300 Winchester magnum

[Bruno2]

I am new to thr and I have some questions about loading some magnum rifle casings . The case mentioned is a belted case and I dont know a lot about them . Does the resizing die go over the belt or stop right before it ? If anybody with experience loading magnum rifle loads would like to chime in with some tricks or do's and dont's please feel free I welcome any advice that I can get.

Thank You very much
Bruno

 

[Shoney]

Bruno2

WELCOME TO THR!!!!

The area just above the belt is called the web. Most dies size down just to the web.

In theory the 300WM and all belted magnums are supposed to head space on the belt, however, this can lead to early case failures by stretching the case. All the 300WM reloaders I know use cases that have been fired in the weapon they are loading for, and size the neck of the case down until it just bumps into the shoulder. This headspaces the case on the shoulder and gives longer life with less chance for case separation.

If you are using cases that are new or have been fired in other weapons, full length resize them for the first firing, then do do as above.

As far as powders go, any of the slower burning powders will do. As far as bullets go, the majority shoot 180 gr bullets. I prefer the 200 gr bullets and hunt exclusively with Nosler Partitions.

Good Shooting!

 

[Bruno2]

When using a full length resizing die how do you go about setting the die up for neck sizing only ?

 

[Shoney]

Lube the case as normal. Screw the die out about 4 full turns from where the die contacts the shell holder at TDC. Size the case and remove it from the die.

Look at the neck and you will be able to see where it has been partially sized. Adjust the die down until it has sized the neck entirely and it just bumps into the shoulder. You should not be setting the shoulder back.

Chamber the case in your weapon and see if the bolt closes without a lot of pressure. If there is hard resistance, size the case down 1/8th turn at a time until it chambers effortlessly.

Now! Load em up.

And Good Shooting!

 

[Bruno2]

thank you

 

[Grumulkin]

Resizing or trimming new brass is a waste of time.

In addition, whether or not you full length or neck resize, after the 2nd or 3rd firing of a belted magnum case, run a wire with the tip bent to 90 degrees down the inside of the case to check for the groove that starts before a head separation occurs.

 

[Bruno2]

Did you smoke a bullet to check for lans contact on this measurement of oal ?

The gun I am loading for is the Thompson Encore is why I am asking .

I got a real good deal on some IMR 7828 that I picked up for about 8lbs I paid around $65.00 , but , I do have some 4831sc .

 

[Shoney]

We have talked a lot about head separation in cases. However, if many of the new reloaders are the same as me when I started out, I had no clue what it was for many years.

Here is a good discussion with pictures on what it is and how to detect it when doing case prep.
http://www.dirtydozensbunker.com/showthread.php?t=53801&highlight=head+separation

 

[NCsmitty]

Good advice from Shoney.
The less you work the brass, the better.

The IMR7828 will work very well for velocity and hopefully will be accurate.


NCsmitty

 

[Grumulkin]

I tried IMR 7828 but didn't get as good results with it as with H4831SC.

I didn't smoke the bullets. I seated the bullets long and kept setting the die to push the bullets deeper little by little until the action closed easily and there were no scuff marks from the lands on the bullet. Smoking the bullets would, I suppose, make marks from the lands easier to see but I've never had to resort to that.

 

[Bruno2]

So you guys answer this for me ( I know its just opinions ) Most of my reloading tactics I picked up from a buddy of mine that passed on just recently . I keep seeing all of these different people posting up on this site with over all length recommendations . All of these guys are posting the guns they are shooting the load out of with these lengths and all of the guns are different (ruger , rem savage , stevens) . Now keep in mind this buddy of mine that I am referring to has shot just about every kind of match that there is and handloaded for 50yrs or better . He told me the overall length of a round should just barely clear the magazine of the gun its being loaded for to retain the best accuracy. The smoking the bullet technique was what he recommended for the thompsons . light a candle hold the bullet above the flame until it blackens and then load the gun ,close it up and open the action , pull out the bullet . The idea is to have just enough contact with the lans to mark the bullet and that would be the ideal oal .

 

[Bruno2]

Something else that I want to get some opinions on about the 300wm . I have never loaded mag rifle before . Some guys have warned me about colder loads in the 300 , they say that they will produce a hang fire sometimes or a delayed detonation . Is this common ? I was planning on staying up around the max .

 

[Grumulkin]

I've never had a hang fire but then, I've never gone below the recommended load on a magnum case. That said, don't stay "up around the max" without working the load up incrementally. With some powders in some cartridges, the most accurate load ends up being around the maximum recommended load but most of the time I've found the most accurate load to be a quarter to a third below the published maximum load.

There is nothing wrong with "smoking the bullet" as long as you don't do it with open powder around but I don't do it that way. You can see the scuff marks on the bullet from the lands without smoking it.

