Crimping rifle rounds

[Kaveman44]

so whats the deal with Crimping rifle rounds? i just bought a RCBS Competition Die Set and was wondering if that will Crimp as well ? i have read that bolt action don't require crimping but semi-auto should. what about pistol rounds as well? Any help is greatly appreciated guys!!!!!

 

[bigedp51]

The RCBS AR Series dies for the .223/5.56 and .308/7.62 are taper crimp dies.

Pistol dies for semi-autos are taper crimp dies, and only used to close up the case mouth flare.

The only cases I apply a heave roll crimp to are hot .357 and .44 Magnums. "BUT" with light practice loads with the .357 and .44 magnum and plated bullets I only apply a taper crimp.

Bottom line, normally I do not crimp any of my rifle cases and you can increase the bullet grip by reducing the expander diameter.

Below many AR15 reloaders use the Lyman type "M" expander die below. The main part of the expander is .003 smaller than bullet diameter increasing bullet grip. The case mouth is bumped onto the .226 section of the expander to aid in straight inline seating. The a taper crimp die is then used to streamline the case mouth.

NOTE, at the Whidden custom die website they sell expander kits with five expanders. These five expanders run from bullet diameter to .004 under bullet diameter to control the amount of bullet grip.

 

[ATH]

I have applied a light crimp to rifle rounds intended for semi auto. I have not crimped others. The only one I do it every time is rounds for my Garand, when you get into the 30cal range the potential for kinetic pulling goes up.

I only crimp pistol rounds in high recoiling rounds...41Mag and 44Mag. Auto rounds no crimp, except a light one for lead 10mm as I need to close the expanded mouth to seat the bullet anyways.

 

[243winxb]

https://apps.dtic.mil/docs/citations/ADA341390

An engineering study was conducted on the 7.62 mm ball cartridge, M80, to determine the cause of a recurring delayed propellant ignition and to identify possible causes of action to correct the problem

 

[dfanonymous]

so whats the deal with Crimping rifle rounds? i just bought a RCBS Competition Die Set and was wondering if that will Crimp as well ? i have read that bolt action don't require crimping but semi-auto should. what about pistol rounds as well? Any help is greatly appreciated guys!!!!!

Semi auto rifles and handguns have a more violent extraction and feed process which is why a large amount of people prefer to crimp.

I like the lee crimp dies personally if you for whatever reason feel the need to have to crimp

 

[lancetkenyon]

I have never crimped my .223 rounds for my AR. Both 50gr V-max and 69 SMK. Neither bullet has a cannelure though. I would not crimp a bullet without one either. Never seemed to cause any issues in a few thousand rounds.

Bolt action rifles of mine never get crimped rounds.

 

[Dry Heat?]

I usually just bump my rounds with a very light crimp, cannelure or not. Never had a problem

 

[243winxb]

http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

Sierra- Reloading for Semi-Autos and Service Rifles.

Never crimped for my M16A1 carbine. Good neck tensions is key.

 

[RT2506]

I have fooled around with the Lee Factory Crimp dies in both rifle and pistol. These dies work differently in rifle than pistol calibers. Rifle calibers use a finger type crimping method that works even if the bullet does not have a crimping groove. You can adjust the amount of crimp you want to use. I use a point between where the fingers are completely open and completely closed. I call this a medium crimp. I use this on all my semi auto rifles because my test show that I get better accuracy. I have also found that the use of this crimp die on rounds loaded for many of the old military bolt actions rifles also increases the accuracy. Most of these rifles have throats a mile long and the bullet has to jump a long ways to the lands. My theory is that crimping the bullet holds the bullet a nanno second longer that no crimp allowing the pressure of the burn to rise to a more consistent point before the bullet leaves the case. This is doing much the same as being able to loading a bullet close to the lands will ****** bullet movement that nanno second as it hits the lands. I have not really experimented with the crimp die in my other rifles because they all have custom barrels and shoot better than I can hold most of the time so have seen no need to take the time and expense of testing. One military bolt rifle that did respond with increase in accuracy that has a short throat is the K-31 Swiss 7.5x55. On the other hand one Military bolt rifle that did not respond one way or the other to using the crimp that had a throat a mile long is the M-96 Swedish Mauser 6.5x55. These rifles are just plain accurate no matter what you do for some reason. I have more than one of each of these rifles and experienced the same with them all. So the bottom line is you will never know until you do the research yourself on your weapon.
Now about the pistol Lee Factory Crimp Die. I use this die on all my semi auto rounds. It basically is a taper crimp die but it's base is also tighter and will size the whole loaded round to speck. Since I started using this die fail to function experiences have about ended even in one finicky 1911 target 45 ACP pistol I have.
I have been hand loading over 40 years. I have done the research and this is my experience. Your millage may differ.

 

[ajkellerusmc]

Dillon Precision in Scottsdale AZ makes great taper crimp dies for pistol and rifle.
Rifle is available in 223,308,300blk, 30-06.

 

[raider1v1]

on my autos i use the lee factory crimp die lightly. the bolt guns its just neck tension

 

[Dirtrax]

I've never really understood why a cannelure is considered acceptable but a crimp "damages" a bullet.

 

[redleg1013]

I fashioned an adapter for a Forster CoAx that allows me to use a torque wrench set to a certain rating when I crimp with my Lee Rifle Crimp Die.... just because boredom and OCD don't play well together sometimes. I haven't done any serious testing to validate or necessitate its use, but, I have it in case one day, I don't hear the word "Dad" uttered a dozen times in five minute span of time.

 

[del2les]

so whats the deal with Crimping rifle rounds? i just bought a RCBS Competition Die Set and was wondering if that will Crimp as well ? i have read that bolt action don't require crimping but semi-auto should. what about pistol rounds as well? Any help is greatly appreciated guys!!!!!

There are multiple reasons a crimp may be required or help and reasons it is not.

The autos have been covered here and the crimp reduces or eliminates bullet push back during the loading cycle which can lead to high pressure and malfunction. Heavy recoiling handguns can have the opposite effect and cause a bullet to slip forward in the case leading to cylinder lockup

In heavy recoiling rifles, a round in the bottom of the magazine may experience the bullet slipping forward and thus jamming the weapon. Had a 458 do this but fortunately it was not while hunting dangerous game.

Also, some rounds give better uniform ignition with an increase in bullet tension especially if neck thickness varies. Light tension necks with light bullets in small cases have been known to jump upon primer ignition. Thus giving erratic sd and performance.