too much pressure?

[aldar]

I've been trying to get my Handi rifle in .243 to group without much luck. Today I started having some problems with opening the latch. The latch release lever was pretty tight. Also, I took a fired shell and put it in the chamber. The gun would not lock up. The primer looked ok and I can read the head stamp fine. I measure the chamber with a modified case and seat the bullets out to .10 less the smallest reading. All cases are now neck sized only and these fit the chamber fine. Does this sound like too much pressure? Am I seating the bullets out too far? Or could this be a problem with the rifle itself?

[Catfish]

If the brass fired in your rifle would not chamber it sounds like presure. You have to rember that in your break down gun you do not have the strenth that a bolt gun has. Mic the brass down on the web where the heavy brass is. If you it is larger than an unfired case it is definitely to high of presure.

[stimpylu32]

aldar

Yep , you have a pressure problem , so Do Not go any higher with that load , if you do only bad things will happen from here on out . My 243 Handi likes the more middle of the road loads .

stimpy

PS --- you have a PM coming . 

[aldar]

Could seating the bullet out too far cause this problem? I had read somewhere here that the closer to the lands you get, the LESS pressure develops.

[stimpylu32]

aldar

 I had read somewhere here that the closer to the lands you get, the LESS pressure develops

Yes , to a point , the furture out you seat the bullet the more case space you create and allow for less presure , till you hit the lands at that point pressure will increase drasticly .

stimpy

 

[LaOtto222]

What the guys have all told you here is true. You may have too much pressure. There are some other things to check too. Make sure your latch is dry- no oil should be on it. Having a oily latch can cause it to open or partially open. Your chamber should be dry - oil in the chamber will cause the pressure on the breech face to go up. This can cause the rifle to want to open and stretch your cases. Another member on GBO was at the range today and he said that he always takes a little alcohol and cotton swabs along to clean the areas I mentioned. One other thing - make sure you are "snapping" your gun shut. This is needed to make sure you get a full latch engagement. These tips only apply to Handi Rifles. These may or may not be your problem - YOUR PROBLEM MAY STILL BE OVER PRESSURE. Proceed with extreme caution.

[Questor]

aldar:

I'm curious that you would be having pressure problems. Where did the data come from? And was it published by the manufacturer of your bullets, or was it for a generic bullet weight? Thanks.

[Lloyd Smale]

I got to ask the same question. Im sure the design was made safe with factory level loads and in most cases with a round like a 243 pressures are higher with factory rounds then they are with the highest loads allowed in a loading manual.

[Selmer]

One thing that no one has mentioned or picked up yet is that you said you are NECK sizing the brass.  With the break action guns (handi and TC's) you need to full length resize, at least in my reading and experience.  When the frame stretches ever so slightly upon firing you create excess headspaced brass and you need to bump that shoulder back to get a good lock up on the next loading of the brass.  I have found this to be definitely true on my Encores and verified with a dial indicator to measure headspace from the breech face of the gun. 
Selmer

[303Guy]

I've been trying to get my Handi rifle in .243 to group without much luck. Today I started having some problems with opening the latch. The latch release lever was pretty tight. Also, I took a fired shell and put it in the chamber. The gun would not lock up. The primer looked ok and I can read the head stamp fine. I measure the chamber with a modified case and seat the bullets out to .10 less the smallest reading. All cases are now neck sized only and these fit the chamber fine. Does this sound like too much pressure? Am I seating the bullets out too far? Or could this be a problem with the rifle itself?

 LaOtto222 has said that oil in the chamber can raise breach face thrust resulting in case stretch.  A dry and rough chamber can stretch the case unduly by not allowing it to expand evenly in the chamber and set against the breach face 'gradually'.  (I use the term gradually rather loosely).  If the case cannot release from the chamber walls progressively, the body will stretch (as in plastic deformation) in the zone close to the case head as opposed to elongating elastically over the length of the body.  This means the case will not spring back and the action will be held under stress after firing. Hence the tight release lever.  If this is happening, you may also experience poor accuracy as the case to chamber wall grip will not be consistent under these conditions, being subject to micro variances in the surface contamination of the brass as well as case strength variances.  Slight lubing of the case will likely do the trick but I suspect that will invoke a howl of protest.  The truth is, a lubed case will likely increase breach face thrust by up to 10 %.  But an excessively rough chamber will also thump the breach face pretty hard as the case gives way suddenly under higher pressure.  So just polish the chamber and keep pressures moderate!

