Blue Bullets Crimp

[Goat259]

Good Evening,

 

I reload using Blue Bullets, .40 180 RNFP. I was pulling bullets to check my crimp and noticed there is a line where it is crimped at. No coating is scraped off but there is a line. On the Blue Bullets web site, it states:  

 

“The perfect amount of crimp will hold the bullet in place but not affect the coating. The best way to check this is to pull a loaded bullet and examine the coating. You should see just a very slight impression (almost none) in the coating from the crimp.”

 

I adjust the crimp die so it lessens the impression, but then I gets to a point of failing to case gauge. What am I doing wrong?

 

 

[GrumpyOne]

Post a pic of the pulled bullet? 

 

Moat times, it is almost impossible to "crimp" a lead/coated bullet without some sort of line...you have to do just enough to secure the bullet, but not too much to resize the bullet when doing so.

[Goat259]

[GrumpyOne]

That may be a bit much crimp on that one, but measure and see if the bullet has been resized any (measure as near to the mark on both sides, record measurement, then measure a new one that hasn't been seated or crimped to compare.) You are very close to being good with the crimp.

[GrumpyOne]

Also, coated and lead bullets are usually oversized and I have found that they don't necessarily case gauge as well as FMJ's. It all depenxs on how tight your gauge is. 

[Farmer]

That’s what mine look like and I don’t have any problems. You’ll drive yourself to drink getting it perfect every time. Different cases, thicknesses ect. I had a bunch of brass that had a small burr on the inside and outside of the mouth that would really leave a mark. Zipped them over the de-burring tool, problem went away. Have to remember that the brass gets work hardened the more it’s loaded so it gets more “springy” so when crimped it can leave that mark but spring back slightly. 

[Goat259]

Is this better?

[GrumpyOne]

Much. If that gauges, shoot it.

[shred]

Either is fine.

 

By far the #1 problem with people's ammo not case-gauging (and therefore being out of SAAM spec) is under-crimping.  Except on a really hard-cast (or sintered) bullet, 25,000 PSI on the back end when it's fired is going to swage any crimp right back out of the bullet.  

 

Coated-bullet makers don't want you breaking through the coating and leading up the barrel and blaming them is why they suggest minimal crimp, but if your ammo won't gauge, try adding some more crimp and see what happens on the range.

 

 

[Goat259]

After some searching, some say to che k for accuracy. With pistol reloads, what’s a good way to check for groupings? I normally just went and shot.

[GrumpyOne]

7 hours ago, Goat259 said:

After some searching, some say to che k for accuracy. With pistol reloads, what’s a good way to check for groupings? I normally just went and shot.

Go out and shoot!

[himurax13]

On 1/13/2023 at 10:06 PM, Goat259 said:

After some searching, some say to che k for accuracy. With pistol reloads, what’s a good way to check for groupings? I normally just went and shot.

Some people pick a distance and shoot from the bench. Try 25 yards and then verify at 50 yards. Once you are sighted in shoot freestyle and see how tight you can keep the groups.

[Goat259]

Thank you for the advice and help. I just received an email back from Blue Bullets. 
 

 

[HesedTech]

On 1/13/2023 at 8:11 PM, shred said:

Coated-bullet makers don't want you breaking through the coating and leading up the barrel and blaming them is why they suggest minimal crimp,

That’s just one reason, the other is too much crimp damages the bullet and can cause possible accuracy issues. I have seen more than one novice reloaded have bullets tumble due to over crimping. And it’s not just coated, plated on soft lead can do the same. 

[shred]

25000 PSI on the back end swages most crimp right back out again even in jacketed pistol bullets.  Hard-cast and plated hard-cast (many early plated were hard-cast which was likely a source of accuracy complaints when they first came out) less so.

 

Try it sometime.  Crimp the heck out of some pistol rounds and see if it really causes accuracy problems.  You'll probably find the not seating repeatably on the case mouth is more of an issue.  Traditional cast bullets have a groove right around them where the lube goes that is way larger than any possible crimp dent and that doesn't affect accuracy.  In the early days of coated bullets when they used the same molds we shot a ton of bullets with lube grooves and no lube and they did fine too.

[ltdmstr]

On 1/13/2023 at 7:56 PM, Goat259 said:

“The perfect amount of crimp will hold the bullet in place but not affect the coating. The best way to check this is to pull a loaded bullet and examine the coating. You should see just a very slight impression (almost none) in the coating from the crimp.”

 

Pretty dumb comment coming from a bullet company.  Taper crimp on .40 SW (or any semi-auto round) should do absolutely nothing when it comes to "hold[ing] the bullet in place."  That's accomplished by sizing the brass adequately so you have an interference fit.  If you're relying on crimp to do that, you're doing it wrong.

 

1 hour ago, shred said:

25000 PSI on the back end swages most crimp right back out again even in jacketed pistol bullets.  Hard-cast and plated hard-cast (many early plated were hard-cast which was likely a source of accuracy complaints when they first came out) less so.

