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jtrump

Messing around with a Light bullet. dumbfounded

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So I'm talking with a few people but figured I would throw this out there for anyone else who may have a reasonable answer as to this.

 

I've experimented with a lot of 9mm loads/powders but never really the light weight stuff.

 

I went to the range today with some 100g Berry's plated 380 bullets,  using 4.9g of WSF @ 1.100 my chrono results were all over the place...   I've never seen anything like it.

 

I ran two strings of 10 rounds,    with a few down the pipe prior to throwing them through the chrono at around 10 feet.

 

JP-GMR 13 14.5  my typical load is a coated 125 with 3.6g of TG at 142PF "tested today to make sure the chrono wasn't screwy"

 

1197     

1242

1217

826

1177

1076

1057

1157

1269

 

Both strings looked similar with a huge SD,  and I had a bunny fart 800 something fps round in the second group of 10.    I'm not sure where to go from here until I figure out why the bullets are all over the map....   any advice greatly appreciated.

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What type chrono ?

 

My Chrony will frequently throw an oddball number at me.

 

Probably something to do with the lighting.

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4 minutes ago, Hi-Power Jack said:

What type chrono ?

 

My Chrony will frequently throw an oddball number at me.

 

Probably something to do with the lighting.

 

Just a pro Chrono,  the $100 ones...

 

I've never had it do it before,  but even if you toss out the 826fps one "Which felt super light"   you still have over 200fps different in some rounds.    I did have the chrono setup under the  shade, but my normal bullets were all fine pf wise and single digit SD,  so that kinda makes me wanna toss the lighting idea out Jack...  I'm so confused lol.

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Possibly placement of powder in the case varied from round to round.

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You made a change and now your SD is all over...what changed?   Your bullets, powder, & recipe...correct?  My guess is one of these three is not up to par.

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Barrel does not like that bullet.

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Could you load up another 100 rds and weigh the powder charge on every 10th round?   Possible problems with you powder measure.

 

At 4.9 gr WSF you are not loading a small charge so I would not think powder placement would be a factor.

 

I also have the Pro'Chrono and do see some changes in velocity but I don't remember ever having those kind of velocity spreads.

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I'm going to blame it on the bullet not really liking that barrel and getting an inconsistent "seal"

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Just to clarify it's a plated berrys .356 100g,     Ive been running gallant's 125 coated in .356

 

Maybe I should clean the gun?   It's been awhile.... 

 

Ive measured the powder drops and they are all pretty much 4.9g, with the exception it teeters  to 4.8 and back to 4.9 on my scale occasionally.

 

I guess it could be it just dosen't like the bullet.... I've never shot any plated in this rifle,   only JHP and Coated bullets.

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Try small rifle primers or small pistol magnums and see if it brings your SD down. 

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Hello: Look in the barrel to see if you have any buildup of the coating from the other bullets. You may want to try some hotter powder like Tite Group also to see if that helps. Thanks, Eric

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1 minute ago, Aircooled6racer said:

Hello: Look in the barrel to see if you have any buildup of the coating from the other bullets. You may want to try some hotter powder like Tite Group also to see if that helps. Thanks, Eric

 

But Eric I'm specifically trying to use WSF ?            I could almost guarantee I could make some 125g coated loads with WSF and not have these wonky results.   "I think anyway"... never had this issue before, most of the time I'm in single digit SD, but sometimes I've got a decent spread depends on what I'm loading.   But not 100fps,   I wish I could pinpoint what's wrong.

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How’s the bullet case tension? Possible setback? 

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1 minute ago, HoMiE said:

How’s the bullet case tension? Possible setback? 

 

This is what I was kind of leaning toward...  there isn't much bullet to work with.  I normally don't put much of a crimp if any on my loads to speak of.   I tightened up the crimp some on these but yes, if I load it to 1.100 on the nose, If I press it against my bench "hard"  I get it down to about 1.080.

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I'd really hate to load any shorter for reliability issues,    If I switch to say a 95 grain bullet I don't see  how it's going to be possible unless I crimp the ever loving s#!t out of it,  there just isn't much bullet inside the case.

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43 minutes ago, jtrump said:

I'd really hate to load any shorter for reliability issues,    If I switch to say a 95 grain bullet I don't see  how it's going to be possible unless I crimp the ever loving s#!t out of it,  there just isn't much bullet inside the case.

Crimping the ever loving s#!t out of it will most likely loosen neck tension, screw up any hope of accuracy etc

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Hello: Try loading some at 1.050" OAL and see what you get. If they feed ok and the chrono shows the same results it could be that the barrel is throated too far allowing the gas to go around the bullet a little bit before it seals. Hope this makes sense? Thanks, Eric

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Posted (edited)
12 hours ago, jtrump said:

I tightened up the crimp some on these..

 

Don’t do that. Crimp makes your velocity and accuracy problems worse. And it DOESNT help retain the bullet more securely in 9mm.

 

Crimp bad.

 

Crimp less. Try again.

 

Edited by MemphisMechanic

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6 hours ago, MemphisMechanic said:

 

Don’t do that. Crimp makes your velocity and accuracy problems worse. And it DOESNT help retain the bullet more securely in 9mm.

 

Crimp bad.

 

Crimp less. Try again.

 

 

measuring at the neck was a .377,   I didn't think that was much crimp :(

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18 hours ago, Sarge said:

Crimping the ever loving s#!t out of it will most likely loosen neck tension, screw up any hope of accuracy etc

 

Agree on accuracy aspect of it,  was not aware that it would actually loosen neck tension, good to know. 

 

So am I just able to get setback purely because of the super small bearing surface on the projectile?

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Posted (edited)

Pull a bullet...

 

If you can feel the effects of the crimp in the side of the bullet, IMO that’s too much crimp for a 9mm round.

 

If you’re worried about setback with short bullets, switch to a U die and enjoy the extra neck tension.

 

 

Edited by MemphisMechanic

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5 minutes ago, jtrump said:

 

Agree on accuracy aspect of it,  was not aware that it would actually loosen neck tension, good to know. 

 

So am I just able to get setback purely because of the super small bearing surface on the projectile?

Yeah the neck tension reduction by overcrimping seems impossible at first glance. What happens is brass and bullet get smashed way too much when over crimping the brass bounces back more than the bullet does basically creating an undersized bullet. I ran into neck tension issues early on with certain bullet/brass combos so I started using an undersized SIZING die by EGW. 

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I have the same rifle, and had trouble with a fast burning powder and any bullet.

Switch to a slower powder

 

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1 hour ago, STIboy said:

I have the same rifle, and had trouble with a fast burning powder and any bullet.

Switch to a slower powder

 

 

I've ran powders much faster than WSF,  I've never had any issue with any combination of bullet weighing 115/125/135 or  147grains.  N320, Titegroup, clays, prima V.

 

You should be having zero issues running a faster powder in a GMR-13 unless something is really wrong.

 

I'm going to try some Jacketed bullets,  back off to my original crimp which is super light and set the chrono out in the sun this go around.    Although I still don't think this is going to solve the issue.

 

 

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Posted (edited)
2 hours ago, MemphisMechanic said:

Pull a bullet...

 

If you can feel the effects of the crimp in the side of the bullet, IMO that’s too much crimp for a 9mm round.

 

If you’re worried about setback with short bullets, switch to a U die and enjoy the extra neck tension.

 

 

 

It's a plated round, I can barley see the line from the crimp and can feel it with a fingernail if i try really really hard, it's not like I can scratch at it, its a very very subtle line at .377

 

I learned this lesson the hard way when shooting limited and decided to try out some plated rounds... Wondering why accuracy sucked ?

Edited by jtrump

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