303Guy

[aldar]

all the loads were taken from manuals for either the powder or bullets or both. Some one else suggested a faster burning powder which I'll try. I have'nt polished the chamber but will give that a try also. as for neck sizing brass, I do this with my Handi .280 with great results. I just finished FL sizing all my brass and I'm going to start all over again!

[LaOtto222]

303Guy - "The truth is, a lubed case will likely increase breach face thrust by up to 10 %."

I know you are correct, the oily chamber or lubed case will increase breech face pressure. That is not good. Breech faces have been cracked due to high pressure there. If the head space is excessive, you may be correct on your thoughts. I do not recommend lubing the cases or the chamber. Do not polish the chamber unless you have a sticky cases and then only polish enough to prevent the sticking cases. You do want the case to stick to the wall of the chamber. Like I said you are going to increase the breech face pressure considerably if you do not let the case "grab" the wall of the chamber. You will end up with the same problem you are having now. The case will stretch and lock up the action. If let to stretch any where along the length of the case it will stretch at the weakest part of the case, not along it's entire length. It may be just below the shoulder, which is thinner than just above the web area. If you have excessive head space, you have a different set of circumstances. You have trouble no matter how you slice it.

[303Guy]

I have a theory on oily chambers.  It is this; the excess oil in the chamber can be 'injected' into the hot, high pressure flame causing a sudden pressure rise due to diesel detonation.  I doubt this is what is happening here.  The scenario with the case locking up or just stretching from too much grip is due to the case gripping too early and too tightly when the firing pin has pushed the case forward.  The case cannot remain locked in the chamber, but instead, 'creeps' back against the breach face progressively as the pressure rises.  That is to say, the case takes up the load along it's length and remains within the elastic limit of the brass.  Excess head space does not seem to be the issue here as aldar has said he neck sizes only.  I mentioned the rough chamber because both my rimmed cartridge rifles have that problem, separating the heads after two or three firings!  I do lube my cartridges and I get almost indefinite case life - apart from split necks and losing them.  (I have now solved the split neck problem).  BUT, I keep my loads moderate!

Just out of interest, lubing a cartridge (not oiling the chamber) does not prevent case grip, but to keeps the grip within the case strength limits.  What it does do is allows the case to set against the breach face earlier and with less shock before gripping the chamber walls firmly.  Excess pressure will still cause case stretch - but I refer to thin walled cases that operate at 43,000 CUP.  No such thing as primer cratering here - way too late!

303Guy

[Selmer]

I didn't necessarily say (or at least mean...) excess headspace.  When the frame flexes on firing the brass flows with it and they you have a shoulder that is too far forward.  That shoulder needs to be set back to get the headspace to the proper dimension, which can be measured with feeler gauges to determine the barrel to frame gap and then taking the barrel off, extractor off, and measuring how far the case head protrudes from the barrel when the case is pushed in and stops on the shoulder in the chamber.  If there you have .008" of case head protruding and only .003" barrel to frame gap, then your lockup won't be tight (if at all) because the case head is pushing too hard against the breech face because the measurement from the shoulder to the case head is excessively LONG, thereby giving lockup problems.  Did that explain it better?  If you have a .003" barrel to frame gap, the you want you case head to protrude only .003" for zero headspace, I like a little headspace, so I set my dies for between .0005" and .001" of headspace, therefore on the .003" barrel to frame gap set up (which varies from barrel to barrel on any given frame...) I would set my FL resizing die to bump the shoulder back so that I only have between .002" and .0025" of protrusion from the barrel, thereby setting up enough space for complete lockup and good ignition because the case can't move forward when the hammer falls on the primer because it is already flush up to the shoulder in the chamber AND flush to the breechface, AKA minimal or zero headspace.
Selmer

