6BR vs 6CM

[joesr]

This post started with the topic of 6br vs 6CM and the point of this post was supposed to be that for people shooting the 6br for 600 or longer shooting the 6CM is a much better choice.

I don’t think that the above statement is arguable. Given the proven barrel life of the 6CM,over 3000 round from the first chambering) and the proven velocities we are shooting the 107 and 115 class bullet.

The 6CM, at 600 yards, blows away the 6br in any wind. Furthermore, in no wind I believe they are equal or possibly the 6CM holds a slight edge as the 6CM was designed for shooting 200, 300, 600 and 1000 yards.

However, the argument has turned slightly to the 6CM vs the 6.5x284.

At 600 yards or under I believe the 6CM is a much better cartridge. Ballistics are better for the 6CM and the barrel life is much longer.

At distances over 600 yards I am still on the fence. I understand the arguments about how larger bullets do better “on the target” and I am all about “on the target”.

However, we have to consider two things.

First: the 6XC has proven to be all but perfect at 1000 yards using the 115’s. You cannot argue with David Tubb’s success with the 6XC at 1000 yards in 2005.

Second: Even if you assume that the reason that David won in 2005 was due to his abilities more than his cartridge. ,I would argue that there were many great shooters on the line, shooting many calibers, in 2005 and to do what David did in some way proves the superiority of the 6mm 115 bullet and the 6XC)

No one has tried shooting the 115 out of the 6CM or a simular cartridge with velocities of 3100 or better.

The velocity that we can shoot the 115 at is the reason that the 6CM is better than the 6.5x284.

It all comes back to velocity. Velocity is not ruling factor, it is the driving factor for long range shooting. You have to have great accuracy, with a great bullet and then enough velocity to make that combination better than everything else.

The competition between the 6.5x284 and the 6CM is very close in this matter and I’m not about to pick a winner, at this time.

Joe Hendricks

 

[rcw3]

Joe

I will agree with you absolutely on one point. In 6mm's, if you can burn a powder like H1000 which is a single base slow burning powder,with a lower flame temperature) your barrels are bound to last longer than if you have to burn faster powders like H4350,which is a faster powder with a high flame temp). I have a number of smaller "hot rod" 6mm's that burn powders like H4350, and it does torch the barrels, and you're lucky to get 2000 rounds out of such barrels if you are driving naked 105-107 gr. bullets in the neighborhood of 2950 - 3000 fps.

Robert Whitley

 

[Raptor]

Joe,
I have to agree with you on the velocity and also no one wants to be beat up by shooting 240gr bullets! I guess I was thinking more along the line of the 6XC and the 260 shooting the 123s where both are very close in veloctiy.

However I was pushing my 140s at 3000fps in the 6.5x284 and like you said the 6CM will push the 115s to 3100+ but then the 6.5x284 will to but neither of us would want to shoot them there.

I also know that you were not comparing the 6CM to the 6.5X284 and only mentioned it as a comparison for balistics. I was just trying to say that what looks the best on paper is "NOT" always the way it works out in real world conditions.

I think you have a fine cartridge and I probably will have one if I stay with the 6MMs. Thanks again for the gentlemanly discussion!!

 

[Raptor]

Robert,
Quick queston, you seem very knowlegable on powders. I was wondering how is RL-22 and VV-500 series powders on barrels compared to say VV-160??? I see in their adds that VV says the 500 series is easy on barrels because of a coating they use.

I have also heard that RL-22 is a double base powder like H4350 so it is harder on throats than other powders. Thanks!!!

 

[joesr]

Robert,
Quick queston, you seem very knowlegable on powders. I was wondering how is RL-22 and VV-500 series powders on barrels compared to say VV-160??? I see in their adds that VV says the 500 series is easy on barrels because of a coating they use.

I have also heard that RL-22 is a double base powder like H4350 so it is harder on throats than other powders. Thanks!!!

Raptor, I'll take a shot at this and Robert can confirm or correct me.

1st RL-22 and H4350 are both single based powders.

2nd VV-500 series powders are double based and are very hard on barrels, regardless on what their ads state. The 100 series powders are great and are single based.

For a choice in powder, if you are looking for barrel life, you are save with any of the IMR powders, any of the popular Hodgdon powders, any of the VV-100 powders. Beyond those powders you are on your own.

However, H4350 is perceived to be hard on barrels, when shooting it is a 6mm, not because of it's chemical make up, but because of it's flame temp and the resulting burning speed.

