Started loading 300 win mag

[flyingagg]

You understood correctly Scotty and thank you for taking the time.
If I get a 375 H&H magazine box and bolt stop would give me a 3.6 Magazine box. Would I need a follower as well? Would this allow me to load longer? I could get OEM from Midwest.

Again thank you
ASD

 

[desertcj]

Now we're getting somewhere, but you still haven't said what the COAL is with the CBTO at 3.023"? Or what length will actually fit in your magazine box. I'm going to bow out of this but hopefully you understand what I've been trying to get at? You might not be stuck with the .220" bullet jump...

I think what he means is from the base of the cartridge to the beginning of the leade is 3.023, there is no bullet involved with his measurement so there is no way to provide a COAL, if I am understanding him correctly.

Ag, I am not totally surprised about the two rifles being different in throat, although, .1" is ALOT of difference, and more than I have ran across, but I don't think its crazy. 300 Wins have been around since 1962, so there are probably alot of worn reamers that were used. Typically, in my experience, a 200 AccuBond encounters the rifling around 3.575", or a bit less in a normal run of the mill 300 Win.

Jump to the rifling isn't a real bad thing at all times, but sometimes it leaves you without much option for load tuning.

The Hornady gauge uses a bullet in a modified case doesn't it. I don't use the Hornady gauge I just use a lightly neck sized case that allows the bullet to slip in the neck. The measurement aren't important to me, I was just trying to get him to see if the longest length he could load in the chamber would fit in the magazine. If it won't and my guess is that it won't, then what's the longest he can load that does fit the magazine. He might end up with something like .075" jump to the rifling which is more in line with where I'd be working my load development.

 

[SJB358]

You understood correctly Scotty and thank you for taking the time.
If I get a 375 H&H magazine box and bolt stop would give me a 3.6 Magazine box. Would I need a follower as well? Would this allow me to load longer? I could get OEM from Midwest.

Again thank you
ASD

That's exactly what we've done for awhile. Get a 3.6" mag box, bolt stop and ejector. That should allow you to reach out to the lands with most bullets. Sometimes you can get away with the standard follower and sometimes you need a longer one. I've seen both cases, just depends on how your gun responds.

Now we're getting somewhere, but you still haven't said what the COAL is with the CBTO at 3.023"? Or what length will actually fit in your magazine box. I'm going to bow out of this but hopefully you understand what I've been trying to get at? You might not be stuck with the .220" bullet jump...

I think what he means is from the base of the cartridge to the beginning of the leade is 3.023, there is no bullet involved with his measurement so there is no way to provide a COAL, if I am understanding him correctly.

Ag, I am not totally surprised about the two rifles being different in throat, although, .1" is ALOT of difference, and more than I have ran across, but I don't think its crazy. 300 Wins have been around since 1962, so there are probably alot of worn reamers that were used. Typically, in my experience, a 200 AccuBond encounters the rifling around 3.575", or a bit less in a normal run of the mill 300 Win.

Jump to the rifling isn't a real bad thing at all times, but sometimes it leaves you without much option for load tuning.

The Hornady gauge uses a bullet in a modified case doesn't it. I don't use the Hornady gauge I just use a lightly neck sized case that allows the bullet to slip in the neck. The measurement aren't important to me, I was just trying to get him to see if the longest length he could load in the chamber would fit in the magazine. If it won't and my guess is that it won't, then what's the longest he can load that does fit the magazine. He might end up with something like .075" jump to the rifling which is more in line with where I'd be working my load development.

If you take a 308 bullet, turn it around in the Hornady OAL tool and measure to the lands, it should be a fixed number. Meaning you can use any bullet and the measurement will be the same. AG was just measuring from the base of the cartridge to where a 308 bullet hits the lands.

A 3.6" mag box really helps out a 300 Win Mag. With a long box you can get near 300 Wby sorta speeds and really tune bullets in regards to seating depth and most of the time, even the long nosed high BC bullets will function through the magazine on a SAAMI chamber.

 

[flyingagg]

Thanks Scotty, That's why I come to you with M70 Questions.
I will order the bolt stop and box today. They still have NOS. I didn't know about the ejector though. Would that be the 375 H&H/300WBY ejctor?

 

[SJB358]

Thanks Scotty, That's why I come to you with M70 Questions.
I will order the bolt stop and box today. They still have NOS. I didn't know about the ejector though. Would that be the 375 H&H/300WBY ejctor?

Yes sir, RUM, H&H, etc length.

 

[flyingagg]

Thank you sir! I appreciate the help. Only thing I could not find is the follower, but there is a chance the new FN made M70 will work. I will check them out when I get the parts.

Again Thank you!
Good Shooting!!!

 

[SJB358]

Thank you sir! I appreciate the help. Only thing I could not find is the follower, but there is a chance the new FN made M70 will work. I will check them out when I get the parts.

Again Thank you!
Good Shooting!!!

No problem, let me know how you make out.

 

[PearsonRidgeMan]

Ok. Thanks. I'll try adjusting the seating depth like you suggest: 3.330 and 3.320. Last question before I load: Should I try a set at 3.310 too ?