[LaOtto222]

aldar - I was going to leave this go...to each their own. I just could not bring myself to turn my back on you. The following paragraph was taken directly from the FAQ section on the Handi rifles. They are talking about stuck cases here. It applies to ejectors, not necessarily extractors so smoothing the chamber that is referred to here is for ejection problems. Of course your problem is not necessarily stuck cases, but what you are experiencing is very closely related. I guess what I am getting at here "Clean, dry chamber and ammo is paramount." Personally I would never purposely lube a case or leave oil in the chamber. In other threads it has been discussed about dry or oily latches with the dry latch getting the most attention. You can do what ever you want, it is free country. All of your troubles may stem simply from too hot of loads, but it could be from the things I have mentioned. Frame stretch in a Handi has been discussed at length in another thread just recently. You have been warned, now you can do what ever you like.

Basics for (necessarily) Failure to Eject, too hot hand loads, Milsurp, dirty or oily chamber or ammo will all cause stuck cases. Clean, dry chamber and ammo is paramount. Next is polishing of the chamber which is standard procedure for any ejector equipped barrel, can be done with a patch wrapped bore mop chucked in a drill, use flitz, JB bore compound or any fine metal polish, just polish it a couple minutes changing the patch and adding polish frequently. You can also use a fired case with a screw stud stuck in the flash hole and chucked in a drill.

[303Guy]

I didn't necessarily say (or at least mean...) excess headspace.  When the frame flexes on firing the brass flows with it and they you have a shoulder that is too far forward.  That shoulder needs to be set back to get the headspace to the proper dimension,.........., AKA minimal or zero headspace.
Selmer

Thanks for clarifying that, Selmer.  I had noticed (with only one break action) that a un-resized case cannot be reloaded to fit the chamber with reliable locking.  But why would a reloaded case that did lock up, be tight to open?

303Guy

[303Guy]

aldar, I must agree with LaOtto222.  What he says makes complete sense.  I think Selmer explains exactly what is happening to you.  In your case it is causing difficult unlocking.  Try lowering your pressures before anything else and see what happens.  You asked whether pressure may be your problem and from what the others have said, it sounds like it.

Regards and good shooting!
303Guy

[Brithunter]

all the loads were taken from manuals for either the powder or bullets or both. Some one else suggested a faster burning powder which I'll try. I have'nt polished the chamber but will give that a try also. as for neck sizing brass, I do this with my Handi .280 with great results. I just finished FL sizing all my brass and I'm going to start all over again!

   Hi there,

       I am afraid that this don't mean much as every barrel is different. I once took a load of a powders makers load data booklet right down to primer case and bullet make an weight. Well it blew the primer pockets in my .270 BSA. In my particular rifle their load was way too hot yet in another BSA .270 rifle it's fine. I always thought the bore wa sa little tight on the first one as the cleaning brush is tighter going through the bore than on the others and this may have caused the pressure to rise.

    Anyway the data was worked up in a pressure barrel or at least a different gun and well it taught me that I was getting too nochalent in my re-loading.

[303Guy]

Brithunter ,  interesting that.  And a good warning to us all!  I have found that one particular bullet produces more pressure in my gun, than the tables would suggest.

303Guy

[Lone Star]

...Just out of interest, lubing a cartridge (not oiling the chamber) does not prevent case grip, but to keeps the grip within the case strength limits.  What it does do is allows the case to set against the breach face earlier and with less shock before gripping the chamber walls firmly...

Some "theory"....      

I will quote from Speer #14, page 139:
"Oil in the chamber or on the cartridge will cause the case to slip in the chamber at peak pressure and increase the thrust on the bolt.  This may cause hard opening at normal pressures."

Sierra # V, page 132:
"...all traces of the lubricant must be removed from the case before firing.  Failure to do so will result in raising pressures and bolt thrust to potentially dangerous levels."

Naramore, Principles and Practice of Loading Ammunition, page 654:
"There is an enormous difference between the back thrust of a dry cartridge and a lubricated one...Lubrication on cases increases the back thrust and while the force of a single cartridge is insufficient to break the lugs on a bolt, the increased stress on them builds up internal stresses until they suddenly crack."