I hope this helps.

Joe Hendricks

 

[Spotcheck_Billy]

Robert,
Quick queston, you seem very knowlegable on powders. I was wondering how is RL-22 and VV-500 series powders on barrels compared to say VV-160??? I see in their adds that VV says the 500 series is easy on barrels because of a coating they use.

I have also heard that RL-22 is a double base powder like H4350 so it is harder on throats than other powders. Thanks!!!

Raptor, I'll take a shot at this and Robert can confirm or correct me.

1st RL-22 and H4350 are both single based powders.

2nd VV-500 series powders are double based and are very hard on barrels, regardless on what their ads state. The 100 series powders are great and are single based.

For a choice in powder, if you are looking for barrel life, you are save with any of the IMR powders, any of the popular Hodgdon powders, any of the VV-100 powders. Beyond those powders you are on your own.

However, H4350 is perceived to be hard on barrels, when shooting it is a 6mm, not because of it's chemical make up, but because of it's flame temp and the resulting burning speed.

I hope this helps.

Joe Hendricks

Correct me if I'm wrong, but ........

It's always been my understanding that double based powders consist of both nitrocellulose and nitroglycerin. If that's the case, Re22,or RL22 depending on how you want to abbreviate it) would be considered a double based powder going by what Alliant has printed on the side of the container.

Isn't it true that double based powders burn with a higher flame temp than single based powders of a similar burning speed and that's why they are generally considered as being harder on throats?

Alan

 

[rcw3]

Joe

I believe the Reloader powders are double base high energy powders. If you look at the labels they all have nitroglycerine in addition to nitrocellulose.

I have always found H4350 to be hard on 6mm and 6.5mm barrels, and I think you are right about the flame temperature. I remember reading that 4350 had one of the higest flame temperatures among the powders offered to reloaders,kind of like racing fuel - delivers the performance but not without a tradeoff).

By and large, while the VV 100 series powders are single base, I have found those hard on barrels too. I have shot 140, 150 and 160 with 6mm's and it seems like all those powders are very hard on barrels, and I don't know why. If you look at VihtaVuori's info, 140, 150 and 160 are both higher energy and faster than 165 and 170. On the other side, some of the VihtaVuori powders deliver some great accuracy and performance too.

Robert Whitley

 

[joesr]

Joe

I believe the Reloader powders are double base high energy powders. If you look at the labels they all have nitroglycerine in addition to nitrocellulose.

I have always found H4350 to be hard on 6mm and 6.5mm barrels, and I think you are right about the flame temperature. I remember reading that 4350 had one of the higest flame temperatures among the powders offered to reloaders,kind of like racing fuel - delivers the performance but not without a tradeoff).

By and large, while the VV 100 series powders are single base, I have found those hard on barrels too. I have shot 140, 150 and 160 with 6mm's and it seems like all those powders are very hard on barrels, and I don't know why. If you look at VihtaVuori's info, 140, 150 and 160 are both higher energy and faster than 165 and 170. On the other side, some of the VihtaVuori powders deliver some great accuracy and performance too.

Robert Whitley

Great...good information...

I have never been a fan of Alliant powders and therefore I don't even test them. Just a personal thing. It is good to know that they are double base. I didn't know.

On the VV powders....the only ones we have used,limited) are N165 and N170, both gave great results, but we keep coming back to H1000.

Retumbo interests me and I'm going to do some work with it. However, my brief testing has shown that there is no significant difference between H1000 and Retumbo,velocity or accuracy).

I am stuck in my small world of the 6CM and what works for it. Possibly, I have found a needle in a haystack with H1000 and this caliber.

Joe Hendricks

 

[Raptor]

Thanks Guys,
I lean from you all everytime I come on here. I have been trying to come up with a good load, with slow burning powder, in my 6.5x55 for 1000yd shooting.

I have tried RL-22, N-165, N-560, H-4350, and now H-4831. The RL-22 is suppose to be the powder of choice for the 6.5x55 according to what everyone tells me. However mine does "NOT" like it. I have gone from 46 to 49grs, bullets in, bullets out and its inconsistant to say the least.

