300WM, 208gr Amax, AI Mag

[Yowie]

Hey guys, I've read various other thread on this and they just get all jumbled up and the answer is lost in the heat haze.

I've bought myself so 208gr amax projectiles for my 300 Win Mag and was just test fitting the round into a case and noticed it was heaps longer then the 180gr rem corelokt factory rounds, also it is longer then what I found wiki said the length to be. I seated the projectile all the way down and still longer. Is this normal or am I doing something wrong?

I need to sort this soon so I can take a dummy round into the gunsmith so he can do his thing with my new madco barrel

Cheers,
Josh

 

[Beiruty]

It is normal. The bullet has high BC for long range shooting. I seat my bullet at COAL of 3.35" or spec + 0.010".

 

[Yowie]

Ok cheers for that mate, I'll work with that. COAL being the case and round? I understood it to be complete overall length

 

[Beiruty]

Correct. COAL, Cartridge overall length, from base to the tip. You may do COAL of Spec + 0.015" and load for a go-check rd. And your loads has +0.010" over spec. Wait form 2nd Opinion as more gun builders experts are here to help.

 

[Yowie]

Yeah, once I get some powder I'll do a load and see what the COAL comes out as with the round fully seated on the powder

 

[scorpion168]

I'm watching this thread. I have some 208 Amax's and H1000 and H4831SC. About to start loading.

 

[ArmyJerry]

tagged

 

[Pfiddy]

Also in for more info

 

[Yowie]

From just looking at it compared to a factory corelokt round it will be approx the red tip longer if seated at max depth. This is using a fire formed case. Once my bench is finished being made I'll use a full resize and see if it makes much of a difference but the fire formed case is 66.55mm (2.620") long which is the spec wiki gives.

Will update everyone later this week on how I go, praying to god that it fits in the mag!! Although other have had no issues on this forum

 

[Yowie]

Ok guys, I've done some measuring with the fire formed cases just to show their length and length with projectile fully seated to the point any further it will fall into the case. See photo with micrometer attached

 

[Alpine 338]

Looking at the picture, it looks as the bullet is seated much deeper than most long range precision shooter load the 208-AMax. Since you're running metric, I can't easily tell where you're at compared to what I'm loading. But if you want to do the math, I'm loading 3.59 to 3.60 inches COAL, that's where my rifle likes them. Now if you have a hunting rifle with short throat, then obviously you will need to run them shorter.

Good luck.

 

[Alpine 338]

Oh, and most of my AI mags will accept a COAL of 3.63 to 3.64 inches.

 

[ArmyJerry]

Did you have your pet gorilla take the measurements????

That projo looks sunk in there a bit far. Trim should be 66.40 ish mm, COAL of 86.85, my AI 300 wm magazine is 92.63 MM, these are all within a few tents of a MM as I dont normally use this metric.

I just measured a new FGMM case it is 66.36 mm.

 

[Yowie]

3.60" is 91mm so makes it easy. Also it will be throated to suit by my gunsmith in the next few week.

 

[Yowie]

Did you have your pet gorilla take the measurements????

That projo looks sunk in there a bit far. Trim should be 66.40 ish mm, COAL of 86.85, my AI 300 wm magazine is 92.63 MM, these are all within a few tents of a MM as I dont normally use this metric.

I just measured a new FGMM case it is 66.36 mm.

Hahaha me and the missus had a good laugh then, thus the nickname yowie.

Ok, well I'll make a round up measure it all and go from there, this is definitely exciting for me new stock, new barrel and custom rounds life is good

 

[Yowie]

For everyone's information on what I'm running this round for/thru

Remington 700 action
McMillan A5 adjustable stock
26" SS Maddco barrel
Atlas CNC bottom metal
AI magazine

All throating and chamber length will be set up for the round I provide him thus all the questions now

 

[Alpine 338]

Good planning Josh, I would have it set at 90.5 mm, and that would give you room to move the bullet out as your throat erodes, and still have room in your magazine.

 

[Yowie]

How quickly does that happen? I won't be running supercharged rounds and barrel maker said I'll get over 5000 rounds out of it

 

[bax]

COL is Cartridge Overall Length. You measured it correctly in your picture. I shoot a heavier bullet than the 208 Amax. My COL is 3.460 inches or 87.88 mm. The nominal case length is 2.610 inches to 2.615 inches or 66.29 mm to 66.42 mm.

Based on your bullet and case dimensions, your COL should be at least, 3.387 and no longer than 3.688. Please allow me to explain. The 300 Win Mag has a very short neck. Your bullet has three sections: the tapered boat tail, the straight shank, and the pointy nose part. You want to seat the bullet so that the short neck bears only on the shank, the boat tail doesn't go part way up into the neck and the pointy nose part doesn't go down into the neck. If you seat the bullet deeper than 3.387 then part of the pointy nose is sunk into the neck -- like your picture. If the COL is longer than 3.688 then the shank ends and the boat tail is part way into the neck.

FYI, the 208 Amax bullet sections are:

boat tail 0.175
shank 0.555
pointy end 0.777

Google 300 win mag dimensions for a case drawing.

As a general rule you would want to start with the shortest throat (the 3.387 end of the range). As you shoot the gun, the throat will erode and it will be best if you seat the bullet further out. Start with the bullet as deep as you can, that will give you the maximum amount of throat erosion.

