So I want to blow the body out with no taper and put a 40degree shoulder on the cartridge in the hopes to get 1.0-2.0 grains extra capacity. The problem is I don't know the internal dimension of the cartridge so I'm not sure that I've increased the internal capacity enough to get that 1.0-2.0 increase. I was thinking perhaps blowing the shoulder forwards .10" or even .20" depending on the neck length. I've got a feeling that 40-42.5 grains of RL-15 and 30.5 inch barrel with a 1:8 twist will be the sweet spot for 130-147 grain VLD's at 2900-3050FPS. But all of the reports I'm reading seems to say that just little extra powder and little extra barrel length to go along with it should yield the results... But I don't have the internal specs yet...
6.5X47MM LAPUA IMPROVED... Need info...
- Thread starter ConnorExum
- Start date
Thanks. 6-6.5x47mm seems to be in the cartridge I had in mind as well just necked down... I actually think the performance of this cartridge will increase when maintained in 6.5mm.
I'm also considering necking up and improving 7mm... I think this might be the best option of them all. Perhaps the 168grain bullet at 2900fps or so from a minimal capacity cartridge is the ticket?
I'm also considering necking up and improving 7mm... I think this might be the best option of them all. Perhaps the 168grain bullet at 2900fps or so from a minimal capacity cartridge is the ticket?
Everyone thinks necking down is the answer because of the lighter bullets, but the answer seems to be neck up. Look at the difference between a 338-06 and 30-06. You take 338-06 and a 30-06 and the same 200grain class bullet and you get 2750-2850fps out of 338-06 according to Hodgdgon's guide; while in the 30 caliber class this same 200grain class bullet gets 2500-2650fps. So I'm unclear why everyone is necking the 6.5x47mm down, the results seem impressive but when you consider that normal cartridge already bests 6mm in every respect why do it? It seems if you want to see a real increase in performance this will only be achieved by necking up to 7mm or larger. My vote is for the 7mm bore. I think a 7mm VLD 168 grain at 2850-2950fps muzzle velocity is the perfect 1000yard rifle . I like the 6.5x47mm just fine but I think after I'm done experimenting with 6.5x47mm Improved I'll neck it up to 7mm and see what happens, my feeling is that up the answer.
Conner,
I am not sure you will be able to get the velocities you are looking for in 7mm version.,I don't know,have not tried).
Seems to me the 6.5 x 47 Lapua handles the 123gr projectiles better than the 142s.
I did the Improved 6mm version for varmints to try to reach higher velocity accuracy node,not necessary for targets)
Recently completed a 6.5x47 Lapua Imp. version for a carry rifle.,switch barrel rig). Been shooting the 6BR barrel, have not done any work with the 6.5 yet,soon)
Again, not trying to rain on your parade. I think cartridge capacity is not there for 7mm @ 2950 fps
Respectfully,
Scott
I am not sure you will be able to get the velocities you are looking for in 7mm version.,I don't know,have not tried).
Seems to me the 6.5 x 47 Lapua handles the 123gr projectiles better than the 142s.
I did the Improved 6mm version for varmints to try to reach higher velocity accuracy node,not necessary for targets)
Recently completed a 6.5x47 Lapua Imp. version for a carry rifle.,switch barrel rig). Been shooting the 6BR barrel, have not done any work with the 6.5 yet,soon)
Again, not trying to rain on your parade. I think cartridge capacity is not there for 7mm @ 2950 fps
Respectfully,
Scott
You could be very well right. But look at the performance with 130 grain VLD's every is getting 2900fps to 2983fps from these cartridges in the standard form. Now if you improve the cartridge say you get an extra 100-140fps increase from a 28 inch barrel to 30 inch barrel I think the gun will each the velocities with 140grain bullet safely.