VV N-165 showed the best results at 100yds but I ran out of it before I could test it at long range. I borrowed some N-560 to try and only shot it at long range. It gave me the best results to date with most groups averaging around the .6 to .7 at 400, 500 and 600yds. I had tried H-4831 when I first broke in the barrel as part of my break in load but only shot one group with it at 100yds and it was nothing to get excited about.,It had horizontal stringing). But then after going over targets I noticed it was my first day back on a bench and from looking at my targets I had a tendency to string my groups horizontally so I gave the 4831 another try at long range. Low and behold I found a shooter!!!! It shot 2"s @ 400, 2 3/8" @ 500yds and 3.1" @ 600yds.

The only problem is I am getting a slight extractor mark on the brass so further testing needs to be done. I am trying to get some N-160 to try in it next. Thanks for your help guys!!!

 

[Raptor]

Robert,
What do you think is the best all around powder for longer barrel life in the 6MMs and the 6.5s??? Thanks again!!

 

[Rust]

Raptor - My experience with RL-22 is limited to the 6.5 X 284. In initial testing I noted that it was quite sensitive to primer choice and oddly enough it worked best with the 139 Scenar or 142 SMK at a target velocity of 2950,where it displayed good ES/SD) with a Winchester primer. I've been told by other sources that they have had similar results.

The drawback was a fairly persistant hard fouling after a 20 round string that was quite difficult to clean which I suspect but cannot prove, came from the deterrent coating.

I ended up sticking with the tried and true H4350 despite the increased erosion rate and low charge density simply because it was more accurate, fouled less and had better ES/SD numbers,single digit).

 

[Raptor]

Rust,
Thank you for the reply. The only experience I had with the R-22 was when I had my 300wm. I didn't care for it then because it seemed that it showed no pressure signs at a certain number of grains but then go up a half a grain and it would blow a primer.

I tried it again in my 6.5x284 and the accuracy was fine and it was the fastest load I tested but I liked the idea of the extreme powders so stayed with the H4831.

 

[mysticplayer]

Sorry, but couldn't find an answer doing a search so...

What is the parent case for the 6CM? Any load data and barrel/barrel length used to get those velocities with the 115gr bullets?

I have read alot of neg comments on H4350 as hard on throats. Any thoughts on H4831SC?

Jerry

 

[joesr]

Raptor - My experience with RL-22 is limited to the 6.5 X 284. In initial testing I noted that it was quite sensitive to primer choice and oddly enough it worked best with the 139 Scenar or 142 SMK at a target velocity of 2950,where it displayed good ES/SD) with a Winchester primer. I've been told by other sources that they have had similar results.

The drawback was a fairly persistent hard fouling after a 20 round string that was quite difficult to clean which I suspect but cannot prove, came from the deterrent coating.

I ended up sticking with the tried and true H4350 despite the increased erosion rate and low charge density simply because it was more accurate, fouled less and had better ES/SD numbers,single digit).

Rust,

I'm going to say something that all 6.5x284 shooters are probably going to yell NO!...but H1000 is an excellent powder for this cartridge. It will yield the velocities you expect and will extend the barrel life.

As the 6.5x284 was being developed, before there was brass for the cartridge, shooters were only interested in velocity and accuracy.

Now that that has been proven very little experimentation has been done with loads or powder choice.

Several of us involved with the 6CM have tried our formula with the 6.5X284 and H1000 looks like it works the same way with this cartridge as it does with the 6CM.

Great velocity, great accuracy and good barrel life.

Give it a try.

Joe Hendricks

 

[rcw3]

On this powder issue, I spoke to a representative from Hodgdon today. What he basicly said is the powders in their extruded rifle powder line have basicly all the same ingredients in the same proportions and are essentially all the same thing,i.e. H4350, H4831SC, H1000, etc.) with exception of grain geometry and how much and what deterrant is used to slow down the burn rate. He also said the difference in flame temperature between theses powders is minimal,not enough to be of consequence). In addition, they're all single base powders as well. He was at a loss to explain why a powder like H1000 might give better barrel life over H4350 when driving the same bullet at the same velocity and indicated he was unaware of any such phenomenon.

I am certainly no expert on this, but my take on all this is that a big issue for scorching the throat is the amount of pressure coupled with the speed of the burn. It seems to me that H4350, in order to get the same velocity with the same bullet as H1000, runs a quicker and higher peak pressure, most likely concentrating the higher pressure and flame burn in a smaller area of the barrel, scorching that area more. H1000 runs a lower pressure, most likely diffusing the pressure peak and the flame burn over a longer period of time and a larger area of the barrel. This is the only thing I can come up to explain the phenomenon whereby a powder like H1000 would result in a longer barrel life.

