Lee neck sizing die problem .

I've reloaded plenty of pistol ammo , but I'm new to rifle (HXP all used up) , so , I think I have all the basic Kit to reload for my '39No.1 MkIII(.303) . All my fired brass comes out of the same gun and the neck-sized and trimmed reloads shot well , but closing the bolt was quite stiff . So on the next batch I thought I should screw in the collet neck sizer an extra turn , as per instructions , giving it that extra push after it stopped , as per instructions . OOPS , there was a nasty crunch , thought I had buckled the case shoulder ... but the case was ok , so I dismantled the die and discovered that I had stripped the thread on the ally screw cap ! Said "oh bother" or something to that effect , then lubed all and full length sized . Can anyone tell me where I'm going wrong with my neck sizing ?

1. You pushed the collet die closed all the way without a case in the die and the collet is jammed and is no longer free floating. You will need to dissemble the die and release the collet. (Over tightened die)

2. You adjusted the collet die too far down or too deeply and you buckled and deformed the shoulder making it hard to chamber. (Over tightened die)

NOTE: When all else fails read the directions for your collet die setup as this is explained very well in the directions.

"DO NOT" full length resize your .303 cases, the Enfield military chamber is 1/8 of an inch longer or deeper than civilian commercial SAAMI reloading dies. Therefore you will need to back off the FL die approximately 1/8th of an inch from the shell holder. Back the die off more than this and screw it down a little at a time until the case chambers with very little force on the bolt. (Bump the shoulder back only .001 -.002 instead of an 1/8th of an inch)

Below, the amount the case is sticking above this case gauge is how much longer the military chamber is than a civilian commercial SAAMI chamber. When you full length resize the case you are pushing the shoulder of the case back too far and shorting case life.

https://www.milsurps.com/images/impo...IMGP6321-1.jpg

The neck sizing die is designed to reduce the neck back to a size that will hold a projectile. Glad to see you trim the case length.
Neck sized cases will need a full length resize after a couple of neck sizes/ reloads. I check and trim case length every reload. I check a few of each neck sized batch in the chamber and if any have more than a little resistance to closing the bolt, I full length resize the lot. The trick here is using an adjustable FLR die. Most use a Lee FLR die. Start with it backed off so it doesn't seem to do much and turn it in half a turn at a time, checking the case in the chamber, until it fits with very little/ no resistance closing the bolt. Do a couple more case to confirm and away you go. Then you may get two or three more neck sizes before the cases are tight, but you may need to use the FLR die to "bump the shoulder back" every time. It will still work the brass much less than taking it back to original size in a factory set FLR die, and your cases, especially the HXP which are among the best there is, will last quite a few times through.
I think the most important thing is to be sure the cases don't exceede maximum length as this can lead to a dangerous situation.

All discussion welcome, I don't think I missed too much?

I've found this too, I think the shoulder does buckle if you screw it in hard enough to get good bullet retention. I will not do rapid fire with such cartridges, either you can't close it or the bullet is liable to be pushed back in. Or course, ally will strip if you stress it hard enough - turning a steel cap would solve that problem. I rarely use the die now.

Lee will replace the broken parts, life time warenty.
(I sell Lee dies as a side interest and have special dies etc made by them for me and customers).

To get a tighter bullet fit you sand down the anvil pin that the collet die sizes on.
To crimp the bullet tight use the factory crimp die.

The case buckled because
The case was too long, you must check overall lenght every re load
or you had scerwed the die down too far.

Lee do a great set of films on their web site to show you how to use their products properly.
here is the link.
Lee Precision, Inc. Reloading Tools and Equipment: Setup and Operation Help Videos

Lee dies are great.
I reload .303 and .303 sporting. 6.5X57R, 8X64S, 7X64, 30X284, 30-30,
577/45, the list goes on and on,
Some of these dies Lee made specialy foe me for compertition, such as the 8X64S as it is not a die they carry. They also have made factory crimp dies and collet dies for certan diamiters of bullet, and swage dies of strange diamiters.

The Lee Collet Die is a little rough after manufacture, specifically the fingers on the collet, they can have burs and rough edges that can cause you trouble with the die and your cases. Lightly sand-polish with fine sand paper to remove any rough edges at these slots marked in red below.

https://www.milsurps.com/images/impo...IMGP7093-1.jpg

For "partial" full length resizing go to your local hardware store and buy washers that fit your dies, with the proper thickness washer your dies will be backed off the shell holder the proper amount without the need to readjust the dies after normal "factory adjustment".

https://www.milsurps.com/images/impo...IMGP7086-1.jpg

Always use a lubed case when setting up your dies to "center the die in the shell holder and align-center the die in the reloading press threads, and then tighten the die lock ring. This prevents inducing any misalignment in the die and your reloaded cases.

Thankyou guys for your advice .
Edward ... Yes, I did read the instructions beforehand , but for all the reading , you only really learn when you try to do it . I know FLR'ing will reduce case life and I only did it because of the problem . Good pictures , thanks . I will try smoothing the slot edges . Your collet die cap looks to be made of steel . Can you confirm this ?
Son ... Yes , I also thought it important to trim the cases (bit of a chore with the little finger & thumb trimmer) but I have since read (somewhere?) that the military .303 chamber is oversized to allow for trench crud etc., so no need to trim !!! I think I'll continue trimming to be safe .
David & MkVII ... No I didn't buckle the case ! I thought I had , but it was the collet cap thread stripping off . To quote part of the instructions - "The neck is sized at the very end of the stroke. It requires considerable force on the press lever."

I'm now thinking (from the above info) it may be caused by rough collet slots combined with an alluminium cap . Or am I still missing something ?

bouletbill

I prefer using a RCBS neck sizing die to using the Lee collet die, the collet die leaves longitudinal marks on the necks. It also has variable crimping results with different type-make cases and increased bullet run out. (wobble)

The cap on my collet die is aluminium and the die should be lubricated with a dry lube like powdered graphite or a dry spray lube for smoother operation. The mandrel floats and moves during the crimping-sizing operation and this can and does cause more bullet run out or wobble.

I'm reloading Greek HXP, Remington, Winchester and Prvi Partizan cases and I did not like variable differences in neck sizing with the collet and case brands. The old fashion basic Lee Loader and a plastic hammer has more uniform neck sizing, less bullet run out and smoother necks along with the results of standard RCBS dies.

If you watch the instruction video your "arm" and your downward force controls internal neck size and thus neck tension. My elbow doesn't have an adjustment knob on it to set at 25 pounds and this can cause too many variable sizing-crimping results.

My Lee Collet die only came out for the photo session in this posting and was put back into the rear of the storage cabinet to gather more dust. Sizing accuracy and uniformity are more important to me than "speed" and I reload for accuracy.