Are you saying the 338edge +p is running 300 grainers 3200 fps? I thought it was 3000-3050.
Wait this is not on a RUM case but a blown out 338 lapua case?
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My New Defensive Edge LRKM
- Thread starter Broz
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Are you saying the 338edge +p is running 300 grainers 3200 fps? I thought it was 3000-3050.
Wait this is not on a RUM case but a blown out 338 lapua case?
Broz
Well-Known Member
No, I am talking about my LRKM which is the first one built in the .338 Terminator +P. It is indeed a blown out 338 LM case with the +P addition. Here is the chronograph pic below which mirrors what Shawn got with initial testing of this rifle with a different chronograph.
Jeff
http://www.longrangehunting.com/forums/f116/my-new-defensive-edge-lrkm-116345/index7.html
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JeffVN
Well-Known Member
No doubt the LRKM throat and chamber design has brought more velocity to the package.
My 338 LM Improved (122 gr. H20 - Lapua headstamp brass) runs a steady 3,000-3,050 fps w/ 300 SMKs @ Retumbo. 3,200 fps is beyond my current capabilities w/ Retumbo - working up a VV570 load currently, but its not going to be 3,200 fps.
Jeffvn
My 338 LM Improved (122 gr. H20 - Lapua headstamp brass) runs a steady 3,000-3,050 fps w/ 300 SMKs @ Retumbo. 3,200 fps is beyond my current capabilities w/ Retumbo - working up a VV570 load currently, but its not going to be 3,200 fps.
Jeffvn
webs
Well-Known Member
Any ideas as to what could happen with a 338-408 cheytac with this +P chamber? Would it even work?
Broz
Well-Known Member
A guess would be an additional 150 fps from the normal 338-408. But that is only a guess from what I have seen it do for other calibers.
Another though it the point of diminishing returns. You can run any caliber to the point it is not practical or has a very low round count capability. I am hopeful the 338 Terminator +P is not to that point.
Jeff
Broz
Well-Known Member
We will see, the original 338 EDGE +P is still going and has seen over 3100 at times if I understand correctly. Don't quote me on this but I think it is right at 0r 0ver 1000 rounds now and still shooting. This is from memory and I have not seen actual results though. So I am optimistic and hoping for 1500. If it dies at 1000 I will do it again with a melonited barrel and see how that works. Only time will tell.
jeff
You might get 1500 but I kind of doubt it because your shooting quite a bit more powder than a Edge. I could see an Edge getting there. If you catch it early enough you could set it back 2" and probably get another 700+ rounds out of it with very little loss in velocity. There has to be a sacrifice somewhere for the velocity and it will most likely be throat life since you are removing part of the rifling already.
Broz
Well-Known Member
I agree about the sacrifice, but not sure I do about the other. Back when I was tuning Blown Nitro and Blown Alky engines, it was the taller thin parts we ground off the pistons in the valve relief. If they were lower they could wick the heat out before they liquified. Leave a taller thin part and it was gone by 1/2 track. Kinda like torching steel. The taller this part will start the cut earlier.
We will see, all speculation at this point. But what I do know is this Mo-fo is an ELR HAMMER!!
Jeff
My 338lm has almost 4000 rounds through the barrel now, using only 570 powder, and 300 grs bullets going 2929 fps at the muzzle.
I still shoot 10 shot groups at 600 yards looking looking like this:
I won the Norwegian 500 meter UNL Championships with it a couple of weeks ago.
That's not too bad, considering it is a 338LM and shooting prone.
I hope to get at least 5000 rounds of good accuracy out my barrel.
I still shoot 10 shot groups at 600 yards looking looking like this:
I won the Norwegian 500 meter UNL Championships with it a couple of weeks ago.
That's not too bad, considering it is a 338LM and shooting prone.
I hope to get at least 5000 rounds of good accuracy out my barrel.
Broz
Well-Known Member
Yrcan, I read that N-570 extends barrel life and reduces throat damage over other powders. Your first hand experience is proof something is working. Thanks for the vote of confidence it would be great if I could get 1500. Who knows maybe. I am doing all I can to get there. Watching barrel temps closely and shooting 2 at a time before a cool down. I have worked with performance oriented rigs all my life, so I know speed cost money. But I am sure this will be a less expensive venture than a 6 sec. 230 mph door slammer or a 160 plus mph boat with twin supercharged mills.
jeff
jeff
I was told when I started shooting my 338LM, that barrel life would be 1500-2000 rounds, MAX. I found my barrel was at its best at about 3000 rounds, but that could also be because I had learned how to handle the rifle then
Viht N570 is a double based powder, and I have been told that it eats the barrels faster than a single based powder, but I have no indication that this is the truth.
