why did crimping improve my accuracy?

[cjmac]

So i crimped a few of my 308 loads for the heck of it. It did improve my group size. But im not sure why ......

 

[JamesnTN]

It created the needed pressure your rifle liked. You can do same via neck bushings as well if you have a neck die that uses bushings.

 

[SS427]

Not sure I would draw a conclusion so quickly. Were all other variables the same? Temp, humidity, wind. (Assuming you are using some sort of wind indicators) Coffee consumption. Did you stab your accuracy voodoo doll in the same place.

I would shoot a few more times before I would go back and crimp all my bullets.

If it did help, I would say the neck tension is why.

 

[cjmac]

I crimped a few . Light,moderate, heavy... it seems to like a light crimp.thats what i tried first. The trick is to keep the crimp die set the same. I guess ill cripm them at the range then lock the die ring where it shoots best. I havent got into bushing dies yet.

 

[Webster]

What size groups are you talking about? How many shots in a group? What distance? I can shoot the same load on three different Saturdays and get different results. My rifle shoots 1/4" groups vertical no wind flags. It might be your shooting ability. You cannot always say it's the rifle or load.

 

[Cort]

In my opinion, crimping a rifle bullet in any fashion deforms the bullet and creates a less accurate condition. I would look hard at neck tension or at seating depth. Your rifle seems to want a little more pressure to perform well. You could also increase the pressure by using a little more powder.

Cort

 

[2506]

"In my opinion, crimping a rifle bullet in any fashion deforms the bullet and creates a less accurate condition."

I can not tell you how many times I had people tell me that same thing for a couple years when I was shooting what we called old men's military rifle matches at my club. We could not get into all those positions anymore so we shot from a bench at 50 yards with carbines and 100 yards with rifles for score. I discovered that with the old military rifles many had very long throats and if I used a Lee Factory Crimp Die on my ammo I got MUCH tighter groups than with the same loads not crimped. I was using match bullets and beat the pants off those saying that crimping a match bullet would ruin it's accuracy. I never told anybody that I was crimping because I wanted to keep having an edge on everybody. ;D This was done with a number of different rifles and calibers. Don't ask me why it was more accurate because I don't know but IT WORKED.

 

[cjmac]

Well seeing as im just getting in to this, .... my group went from under a inch to 5 rounds in the same hole. So why do people throw charges rather than weighing them . Please someone explain how it works..

 

[Grimstod]

I can't say much about the physics behind crimping but I do have my own testimony that I will share if your willing to listen.

I came from a different forum that was all surplus guns. Every one there used old beat up surplus guns that had in some cases almost an inch of freebore cause they were, well just shot to heck. Then I experimented with non crimped bullets. Wow so much better. All I had to do was load a little longer and go up a little on my charges. Got better velocities and better groups! First I did not say that I was no longer crimping but after everyone there was beginning to beg me for my secret formula I sprung it on them. Crimping SUCKS! After I told everyone I did not crimp my ammo I even had a member call me and tell me he would "correct me in my ways and prove me wrong." Well he has never out shot me and has never proven anything. I also got a lot of emails almost threatening me. It was like I had just violated some religious code or something. : Thats when I decided to move here, and hay all the books say its detrimental to accuracy. Can ALL the books be wrong at the same time? I think not.

So remember with reloading there are hundreds of factors involved with accuracy. If you change just one thing and get a different result that surprises you go back and check everything els again. Its easy to make mistakes with this stuff. I say to be a good reloader you have to be ULTRA OCD! ;D

 

[TAJ45]

In my opinion, crimping a rifle bullet in any fashion deforms the bullet and creates a less accurate condition. I would look hard at neck tension or at seating depth. Your rifle seems to want a little more pressure to perform well. You could also increase the pressure by using a little more powder.

Cort

A bud just e'd me and said he took the day off and did some shooting.

"I just screwed my 14 twist 6BR barrel on today and shot a .197 group with 32.2 gr of 8208....had a .3++ vertical group with 32.0gr to start with and bumped the charge up .2 on powder and it took the vertical out and got the .197 group."

So, like was quoted above, maybe just a bit more pressure for that load that day?

 

[Steve Ladino]

Well I think some people mean that they weigh and say they throw and visa versa but not all. The folks i shoot with weigh their powder on scales to the 1/10 of a grain or less. I know many bench rest shooters use very high precision powder throwers at the range where they adjust the volume of the powder to suit the conditions of the day. Throwing powder can achieve very accurate & uniform charges if you are absolutely consistent with the operating method while maintaining the powder level in the hopper.

 

[cjmac]

Sounds like i need to get set up to load at range. Any ideas

 

[LCazador]

Let's just say that you have an old worn throat and pressure will fall off as that throat lengthens. You can cure some of that by crimping and increasing that pressure gap back to where your rifle shoots good. The problem with all this is that as that throat wears down again, the same crimp that shot good, will change. Also there is the need to keep the cases the same length they are now, because as that case length changes so will the crimp pressure and the bullet tension. Crimping is just one more variable to deal with, and consistency is always a problem. Like many have said more powder/ pressure via other more controllable means is a better way to go.

 

[cjmac]

Never thought of it like that.... i think ill take my powder measure and other press to the range next trip.