RIFLE CRIMPING

[tigger]

Hi guys do any of you crimp your hunting loads? I reload for my 6.5x55 using R22 Barnes TTSX bullets for stalking but do not crimp at present, but I've been told I really should do especially as you could load and unload many times In a day and it can leave a bullet in the barrel and spill the powder in the chamber etc is this a real risk or have I been fed false information any help greatfully received

Edited October 3, 2012 by tigger

[kent]

Hi guys do any of you crimp your hunting loads? I reload for my 6.5x55 using R22 Barnes TTSX bullets for stalking but do not crimp at present, but I've been told I really should do especially as you could load and unload many times In a day and it can leave a bullet in the barrel and spill the powder in the chamber etc is this a real risk or have I been fed false information any help greatfully received

 

I have never, ever had this happen nor have i seen it happen in many years- i have herd tell of it once but the guy new squat about loading his own. If it did happen a drop rod from the muzzle would get the bullet out (which shouldn't contact the rifling ever in a hunting load so it would stick anyway). The advantage in a crimped load to my mind is they tend to be truer in creating consentric rounds than many other lower priced bullet seating dies. Personally i choose not to crimp and use either high quality bullet seaters in the press or chamber type benchrest hand dies

[tigger]

 

 

I have never, ever had this happen nor have i seen it happen in many years- i have herd tell of it once but the guy new squat about loading his own. If it did happen a drop rod from the muzzle would get the bullet out (which shouldn't contact the rifling ever in a hunting load so it would stick anyway). The advantage in a crimped load to my mind is they tend to be truer in creating consentric rounds than many other lower priced bullet seating dies. Personally i choose not to crimp and use either high quality bullet seaters in the press or chamber type benchrest hand dies

 

Thanks for your reply mate most helpful

[dicehorn]

The only way I could foresee your bullet sticking in the bore would be if you seated them well into the lands. Personally, on my 3 rifles and 7 other calibres I reload for I have never seen the need. Some will say crimping makes your ammunition a little more accurate - the best my tac has done on a 4 shot group is .030" - I dont think if I had crimped the bullet I would have improved on it.

[pigeon pete]

i used to when i was green on reloading ,and my RFD said dont bother and if you dont get the right pressure on every crimp it will affect your pressures and your grouping and it helps your case life ,and you will damage the bullet as well ,i use a AR15s/p and i have no probs with mag feeds

[tigger]

Thanks for your replies guys and I'm currently around 25-30 thou off the lands so in theory as has been said if I'm not seated in the lands then there is no way the bullet could be pulled out of the case.....

[Vince Green]

The only thing, taking the opposite view, not crimping means you are relying on neck tension to hold the bullet. This is variable according to the thickness of your case walls and to what size your resizing die brings your cases back to. It does vary from die to die. I have two .303 resizing dies of different makes and they are quite noticably different in this respect.

 

My mate's 6.5x55 bullets would drop out of the cases if he didn't crimp them. Its not a clear cut yes or no

[Bewsher500]

crimping is done for a number of reasons, if it was of no value the millions of factory rounds people buy every year would not be crimped.

 

It guarantees a set neck tension if done properly.

consistent neck tension gives more consistent pressure curves and lower SD and MV variance

that in itself leads to more consistent loads and accuracy (dont confuse accuracy with consistency)

 

people who use it swear buy it. it can be the difference between 1.5" groups and .5" groups on cartridges like the .22 hornet.

a proper crimping die will not allow you to crimp harder or lighter from round to round.

 

other reasons to crimp are in semi autos where recoil can seat bullets further in if not held in the neck hard enough.

 

worth trying especially if you have a grouping issue.

 

if you are seating into the lands then in my opinion your ammo is too long. without any jump you will struggle to get consistent pressure curves

[dully1963]

Just a little heads up if you are running max powder loads and you decide to crimp you are heading for disaster as your pressures will go through the roof. I use 1 thou of neck tension and I can put them into the lands and exstract them no problem but thats on my gun, so its what suits you and your gun. Get a good set of dies and a good reloading book and beware of bad advice

as there is more than you think on these sites

Now before anybody takes offence I,m not saying any of the advice given is wrong I,m just saying each gun is different so whats good for one may not be for another just do your load developement so you are happy and confident in your loads

hope this helps

Dully1963

[wymberley]

When issued with our rifle and five rounds before going on guard duty it was routine procedure to pull the bullets out of the cartridge, check if there was any powder and replace the bullet. This was only possible because the rounds had been in and out of a magazine more times than.................well, think of your own analogy.

[Bewsher500]

Just a little heads up if you are running max powder loads and you decide to crimp you are heading for disaster as your pressures will go through the roof. I use 1 thou of neck tension and I can put them into the lands and exstract them no problem but thats on my gun, so its what suits you and your gun. Get a good set of dies and a good reloading book and beware of bad advice

as there is more than you think on these sites

Now before anybody takes offence I,m not saying any of the advice given is wrong I,m just saying each gun is different so whats good for one may not be for another just do your load developement so you are happy and confident in your loads

hope this helps

Dully1963

 

surely everyone uses "1 thou" of neck tension? That is generally regarded as the figure that brass will stretch to, to accommodate a bullet i.e. 1 thou less than the diameter of the bullet.

