.22LR Chamber question.

First topic message reminder :

As I have mentioned in another topic I installed a Lilja tight bore barrel that was chambered with Lilja match reamer in my homemade conversion. My old barrel worked fine as to function but I never tested it for group size. Now with the tight bore lilja barrel chambered with lilja .22 match reamer (both reamers were new from Manson) I get failure to eject. Has no problem loading a round from the magazine but ejection fails. Either the empty round is in the chamber or trapped between the breech face and slide long ways not stove piped.
 I was thinking I would have to increase recoil spring weight because the tighter bore would increase pressure but it seem recoil spring is to heavy! My old barrel was sleeved with barrel from Brownells using a Bentz chambering reamer. Both barrel have 1-16 twist.
 I covered all areas of possible contact between barrel and slide with magic marker, no rubbing detected.
 Any thoughts or suggestions? Tomorrow I'll try some HV 22 rounds.

gwhite wrote:The GBPL has changed a lot over the years.  When I was in college in the early 1970's, they had 6 divisions, with teams separated (roughly) by skill level.   Each Division had four or five teams.  The "A" Division had the WSA team in a tight rivalry with the MIT Varsity team.

Lots of clubs have shut down, and it's harder & harder to recruit bullseye shooters.  The League is down to two divisions, A & B.  It's handicapped, with A Division shooting a 60 shot match, and B Division shooting a 30 shot match.  Since the pandemic, teams CAN shoot shoulder to shoulder, but people can also shoot postal.   After years of slowly losing shooters, the combination of the handicap system and being able to shoot postal has actually helped us grow a bit.

I shoot with the WSA A Division Team, and my wife is the team Captain.  A Division has 5 teams, and B Division has 6.

Well, we've sidetracked the original conversation a bit, so in for a penny, in for a pound. Might as well go all the way.

When I shot GBPL, circa 2005-2006, there were maybe 10-20 teams. We traveled all around the Greater Boston area to shoot.

I had shot all over the USA and all over the world. This was an absolutely new shooting subculture to me.

The interesting thing to me was that none of these shooters shot local 2700s, let alone Regionals, let alone Camp Perry.

Like I said before, quite nice people. Just very comfortable in their own little niche.

I imagine that you deal with that in your position. I deal with it locally. Not sure what it takes to get people out of their comfort zone and shoot a match that's more than 20 miles from where they live. (And in some cases, within 20 miles of where they live, but not the format/location of their comfort zone. I just don't understand it.)

When we decided to try the Lilja reamer we understood it might not work, I did have the Bentz reamer that is slightly bigger and longer so I could fix the problem by re-reaming with the Bentz reamer. But when getting the drawing from Manson for the Lilja reamer it was slightly larger in diameter than the Lilja posted on the 4D site. As mentioned the guy a JSG though it should work in a semi.pistol but did say the brass should not contact the chamber even in a bolt gun and that's why I honed the chamber deeper to greater than the length of the brass. If anything it made the situation slightly worse. Plus as I mentioned first 2 rounds failed to feed with 5 rounds in the mag,4th round too but remaining 3 fed, fired and were ejected, don't remember if slide locked back. Feed problem was corrected, feed ramp angle needed to be increase to make slight flat on the bottom of the ramp smaller. Feeding issues were eliminated even with 6 rounds in the mag. However as I continued to test ejection became a problem but hammer was cocked! Now hammer isn't being cock so slide is moving back less. Thinking there was some rubbing that resulted in possible galling I check every thing, all is smooth. Only thing preventing slide movement is hammer and disconnector pressure.  Only thing left to check is main spring housing. Maybe the plunger is galling. Quite some time ago I read about some pistol requiring a firing pin to be fluted to prevent air from slowing down the pin and creating light hits. Maybe with the tight bore the slide is being pushed back faster and the main spring cap causing the problem. Maybe a vent hole drilled near the bottom will help.
 I would like some feedback about the pressure curve I mentioned earlier, would post the link but when I try it as copied it don't work, only way I can get it is as mentioned. I did save the image to a file, works for me but if I attempt to attach it I get a message I can do it. The curve is as I expected it to be but thought there would be a greater time shift between the lower and high pressure curves.

