300 win mag problem

[jeremyro]

I have a Remington 700 long range in 300wm. It is my only 300wm rifle and i am having a strange problem I have never had before. When I reload for it some of the rounds do not want to chamber. Sometimes they just barely won't let the bolt close, sometimes I can't even get the round all the way into the chamber. All the brass is from Remington factory ammo and has been neck sized. The factory ammo had no problems. I neck size my 30-06 and 338lm with no issues. There are no rifling marks on the bullets and the brass looks totally normal. I tried full length resizing and they chamber much easier, but several still had issues. I can't figure out what might cause this. I am wondering if it is a problem due to it being a belted cartridge, but really not sure. Thoughts?

[mschn99]

I have a Remington 700 long range in 300wm. It is my only 300wm rifle and i am having a strange problem I have never had before. When I reload for it some of the rounds do not want to chamber. Sometimes they just barely won't let the bolt close, sometimes I can't even get the round all the way into the chamber. All the brass is from Remington factory ammo and has been neck sized. The factory ammo had no problems. I neck size my 30-06 and 338lm with no issues. There are no rifling marks on the bullets and the brass looks totally normal. I tried full length resizing and they chamber much easier, but several still had issues. I can't figure out what might cause this. I am wondering if it is a problem due to it being a belted cartridge, but really not sure. Thoughts?

Most belted magnums, including the .300 win mag, do not use the belt for any functional purpose. I would try to seat the bullets just a little more into the casing and see if that helps. Compare your depth to a factory bullet and see how they compare. All guns are different. My ruger M77 mark 2 in 300 win mag requires the bullets to be set a lot further into the casing than my remington classic in 300 for instance

[jeremyro]

All the seating depths are identical between rounds that will and will not chamber. I have ruled out the bullet hiring the lands as an issue

[Jimmy's]

Try a full length sized case rather than just the neck.

[LynnJr]

Jeremyro
It isn't the bullets but to assure yourself take a round that fits tight and pull the bullet out of the case and recheck it in the chamber.

The area right in front of the belt swells up and most full length dies don't touch that area.
You can keep twisting the full length die tighter and tighter and see if that helps but what happens is it usually forces the shoulders back too far before the area closest to the belt gets properly sized.
There is a collet type die made by Innovative Technologies owned by Larry Willis that fixes your issue.
If you look at the two pictures you slide the collet which has 8 slits on it onto the case until it stops against the belt.
After that you insert it into the tapered die body which pinches it thus reducing the brass diameter in front of the belt.
This pinch will make your over all length grow about 0.001 inches

[pacrat]

I have a Remington 700 long range in 300wm. It is my only 300wm rifle and i am having a strange problem I have never had before. When I reload for it some of the rounds do not want to chamber. Sometimes they just barely won't let the bolt close, sometimes I can't even get the round all the way into the chamber. All the brass is from Remington factory ammo and has been neck sized. The factory ammo had no problems. I neck size my 30-06 and 338lm with no issues. There are no rifling marks on the bullets and the brass looks totally normal. I tried full length resizing and they chamber much easier, but several still had issues. I can't figure out what might cause this. I am wondering if it is a problem due to it being a belted cartridge, but really not sure. Thoughts?

Could be any one of several issues. Not enough info to diagnose all of the likely causes. I'm an answer a question with a question guy until all relevant info is revealed.

Quick review of factory ammo. Typically factory ammo is just "shy" of SAAMI specs. Done on purpose, so it will chamber in all factory rifles produced. Making it always easier to chamber, but not as accurate as properly hand loaded ammo.

[1]...Did you trim all the cases? If not, necks could be conflicting with leade in throat. Jamming the neck, pinching the bullet. This will not leave any marks on bullet.

[2]...Measure "web" diameter of easily chambered rounds just above the worthless POS belt, and compare with the problem cases.

[3]...Do a comparative headspace measurement [base to datum] between easily chambered, and problem cases. Can be done with a 40 cal pistol case and calipers. NO, it will not give a true headspace determination. But will give you a visual comparison to help base diagnosis on.