I have a first class Bartlein barrel, it is the best barrel I have every had for this gun. As of today, it has 1,247 rounds through it. I figure that this one will go to about 2,000 before the throat gets so eroded that it will stop shooting. This is my fifth barrel on this gun. No other barrel lasted this long - the first one was gone after 900 rounds. I ordered a new Bartlein barrel to be chambered and fit this winter. When this one stops shooting, I will have a new one to switch to.

What do other Hide members think about 300 Win Mag barrel life? I think 2,000 rounds is about the outer limit.

 

[Alpine 338]

I've heard 2000 rounds is the limit on barrel life with the 300WM. Obviously, the barrel maker, barrel contour, type of bullet used, type of powder used, velocity, how you take care of the barrel, and how often it's over-heated are all factors in barrel life.

I'm running a Schneider M40 contour with P-5 rifling. I have around 1500-rounds through it, and it's still shooting very accurately. Measuring my throat using a Hornady length gauge shows my throat has moved very little. So I'm expecting to get at least 2000-rounds through it, and hoping to get 2500.

I think your barrel maker is being unrealistically optimistic telling you that you would get a barrel life of 5000-rounds.

 

[Yowie]

COL is Cartridge Overall Length. You measured it correctly in your picture. I shoot a heavier bullet than the 208 Amax. My COL is 3.460 inches or 87.88 mm. The nominal case length is 2.610 inches to 2.615 inches or 66.29 mm to 66.42 mm.

Based on your bullet and case dimensions, your COL should be at least, 3.387 and no longer than 3.688. Please allow me to explain. The 300 Win Mag has a very short neck. Your bullet has three sections: the tapered boat tail, the straight shank, and the pointy nose part. You want to seat the bullet so that the short neck bears only on the shank, the boat tail doesn't go part way up into the neck and the pointy nose part doesn't go down into the neck. If you seat the bullet deeper than 3.387 then part of the pointy nose is sunk into the neck -- like your picture. If the COL is longer than 3.688 then the shank ends and the boat tail is part way into the neck.

FYI, the 208 Amax bullet sections are:

boat tail 0.175
shank 0.555
pointy end 0.777

Google 300 win mag dimensions for a case drawing.

As a general rule you would want to start with the shortest throat (the 3.387 end of the range). As you shoot the gun, the throat will erode and it will be best if you seat the bullet further out. Start with the bullet as deep as you can, that will give you the maximum amount of throat erosion.

I have a first class Bartlein barrel, it is the best barrel I have every had for this gun. As of today, it has 1,247 rounds through it. I figure that this one will go to about 2,000 before the throat gets so eroded that it will stop shooting. This is my fifth barrel on this gun. No other barrel lasted this long - the first one was gone after 900 rounds. I ordered a new Bartlein barrel to be chambered and fit this winter. When this one stops shooting, I will have a new one to switch to.

What do other Hide members think about 300 Win Mag barrel life? I think 2,000 rounds is about the outer limit.

Yeah I see what your saying and understand that the bullet needs to be held by the flat bit. Here is one I've hand seated and shows what you have mentioned.


The barrel maker says that and he sells most of his barrels to AI and I guess the type/grade of stainless steel matters to, we had some hard aircraft stainless at work which the lathe struggled to turn back but holy hell didn't it come up good

 

[bax]

You seated the bullet with the straight shank part showing. From a barrel life perspective, the idea starting position is with no straight shank showing. As the throat erodes, you can seat the bullet further out. That will maintain the distance relationship between bullet and the throat.

For example: you start with the bullet 0.015 off the lands and the edge of the bullet nose just at the case mouth -- that is the COL is 3.387.

After 500 rounds, the throat erodes by 0.025. You seat the bullets at 3.387 + 0.025 or COL = 3.412. After 1,000 rounds, the throat erodes another 0.025 and you now seat bullets so that COL is 3.437.

There is a counter argument. If you shove the bullet way down into the case, it takes up room that you could put powder into. That is, if you seat the bullet longer then there is less bullet inside the case and all the more room for more powder. If it was me, I would not start the COL in a place where I could not adapt to throat erosion.

About barrel life. I have four of the most beautiful and expensive .308 caliber stainless steel tomato stakes you ever saw (long ago I tossed the 6PPC tomato stakes). None of those barrels lasted longer than 1,100 rounds. They were Hart, Schneider, and there might have been a Shilen in there. This Bartlein has 1,247 rounds through it. I shot a lot this summer and the gun was running well so I didn't fiddle with it, I just shot it. I just checked the max COL with a Hornady gauge. I took five measurements and they all came out 3.474 plus or minus 0.001. The throat hasn't moved since I worked up this load with about 200 rounds through the barrel.

Unfortunately I doubt my measurement. The gun hasn't been cleaned for about 100 rounds so I will clean the barrel and remeasure.

I shoot 240 grain bullets at about 2,675 fps. Heavy bullets going more slowly is consistent with longer barrel life (read "Applied Ballistics for Long-Range Shooting" by Brian Litz). But igniting 68 grains of slow-burning powder, letting it build to over 60,000 PSI and using it to push a bullet to 2.5 mach just has to be hard on the steel. Every BR gun I every owned eventually alligator-ed the first few inches past the throat so I just don't believe that throat has not moved.

 

[Yowie]

Yeah I see what your saying their bax, if I seat it to 90.5mm that gives me about 1.5mm of play room but it's all pending how much room the H1000 takes up. I'll be starting at 75gr but will make a 76.5gr load for the armour as it will give me a bit of room with 76gr. Which apparently around the magic mark for what I'm shooting.

Thanks again for the input mate