The COAL is not a fixed number for an individual gun though there are SAMI specifications for COAL. SAMI specs are so a cartridge will fit in and cycle through any cgun for that cartridge that's made to SAMI specs. The things to consider in deciding what length to make cartridges to be fired in your gun are:

1. The cartridge has to be short enough to cycle through the magazine if the gun has a magazine.

2. The bullet has to be seated deeply enough in the case to hold it securely. This means a seating depth of at least 1 caliber length.

3. As long as conditions one or two have been met, the best accuracy is frequently obtained when the bullet is seated so it almost touches the lands; an exception is Barnes bullets which are said to shoot best with a little jump to the lands.

Seating a bullet to almost touch the lands makes up for some imprecision in the alignment of the chamber and throat with the bore. If the chamber/throat/bore have been cut in precise alignment, seating a bullet to almost touch the lands isn't as critical an issue.

 

[Bart B.]

Shoney says:

In theory the 300WM and all belted magnums are supposed to head space on the belt, however, this can lead to early case failures by stretching the case. All the 300WM reloaders I know use cases that have been fired in the weapon they are loading for, and size the neck of the case down until it just bumps into the shoulder. This headspaces the case on the shoulder and gives longer life with less chance for case separation.

In fact, belted cases are supposed to headspace on the belt; their headspace gages only measure that dimension and are less than an inch long.

People I know who've shot belted cases in high power rifle matches winning and setting records use new cases or full length sized ones sized all the way to the belt. They (and I) got 20 or so reloads per case and best accuracy either way. Anytime the case bumps on the shoulder when the bolt closes, accuracy suffers, especially in rifles whose bolt face isn't squared with the chamber (not the bolt) axis. But you won't see the difference unless you shoot at least 20 shots per group from a rifle/ammo/shooter/position system capable of 1/3 MOA 100-yard accuracy.

 

[MCMXI]

Bart, I'm going to shoot a 20-shot group (plus two sighters) this Sunday at 600 yards with my .300 Win Mag in a match. I neck size only (fifth loading of these cases), use Reloder 22 powder, CCI 250 primers and Hornady 208gr A-MAX bullets. I recently bought a Redding case neck gauge so may bother to measure and sort the cases beforehand. I'm hoping for 0.5 MOA but either way, I'll report the results so that others can see what's possible with neck sizing only, a quality rifle/scope and an average shooter.

 

[Bart B.]

1858's plans:

Bart, I'm going to shoot a 20-shot group (plus two sighters) this Sunday at 600 yards with my .300 Win Mag in a match.

Well, I'll be rooting (as in cheering, not like a hungry hog) for you. Is this an F class or regular prone match on the NRA's MR target?

Best I've done with similar cartridge (.30-.338, 66 grains IMR4350, Sierra 190 HPMK, RWS5341 primer) using full length sized Winchester cases was a 198-12X at the Nationals in a prone, any-sight (scope) 1000 yard team match. My best score at 600 was with a .308 (brand new cases, metered powder charges, Sierra 155's) in a prone match; 200-14X with aperture sights.

 

[MCMXI]

Is this an F class or regular prone match on the NRA's MR target?

It's an F-Class "tactical" match in the sense that the course of fire is as follows:

200 yards slow fire with two sighters - 10 rounds in 10 minutes
200 yards rapid fire with two sighters - 10 rounds in 60 seconds
300 yards rapid fire with two sighters - 10 rounds in 70 seconds
600 yards slow fire with two sighters - 20 rounds in 20 minutes

I don't like shooting rapid fire stages with the .300 Win Mag (barrel gets too hot) so I'll be using an AR at 200 and 300 since my .308 is in surgery.

The targets are a modified MR 63CF at 200 yards, an MR 63CF at 300 yards and an MR 1F at 600 yards. Basically they all have 1/2 MOA X-ring, 1 MOA 10 ring, 2 MOA 9 ring, 3 MOA 8 ring, 4 MOA 7 ring and 6 MOA 6 ring. The rings are slightly smaller than the dimensions listed but take into account the fact that the bullet hole only needs to touch the ring to score higher.

 

[Bart B.]

1858, some time ago you posted:

Bart, I'm going to shoot a 20-shot group (plus two sighters) this Sunday at 600 yards with my .300 Win Mag in a match.

As the lady in the fast food TV commercial exclaimed...."Where's the beef, er...I mean group?"

 

[MCMXI]

Bart, despite all of my reloading efforts, I had a terrible day at 600 yards and wasn't able to get any good data. More specifically, my technique was so inconsistent that it would be impossible to extract anything useful (in terms of the loads) from the holes in the paper. I will say that given how bad that stage was for me, I was expecting a lot worse when I was handed the target. That particular rifle is about to head off for surgery to get a new chamber and bolt so it'll be a while before I'm able to have another go at it. I assure you that I will make the necessary corrections and get back on it ASAP.