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10/6/2016 3:08:26 PM EDT
I live in the UK and shoot a .223  Sabre Defence AR15A4 straight pull (no Gas system) last week after a few rounds I had a boom which blew the mag out of the magwell, had to mortar the rifle to extract the case which had a small split at the base and bent the extractor, bolt and BCG all fine, replaced the extractor and cycled a few dummy rounds with no problem, Ive been told to check the headspace, is this correct??
10/6/2016 3:40:06 PM EDT
[#1]
Yes.  Check the headspace.  It could also be a bad catridge.  I had a Tula steel case 308 do the same thing
10/6/2016 3:53:38 PM EDT
[#2]
Blowing the magazine out but otherwise not really damaging anything is about the gentlest KB you can have, and usually comes from partial head separation, either from weak brass from too many reloadings, or a defective/brittle new factory casing. It can also indicate long headspace leaving too much of the cartridge base unsupported.

Do check the headspace, and if it's OK, examine your brass.

You didn't state if the ammo was new, commercial or surplus, or reloads.
10/6/2016 4:05:09 PM EDT
[#3]
Home loads, 55gr FMJ RG cases, 25 gr H335, failure identical to this     http://www.fototime.com/297776127F09BE8/standard.jpg
10/6/2016 4:57:30 PM EDT
[#4]
Quote History
Quoted:
Home loads, 55gr FMJ RG cases, 25 gr H335, failure identical to this     http://www.fototime.com/297776127F09BE8/standard.jpg
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Are you trimming your cases?  I have found that many cases require trimming after the first firing.
10/6/2016 6:05:11 PM EDT
[#5]
You using an aluminum lower or the plastic one-piece receiver/stock made by Cav Arms for Sabre Defense?
10/6/2016 6:17:04 PM EDT
[#6]
Case head separation.
10/7/2016 2:31:18 AM EDT
[#7]
Xr15 aluminium lower
10/7/2016 2:33:33 AM EDT
[#8]
Yes ,always check after each reload, resize with RCBS small base die
10/7/2016 2:46:01 AM EDT
[#9]




Quote History
Quoted:





Home loads, 55gr FMJ RG cases, 25 gr H335, failure identical to this     http://www.fototime.com/297776127F09BE8/standard.jpg
View Quote View All Quotes
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Quote History
Quoted:





Home loads, 55gr FMJ RG cases, 25 gr H335, failure identical to this     http://www.fototime.com/297776127F09BE8/standard.jpg





That looks more like overpressure and/or timing issue, assuming that was from a semi auto. From a bolt action, that's a case head failure, whether overpressure or weak brass.
How do you clean your cases?

Quoted:




Yes ,always check after each reload, resize with RCBS small base die




Do you size to minimum spec, or bump the shoulder just enough for reliable feeding? IME, even 0.004" headspace will show up as flattened primers.
 
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