I am so often amazed at what I read on-line.   I guess I shouldn't be. 
.

[Brithunter]

Hi All,

    I wonder if anyone here is aware that the method used to proof the Lee Enfield rifles in production was to fire cartridges dipped in Rangood oil to increase the back thrust and so set up the surface of the locking lugs. The chambers were reamed 0.002 tight as this was the amount that the extra pressure peended the lug and recces surfaces.

[303Guy]

Brithunter was this standard practice or just some production lines?  Were can I read up on it?  I have heard of this practice but wondered whether sufficient consistency and predictability could be obtained to use it for 'proofing'.  I believe that an excessive oil film in the camber - one that essentially fills the gap between case and chamber - will 'hydraulically 'float' the case rearward, actually 'adding' to the normal thrust.  That is of course, 'dynamic' lubrication.  Case grip op the chamber walls - as long as it does not suddenly give way - will reduce the bolt face thrust by the amount of the elastic strength of the brass - which is no more than 10% of the load.  I had the impression that 'proof' loads were 25% over-load.

Just for the record - my 303 loads are considerably milder than factory loads.

Regards
303Guy

[Lone Star]

Naramore "Principles and Practice of Loading Ammunition" page 304:

"The Oiled Case System.  The method of measuring the high pressures developed in gun chambers that has been most widely used is one in which the pressure is allowed to act on a small cylinder of metal, soft enough to be appreciable compressed by the applied force and hard enough to resist too drastic deformation.  For many years the British used this principle in their Whitworth or “oiled case” system.  In this, a steel washer-like “pad” having flat parallel surfaces and a hole for the passage of the tip of the firing pin, was placed in the back of the cartridge.  Between this and another similar steel washer a thick copper washer of definite thickness was placed and the whole was held in firm contact with the cartridge head by the breech. When the cartridge was fired, the back thrust of its head caused the copper washer to be compressed and the amount of shortening bore a relationship to the maximum pressure exerted on it.  As the normal action of a cartridge is to expand and grip the chamber walls when it is fired and as cartridge cases are normally subject to variations in temper, thickness and such, special cases had to be used and they had to be dipped in oil and drained so that they would slide back when fired….it was never favorably regarded in this country.”

[Brithunter]

Ahh now somewhere I had an article which showed the manufacturing and testing of the British Lee Enfield rifle. Sorry but I don't have or know of where I read it, it might have been in a HBSA report or I may have found it online. I will try to trace it.

[303Guy]

Lone Star , thanks for the interesting info.  Clearly, I am going to have to get hold of a copy of Naramore "Principles and Practice of Loading Ammunition" .  I must admit, I would have thought the oil would raise the thrust above the "no friction" level.  Still, as long as the results are consistent.  Mind you, I am told the military rifles were designed with 'generous' chambers so as to operate safely under 'adverse' conditions - dirty chambers among other things.

Brithunter, thanks for your trouble, much appreciated.

303Guy

[303Guy]

[quote"Oil in the chamber or on the cartridge will cause the case to slip in the chamber at peak pressure and increase the thrust on the bolt.  This may cause hard opening at normal pressures."

I am a little surprised Speer say the case will slip in the chamber at peak pressure!  I would have expected the case to be firmly loaded against the bolt face before peak pressure occurs if the case was oiled.  Even slightly.  Well OK then. 

I am afraid I have been using the wrong term.  'Lubed' could mean oiled or anything else.  That would include 'thick film' and 'thin film' lubrication.  Let me to correct myself.  I am actually meaning 'reducing' friction to normal levels!  (Not eliminating it).  Just handling the case i.e. rubbing it with the fingers, or a film of tarnish or even fine dust can 'lubricate' the case in the chamber at the levels of pressure and force at play during the firing of a cartridge.  A loaded cartridge that has been 'wiped dry' is ' *(that word)* '!   Also, by a 'rough chamber', I mean one that leaves reamer marks on the case.  So.... I will have to find a better term.  Anyway, I am not suggesting anyone should actually go out and start oiling their ammunition!!!

303Guy