Thread: New Defence Force rifles need firing pins replaced

Originally Posted by Danger Mouse

Facepalm. I knew units were struggling to get live rounds but didn't realise this. What a dick move. Ammo is the cost of going business. 55gr is probably too light for the twist rate too

I very much doubt that a shot will ever be fired in anger. A paper target will never know the difference.

I struggle to see how the 55grn wont work just fine...it will be overstabalized so will be spinning much faster than it should making it more likely to do naasty things at business end... a fmj SHOULD stand up to the additional Gforces placed on it by the fast twist.... can anyone tell me WHY they wont work???? I understand a slow twist not making heavy stable enough but not the other way around....

Originally Posted by Cordite

Well, better to find out in peacetime.

- so what's the lock time of an AR15?

African or European?
Anyone?

Originally Posted by csmiffy

African or European?
Anyone?

Holy Grail

I got to try out the 308 version LMT 14.5” the local AOS got a year ago. They were brand new hadn’t been fired so I invited them out to break them in. Worked without any issues and were pretty accurate. Shot them out to 550 yards with the 1.5-8 mark 4 leupold.

Originally Posted by Micky Duck

I struggle to see how the 55grn wont work just fine...it will be overstabalized so will be spinning much faster than it should making it more likely to do naasty things at business end... a fmj SHOULD stand up to the additional Gforces placed on it by the fast twist.... can anyone tell me WHY they wont work???? I understand a slow twist not making heavy stable enough but not the other way around....

My experience is that over-spun light bullets tend to shoot inaccurately, especial if low quality. I guess it's a bit like a badly balanced turbo...

I am sure 55 gr will still work fine at normal combat distances but you want the extra weight of the 62-77 gr at longer distances anyway.

I remember that the steyr had plenty of problems when new including breaking firing mechanisms.

Try shooting 55grs in a 1:7 twist, then 62's will start coming good and then 75 & 77s seem to be sweet spot.
1:8 seem to shoot 55's ok, guess it all depends on your accuracy expectations and quality barrels like JP will probably group anything well.

Originally Posted by Cordite

Well, better to find out in peacetime.

Speaking of firing pins, you AR15 afficionados. I suppose a lot of shots will not be squeezed off calmly using a bipod - so what's the lock time of an AR15?

Between 2-16 milliseconds, depending what site on the net you read.

this is the best explanation twist v bullet weight that I have found.

Originally Posted by Max Headroom

Attachment 95449

this is the best explanation twist v bullet weight that I have found.

Well I can verify the findings in the Green circle....

55gr runs perfectly fine through a 1:7 Twist. Poor accuracy would be a reflection on ammo quality, the rifle, the shooter, or all three. 55gr M193 generally has excellent terminal performance at closer ranges too. It will fragment in soft tissue out to 150m or so. Years ago the defense force purchased some 55gr from FN that would spin apart after leaving a 1:7 twist, and it was consequently sold off as surplus.

50gr Z-Max out of 1:7 18" @100m.......Eotech with magnifier.

I know there are rules of thumbs and the military wouldn't waste time throwing such a light slug but never discount it for your own plinking. It might just work sweet.

Another point of view. I have a 1:7 twist rate in my NEA DMR, and found 50gn to group significantly better than 55gn.

I was shooting SA army 55g ammo in SA recently and I found it fine at 100m & not bad at 200m through a 1/7 16" barrel.
When you get to 300m and 400m the groups noticeable start to open out, compared to SS109 62gr and similar ammo.

Originally Posted by grunzter

I was shooting SA army 55g ammo in SA recently and I found it fine at 100m & not bad at 200m through a 1/7 16" barrel.
When you get to 300m and 400m the groups noticeable start to open out, compared to SS109 62gr and similar ammo.

Absolutely, probably where the light stuff just runs out of energy and gets affected more by the elements.