I can no longer see the lands in my barrel, teh grooves are gone, you can see them abot an inch from where the riflings should start, and still I get very nice groups. I tell myself that it is because of the long barrel that this is possible. I likie to think that even though the bullets gets a rough start, it will settle during the long barrel time, and be ok when it leaves. I have no other explanation to it. If you look inside my barrel, you would say it is worn out, but, no.
This is a 10 shot group I shot this winter when the barrel had 3000 rounds through it. Used 250 grs Scenar bullets, and the range was 600 yards.
I do not think I will ever repeat this one.
Viht N570 is a double based powder, and I have been told that it eats the barrels faster than a single based powder, but I have no indication that this is the truth.
I can no longer see the lands in my barrel, teh grooves are gone, you can see them abot an inch from where the riflings should start, and still I get very nice groups. I tell myself that it is because of the long barrel that this is possible. I likie to think that even though the bullets gets a rough start, it will settle during the long barrel time, and be ok when it leaves. I have no other explanation to it. If you look inside my barrel, you would say it is worn out, but, no.
This is a 10 shot group I shot this winter when the barrel had 3000 rounds through it. Used 250 grs Scenar bullets, and the range was 600 yards.
I do not think I will ever repeat this one.
Broz
Well-Known Member
Here is what Vit. claims about the 500 series powders:
Quote from the Vit. web site:
"N500 series
Adding nitroglycerol to the traditional single base powder makes possible in addition to geometry and coating a third controlled variable of ballistic properties: energy content. Vihtavuori calls powders that have nitroglycerol added (maximum 25%) high energy NC-powders, which form N500 series.
Adding nitroglycerol to the high energy N500 series is done by impregnation. After that, the grains are coated with a new type of chemical which results in very progressive burning characteristics.
The composition of a typical high energy powder is as follows:
* nitrocellulose * nitroglycerol
* coating agent * stabilizer
* flame reducing agent * wear reducing agent
Geometrically the powders in the N500 series are equal to the N100 series. Although these new powders have a higher energy content, they do not cause greater wear to the gun. This is because the surface of the powder has been treated with an agent designed to reduce barrel wear. N500 series powders work well at different temperatures, even better than the traditional N100 and N300 series. Temperature sensitivity naturally depends very much on the weapon and on the cartridge. The manufacturing technique employed permits a very high bulk density, which in turn makes it possible to use a bigger charge in a certain limited loading volume."
Quote from the Vit. web site:
"N500 series
Adding nitroglycerol to the traditional single base powder makes possible in addition to geometry and coating a third controlled variable of ballistic properties: energy content. Vihtavuori calls powders that have nitroglycerol added (maximum 25%) high energy NC-powders, which form N500 series.
Adding nitroglycerol to the high energy N500 series is done by impregnation. After that, the grains are coated with a new type of chemical which results in very progressive burning characteristics.
The composition of a typical high energy powder is as follows:
* nitrocellulose * nitroglycerol
* coating agent * stabilizer
* flame reducing agent * wear reducing agent
Geometrically the powders in the N500 series are equal to the N100 series. Although these new powders have a higher energy content, they do not cause greater wear to the gun. This is because the surface of the powder has been treated with an agent designed to reduce barrel wear. N500 series powders work well at different temperatures, even better than the traditional N100 and N300 series. Temperature sensitivity naturally depends very much on the weapon and on the cartridge. The manufacturing technique employed permits a very high bulk density, which in turn makes it possible to use a bigger charge in a certain limited loading volume."
Well, there you go
I did not know that.
I guess you just have to shoot and see. I guess, you will have more than 2000 rounds of barrel life. I do not know what quality your barrel is, but I guess it is a high quality barrel. I only use Lothar Walter barrels, Match Grade SS. They cost 1300 USD here in Norway, but is worth every penny
Looking forward to see how your rifle performs
I did not know that.
I guess you just have to shoot and see. I guess, you will have more than 2000 rounds of barrel life. I do not know what quality your barrel is, but I guess it is a high quality barrel. I only use Lothar Walter barrels, Match Grade SS. They cost 1300 USD here in Norway, but is worth every penny
Looking forward to see how your rifle performs