 

Try it sometime.  Crimp the heck out of some pistol rounds and see if it really causes accuracy problems.  You'll probably find the not seating repeatably on the case mouth is more of an issue.  Traditional cast bullets have a groove right around them where the lube goes that is way larger than any possible crimp dent and that doesn't affect accuracy.  In the early days of coated bullets when they used the same molds we shot a ton of bullets with lube grooves and no lube and they did fine too.

 

My coated SNS 9mm bullets have two lube grooves and no lube.  The loaded rounds are crimped in between the two grooves.  And they are just as accurate as my jacketed bullets.

[HesedTech]

12 hours ago, shred said:

Traditional cast bullets have a groove right around them where the lube goes that is way larger than any possible crimp dent and that doesn't affect accuracy.  In

It’s not the groove or dent  causing accuracy issues. It’s when the bullet is damaged, swaged smaller in the process or the coating/plating fails. When the bearing surface gets damaged it can cause tumbling and accuracy issues. Seen it first hand. 

[shred]

Coating damage in the crimp zone seems to be mostly irrelevant at typical distances and velocities used in USPSA.  Anyone shooting long enough has seen sideways bullet holes in targets and the spiral-comet marks from some coated bullets, but its surprising how much abuse a bullet can take and still fly straight, so without in-flight high speed video, I'd say those are from other causes.  

 

Here's some 147gr 9mm Blue Bullets I mangled-- scraped the coating off on one side on some, scraped it off all the way around on some more, drilled a divot in the side of four and three with deep slots from tipping over in the press and being jammed into the case sideways.

 

Then I loaded them and shot them at 25 yards, along with 5 rounds of non-mangled bullets as a control (one of the slotted ones was too mangled to load, so I only shot 2 of them).

 

The pistol I used tends to throw the first (hand-cycled) shot high and isn't terribly accurate, but was one I didn't mind jacking up if it came to that.  If I get time, maybe I'll redo the test with extreme crimp.

 

[shred]

Here's what the backside of the target looked like when I was done (it was an old no-shoot with a couple pre-patched holes)

 

 

 

And the color coding of which was which

 

 

[rishii]

I have no idea where I read or heard this

supposedly the most important part of the bullet when it comes to accuracy is the base, you could damage the nose and it wouldn’t affect accuracy as much as a damaged base

[shred]

Probably true.  There's a classic book "The bullet's flight from powder to target" somebody pointed me at a few days ago (out of copyright, download from Google books or pay somebody on Amazon to print out the Google scan if you want paper).

 

I've only scanned most of it, but in the early 1900s some hardcore old-schoolers set up a range where they could put paper each and every foot if they wanted out to 200 yards and spent the next 12 years shooting to see how bullets flew for real and what factors came into play.  Mostly lead and rounded-nose bullets, not unlike today's pistol bullets.

 

These guys would drill out metal from bullets, then fill some of the holes with wood to see if it was the weight imbalance or the wind over the hole that caused what they were seeing.  They made swirly-mark targets by drilling bullets, then analyzed the metal content of the targets to see where on the bullet the metal came from.  

 

They claimed they had so much data they could replicate 'bad' groups impact for impact by carefully damaging the bases of bullets so they'd fly where they wanted them to out of a more accurate barrel.  

 

Base damage was by far the biggest factor.

[dmshozer1]

On 1/20/2023 at 1:37 PM, rishii said:

I have no idea where I read or heard this

supposedly the most important part of the bullet when it comes to accuracy is the base, you could damage the nose and it wouldn’t affect accuracy as much as a damaged base

True,

The last part of the bullet, the base, is the last thing that leaves the barrel.

If one side of the base is de formed it will send the bullet to one side or

the other. This is one reason why the crown of your barre is so important for accuracy.

This is the reason hollow point bullets are more accurate than round nose. The base is perfect

but the nose is usually pretty rough looking.

Shred's post is a good example.

[Guitarmageddon]

*If you pull the bullet, and dont take coating with it, its probably fine. Likewise, if you arent scraping coating while seating, its probably fine.
**If your finished round case gauges, its also probably fine.
***Ideal crimp is somewhere around 2x wall thickness of your brass, plus bullet diameter, which for blues is usually .4005-.401 on the high end.

Crimp for me is usually .4215 measured right at the case mouth.

[Guitarmageddon]

Also side note, it seems blues have slightly altered their bullet profile in the latest orders Ive received. not too much to make any meaningful difference though, at least in my reamed chamber

[gnappi]

Don't overthink crimping. Make sure the shortest case you have gets a good crimp, and you're done. In the couple of years I've been powder coating using a taper crimp I have yet to have bullet setback into the case after hitting the feed ramp.  Oh, I size my bullets after coating, and all fit my case gauge unless I run into a "glocked" sample  and the small base sizer didn't iron it out fully.  

 

IMO a more important issue is belling the mouth with PC'd bullets. Again you want the shorter cases belled enough to not cookie cut the powder coating off the bullet leaving exposed lead on the bullet base. 

 

 

Edited February 9, 2023 by gnappi