46 varminter and Rem Model 7 223
2 projectiles, both 50gr
Nosler BT and Hornady #2240

Sako loves the Hornady and the Rem Model 7 the Nosler.
Swap them and be prepared to be disappointed with the results. < I was !

 

[FNSafari]

The swiss GP11...my theory on the wax ring near the neck is 1) sealant 2) to help center the loaded rounds front area to the bore.

 

[FNSafari]

On a side note: not being a competitive shooter, I get a little confused on this .5 moa or whatever definition that is thrown around. I understand this is an aggregate number, but how many shots is the norm? Is wind, or the occasional bad load or pull, included in the statistic? And is there is standard range? I would shite can any barrel that wont shoot consistently under .5 at 100, excluding my induced errors, but after stretching out the distance then the other factors can over ride the rifle's precision capabilities for moa 'averaging'. I assume accuracy is a misnomer and not part of the 'moa calculation' as this is due to skill and not physics. So what is the true scoop?!

old saying(no idea if true) is 3 shot tests the rifle, 5 shot tests the shooter.

 

[Tesoro]

True! and 10 shots tests the reloader!

 

[davidjoe]

A bullet that is relatively less discussed, but I consider to shoot the smallest groups of all the 7mm’s and .338’s I have shot, is the Lapua Scenar. I have less experience with their 30’s but the 155’s are fantastic.

The Scenar line has a long bearing surface. That may or may not contribute to their inherent accuracy but it is an intentional design element of Lapua’s seen in different weight classes and calibers.

An unintentional element would likely be the fact that their meplats are relatively large. In other words, Lapua probably determined that uniformity and integrity were maximized with the amount of tipping pressure they apply, and it merely turned out that the meplats are fairly large, as opposed to their setting out to form large meplats for some ballistic purpose.

When a company as smartly staffed as Lapua incorporates an intentional profile design that can have admitted downsides, like seating depth and higher pressure, that element has likely been deemed extremely beneficial.

The Lapua Scenar is challenged to buck the wind as well as its main rival, but it most assuredly shoots as small or smaller, with no modification to its tip being done by the user and no sorting.

In the .338 300 grain bullet, again with a long body for overall length, it is hands down the smallest grouping cup and core bullet, assuming no environmentally caused shooter errors.

 

[Diverjeff]

A bullet that is relatively less discussed, but I consider to shoot the smallest groups of all the 7mm’s and .338’s I have shot, is the Lapua Scenar. I have less experience with their 30’s but the 155’s are fantastic.

The Scenar line has a long bearing surface. That may or may not contribute to their inherent accuracy but it is an intentional design element of Lapua’s seen in different weight classes and calibers.

An unintentional element would likely be the fact that their meplats are relatively large. In other words, Lapua probably determined that uniformity and integrity were maximized with the amount of tipping pressure they apply, and it merely turned out that the meplats are fairly large, as opposed to their setting out to form large meplats for some ballistic purpose.

When a company as smartly staffed as Lapua incorporates an intentional profile design that can have admitted downsides, like seating depth and higher pressure, that element has likely been deemed extremely beneficial.

The Lapua Scenar is challenged to buck the wind as well as its main rival, but it most assuredly shoots as small or smaller, with no modification to its tip being done by the user and no sorting.

In the .338 300 grain bullet, again with a long body for overall length, it is hands down the smallest grouping cup and core bullet, assuming no environmentally caused shooter errors.

Good to hear,I've been shooting the 300 gr. Berger OTM'S and picked up 300 of the 250 and 300 gr. Scenars for my 338LM about a year ago but haven't gotten around to trying them yet.Thanks for the review brother.

 

[dcali]

A bullet that is relatively less discussed, but I consider to shoot the smallest groups of all the 7mm’s and .338’s I have shot, is the Lapua Scenar. I have less experience with their 30’s but the 155’s are fantastic.

The Scenar line has a long bearing surface. That may or may not contribute to their inherent accuracy but it is an intentional design element of Lapua’s seen in different weight classes and calibers.

An unintentional element would likely be the fact that their meplats are relatively large. In other words, Lapua probably determined that uniformity and integrity were maximized with the amount of tipping pressure they apply, and it merely turned out that the meplats are fairly large, as opposed to their setting out to form large meplats for some ballistic purpose.

When a company as smartly staffed as Lapua incorporates an intentional profile design that can have admitted downsides, like seating depth and higher pressure, that element has likely been deemed extremely beneficial.

The Lapua Scenar is challenged to buck the wind as well as its main rival, but it most assuredly shoots as small or smaller, with no modification to its tip being done by the user and no sorting.

In the .338 300 grain bullet, again with a long body for overall length, it is hands down the smallest grouping cup and core bullet, assuming no environmentally caused shooter errors.

Spot on. Laupua Scenars have a well earned reputation for accuracy because they have made some tradeoffs to get there. When you add it all up, they pay for accuracy with BC, and I have no doubt they did that intentionally. I think that is why they're not more often seen at matches - they're just a step behind, say, Berger, who heavily optimizes their designs for BC. That doesn't mean they're not excellent bullets, though. I've not shot a ton of them, but the ones I have were very well behaved.

