Sticky extraction (gas off) w/ handloads

[kotengu]

At the 600yd match this weekend I thought I'd try some 190gr loads I worked up over the winter (for the Vandenberg FAL) and had laying around, but in the first (of three) match they gave me all sorts of fits! I have been shooting LR with the gas off, mostly so I don't punish the other guys with my brass so much, and never had a problem with sticky extraction. This time - I had to beat the charging handle almost every time to get the !#$%! things out!

After the first shot, my immediate thought was "it's too hot" - so I checked with the high master guru who was keeping score for me and he verified the brass showed no pressure signs - he thought I had probably sized them a little big.

I finished that match and switched to my "old standard" (168gr SMK's) and turned the gas back on (and yelled "incoming" to the people on my right) and had no problems for the last two matches, and shot much better scores.

The performance of the 190's was pretty erratic, too - but that could have been due to my state of mind and having to beat open the bolt every shot. I would have changed ammo after that first shot, but I didn't bring enough "back up" for all three matches, and with a 2nd opinion that they didn't seem hot (and previous pressure testing) I figured might as well shoot 20.

On getting home, I measured the fired cases and the unfired rounds and compared them to my 168gr load, and all the measurements are identical (±0.0005" for the diameters at neck, shoulder, and head, OAL of fired brass varied some for both, but they were all within the same range).

I don't get it - what made it stick so bad? I worried a little about temperature sensitivity of the powder (IMR4895), so I even backed off the load 0.5 grain, since my initial testing was done in 58° weather, and at the match it was about 80°.

Any ideas?

[idsubgun]

What surprises me is that you didn't experience "sticky" extraction before. Everytime I had a FTE, or anyone else I know, we had to almost jump on the charging handle to extract the casing.

[ByronF]

id,

Our FTE pogo exercises are usually the result of the bolt trying to cram the empty case back into the chamber. If the case never leaves the chamber it shouldn't be nearly as difficult to extract.

Having said that, it is never easy for me to extract rounds with the gas turned off. I think it's because the tilting bolt locking system doesn't really give the shooter much mechanical advantage. Rotating bolt rifles seem much easier to extract, probably because of the stronger camming action. My Garand is slick as snot in straight-pull mode.

Your brass probably isn't showing any signs of excessive pressure, but the pressure is surely significantly greater with the 190 gr bullet. Not enough to flatten primers, but enough to cause sticky extraction in a rifle with little mechanical advantage when unlocking. The same round would probably extract just fine with a bolt gun.

Byron

[idsubgun]

Sometimes there are no visable signs of excess pressure on the brass. Checking the brass is just one way of telling. One of the other things to look for is hard extraction.

[kotengu]

"Your brass probably isn't showing any signs of excessive pressure, but the pressure is surely significantly greater with the 190 gr bullet. Not enough to flatten primers, but enough to cause sticky extraction in a rifle with little mechanical advantage when unlocking. The same round would probably extract just fine with a bolt gun."

That makes sense - so if we follow that theory out, when I do load testing (with the gas off, as I usually do), and stop pushing the limit (even back down a notch) when the extraction starts to get sticky, I'll be shooting at a lower pressure than if I did the same testing with a bolt gun (ie: waiting for the bolt lift to get sticky), right?

So in effect (ASS-U-ME-ing that the theory is right), what appears to be a max load in the FAL, developed this way, should be more than safe - due to the less efficient mechanical advantage of the manual bolt.

Of course I'll still check all the other signs for pressure - but that's a pretty good theory. Only question is - I've had a few loads in testing that cratered the primers, but extraction was OK. How does that work in?

"One of the other things to look for is hard extraction."

Yeah - that's what made me stop after the first shot, and check with the HM behind me. I still felt much less than confident in my ammo at that point, and unsure of the pressures involved, so that probably explains the erratic performance (more due to the nut behind the trigger than the ammo). I wish I would have thought to section the brass and look at the webbing on the inside of the case, but I tossed ALL the brass from yesterday's match in the trash already (not wanting to re-use questionable brass), so the two loads are all mixed up now......

[racer766]

The two times I've shut off the gas system I remember I had to really yank on the handle to eject.

If the gas system properly ejects, and it's unmodified, and you have the dial in the middle of the range, what's the problem? If you don't want to throw brass use a brass catcher.

http://www.bushmaster.com/shopping/ak/el-fn-fal-001.asp

http://www.3bucc.com/

are the first couple of products to come up with Teoma.

Apparently DSA has one as well.

[W.E.G.]

The few times I fired a FAL with the gas turned off, I had no joy trying to get the bolt open. Definitely in the "I'll never do that again" category.

If you had to break out of position from shot-to-shot, its no wonder your accuracy results were "erratic". I wouldn't blame the ammo or the rifle. I blame the shooter on that one. If you have to rebuild your position each time, you will shoot large groups...no matter what rifle you choose.

If you are worried about pounding adjacent shooters with brass, while firing from the prone position, just position your shooting stool close to the ejection port to deflect the artillery.

[kotengu]

"The two times I've shut off the gas system I remember I had to really yank on the handle to eject."

Yeah, I've heard that from several people - but mine has always been easy as pie up until now. What makes me wonder is why it suddenly changed.

The brass-artillery is only part of the reason I have been shooting LR with the gas off. Somehow in my head it seemed like I was eliminating one or more variable in the accuracy game (the heavy reciprocating mass and the bleed off gas). I've shot my smallest groups with the gas off, but that's usually during load testing and I want to keep each piece of brass seperate and nearby anyway - so I can't say they wouldn't be that small with the gas on. Gary may be right, though - the small gain I get from that seems to be overshadowed by the position building troubles.

Hey Gary (or anybody who shot a .30 cal prone slowfire a good bit) - when you shot the M14 did you keep it in your shoulder from shot-to-shot, or take it down to load and scope, then put it back?

[W.E.G.]

Drop it out of the shoulder after each shot.

Its the re-positioning of the front elbow that will ruin your groups.

If you want to keep up with your brass with excruciating anality, just use a black magic marker and number each case on the side. Firing the round will not remove the mark.

BTW, the bullet is already long gone out of the barrel before the bolt unlocks.