I know some guys tried H1000 in the 6.5 x284, but I think why many shy away from it is the ES and SD numbers with that powder. H4350 has consistenly given 1000 yard shooters very low ES and SD numbers.

Like I said, I'm no expert in these matters but barring another explanation, that's what seems logical to me.

Robert Whitley

 

[243Mendoza]

...
2. The 6CM does have better barrel life than the 6BR. I expect 3000 rounds from every barrel and 4000 rounds from most.

Joe, my 6BR barrel has over 5000 rounds through it and it can clean a target at 600yd with a good x-count,over 50%)

3. Beating out the 6.5x284....ballistically the 6.5 is better. But when you look at the accuracy of the 6CM it is the fact that the average 6CM barrel will out perform the average 6.5x284 barrel at long range.

Haven't seen any data to back that up.

There is no magic in this, it is simple ballistics, physics, metallurgy and luck that has led me to this conclusion.

Please show the ballistics and physics calculations. I've read,from Tubb) that the 115 at 3100fps will equal the 142 at 2950. But many people will shoot the 142 at 3050.

 

[joesr]

...
2. The 6CM does have better barrel life than the 6BR. I expect 3000 rounds from every barrel and 4000 rounds from most.

Joe, my 6BR barrel has over 5000 rounds through it and it can clean a target at 600yd with a good x-count,over 50%)

You are the first person I have ever come across that claims 5000 rounds through a 6BR barrel and shooting the longer ranges.

Possibly you just have a great barrel that will not give up. However I would be very interested to know what bullet you are shooting and at what velocity.

I know that when you push the 6BR to try to get good velocity out of the 107 barrel life suffers.

I can not explain the barrel life you are getting from your current barrel, but it is not the norm.

Furthermore, and I'm not saying you are doing this, but may people over estimate the amount of rounds through a barrel. I know that because I used to do the same thing. I track every round through my barrels in a book that I keep with every gun. If you don't do this the estimation is flawed.

3. Beating out the 6.5x284....ballistically the 6.5 is better. But when you look at the accuracy of the 6CM it is the fact that the average 6CM barrel will out perform the average 6.5x284 barrel at long range.

Haven't seen any data to back that up.

That is because there is no current data on this. This is all based on my and my customer's experiences.

It is all based in fact, but the the size of the sample is too small to come up with any data.

However, I will state that the 6mm's seem to be inherently more accurate than other cartridges. Furthermore, my personal experience has proved that getting a winning load from a 6mm is much easier than getting one out of the 6.5mm.

There is no magic in this, it is simple ballistics, physics, metallurgy and luck that has led me to this conclusion.

I use the "magic" term only meaning that the combination of barrel life we are experiencing due to powder choice and cleaning coupled with the great accuracy and great velocities the 6CM yields is exceptional.


Please show the ballistics and physics calculations. I've read,from Tubb) that the 115 at 3100fps will equal the 142 at 2950. But many people will shoot the 142 at 3050.

3050 from the 142 out of the 6.5x284 is on the very upper edge. As far as I know most people are not shooting the 142 this fast out of this cartridge. Mostly because it is not as accurate as when the 142 is shot slightly slower.

However, I'll take your word that many people shoot the 142 that fast out of the 6.5x284.



I'm not trying to make this about what cartridge is best.

No cartridge is best. The shooter has to pick the cartridge that best meets his or her needs.

I will not try to get into the bench rest game of 200 or 300 yard shooting. It is not my game and I know little about that game.

If we limit the discussion to 600 yard shooting. The shooter has to make a choice between shooting a cartridge that has proven accuracy in the short range benchrest shooting and can drive the 107 at velocities at 2700 or 2800 fps. The 6BR has has expected barrel life of around 3000 rounds shooting it this way.

Or

The shooter can choose to shoot a cartridge that will shoot the 115 at 3000 to 3200 fps with the same accuracy,at these distances) and give you an expected barrel life of 3000 or more. The 6CM, or for that matter the 6XC is far superior to the 6BR simply because of the larger bullet and more velocity. Unless you shoot every match with zero wind the 6BR simply should not be the chosen cartridge for shooting this type of competition.


Once you go to 1000 yard shooting; it is like flipping a coin. The 6CM, 6XC and 6.5x284 are all great choices for this shooting. The one thing that needs to be stressed here is that if you shoot both 600 and 1000 yard matches with the 6CM or 6XC you can shoot both with out giving up anything.

The advantage of the 6CM is longer barrel life and more velocity than the 6XC. However, both are great choices.