 

[Bill Norris]

True! and 10 shots tests the reloader!

Spot on.

 

[gunsandgunsmithing]

Spot on. Laupua Scenars have a well earned reputation for accuracy because they have made some tradeoffs to get there. When you add it all up, they pay for accuracy with BC, and I have no doubt they did that intentionally. I think that is why they're not more often seen at matches - they're just a step behind, say, Berger, who heavily optimizes their designs for BC. That doesn't mean they're not excellent bullets, though. I've not shot a ton of them, but the ones I have were very well behaved.

I think the same applies to several common Sierra bullets. What they give up in bc is made up in accuracy and ease of tuning. Just my thoughts. They almost always shoot well and are much less seating depth sensitive, IME. We all love teeny tiny groups and bc but this style just seems to tune fast and easy, which can equal more barrel life.

 

[searcher]

On a side note: not being a competitive shooter, I get a little confused on this .5 moa or whatever definition that is thrown around. I understand this is an aggregate number, but how many shots is the norm? Is wind, or the occasional bad load or pull, included in the statistic? And is there is standard range? I would shite can any barrel that wont shoot consistently under .5 at 100, excluding my induced errors, but after stretching out the distance then the other factors can over ride the rifle's precision capabilities for moa 'averaging'. I assume accuracy is a misnomer and not part of the 'moa calculation' as this is due to skill and not physics. So what is the true scoop?!

You are correct in that "other factors" can, and do, take over from the rifle's precision. But one does want a "baseline" as to what the load is capable of, in absence of these outside influences. Some guys use three shots- some five, some ten to assess the accuracy - summed in MOA. What really matters is the consistency of those results. To better know that, the more shots fired with that load, the better one knows the average outcome. All shots count in any group, though if one knows they "pulled" a shot, it should be discounted. If there was a significant condition change and the shooter knew they were not on top of it, perhaps they will want to discount that when assessing what they think the load will do. After all, why count it if you know it wasn't the rifle. I shoot five shot groups, but never trust a single group when assessing pure accuracy for the load. It takes an average of several groups in different conditions, averaged. Like shooting in a match, there should be multiple groups fired for an aggregate. In matches, everything counts - and shots do get away due to conditions. and that is just part of the game. You can't separate the rifles inherent "accuracy" from skill and physics, as they all work together to create whatever MOA is achieved. My thoughts, anyway.

 

[gunsandgunsmithing]

You are correct in that "other factors" can, and do, take over from the rifle's precision. But one does want a "baseline" as to what the load is capable of, in absence of these outside influences. Some guys use three shots- some five, some ten to assess the accuracy - summed in MOA. What really matters is the consistency of those results. To better know that, the more shots fired with that load, the better one knows the average outcome. All shots count in any group, though if one knows they "pulled" a shot, it should be discounted. If there was a significant condition change and the shooter knew they were not on top of it, perhaps they will want to discount that when assessing what they think the load will do. After all, why count it if you know it wasn't the rifle. I shoot five shot groups, but never trust a single group when assessing pure accuracy for the load. It takes an average of several groups in different conditions, averaged. Like shooting in a match, there should be multiple groups fired for an aggregate. In matches, everything counts - and shots do get away due to conditions. and that is just part of the game. You can't separate the rifles inherent "accuracy" from skill and physics, as they all work together to create whatever MOA is achieved. My thoughts, anyway.

Yes, sometimes it's just common sense. If you're not being scored for a match and you know you screwed the pooch on a shot at your own fault, of course that shot means nothing in regard to how the rifle will shoot and should be discounted. But really, doing away with those mistakes is when you start to see the true potential of the gun and tune. Lots easier said than done, though. So that bad shot matters and it's telling you a lot. Just not about the gun. Lol!

 

[searcher]

Yes, sometimes it's just common sense. If you're not being scored for a match and you know you screwed the pooch on a shot at your own fault, of course that shot means nothing in regard to how the rifle will shoot and should be discounted. But really, doing away with those mistakes is when you start to see the true potential of the gun and tune. Lots easier said than done, though. So that bad shot matters and it's telling you a lot. Just not about the gun. Lol!

Yes - we do learn from our mistakes - and a big part of that is KNOWING it was you when you pulled the trigger. For sure!

 

[gunsandgunsmithing]

Yes - we do learn from our mistakes - and a big part of that is KNOWING it was you when you pulled the trigger. For sure!

I'm pretty hard headed, so there are times I just make the same mistake more than once. But yes, flags are your best friend for at least knowing when NOT to shoot or telling you why a shot came out of the group a lot of times. Then there are times when I still don't know what happened. Hate those days. Lol! Typically,
I consider any day that I learn something, a good day. It's those days that I just don't see it or know why that makes me make the same mistake again. Those days are the worst. Burnt up a lot of ammo, shot like crap and would do it all again! Lol!