I managed to get the link of the chamber pressure chart
https://www.varmintal.com/22lr-chamber-pressure.png

Very interesting, but it's presumably for a rifle length barrel.   I haven't had enough caffeine this morning to try to figure out how long a .22 stays in a 5" barrel, but the pressure would drop to zero somewhere in the middle of the curves when the bullet escapes.  It will be accelerating at the start, so it will spend more time in the first half of the barrel than in the second half.

For the two cases shown, the big difference is in the peak pressures, which hopefully occurs well before the bullet escapes.  As far as cycling reliably in a semi-auto pistol, a lot is going to depend on how springy the brass is, how much friction there is between the brass & the chamber, and the taper of the chamber.

You probably mentioned earlier, but what have you found with different ammo?  My experience with fussy pistols is that Aquila has a little less recoil, and won't cycle some pistols.  CCI has a bit more kick, and we used to use RWS Target Rifle for a bit more kick that that.  The bullet shapes are also different, which affects feeding issues.   We've switched to shooting Norma TAC-22 (which is loaded by RWS) as a cheaper alternative to Target Rifle, and it uses the same bullet shape, which has a less pronounced shoulder on the bullet:

The pressure chart of the link provided shows very little difference between higher and lower pressure except the peak. What I don't understand is the return to 0psi I assume the fast drop in pressure is at the point the brass is ejected. I'm surprised it is a vertical line. The time increments is in .1ms or 1/10000 if a second. More confusing is the difference between the high and low pressure, pressure is shown to be dam near the same at about 500psi, being that the .22LR brass is about .04 square inches the pressure on the brass is therefore 20psi. Yet the lower pressure drops to 0psi longer than the higher pressure.
 Granted the bullets are different but the brass is the same length. Longer bullet and possibly a shorter taper to the bore would have the bullet hit rifling and prevent closing but the rounds used pass the plunk test. Round is not "stuck" in the chamber, it's easily removed with the fingernail with no effort. Slide completely closes and even if the slide is pushed closed is don't move nor changes the results. I have purchased and used TAC-22, might have some.
 I have tried the slower SK Match up to the faster RWS and there is no change.
The other odd thing is the situation seem to be getting worse, as I mentioned the 3 round of the first 5 tried in the gun worked and ejected, then hammer was locked back but brass not ejected and as of last test the hammer fails to cock.

I didn't see any indication this was in a semi-auto.  If not, and this is in a rifle barrel, the pressure drops when the bullet exits.  The lower pressure equals lower velocity, so it takes longer for the bullet to get to the muzzle.  Hence the later pressure drop.

As for things getting worse, if it's REALLY marginal, chamber fouling could push it over the edge.  As a quick test, try oiling the cases with FP-10.  If they work better longer, is a chamber thing.  Norma also uses a greasy lube that seems to work better in tight chambers.  I have a Morini free pistol, and if I shoot Federal Gold Medal in it, I have to brush the chamber multiple times during a 70 shot session to get the cases to extract.  Norma TAC-22 just keeps on ejecting for a whole session.

Frank,
The quick drop to zero corresponds to the bullet exiting the barrel.
The slide will begin moving somewhere near that time where the pressures have dropped and are somewhat linear. Being more precise, it will begin when the pressure times case-wall area times coefficient of friction (brass case to steel with/ without lubrication) is less than the chamber pressure x area of the bore pluss the force that the spring experts on the back end of the case.
Your concerns about tight bore and pressure would only be a problem way on the left of the pressure/time graph. As soon as the bullet has been formed to the rifling, the effort to move it in the barrel will not have large differences between a a tight bore or a standard bore.
Whites comments and suggestions above are spot on.

