BigUglyMan
CGN Ultra frequent flyer
- Location
- New Scotland
I crimp hard kickers and anything using cast bullets.
Crimp or no crimp?
- Thread starter Rifter
- Start date
So much misinformation from some. You crimp to stop the bullet from being driven into the case from recoil, causing higher pressure.
If you are shooting a single shot you do not need to crimp, because there is no other rounds affected. If you are shooting stout or max loads and other rounds are in the gun being affected by recoil, you need to crimp. If you are shooting the stout or max loads in a tubular or box mag you still need to crimp. That is it in a nut shell.(pun)
If you are shooting a single shot you do not need to crimp, because there is no other rounds affected. If you are shooting stout or max loads and other rounds are in the gun being affected by recoil, you need to crimp. If you are shooting the stout or max loads in a tubular or box mag you still need to crimp. That is it in a nut shell.(pun)
For what its worth i Loaded 20 rounds for my .308 and 20 rounds for my 7.62x54R. Didnt crimp any, did neck size the brand new brass first. Loaded them 5 into the mag and fired off a round in each gun, took the remaining 4 out of the magazine to check OAL and none had changed at all from when i loaded them, good enough for me. With the neck size die im using neck tension should remain the same even after multiple loads but ill continue to check OAL for shifting on each batch to ensure they arnt starting to shift after a few reloads, and ill start crimping if i need to. Thanks guys.
for safety(recoil kicks projectile back), neck tension consistency and simplified/unified reloading process out of all my pistols/bolt/semi, I always do light crimp so that I don't have to think or keep track of which should/need crimp, which ones are not.
There are many reasons for crimping and crimping deals with neck tension or bullet grip by the case neck. I ordered a carbide expander for my .243 Redding die and it measured .2428 and my opinion it was far too large in diameter and I never use it. Many competitive shooters today are using .002 to .003 bullet grip, meaning they either use a smaller bushing or reduce the diameter of the expander.
Whidden custom dies sells expander kits with five expanders from bullet diameter to .004 smaller than bullet diameter. And the dies neck diameter, case neck thickness and brass spring back have the greatest effect on neck tension.
Crimping deals with the type firearm and understanding neck tension and being able to measure your case necks, annealing, etc.
Below I use a Lyman type "M" die on my target .223/5.56 cases for my AR15 A2 HBAR and "lightly" taper crimp the case mouth. And this is to only streamline the case mouth, and you can see the main part of the expander is .003 smaller than bullet diameter. The case is just pushed far enough on to the .226 diameter part of the expander to help the bullet start straight when seating to reduce neck runout.
Below is from Sierra's exteriorballistics.com
http://www.exteriorballistics.com/reloadbasics/crimp.cfm
"Regardless of which type of case a crimp is applied, one of the primary reasons for crimping remains the same; to increase neck tension, thereby ensuring proper powder ignition. In many cartridges, such as the .357 and .44 Magnums, large charges of slow-burning powders like H110 and Winchester 296 require firm initial resistance to the bullet’s movement. This building pressure aids in giving complete combustion, enhancing accuracy and shot to shot uniformity."
Bottom line, try no crimp and crimping and see what gives you the best accuracy and what works best in your "type" firearm. Ask yourself if you have enough neck tenshion and how much is needed. Example with light practice loads in my .44 magnum with plated bullets I use a very light taper crimp without any problems after using a type M die expander. So see what works best for you and I didn't see any "misinformation" here and just opinions of what works for the person pulling the press handle.
Whidden custom dies sells expander kits with five expanders from bullet diameter to .004 smaller than bullet diameter. And the dies neck diameter, case neck thickness and brass spring back have the greatest effect on neck tension.
Crimping deals with the type firearm and understanding neck tension and being able to measure your case necks, annealing, etc.
Below I use a Lyman type "M" die on my target .223/5.56 cases for my AR15 A2 HBAR and "lightly" taper crimp the case mouth. And this is to only streamline the case mouth, and you can see the main part of the expander is .003 smaller than bullet diameter. The case is just pushed far enough on to the .226 diameter part of the expander to help the bullet start straight when seating to reduce neck runout.
Below is from Sierra's exteriorballistics.com
http://www.exteriorballistics.com/reloadbasics/crimp.cfm
"Regardless of which type of case a crimp is applied, one of the primary reasons for crimping remains the same; to increase neck tension, thereby ensuring proper powder ignition. In many cartridges, such as the .357 and .44 Magnums, large charges of slow-burning powders like H110 and Winchester 296 require firm initial resistance to the bullet’s movement. This building pressure aids in giving complete combustion, enhancing accuracy and shot to shot uniformity."
Bottom line, try no crimp and crimping and see what gives you the best accuracy and what works best in your "type" firearm. Ask yourself if you have enough neck tenshion and how much is needed. Example with light practice loads in my .44 magnum with plated bullets I use a very light taper crimp without any problems after using a type M die expander. So see what works best for you and I didn't see any "misinformation" here and just opinions of what works for the person pulling the press handle.
