Problems with bullets being driven back into the case...

Reloading info for the 5.7x28mm

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claybrdr
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Problems with bullets being driven back into the case...

Post by claybrdr » 17 Mar 2010, 14:52

I am loading 40 gr VMax bullets and using RCBS FL dies and have had problems of bullets hitting the feed ramp and being jammed back into the case. I have gone through 3 iterations of increasing the amount of roll crimp and though I have not been back to the range to try #3, #1 and #2 crimps were not effective. I am to the point that the crimp is pretty substantial and may be distorting the bullet to where I will have accuracy problems if the other problem is fixed. What do you recommend? Thanks.

VITALIY
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Re: Problems with bullets being driven back into the case...

Post by VITALIY » 17 Mar 2010, 17:20

Wow, thats odd, usualy vmax hardly need any crimp. What gun you use to shoot them? If it is one of the first batch ar57, than crimp isn't going to help you.
Just out of curiosity, isn't the bullet supouse to have canelure for roll crimp to be used effectively? Don't think that the vmax has it.

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fatherfoof
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Re: Problems with bullets being driven back into the case...

Post by fatherfoof » 17 Mar 2010, 17:35

Every so often, things just aren't made right- trainee may have worked the assembly line that day. I have a couple XD mags in 357 Sig that when placed next to other, are a quarter inch lower on the lip. Same feed problem as yours. The other mags feed perfectly. Borrow somebody's magazine at the range and compare it closely to your's-- just a starting point.
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I8asquirrel
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Re: Problems with bullets being driven back into the case...

Post by I8asquirrel » 17 Mar 2010, 20:23

Claybrdr, be carfull with to much crimp on a none canalured bullet I think you can raise your chamber pressure to an un acceptable high. i think fatherfoof might be on track that it could be a mag problem? I have a FN57 and AR57 and shoot the same 40gr V-max laod through them both with good results....good luck

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f3rr37
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Re: Problems with bullets being driven back into the case...

Post by f3rr37 » 17 Mar 2010, 22:26

Try not crimping, see if you get the same results.

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 18 Mar 2010, 03:02

Thanks, Ill try your suggestions.

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 18 Mar 2010, 03:18

The gun is an AR57 and so are the mags. I had no troubles shooting factory FN blue tips but that was a different mag. Just now, I looked at the mag I have been using with the reloads and see the problem (or the result of the problem)! The (__) shaped cutout just in front of the nose of the bullet is being hit when the cartridge is stripped from the mag. The bevel doesn't seem shaped the same as the other mags or maybe it has just been deformed by cases hitting it on the way out....

I'll try another mag and will try to reshape the opening on the "bad" mag. Again, thanks for your thoughts.....

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 19 Mar 2010, 10:38

Well, the mag isn't the problem. I tried another mag and the reloads messed it up too.

The RCBS FL dies are not pushing the shoulder back to where it needs to be to match up with factory ammo. The die is screwed down against the shell holder so there is no more way to push the shoulder back. It appears that the way I have them loaded, they nose dive coming out of the mag. Have emailed RCBS and maybe they will have a clue....

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f3rr37
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Re: Problems with bullets being driven back into the case...

Post by f3rr37 » 19 Mar 2010, 11:04

'Tis why most people here recommend against using RCBS dies for reloading the 5.7x28

BOHICA
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Re: Problems with bullets being driven back into the case...

Post by BOHICA » 19 Mar 2010, 11:06

I had similar problems with the RCBS 5.7x28 die set I bought and after many frustrating problems, including inconsistent bullet seating) replaced them with a set of Lee Custom 5.7x28 dies and they have worked flawlessly for over 2000 rounds now -- best $50 I ever spent!!! Do yourself a big favor and junk the RCBS and find a set of Lee's for your 5.7 and you'll actually enjoy reloading as much as shooting. If you aren't already using Ramshot True Blue powder (the powder used in the factory ammo), give it a try too. I switched to it from Accurate #5 and found it burned cleaner and shot more consistently than No.5.

Good shooting...

VITALIY
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Re: Problems with bullets being driven back into the case...

Post by VITALIY » 27 Mar 2010, 18:37

You can try to shave off some metal from the base of the sizing die(the part of the die that comes in contact with shell holder), in .005" incruments, till the desiered shoulder movement has being reached. I've done that wit .223, on several ocasions. Sizind dies are like chambers, all defferent one frome another. Another trick that may complement this modification is "doble striking" the shell wile sizing: just size it as usualy, than turn the shell 180* on the shell holder and size again. Hek i even triple strike my 6.8spc reloads :D

dsv424
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Re: Problems with bullets being driven back into the case...

Post by dsv424 » 30 Mar 2010, 05:47

This sounds like the same problem I was having when I started reloading for my AR-57. You might want to check the case shoulder and see if there is a slight bulge there. The way I confirmed was to slide the rounds into the chamber and see if they fit. To correct the problem I re-sized all the ones that would not chamber. In the end I had to QC all my rounds this way and discovered I had about 3 or 4 in ever batch of 50 that had the bulged shoulder. The symtom I was experiencing was the bullet got pushed into the case and the soft ballistic tip would be smashed and I had powder all over the inside of the chamber.

dsv424
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Re: Problems with bullets being driven back into the case...

Post by dsv424 » 30 Mar 2010, 05:53

BTW, you may want to check this string I started when I had the problem.
viewtopic.php?f=19&t=4310" onclick="window.open(this.href);return false;

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 04 Apr 2010, 15:35

That's exactly the problem I'm having...the pics of the smashed bullet tips mashed back into the case are identical to what I have experienced. Additionally, the lip of the AR57 mags are being hit by the cartridges coming out of the mag and being deformed. Bought a set of Hornady dies and same result. I'm coming to believe its a cycling problem ie too fast or too slow. I've been loading 7.3 gr HS-7 and the Hornady 40 gr V-Max with pulled carbine primers and a OAL of 1.560.

Factory FN blue 40 gr Vmaxs run flawlessly. Wish I could get some True Blue since it seems a favorite here.

Thanks for the ideas...

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 05 Apr 2010, 07:51

My reloads cycle perfectly manually and seat in the chamber just like the factory ss197 load. I weighed the buffer that came with the AR57 and it weighs a whopping 8.1 oz. The buffer that was in one of my .556 ARs weighs 3 oz and the buffer in my 9mm Rock River AR weighs 5.6oz.

What's the chance that the 8.1 oz buffer is too heavy for my reloads?

dsv424
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Re: Problems with bullets being driven back into the case...

Post by dsv424 » 06 Apr 2010, 06:38

If you have Cabela's near by you may want to check there for True Blue powder. The one in the Dallas/FT. Worth area always had it in stock. It was the only place I ever found it, other than ordering on-line and I can't justify the hazmet fee. As far as the problem possibly being the buffer I can't answer that. When I got my AR-57 I did buy a Rock River lower for it though.
Every since I have been paying special attention to the case shoulder I have not had the smashed bullet problem. If I remember correctly I think it was a improper resizing die setup that caused the shoulder issue.

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 06 Apr 2010, 11:28

Thanks, I have some True Blue coming from powder valley. I am going to chrono the SS197 loads and see how they vary with my reloads. Will try a different buffer accordingly.

claybrdr
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Re: Problems with bullets being driven back into the case...

Post by claybrdr » 17 Apr 2010, 09:57

Problem solved!!! It WAS a cycling issue and after I dropped the speed of my loads to the 2,200 fps range, cycling was perfect. Evidently my 2,400 fps loads were too much for the 8# buffer that came with the AR57 upper. I suspect the faster loads would also work flawlessly with say a 10-12 # buffer.

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