How do BR shooters get away with it?

[LHSmith]

I thought they sent 3 fired cases to the die maker and had custom dies made.

That's one option. In SR BR one could also buy a Harrells die in the popular 6 PPC and 30 BR.They offer up to 4 different body sizes, so usually the match is very close to ideal. The other option is to have the smith cut the die with an optimum dimentioned sizing reamer. In many cases these days the competitor does his own smithing.

 

[Mulligan]

The smallest group I've ever shot at a 1000-BR match was a 2.553" (LT-Gun) with brass on its 19th-cycle, never annealed, (0.0095" neck walls). Those same 5 cases on there 18th-cycle shot a 3.261" group at a previous match. On there 17th-cycle they went slightly over 2" while testing at home.

The 2nd smallest group I've ever shot at a 1000-BR match was a 2.676" with brass "Annealed +2-cycles", and was its 7th life-time cycle, only annealed (Amp) the one time.

As Alex stated: "testing" is what proves out to our own scenario's. Good to hear what works for others, but often is not what ends up working for me.

My 2-Cents
Donovan

Tag

 

[Webster]

That's one option. In SR BR one could also buy a Harrells die in the popular 6 PPC and 30 BR.They offer up to 4 different body sizes, so usually the match is very close to ideal. The other option is to have the smith cut the die with an optimum dimentioned sizing reamer. In many cases these days the competitor does his own smithing.

In the 80s I had a 6PPC that Fred Sinclair built. I assume the die he sold me was cut with the reamer. I need an explanation for the following. If the chamber and die are made from the same reamer then the die has the same dimensions as the chamber. This should result in no sizing since the fired case would expand to fill the chamber then spring back. Using the die would be the same as putting the fired case back in the rifle and closing the bolt???

 

[Tim Singleton]

In the 80s I had a 6PPC that Fred Sinclair built. I assume the die he sold me was cut with the reamer. I need an explanation for the following. If the chamber and die are made from the same reamer then the die has the same dimensions as the chamber. This should result in no sizing since the fired case would expand to fill the chamber then spring back. Using the die would be the same as putting the fired case back in the rifle and closing the bolt???

It will be ok for a few firings and indeed may have been the norm 20-30 years ago
After several firings it just doesn't spring back like it did when new
It will become to tight in short order. The bolt will be hard to close and hard to open. This isn't acceptable to upset the gun in the rest struggling with a hard bolt lift

 

[LHSmith]

Don't forget the fact that the chamber stretches upon firing -the higher the pressure the more expansion- which at some point springback may not overcome. It may be after the first firing (with hot loads) or never if one solely uses reduced loads or book starting loads. So much has changed in the game since that rifle was built. Most competitors find the best accuracy (in real world conditions- not just early am calm) by loading in the upper pressure atmosphere.

 

[Webster]

Don't forget the fact that the chamber stretches upon firing -the higher the pressure the more expansion- which at some point springback may not overcome. It may be after the first firing (with hot loads) or never if one solely uses reduced loads or book starting loads. So much has changed in the game since that rifle was built. Most competitors find the best accuracy (in real world conditions- not just early am calm) by loading in the upper pressure atmosphere.

Do we have two situations that require different die adjustments?
1. Just enough shoulder contact to get a correct shoulder bump.
2. The case has to go deeper into the die beyond shoulder bump to reduce the case diameter above the extractor groove. This would give more bump than you want.

 

[Tim Singleton]

Do we have two situations that require different die adjustments?
1. Just enough shoulder contact to get a correct shoulder bump.
2. The case has to go deeper into the die beyond shoulder bump to reduce the case diameter above the extractor groove. This would give more bump than you want.

This is where the die fitted to your chamber comes in
It will do as you describe. Set the shouldwr back .002 and squeeze the base to whatever spec you desire

 

[savagedasher]

I don't know of any die that sizes the base or head of a case .
A friend has a
Reloading and manufacturing of new ammunition shop . He made a roller that does only the base of the case . The reason for it was for tight chamber guns . He reloads over 8 million rounds a year and manufactured twice that amount . His operation runs 24 --7
He has
Over 24 employees .
If someone is going to load custom loads the first you need is custom dies . Larry

 

[TAJ45]

I think your right to a point Tommie that some tend to gravitate to equipment trends without a doubt. There are always going to be people who do that in every sport. Perfect example is drag racing. Years ago when I was on a funny car crew in the mid-70's, when Don Prudhomme started winning races beginning in 75 with his new Ed Pink blower, everybody started to order them. Same with the injectors. When he went from the Enderle to the Crower 8 port, everybody started to change to a Crower. You can show up with a bra on your head and if you win, the next week you'll probably see some people wearing one at the next match. Humans are just a weird creature of habit.

Similar to bass fishing. If someone hits it big at the lake tossing a pink fluetailed worm, betchure sweet cheeks that will be the worm the bass will be seeing till the next big catch occurs with a diff color and configuration.

 

[savagedasher]

Similar to bass fishing. If someone hits it big at the lake tossing a pink fluetailed worm, betchure sweet cheeks that will be the worm the bass will be seeing till the next big catch occurs with a diff color and configuration.

The only way I can think it will stop is when someone comes up with a
Sky Blue Pink Stock. Larry

 

[ImBIllT]

We're told bench rest shooters know everything there is to know about reloading. They bring a trailer full of gear with them. They load 5 rounds at a time. After shooting those 5 rounds they go back to their machine shop on wheels and reload those 5 cases and fire them again.

