Short stroke with handloads

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snooze98k

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So two owners of new DDm4 v11's (1-7 twist) one with a rifle length gas system, myself with a mid-length system are having some issues understanding our handloads short stroking and causing ftf/fte.
We have loaded benchmark/h335/w748 that all have this issue at mid-max powder charges with a 55gr sp.
we have tried cci/federal/winchester small rifle primers (not the magnums)

We have cycled 21.7grains of h335 almost reliably but the powder charge is more than 3grains below max.

Any ideas? Maybe its the cold weather? Both of us have different cleaning/oiling habits and the guns are both sub-200 rounds new!
 
H335 is a temperature sensitive powder. At 21.7gr that's quite low to cycle your rifle properly. Start with 23.5gr and go up from there. Hornady 55gr fmjw/Cannelure with 25.3gr of h335/Win748 is my pet load for all of my ARs. Gluck
 
Trinimon said:
Does it cycle fine with regular factory ammo?
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Most important question...

When I had my M&P 15 (mid length) it cycled 24.5 gr of W-748 under a 55 gr V-Max flawlessly. Horny d lists 23.2 gr as max for H-335/55 gr bullet. I'd be happy to go over that in a bolt gun, not so enthusiastic in a gas gun.

Hornady max load data always seems on the low side compared to others such as Hodgdon, but if your going to go over it I'd be eyeing the brass closely first few shots.
 
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Tested norinco 556 and american eagle ammo with no hiccups in my m4(60 rounds total) i am aware my lyman 49th tends to read on the high side. Brass/primers show no issues of cratering or primer deformation. Brass is all in good condition and no issues there (twice fired range pickups)
My recoil gauge (i.e my shoulder) clearly shows less recoil on the limp loads.

Had cyclical success with 24g imr4064 (slower powder? But also unobtanium) pushing 52gr bthp.
As much as 4064 works, it is very very odd that 3powders so well known to AR's don't cycle 2 different ar's. I'm not that new to reloading for bolts. The gas system is definitely new to me.


Cleaned the firearm again and changed the oiling practice to follow 100% manufacturer reccommendations. Possibly try to load up some minimum specs across some different books (i.e lyman 22.8, hornady 21.7 etc...)
 
How cold was it? Saturday/Sunday wasn't too bad here around noon.

From the Hodgdon online manual

Winchester 748 .224" 55 gr SP 2.200" COL No Start Listed Max 26.3 gr 3,150 FPS 39,000 CUP

H335 .224" 55 gr SP 2.200" COL Start 23.0 gr 3,018 FPS 40,800 CUP Max 25.3 gr 3,203 FPS 49,300 CUP

http://www.hodgdonreloading.com/data/rifle
 
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As mentioned above, I'd check how they run with commercial ammo. If commercial loads cause short stroking, check to see if your gas blocks are aligned and firmly attached.
 
waepek said:
Recalibrate your scale.
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Good point here. Did you calibrate your scale using check weights?

If you're using a digital scale, let it warm up for 20mins before weighing your powders to reduce any drifting. I've had a digital scale drift + a few grains so when I thought I was weighing 43gr was actually 40gr. Fortunately i realized that the scale drifted before I started seating my bullets. I ended up redoing the whole loading tray from scratch. I guess I'm lucky that the scale didn't drift the other direction and I'd have been +3gr hotter.
 
redshooter said:
Horny d lists 23.2 gr as max for H-335/55 gr bullet. I'd be happy to go over that in a bolt gun, not so enthusiastic in a gas gun.
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Sierra lists 25.7 as max/hunting load with 55gr and H335. I have found Sierra to be conservative which would make the Hornady load rather anemic.
I am currently pushing a 62gr bullet to 3000fps (20" barrel)with 25.6gr of H335 with zero pressure signs or reliability issues (it also happily runs my 14.5" but is 150fps slower) .
But I know what load gets me what velocity because I test using a chronograph.
 
snooze98k said:
This right here

Reloading 101: double check your work....

This is embarrassing!!!!

Pulled the bullets and checked with my beam scale and found
17.1gr benchmark
f:P::HR::slap:

Thanks for the input everyone!
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Meh, it happens. At least ya know the cause now. Fortunately no kaboom from a squib or overly hot load.
 
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