Now 7mm, well if you notice every cartridge that is necked up shows an increase in performance for the same mass projectile or greater. For example the 338-06 has the same powder capacity as the 30-06 but will shoot the .338 250grain bullet at 2400fps according to Hodgdon where as the 30-06 is about 2150fps. That's a 250fps increase and it has to do with the way the bore volume and ideal gas laws. The smaller the bore the less efficently the gases expand in the bore. So basically you get greater expansion in the bigger bore more pressure higher velocities for the same amount of powder. I would be willing to bet that if 6.5x47mm improved yields 2885-2950 fps safely with 140-142grain bullet that same cartridge with 7mm bullet will yield that or greater performance with 168grain bullet given that both the extra mass of the bullet and the increased bore diameter will increase pressure.
If you don't like the 338-06 example look at the 30BR compared to the 6mmBR it can push a 118 grain projectile to 2950-3050 where as the 6mm BR is hard pressed to get 6mm 105's to 2950 velocity. 13 extra grains of weight and the same powder capacity. I've even read stuff with the 125grain bullets doing 3050fps out a 30br... So I think we might have to re-think the way in which we wildcat a cartridge.
Let's see what you get from the improved version of the straight 6.5x47mm I bet you'll see that if you equalize the analysis so that the velocity is understood to be percent increase of the total increase in the projectile's mass the 6.5 version is yielding performance unmatched by the 6-6.5x47mm version. And I would be willing to bet that a 7mm version with the same powder capacity would get 2950 fps from a 168grain VLD.
But I could be very wrong, but all the data I've seen on cartridges that are necked down compared to necked up seems to show that an increase is possible for any given weight and some beyond the baseline cartridge.
Now 7mm, well if you notice every cartridge that is necked up shows an increase in performance for the same mass projectile or greater. For example the 338-06 has the same powder capacity as the 30-06 but will shoot the .338 250grain bullet at 2400fps according to Hodgdon where as the 30-06 is about 2150fps. That's a 250fps increase and it has to do with the way the bore volume and ideal gas laws. The smaller the bore the less efficently the gases expand in the bore. So basically you get greater expansion in the bigger bore more pressure higher velocities for the same amount of powder. I would be willing to bet that if 6.5x47mm improved yields 2885-2950 fps safely with 140-142grain bullet that same cartridge with 7mm bullet will yield that or greater performance with 168grain bullet given that both the extra mass of the bullet and the increased bore diameter will increase pressure.
If you don't like the 338-06 example look at the 30BR compared to the 6mmBR it can push a 118 grain projectile to 2950-3050 where as the 6mm BR is hard pressed to get 6mm 105's to 2950 velocity. 13 extra grains of weight and the same powder capacity. I've even read stuff with the 125grain bullets doing 3050fps out a 30br... So I think we might have to re-think the way in which we wildcat a cartridge.
Let's see what you get from the improved version of the straight 6.5x47mm I bet you'll see that if you equalize the analysis so that the velocity is understood to be percent increase of the total increase in the projectile's mass the 6.5 version is yielding performance unmatched by the 6-6.5x47mm version. And I would be willing to bet that a 7mm version with the same powder capacity would get 2950 fps from a 168grain VLD.
But I could be very wrong, but all the data I've seen on cartridges that are necked down compared to necked up seems to show that an increase is possible for any given weight and some beyond the baseline cartridge.
sewwhat89 said:
I think this is will be more efficient and have better barrel life... Besides I like to tinker.
I know this seems unpopular but let's look at the facts every cartridge that is necked up shows an increase in performance from efficiency due to increase in pressure for the same case-capacity. Every case that is necked-down shows the exact opposite for the same case capacity.
I think we have to take a page from John Searle's advice about dealing with philosophy of mind, when dealing with two options that seems wrong change the question. I think we are faced with problem of always trying to use the brute force method to achieve velocity. That is to say we ram more powder down the same size bore and accept the efficiency problems if we get the magic number we want. And that is fine if you're designing hunting arms that shoot maybe a 1000 rnds in 10 years. However, in the target shooting world that doesn't seem very viable to me. We need to push efficiency over brute force, we need to squeak out every last bit of pressure from a minimal powder charge so we increase barrel life. After all why build a cartridge and gun combination that destroys 1/3 of the barrel life in load development and practice sessions? That seems to be counter productive to me.