Joe Hendricks
Hendricks Shooting Improvements
6CM@comcast.net

 

[joesr]

On this powder issue, I spoke to a representative from Hodgdon today. What he basicly said is the powders in their extruded rifle powder line have basicly all the same ingredients in the same proportions and are essentially all the same thing,i.e. H4350, H4831SC, H1000, etc.) with exception of grain geometry and how much and what deterrant is used to slow down the burn rate. He also said the difference in flame temperature between theses powders is minimal,not enough to be of consequence). In addition, they're all single base powders as well. He was at a loss to explain why a powder like H1000 might give better barrel life over H4350 when driving the same bullet at the same velocity and indicated he was unaware of any such phenomenon.

I am certainly no expert on this, but my take on all this is that a big issue for scorching the throat is the amount of pressure coupled with the speed of the burn. It seems to me that H4350, in order to get the same velocity with the same bullet as H1000, runs a quicker and higher peak pressure, most likely concentrating the higher pressure and flame burn in a smaller area of the barrel, scorching that area more. H1000 runs a lower pressure, most likely diffusing the pressure peak and the flame burn over a longer period of time and a larger area of the barrel. This is the only thing I can come up to explain the phenomenon whereby a powder like H1000 would result in a longer barrel life.

I know some guys tried H1000 in the 6.5 x284, but I think why many shy away from it is the ES and SD numbers with that powder. H4350 has consistently given 1000 yard shooters very low ES and SD numbers.

Like I said, I'm no expert in these matters but barring another explanation, that's what seems logical to me.

Robert Whitley

Attached is my initial theory of why powders like H1000 give longer barrel life. Based on your conversation you had with Hodgdon today probably Number 1 does not apply,for Hodgdon powders), but number 2 and three help to explain this.


"The reasons for longer barrel life:

1) First the slower burning powder burns at a cooler temperature than faster burning powders. These lower temperatures have a great affect on barrel life. The barrel is not subject to as hot of a temperature and therefore the bullets do not have as much of an affect on the steel as with faster burning powders. This is more important during rapid fire and during a practice session. The barrel’s steel is less malleable because of lower temperatures. You are not subjecting your barrel to the same temperatures you do with faster burning powder.

2) Second the pressure curve is much different with a slower burning powder. With a slower burning powder the pressure peak is down the barrel much farther and more importantly the peak pressure is lower. What this means is that you are subjecting your barrel to a lower stress on every shot and the stress is spread over a larger portion of the barrel’s length. Again, think of the paperclip, if you only bend it a little and bend it in different places it takes much longer to break it. The lower pressure and the pressure applied over a greater amount of the barrel adds to the life of the barrel.

3) Third, it burns slower. Therefore the powder is burning as it goes down the barrel. Given a more even affect to the barrel. The burning powder is less concentrated in the length of the barrel and barrel ware is more uniform."

The fact is, and I have been saying this for some time, is that the propellant you shoot through the barrel is more important than the velocity with which you shoot the bullet in regards to barrel life.

Once you understand that propellants,powders) affect barrel life more than any other factor the shooter has to make a calculated choice in their cartridge.

You have to pick one that gives you winning accuracy and winning velocity for the best bullet available,depending on the yardage you are shooting).

If you can obtain better barrel life while doing so you are doing better than most shooters.

Joe Hendricks
Hendricks Shooting Improvements
6CM@comcast.net

 

[rcw3]

Joe

I agree with you on your points 2 and 3, but as to point 1, the fellow at Hodgdon says the difference in burn temperature among all their extruded rifle powders is less than 100 degrees,which he said is insignificant). I never realized that all their extruded rifle powders are also all made from the same stuff in the same proportions,i.e. one "cookie dough mix" for everything) but it is only grain geometry and flame retardent coatings that are different.

To me the faster and higher pressure spike of the faster powder,like H4350 vs H1000) is what really appears to do the damage.

But as an additional thought, if you are running higher pressure with the quicker powder, there is probably more heat,i.e. put compresssed air in two cannisters, one much higher pressure than the other and you will feel how the high pressure one is hotter right after filling). Maybe it's not so much the burn temperature but the extra heat caused by the extra presssure.


Robert Whitley

 

[ghermitage]

Maybe there is an additional factor here - a pressure or temperature threshold at which the steel wear rate increases sharply. Stay under the threshold and all is well, exceed it and there is a significant reduction in barrel life.