Seat and Crimp
Quote from Alan on August 30, 2023, 1:26 amI am new to reloading and have a couple questions on seating and crimping. I am working with .223 and 9mm Dillion Steel Die sets on an XL750.
Seating:
I setup the seating die according to the instructions and videos, how ever for example on .223 I set it up to set a OAL of 2.200. I load several cases and I am getting inconsistent lengths. They range from 2.198 to 2.205 - What is an acceptable tolerance (and where do I look it up at)?
Crimp:
Again I followed the instructions and videos on how to set this, and they say .001 ~.004 from the neck size. What they don't tell me is when do I get the base neck size? After it has ran through the sizing die? After the bullet is seated? The first batch I did I had issues when running them through the rifle. The bullets were being pressed back into the case as they are being chambered. I assume this is a crimp issue.
Any help, advise, web sites would be wonderful. Thanks
I am new to reloading and have a couple questions on seating and crimping. I am working with .223 and 9mm Dillion Steel Die sets on an XL750.
Seating:
I setup the seating die according to the instructions and videos, how ever for example on .223 I set it up to set a OAL of 2.200. I load several cases and I am getting inconsistent lengths. They range from 2.198 to 2.205 - What is an acceptable tolerance (and where do I look it up at)?
Crimp:
Again I followed the instructions and videos on how to set this, and they say .001 ~.004 from the neck size. What they don't tell me is when do I get the base neck size? After it has ran through the sizing die? After the bullet is seated? The first batch I did I had issues when running them through the rifle. The bullets were being pressed back into the case as they are being chambered. I assume this is a crimp issue.
Any help, advise, web sites would be wonderful. Thanks
Quote from Xiphos on September 1, 2023, 10:28 pm#1. The 223/5.56 does not require a roll crimp into the cannelure for reliable operation. The roll crimp is mainly used for tubular magazine feeding to keep the projectile from moving back into the case during recoil. Tubular magazines also require flat or round-nosed projectiles to keep from setting off the primer directly in front of it.
As the AR uses a detachable box magazine this problem is obviated.
Only on heavy recoiling shells like the 375 H&H Magnum are roll crimps ever used to prevent set-back on projectiles in a box magazine. All factory ammunition in 375 has a roll crimp because they are assuming it will be used in the worst of circumstances. In custom handloading, depending on neck tension, roll crimping may not be required unless the same shells live in the box magazine with repeated firing of fresh rounds in the chamber.
#2. I do not load 9mm; however, I have loaded thousands of 45ACP. Virtually all semi-auto cartridges are head-spaced on the mouth of the shell. After seating the projectile to the correct depth, removal of the "bell" introduced during the powder insertion process (to ease the insertion of the projectile) must be done for the loaded round to enter the chamber and headspace properly.
If you are concerned that you are not removing the bell correctly, I suggest you obtain a headspace-checking die to verify the loaded round will function.
19846 - EGW Checker | 9mm (chamber checker) Dillon Precision
There is also one available for the 5.56 as well.
#1. The 223/5.56 does not require a roll crimp into the cannelure for reliable operation. The roll crimp is mainly used for tubular magazine feeding to keep the projectile from moving back into the case during recoil. Tubular magazines also require flat or round-nosed projectiles to keep from setting off the primer directly in front of it.
As the AR uses a detachable box magazine this problem is obviated.
Only on heavy recoiling shells like the 375 H&H Magnum are roll crimps ever used to prevent set-back on projectiles in a box magazine. All factory ammunition in 375 has a roll crimp because they are assuming it will be used in the worst of circumstances. In custom handloading, depending on neck tension, roll crimping may not be required unless the same shells live in the box magazine with repeated firing of fresh rounds in the chamber.
#2. I do not load 9mm; however, I have loaded thousands of 45ACP. Virtually all semi-auto cartridges are head-spaced on the mouth of the shell. After seating the projectile to the correct depth, removal of the "bell" introduced during the powder insertion process (to ease the insertion of the projectile) must be done for the loaded round to enter the chamber and headspace properly.
If you are concerned that you are not removing the bell correctly, I suggest you obtain a headspace-checking die to verify the loaded round will function.
19846 - EGW Checker | 9mm (chamber checker) Dillon Precision
There is also one available for the 5.56 as well.
Quote from ARMTGuy on September 18, 2023, 9:11 pmwith a full metal jacket projectile, your overall variation of .007" is actually on the low side. The variation is in the nose of the projectile, the diameter where the seat stem contacts the bullets varies from one bullet to the next. I've personally measured up to .025" overall variation in length.
Regarding your crimp question, measure the case neck diameter at the case mouth before crimping, then again afterwards. .001-.002" is plenty of crimp for a 223.
with a full metal jacket projectile, your overall variation of .007" is actually on the low side. The variation is in the nose of the projectile, the diameter where the seat stem contacts the bullets varies from one bullet to the next. I've personally measured up to .025" overall variation in length.
Regarding your crimp question, measure the case neck diameter at the case mouth before crimping, then again afterwards. .001-.002" is plenty of crimp for a 223.