I would think the pressure at the point the bullet exits the barrel is at the peak, I doubt the chamber pressure is only about 500psi when the bullet exits. Since it's chamber pressure I'm thinking the drop from about 500psi to 0 is during blow-back. The short distance to the breech opening along with the muzzle opening will lower pressure fast. If the graph was for bolt action I think the reduction in pressure would be slower and not drop from 500psi as fast as it's shown. It would too have to be curved since the time intervals on the graph are in .1ms or 1/10000th of a second.
 Even if it weren't it don't explain why high pressure drops to 0 in less time than low pressure. If it were 500psi that would be a rather slow moving bullet.
 Even a common air hose when disconnected pressure drop takes time, granted an air hose is much longer than a pistol barrel but the hose if disconnected and allowed to fall to the floor will act like a snake until pressure is lowered. In addition the pressure in an air hose is only about 125psi.

Frank, 
Peak pressures are within the first inch or two of bullet travel
The case sticks to the side of the chamber under peak pressures.

Well at this time it don't matter! Problem solved! Since I'm building the gun the hammer and sear are from my other 1911. Mainspring housing was welded to grip safety so it's one piece. Installed a new/modified slide stop and slide stop pin. Thinking maybe the thumb safety being new and not fitted to the hammer and sear might be causing problems, maybe the new slide stop if binding or issues in the mainspring housing I removed all from the frame! While off I put a few drops of Kroil micro-oil in the mainspring opening. (was late, my intention was to change the mainspring housing and internal parts) assembled the gun without the thumb safety and slide stop, worked great! put in the thumb safety, again worked great! Added the slide stop without the springs and plungers for the stop and safety, worked again! Installed all the components, gun again worked great! Seem all it needed was a few drops of oil in the mainspring housing! Lilja chamber seem to work fine now! Now that it's working I'll put parts back in my ball gun, install all new and fit thumb safety.
Seems like all it needed was a few drops of oil on the main spring and spring cap!

So a lesson in checking the simple things first. Interested to see how it groups.

Yeah! The tighter chamber and smaller bore diameter seemed to be the cause since the gun functioned great with a Brownells sleeve and Bentz reamer. Possibly a slower speed of the slide was OK or there was enough oil on the main spring to allow it to function for a while. As I mentioned the 3 first rounds of the 5 did work but the more I shot the pistol with the new barrel it got worse. That's what started me looking at the mainspring. Might remove the main spring and spring cap to check the bore. As I mentioned I did weld the mainspring housing and grip safety together so heat may have formed an oxide layer that started to crumble off. Possibly the air escaping brought the oxide flakes up to cause the spring cap to rub and cause drag, oil may have "glued" the flakes together so the air don't move them. I thought I did clean and polish the hole but in my haste to complete the gun I may not have. Will polish the hole surface and be-sure the hole is clear of any residue!  I think I have another 5 pound recoil spring (I think the 5 pounder is what I used), did buy different weights from Wolff so I'll check what I didn't use, possibly mic. the wire size. I'll try a full length spring since I know I cut a turn or 2 to get the slide to lock back with the sleeved barrel.
 Will have to make an extractor, when shooting I looked to see the direction the brass was ejected, they seem to go straight up. and slightly to the right but very little. With scope mount and scope the brass will probably bounce back in and cause jams though I could load only one round in the magazine to test group size. Nelson had one scope mount with iron sights that is made from aluminum, I bought it, wanted another but it was the only one. I have to drill and tap the barrel, I intend to use 6-40 flat head screws not 6-32. I'll let everyone know the group size, if great I have a Lilja 1" diameter .2215 -.217" barrel, might screw it in a Nelson/Marvel style block to check group size. Might get a Lilja tight bore barrel in 1" diameter to put in Nelson/Marvel blocks. One piece might be great but making it from 2" diameter blank barrel is a lot of work! Quite a bit more than I expected! However I do have 2 additional barrels made, one for a friend and another for Adam. Will have to chamber them and complete a few other dimensions so they can be tested in a Nelson and AA conversion. Dec 31 the JSG reamer will be shipped, Will have to test that one, it's tighter than a Bentz but not as tight as the Lilja.