 

[dcali]

I think the same applies to several common Sierra bullets. What they give up in bc is made up in accuracy and ease of tuning. Just my thoughts. They almost always shoot well and are much less seating depth sensitive, IME. We all love teeny tiny groups and bc but this style just seems to tune fast and easy, which can equal more barrel life.

I agree. I think most of these bullets were designed before long range shooting became so popular. If you're talking about shooting less than 500 yards, a more conservative design makes even more sense.

 

[Capt. Oblivious]

Have a look at the bearing surface of these things

9,1 g / 140 gr Naturalis N563

The Lapua Naturalis bullets have been produced for almost 20 years, and have since been a top choice for hunters around the globe. The projectile design uses state of the art technology to produce…

www.lapua.com

I load them for a friend of mine and at first I thought these things are going to be pipebombs, I was shocked how accurate they were in his rifle, 5 shots less then 0.5moa at a 100y easy

 

[searcher]

Have a look at the bearing surface of these things

9,1 g / 140 gr Naturalis N563

The Lapua Naturalis bullets have been produced for almost 20 years, and have since been a top choice for hunters around the globe. The projectile design uses state of the art technology to produce…

www.lapua.com

I load them for a friend of mine and at first I thought these things are going to be pipebombs, I was shocked how accurate they were in his rifle, 5 shots less then 0.5moa at a 100y easy

I always wondered about those. Lapua makes some great bullets. Their "L" bullets are crazy accurate for targets.

 

[jackieschmidt]

Accuracy is relative to the task at hand.

If you are shooting Ground Hogs out past 500 yards, you obviously need a more accurate rifle than if you are shooting at a White Tail at 100. But that Ground Hog Rifle might not be suitable to take a White Tail.

If you are talking competitive shooting, a bullet that is “accurate” out past 600 yards might be totally useless in a Short Range Benchrest Match, and visa-versa.

In short range, we sacrifice all aspects of of ballistic performance toward the combinations ability to stack one bullet atop the other at 100/200/300 yards. Often the bullets and combination we shoot defy the norm, especially in the 30 caliber realm in weights of 112 to 115 grains. They are short and stubby. But one thing most of the better ones have is a nice long shank in relation to the diameter and the overall length.
As an example, my 112 30 caliber is still .308 clear out to the mark. That is pretty long, longer than the diameter of the shank.

Bullets such as this are some of the most accurate bullets made when shot out of a 1-17 or 1-18 twist barrel at 200/200/300 yards.

I believe the true test of any concept is the aggregate. One five shot group is not very informative. Even two or three can still leave doubts. In a rifle destined for competition, you need to shoot it as many times as required in the aggregate. That would usually be five.

I did a serious test of a new Bartlien 30 caliber 1-18 400 mod barrel last week, and I had to account for every shot. No give always. This takes some serious concentration. Shooting my own 112, you can see how capable these short 30’s are at 100 yards in five 5-shot groups.

 

[DeltaBravo]

When I first got into this sport, I started with an 8-twist ratchet rifled Shilen barrel with 4 grooves. Began with 87 grain V-Maxes and whatever the powder was (don't recall because I was looking for a load). I finally gave up on the V-Maxes at about 200 rounds because nothing worked. In fact, I was sometimes lucky to get on the paper at 100 yards! Went to Burger 80 grain varmint target bullets and things began to work out.

To get an idea of the aggravation involved, here's a picture of one of my targets. All of the holes are single shot!

I'm still shooting Shilen barrels (12-twist 6 groove now) and have shot their ratchet rifled barrels in 14-twist (4 groove again) with good results using Bart's 68 grain boat tails.

Dennis

 

[boltfluter]

Accuracy is relative to the task at hand.

If you are shooting Ground Hogs out past 500 yards, you obviously need a more accurate rifle than if you are shooting at a White Tail at 100. But that Ground Hog Rifle might not be suitable to take a White Tail.

If you are talking competitive shooting, a bullet that is “accurate” out past 600 yards might be totally useless in a Short Range Benchrest Match, and visa-versa.

In short range, we sacrifice all aspects of of ballistic performance toward the combinations ability to stack one bullet atop the other at 100/200/300 yards. Often the bullets and combination we shoot defy the norm, especially in the 30 caliber realm in weights of 112 to 115 grains. They are short and stubby. But one thing most of the better ones have is a nice long shank in relation to the diameter and the overall length.
As an example, my 112 30 caliber is still .308 clear out to the mark. That is pretty long, longer than the diameter of the shank.

Bullets such as this are some of the most accurate bullets made when shot out of a 1-17 or 1-18 twist barrel at 200/200/300 yards.

I believe the true test of any concept is the aggregate. One five shot group is not very informative. Even two or three can still leave doubts. In a rifle destined for competition, you need to shoot it as many times as required in the aggregate. That would usually be five.

I did a serious test of a new Bartlien 30 caliber 1-18 400 mod barrel last week, and I had to account for every shot. No give always. This takes some serious concentration. Shooting my own 112, you can see how capable these short 30’s are at 100 yards in five 5-shot groups.View attachment 1497580
View attachment 1497571

That's some fine shooting on your part! Nicely done, and with your own home grown bullets. Very cool!
Paul