New guy. PLEASE help me here. Thanks

[shooters]

Ok, I'm still learning here, but this should be easy for every experienced reloader. On my 300 RUM Sendero ll, I'm having a hard time here with MAG OAL, LANS OAL, and what to load. My MAG OAL is 3.683. I've got that figured out. Shells WILL feed into the chamber from the magazine with reliability at 3.650 with no issues. Thats .033 under magazine which seems like A LOT! Do any of you go closer to MAG OAL without chamber issues?

Now, I don't have the correct tools to measure ot the LANS. I grabbed a black sharpie, colored an accubond up, loaded a round WAY out to like 3.900. Round would NOT chamber. I finally got a round to chamber very very very tightly at 3.853, and I did see marks on the black colored accubond, but I'm pretty sure I was ramming the bullet into the rifleing. I could barely open the bolt. Super tight. So, I gradually seated the bullet over and over until I could NOT feel or hear the bullet sticking slightly in the lans on ejection. That came to 3.823. I would imagine that that is where my lans are, right?

So, my loads will be at 3.650.
My lans are at 3.823. I think.
Thats .173 off the lans which I believe is HUGE.

That should NOT create any pressure spikes, right? You have to be around .010 or dang near touching to create pressure, right?

Please, if anyone can tell me if this has all done "somewhat" correct and I'm not going to kill my self, I would appreciate it. I think if I'm under Magazine OAL, I will always be fine. I don't think the mag will allow me to load to far out unless I'm shooting a single shot. Thanks so much for the help.

 

[Korhil78]

Shooters,

If you have an accurate load and it fits in the mag with no pressure signs show via sticky bolt, case stamping or flat primers then you are fine. Just remember ... The further in you seat bullets the less the pressure. The further out that you seat bullets then the higher the pressure.

 

[Korhil78]

You can even load it to mag length and be fine. Just start a few grains lower and work back up and see what ur accurate load is at that length. If you have a accurate load at 3.650 and no pressure signs then I would leave it as is.

 

[kcebcj]

First off you need to get some tools. The RCBS Precision Mic works pretty good for what your trying to do but there are others.

For now though take a fired unprimed case and cut four slits down the neck to where the shoulder starts. Clean up the saw cuts with some fine sandpaper. By hand insert a fresh bullet into the brass. If it's really easy remove the bullet and carefully squeeze the four tabs in just a bit. You want the bullet tight enough that it's difficult to pull out with your fingers.

Once you have that insert the bullet leaving it out so it will contact the lands and chamber it. Remove it carefully. Repeat that until you're comfortable that you have a accurate number at the lands. Instead of using a sharpie smoke the bullet with a match each time so you can see the marks and it gives you a pretty good idea what going on especially if the bullet slips when ejecting it.

If you don't have the tools to measure your test setup at the lands you can measure the OAL with a dial caliper.

If this is a hunting rifle your max length has to fit the mag box or you have a single shot so start there. Get them as long as you can to start because future seating adjustments will only shorten them.

Against or into the lands will create the most pressure. As you move away the pressure lessons. When working up a load and have the seating depth you want to start with a couple grains minimum below the book high and work up in half grain increments checking each for signs of pressure. If you have access to a chronograph use it as you work up and watch the fps. Where you stop is up to you but I personally don't like to exceed the book high for a hunting rifle that will be used during big temperature swings and such. If you're inexperienced don't exceed the book max!

 

[shooters]

You can even load it to mag length and be fine. Just start a few grains lower and work back up and see what ur accurate load is at that length. If you have a accurate load at 3.650 and no pressure signs then I would leave it as is.

So, if I go from 30 thousands under mag to 20 thousands under mag, is there going to be any noticable visible difference in accuracy, or are most people just not that good to see a difference?

Ok, if mag is

..... 3.683 and if I go 20 thousands under to 3.663 and have no issues with feeding, am I wasting my time to change loads from 3.650? Thats another 13 thousands I could move them out and have zero feed issues. Is it even worth the time or does accuracy improve that much? Thanks

 

[shooters]

Book says 3.600 OAL and loads from 91g to 95g max.
Mag OAL is 3.683
If I go 3.663 which is .063 over book, and .020 under Mag OAL, do I still need to start under 91g by a few grains, which is book low, or do you mean a few grains under MAX what the book says, so 93 grains?

 

[shooters]

Word of caution, be carful smoking an accubond bullet! It heated up a little too much and the polly tip came exploding out of it next to my face. Ha ha. Funny, but would have sucked if it hit an eye.

 

[Korhil78]

This is what I would do. If you are going tO hunt with this rifle, start your bullet length to the OAL of your magazine and start at 91 gr and work up. If you start noticing pressure problems then you won't go any higher in powder charge. Take your mOst accurate load from those. If the most accurate load Is acceptable accuracy for you then I would leave it at the mag length with the specified powder charge. If you want, you can take the most accurate load from the previous loads and seat the bullet in deeper and see if that tightens the group up fOr you. Example:

Load rounds to OAL of 3.683
Load one set at 91 then 91.5, 92, 92.5, 93 and so on. Shoot the sets in that order noting the accuracy. Go until you notice pressure signs or get to max load. Take the most accurate load and then reload it to see of the accuracy is repeatable. If the accuracy is good enough, you can leave it like it is or if you think you can get better accuracy out of the load, you can seat the bullets in .005 deeper to see if it works better. Some people go in increments of .001 deeper.

With a 300 RUM, I would just do three shot sets. Let it cool between each set.