Perhaps the 47mm case is too small for a 7mm hybrid cartridge but we need to start testing and developing early find out what is the optimal charge for a 7mm 168grain bullet. One that will give a barrel 3000-3500 accurate rounds before it is dead.
I think the 7mm will be the caliber of the next century. I think a proper cartridge that both has the speed to utilize and barrel life is the key to making the 7mm a world beater.
I think we have to take a page from John Searle's advice about dealing with philosophy of mind, when dealing with two options that seems wrong change the question. I think we are faced with problem of always trying to use the brute force method to achieve velocity. That is to say we ram more powder down the same size bore and accept the efficiency problems if we get the magic number we want. And that is fine if you're designing hunting arms that shoot maybe a 1000 rnds in 10 years. However, in the target shooting world that doesn't seem very viable to me. We need to push efficiency over brute force, we need to squeak out every last bit of pressure from a minimal powder charge so we increase barrel life. After all why build a cartridge and gun combination that destroys 1/3 of the barrel life in load development and practice sessions? That seems to be counter productive to me.
Perhaps the 47mm case is too small for a 7mm hybrid cartridge but we need to start testing and developing early find out what is the optimal charge for a 7mm 168grain bullet. One that will give a barrel 3000-3500 accurate rounds before it is dead.
I think the 7mm will be the caliber of the next century. I think a proper cartridge that both has the speed to utilize and barrel life is the key to making the 7mm a world beater.
JimT
Banned
I have a 6.5x47 Lapua that I use in highpower silhouette and I love it. However, I don't think a necked up case will push a 168 grain 7mm bullet at 2950 fps.
I have also noted,in most cases, the fact that necking up a cartridge will produce higher velocities for the same bullet weight. However, I noticed that this was not the case when comparing the 7mm-08 Remington to the .308 Winchester using 168 and 175 grain bullets,Sierra Manual, 5th Edition). In this instance the two cartridges are shown getting 2700 and 2600 fps respectively. Of course the 7mm-08 will have the advantage downrange due to the 7mm projectiles having a much better BC.
I am currently accumulating components to put together a 7mm-08 Ackley Improved that I hope will push the 168's at 2850-2900fps using a 27 inch barrel and the 175's at 2750-2800 fps. I think this case capacity will be optimal for this caliber.
I do agree with you that the 7mm is the way to go over the 6.5mm for bullets weighing over 123 grains.
Hope this helps you sort this out.
I have also noted,in most cases, the fact that necking up a cartridge will produce higher velocities for the same bullet weight. However, I noticed that this was not the case when comparing the 7mm-08 Remington to the .308 Winchester using 168 and 175 grain bullets,Sierra Manual, 5th Edition). In this instance the two cartridges are shown getting 2700 and 2600 fps respectively. Of course the 7mm-08 will have the advantage downrange due to the 7mm projectiles having a much better BC.
I am currently accumulating components to put together a 7mm-08 Ackley Improved that I hope will push the 168's at 2850-2900fps using a 27 inch barrel and the 175's at 2750-2800 fps. I think this case capacity will be optimal for this caliber.
I do agree with you that the 7mm is the way to go over the 6.5mm for bullets weighing over 123 grains.
Hope this helps you sort this out.
JimT said:
But look at the parent case is still the 308, designed for a 30 caliber cartridge so you're not really necking up like I would be for the 6.5x47mm to a 7x47mm. I think a better comparison would be the .338 Federal where you get a 308 with a .338 caliber bullet of 180grains doing 100-125extra FPS over the .308. that being said you could be right that 47mm case is too small for the job. But I figured that improving it getting 40-42.5 grains of usable powder charge with 100percent load density in the increased bore would give me the extra 200fps over the 139grain 6.5 even with 29grain increase in projectile weight. But you know even if I only get 2880fps the 7mm 168grain projectile will far out perform the 6.5 140grain bullets. So I might be overly optimistic at this point but I think the experiment is worth trying out.