Not all cases are created equal, not all chambers are created equal, not all reamers that chambers are cut with are created equal, not all FL sizing dies are created equal.

Typically FL sizing dies return cases to minimal SAAMI specs. But due to manufacturing tolerances some don't return cases to the point that they will easily chamber in all rifles. That is why they make "Small Base" dies for some problematic rimless cartridges.

The Willis collet sizer that LynnJr shows costs $96.95+shipping. I would be sure it is a base swelling problem before ordering.

http://www.larrywillis.com/

JM2c

[RandyD]

I agree with LynnJr and pacrat. I reload the .300 Win. Mag., and I use and recommend the Larry Willis collet die.

[jeremyro]

Aaaaaand Lynnjr. wins again. I pulled a bullet from a round that would not chamber. It was a tiny bit shorter than a fired brass that would chamber so OAL was ruled out. I then put the case through the FL resizer and tried again. It chambered better, but was still difficult. I looked at the case and sure enough there was a gap at the bottom where it had not been resized. There was a tactile transition where the sizer stopped. So it looks like $90 die here I come.

[LynnJr]

Jeremyro
Take a single cut file to one sacrificial case and file down the area right in front of the belt. Go around the entire case and see if it fixes the issue before spending hard earned money.
I gave my die away when I quit shooting 300 Ackley's in 1000 yard competition to Dangerous Bob Dorton only to buy one here on Calguns for $55 shipped.
If you determine it is indeed the area in front of the belt you can do a google search for a used die.

[killshot44]

That "worthless", POS belt is what the case headspaces on.....

If the base ahead of the belt isn't sized, the cases won't chamber. The Willis Collet die solves the problem.

[LynnJr]

I haven't kept up with the 1000 yard benchrest crowd since 2010 but back then it was kind of common to cut the belt off of your brass and headspace off of the shoulder using RWS brass.
When Dakota Arms came out with there line of cartridges they would have taken over because they didn't have a belt but the 300 WSM came into vogue.

[iroquois]

I agree with LynnJr and pacrat. I reload the .300 Win. Mag., and I use and recommend the Larry Willis collet die.

I also recommend the Larry Willis collet die.
I've been using it for years.

[pacrat]

That "worthless", POS belt is what the case headspaces on IN A DOUBLE RIFLE.....

If the base ahead of the belt isn't sized, the cases won't chamber. The Willis Collet die solves the problem.

FIFY

The worthless POS belt outlived its usefullness along about 1920 or so. It is only there so H&H could market the same cartridge in Double Rifles that required a "rim". As they used in their magazine rifles that didn't.

Unless someone happens to have both a magazine rifle and a Double Rifle in .375 H$H etc, and want to use the same ammo in both. It is a useless POS. That only serves to complicate reloading while adding nothing to the strenght of the case.

Today it is nothing but a POS marketing gimmick. For the know nothing new gun buyers that succumb to MAGNUMITIS.

Useless as teats on a boar.

JM2c

[ar15barrels]

That "worthless", POS belt is what the case headspaces on....

Only if the person sizing the cases chooses to use the belt instead of the shoulder.
When you are sizing your own cases, it is better to use the shoulder to locate the case in the chamber than the belt.
When you are using factory ammo, the shoulder will often be significantly shorter and the belt is indeed being used to stop the cartridge in the chamber.

[jeremyro]

Jeremyro
Take a single cut file to one sacrificial case and file down the area right in front of the belt. Go around the entire case and see if it fixes the issue before spending hard earned money.
I gave my die away when I quit shooting 300 Ackley's in 1000 yard competition to Dangerous Bob Dorton only to buy one here on Calguns for $55 shipped.
If you determine it is indeed the area in front of the belt you can do a google search for a used die.

I am not quite sure what you are saying here. Are you saying to file down the bulge in front of the belt and make sure that that is what is causing the issue? I am almost positive it is after the Fl sizing test. It barely chambered before Fl resizing, but after it chambered up to the hump fine, then got tough when it hit the hump.

Another note. How is it blowing the case out so that it will not chamber? Shouldn't the case chamber in the same barrel after firing? I am not understanding how it is getting larger than the chamber.