How do they get away with not annealing after each firing? Do they trim/chamfer/debur after each firing? Do they clean with steel pins in an overnight bath of secret solutions?

If not, why do we?

Because you don't need to anneal after every firing, especially with a tight chamber and neck sizing, or neck sizing and shoulder bumping. I have gone over 20 firings without annealing and I've never had a split neck. I build a batch of brass, sort by weight, ever time a shot goes out and I don't know why, I turn that case upside down. If it goes out on the next firing, I throw it away. After a while my groups are small, so I combine all my batches, anneal so the next are the same harness, completely re-prep my brass, and weight sort again. The only time I anneal is when I combine groups with a different number of firings. My hunting guns don't get shot that much, and my competitive guns all have tight necks.

 

[ImBIllT]

In the 80s I had a 6PPC that Fred Sinclair built. I assume the die he sold me was cut with the reamer. I need an explanation for the following. If the chamber and die are made from the same reamer then the die has the same dimensions as the chamber. This should result in no sizing since the fired case would expand to fill the chamber then spring back. Using the die would be the same as putting the fired case back in the rifle and closing the bolt???

There are different ways to do it.
1. Cut with the same reamer to the same headspace and then mill the top for bushings and it's a neck sizer.
2. Run the reamer in a couple thousandths short and it's a bump die.
3. Run the reamer in a couple thousandth short and mill the top for bushings and it's a bump/neck die.
4. Run it in a hair shorter and mill the top for bushings and it's a full length die.
5. Have a custom sizing die reamer made.

 

[Webster]

There are different ways to do it.
1. Cut with the same reamer to the same headspace and then mill the top for bushings and it's a neck sizer.
2. Run the reamer in a couple thousandths short and it's a bump die.
3. Run the reamer in a couple thousandth short and mill the top for bushings and it's a bump/neck die.
4. Run it in a hair shorter and mill the top for bushings and it's a full length die.
5. Have a custom sizing die reamer made.

Has anyone publish how much a steel chamber expands when firing. Someone must know since they put strain gauges on barrels to measure barrel stretch. Many people mention barrel expansion affecting how much a case expands without knowing if the barrel expands 0.0001", 0.001" or whatever number.

 

[Toby Bradshaw]

Has anyone publish how much a steel chamber expands when firing. Someone must know since they put strain gauges on barrels to measure barrel stretch. Many people mention barrel expansion affecting how much a case expands without knowing if the barrel expands 0.0001", 0.001" or whatever number.

For 65K psi, 1.25" steel barrel, and 0.470" chamber the diametrical expansion is about 0.002". Some of the simplifying assumptions are probably violated, but that's in the ballpark.

 

[ImBIllT]

Has anyone publish how much a steel chamber expands when firing. Someone must know since they put strain gauges on barrels to measure barrel stretch. Many people mention barrel expansion affecting how much a case expands without knowing if the barrel expands 0.0001", 0.001" or whatever number.

It depends on the thickness of the chamber, and of course the portion of the chamber in the action will then depend on the shape, thickness, and material of the action. They expand quite a few thousandths. They don't exceed the elastic limit and therefore return to original size. If the brass grows .001" then the elastic limit was exceeded by .001". The brass may have expanded .005" and only exceeded the elastic limit by .001". It could be calculated, but one would have to know the alloy and hardness of the brass, and the hardness increases everytime it is worked, so the number doesn't really matter. The thickness of the brass changes how far it can be deformed without exceeding the elastic limit as well. Thinner brass and thinner barrels will deform farther without incurring permanent deformation, but it requires less force. A thicker barrel will expand less when fired. The brass will obviously not deform more than the barrel. Thinner brass can deform more without deforming permanently. Thin brass in a thick chamber will need little to no sizing.

 

[ImBIllT]

For 65K psi, 1.25" steel barrel, and 0.470" chamber the diametrical expansion is about 0.002". Some of the simplifying assumptions are probably violated, but that's in the ballpark.

Is this barrel expansion, or is this the size of the brass after firing? Just wondering. If this is the difference between pre-fired brass and post-fired brass, then the barrel actually expanded further.

 

[Toby Bradshaw]

Is this barrel expansion, or is this the size of the brass after firing? Just wondering. If this I the difference stern pre-fired brass and post-fired brass, then the barrel actually expanded further.

Barrel expansion at peak chamber pressure.

 

[ImBIllT]

Barrel expansion at peak chamber pressure.

Cool. So the size difference between pre, and post fired brass would be less than .002", however, if the brass changes size, then it would need to be stuffed into a die .002" smaller than the fired size to return to pre-fired size. The post-fired size would change over time as the brass hardened.

 

[dmoran]

@Webster
All my custom F/L dies were made with Die reamers, that are slightly undersized in dimensions then the Chamber reamers, then polished and hardened (same for Body-dies). All my custom Seating and Neck-sizing dies were made with the Chamber reamers (and are NOT hardened).
Donovan

 

[Webster]

We're told bench rest shooters know everything there is to know about reloading. They bring a trailer full of gear with them. They load 5 rounds at a time. After shooting those 5 rounds they go back to their machine shop on wheels and reload those 5 cases and fire them again.

How do they get away with not annealing after each firing? Do they trim/chamfer/debur after each firing? Do they clean with steel pins in an overnight bath of secret solutions?

If not, why do we?

At a big match almost everyone has a good rifle. I believe the difference is gun handling at the bench and consistently reading down range conditions better than 90% of the shooters at the line.