 

[SJB358]

Ok. Thanks. I'll try adjusting the seating depth like you suggest: 3.330 and 3.320. Last question before I load: Should I try a set at 3.310 too ?

I would if you have the time and supplies.

 

[Double Dropper]

200 grain Accubonds and RL-26 ADG brass and Fed 215GM primers overal length is 3.525, and using 75 grains shes just under 3000fps. Very consistent and no pressure signs, the only thing more accurate was Hornady 195 ELD-M bullets just over 3000 fps and stacks them. Debating trying the ELD-Ms on deer size game.

 

[desertcj]

Eld-M's of that weight will absolutely hammer deer size game! My buddy and I killed 4 antelope with the 7mm, 180gr version and they were passing through with 4-6" exits even at 500+ yards.

 

[SJB358]

200 grain Accubonds and RL-26 ADG brass and Fed 215GM primers overal length is 3.525, and using 75 grains shes just under 3000fps. Very consistent and no pressure signs, the only thing more accurate was Hornady 195 ELD-M bullets just over 3000 fps and stacks them. Debating trying the ELD-Ms on deer size game.

You can't go wrong with either. I'd think the ELD's would be a bit more decisive on impact, but I don't think the old AccuBond is going to be bad either.

 

[Double Dropper]

Cool, think based upon comments that 195 is gonna get a try out.

 

[REDGREEN]

I had RCBS make me neck sizer dies for all of my rifles. Only time that the full length dies are used are with new brass or when I start to get a stiff bolt closure. I also anneal every 3 to 5 firings. My brass lasts for years, due to no unnecessary case stretching. I also trim to .005 below maximum length for my chambers. I also love the 300 Winchester magnum, and the 300 Wby magnum. Never had any problems with web separation with either.

 

[PearsonRidgeMan]

PearsonRidgeMan Back again: Yesterday I fired 15 rnds. 3 each 180grn for clean out after cleaning bbl. 9 ea loaded 200grn AB, w/70.5 grn H4831SC, seated 3 at 3.3400, 3 at 3.3500, and 3 at 3.3600 (using the CTOL Ogive method the measured: 3 at 2.7180, 3 at 2.7280, and 3 at 2.7380 respectively)

Please see my target (if I can figure out how to attach it).

I also re-measured the CTOL to the lands using the Hornady O.A.L. gage and found that my "Jump" was actually larger than I measured the first time (as a Rookie I mixed measurements). Anyway, the (avg of 5 msmts) CTOL to the "Lands" is 2.9832". You can see my CTOLs above. Bottom line is the Jump when the OAL is 3.340 per the book is a whopping 0.265" !!

My target shows four groups measuring from 1.25" to 1.85".

My question is: Is it really going to make any difference at all to fiddle around with the seating depth when the JUMP is over 1/4 inch ??

 

[PearsonRidgeMan]

Sorry, I can't figure out how to load the photo of the target.

 

[elkeater2]

Scotty said:
"Matter of fact, I try to control headspace from the first shot. If I think there is too much slop with any case it gets necked up and resized just enough to chamber to minimize stretching. That’s with any case.

Folks that gripe about them are believing the hype they are outdated and not needed. I agree they aren’t needed but outdated, nope..."

Scotty, I have found what you advised about checking for too much slop to be critical when loading for my Encore. Factory Win 25/06 ammo especially would stretch excessively on first firing and only last 3 or 4 loads before starting case head issues, even when sizing minimally. Factory empty brass, necked up and sized to just fit, last for many more loads without problems. I have now done this with new 7-08 Nosler brass with good success. I haven't seen the "too much slop" before first firing discussed much. Thanks. EE2

 

[SJB358]

No problem EE2. Only takes a second to check and brass is pricey. Might as well make it last.

PRM, try taking your load the other direction and make them shorter in 10-15 thou increments and see what happens.

If that is still unacceptable then move on to another bullet. Lotsa great options in the 200 grain class.

 

[Darkhorse]

You asked; Will a .010" change in seating depth matter if your already 1/4" from the lands starting out? From my experience and testing my answer is absolutely yes. I did a lot of testing of this subject some time back and perhaps my comments are relative. At least for those who are just thinking of using seating depth to improve accuracy.
I never measure OAL, it is not relative to what I do. I only measure to the ogive and I use the Hornady bullet comparator and a set of Starret dial calipers for this.
When a round is fired the barrel will oscillate, meaning the end moves around. If your bullet exits when the end is to the right that round will impact the target to the right. If your next bullet exits to the left that round will impact the target to the left. And so on to end in a spread out group.
However if you can find a node, a spot where your barrel end is motionless, and you can manage to get your shots off in this spot then group will tighten up. There is more than one node and by changing seating depth you move where the bullet exits the barrel. So the whole thing about seating depth is you are searching for a node.
This same thing applies to the powder charge. By varying the powder charge you vary the speed of the projectile and it will exit the barrel at different points also. One of these targets were shot with one seating depth but varying powder charges.
Notice how the group moves to different points with changes to the seating depth or powder charge.
I do extensive case prep to insure there is as little runout as possible to include partial neck turning, to give the load it's best chance.
I seat my bullets with a Hornady inline bullet seater. I also use standard loading dies. This combo gives me groups hovering around 1/2" consistently.