That is not neck tension though. Thats just the resultant bore of the neck after seating.

 

when you say "into the lands", what do you mean?

Why would you seat the bullet so the ogive is past the edge of the lands? your neck tension is largely irrelevant with that practice

[dully1963]

Hi Brewsher

first of if you are really interested great I like to see people trying to get as much info as possible to improve themselves and there sport but sadly like on so many other forms there are some people who seem to get off argueing

Anyway as for 1 thou of neck tension that equates to being 2 thou smaller than the chamber (ie 1 thou all the way round) and yes your right the neck tension of a thou is largely irrelevant when the bullet is jammed but it offers a consistant force when the bullet is pushed into the lands consistanty is the key

as for jumping I would use a bushing of 2 thou and some people even go to 4 thou but i find i do not need it

The short answer to why different seating depths and neck tension change accuracy (ie into the lands or jump) is that they change the timing of when the bullet exits the muzzle in the barrels swing cycle, and since some points in the swing of the barrel produce better accuracy than others, loads that time the exit so that it happens at the best point are more accurate. Since the barrel continues to vibrate at a regular frequency, there are multiple opportunities for bullets' exit timing to occur at the most advantageous point it the cycle.

hope this helps a bit

regards

dully1963

[Bewsher500]

Hi, I am genuinely interested in what people get to work and why they do it but am not sure I understand some of the post.

Anyway as for 1 thou of neck tension that equates to being 2 thou smaller than the chamber (ie 1 thou all the way round) and yes your right the neck tension of a thou is largely irrelevant when the bullet is jammed but it offers a consistant force when the bullet is pushed into the lands consistanty is the key

When I say 1 thou of neck tension, what I mean is if you seat a bullet and then pull it you will find the neck size is 1 thou smaller than the bullet diameter. You have effectively resized the neck with the bullet, the natural tension of the brass leaves it 1 thou smaller (give or take a few 10 thousandths!)now being 1 thou smaller is not a measure of neck tension, your brass elasticity and thickness of neck wall dictate that.you could have the best most consistent neck tension in 100 rounds and then negate it by seating the bullet past the lands. Ogive curve is rarely uniform and you could get different "tension" in the lands from chambering the bullet and then rechambering it but rotated 90deg this time.That is what I meant by neck tension being irrelevant when seating into the lands. the tension on the lands is going to be greater than the neck if pushed in past the ogive

as for jumping I would use a bushing of 2 thou and some people even go to 4 thou but i find i do not need it

I dont really understand this bit either.By "Jumping" I understand that to mean the jump between seated bullet ogive and lands.The bushing of 2 or 4 thou does that mean that you size the inside of the neck to 2 or 4 thou less than the bullet?if not what does the bushing do to affect the seating depth?I know why bullet seating depths affect accuracy, that wasnt the question.Question was: why seat the bullet so that it is seated past the lands?There just seems more negatives than positives to doing it. Including uncontrollable pressure spikes. No? Edited October 6, 2012 by Bewsher500

[kent]

I thought this was a crimping thread?

[Bewsher500]

it is.

If crimping doesnt effect neck tension what does it do?

if the OP is loading long enough to lose bullets in the rifling then all the above questions are relevant. No?

[Vince Green]

Actually when you consider that a rifle bullet is forced to accelerate from 0 to around 3000 fps in something like two thousandths of a second the sheer inertia that has to be overcome renders the resistance from crimp/ no crimp debate so negligable it isn't really worth talking about,

 

I can unseat a crimped in bullet using my bullet puller in a couple of bangs on the floor. In KE terms its tiddly. Yet the forces required to drive a rifle bullet forward into the rifling must be many times more. The bullet has to deform to fit the rifling. The rifling doesn't just cut like a machine tool, at least not in an ideal situation. The rifling has to press into the bullet to make the jacket deform and grip the core. Otherwise the core will not rotate when the jacket does. A bullet fired at 3000 fps in a 1 in 12 barrel is rotating at 180,000 rpm and it is forced to reach that rotational speed in 2 thousandths of a second. The easiest thing for the core (most of the mass of the bullet) to do is just to stay put while the jacket rotates around it as it goes down the barrel. Core spin is real, it does happen

 

The more you get into it the more complicated it all gets

 

Benchrest shooters don't crimp and that has led to a slightly incorrect view that it is more accurate not to crimp. that however slightly misinterprets their motive. What they find is that it doesn't make any difference if they do or they don't. However their big motivation is to preserve their valuable, (often highly expensive) and hard to get cases in weird calibres that are batched for consistancy

Edited October 6, 2012 by Vince Green