Do you have QUICKLOAD? I cannot run Quickload on my Macbook Pro so I cannot do the testing but I would love to see what it shows performance wise for a improved 6.5x47mm with the shoulder pushed forward .010", 40 degree shoulder, no body taper necked up 7mm out of a 30 inch barrel.
Your post got me interested, I did some quick testing using the quick design and quickload. I have attached a quick drawing of a 7X47 Lapua IMP,not perfect, but should be pretty close) then I used that data with the quickload software. Win 760 gave the top velocity with a 30" barrel with pressures at 60,000 at about 2734 fps with a load of 41Gr, VV 550 was close using 40.2 gr at 2708 fps.
These numbers are probably not exactly what you will get, but they are generally very close from my previous experiences. I don't think you are going to see anything close to 2900fps with a case this small. I have attached the cartridge drawing, but unfortunately I could not get the quickload data to be small enough and still be readable to post for you.
Ben
These numbers are probably not exactly what you will get, but they are generally very close from my previous experiences. I don't think you are going to see anything close to 2900fps with a case this small. I have attached the cartridge drawing, but unfortunately I could not get the quickload data to be small enough and still be readable to post for you.
Ben
Attachments
benjamin199 said:
Thanks...
I guess we need more space, what was the load density?
However even at 2737fps the 168grain .690 JKL bullet showed serious advantages in JBM at 1000 yards 10mph 90 degree wind was 61.7 inches of drift...
That's 3.3 inches better than 130grain JKL with .620 BC at 1000 yards 65.0 inches of drift...
Okay, so we need more capacity, what was the capacity of charge.
The Win 760 was a compressed load around 102%
i have been shooting a 7 x 47 lapua for the last 2 years it has a Pac-nor 1 in 10 6 groove barrel the shoulder is moved 1mm foward and stil 30* it shoots 130 sierra mk easy at 2900 velocity and 145 speers at 2850 with no preasure signs i use this rifle to shoot 500m fly 600yd benchrest and 1000yd bench also hav shot f-class with it i use 39.4 gn of varget cci br4 and have reloaded the shells at least 20 times so far without any drama hepe this helps with the situation
john mc
john mc
So we need more capacity... What if the shoulder is moved up .015" or even .020" no body taper and 40degree shoulder... We need to get the pressure back up 63,000psi. That is what is dropping performance. Another 1 grain or so of powder should get it up there. Performance won't by the 2900fps I had hoped for but 2800fps might be doable.
ConnorExum said:
How about a 404 Jef cut down to 47mm with no body taper and 40deree shoulder... What sort of powder capacity would that give us? It appears we need about 50grains to get the velocity I want and not 41-42grains.
What about about a 300 Pegasus cut down to 47mm and given a 40degre shoulder and no-body taper? Then topped with 168grain-180grain 7mm bullet...
You have to admit if the Quick Load data is correct with 5% that the 6.5x47mm necked up 7mm is one damn efficient cartridge. Not as efficient as I had hoped but perhaps a bigger diameter cartridge of the same basic size will do the trick. I'm looking 2800-3000fps with the 168grain 7mm JKL...
You have to admit if the Quick Load data is correct with 5% that the 6.5x47mm necked up 7mm is one damn efficient cartridge. Not as efficient as I had hoped but perhaps a bigger diameter cartridge of the same basic size will do the trick. I'm looking 2800-3000fps with the 168grain 7mm JKL...
ConnorExum said:
Sounds like a 7mm Dakoa improved if you ask me. there gets to be a point of diminishing returns, and I think we we are getting close.
SDH
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