Reloading question:Pressure Problem?

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duckjihad

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I reload conservatively. I full length resize. I'm well within spec's on powder, max case length, cartridge length etc. When I load for my .338 mag, I'll have much trouble opening the bolt after firing. I set the dies as described in the instructions. Any ideas? I don't get this problem with my other rifles, and the 338 never has trouble with factory ammo. Could my dies be outa whack? Ever see this before?
 
too much information

But maybe not enough.

Am I right in thinking that when you have fired the round, you struggle to cycle the bolt?

Then it's probably a pressure problem or your case is too long before you start. What does the case look like when you extract it? Any damage? Bulges? Cracks? Where are the pressure signs?

I would advise against using standard settings on your dies as there is no such thing as a standard rifle. Factory ammo is built to fit every rifle so it's at the extreme end of one size fits all. One of the benefits of loading your own is that you can get a great fit. Brilliant in your rifle but awful in someone else's.:eek:

I would probably start with measuring the length of the case and then the over all length of the cartridge.

Every time you use a case, it gets longer. Measure it to ensure that you haven't gone over 2.5" as this is what Hornady recommend as maximum. If it's longer, trim it down, debur and load up.

OAL is important for loads of reasons (sucking eggs? I hope I'm not telling you stuff you know!) but it should be about 3 - 5 thousands back from the point where the bullet touches the lands. If the AOL is too long then the bullet is not free enough from the case before it's in the barrel. too little and you get 'bullet jump' where it's neither in the case or in the barrel - not good.:fire:

Just had a thought - you say that you load conservatively. Are you using enough powder? What's your loading details? Tell us what powder and stuff and I'm sure more light will be cast.

Finally, you could use a neck die instead of a full length as after you've fired it, the case now fits the chamber. It takes lots of energy to push that brass to expand into the chamber. You could be using that power to get the bullet down the barrel. And every time you work it through a die, to make it thinner and back to where it was before you started, it gets a little harder. Brass work hardens. Try a neck die and see what happens.

Anyway, serves you right for using a cannon! :D
 
Need to know if the reloads stick even if chambered and extracted WITHOUT firing them.

Cross-references on your conservative loading data? Some sources' data have been revised downward not so much because of lawyers, but because reliable pressure testing showed the "educated" guesses on so-called "pressure signs" were, um...WRONG.
 
I'm going to assume you've read what everyone else wrote so I'll write something new. Is it possible that you aren't chamfering the mouth of your trimmed brass? If so, it's possible that you have a burr on the mouth that is getting things buggered up. One sign of over pressure is a flattened primer. If you are finding this is happening, the two most likely culprits are powder volume and OAL.

Oh one more thing. IMR and Hodgden make powders with the same numbers, they are NOT interchangable powders! Hope this helps.
 
Thanks for the input. The cartridges chamber fine. No tightness noticed when loading into the weapon. I am seeing a shiny ring on the brass just forward of the belt and my primers are getting flattened. After firing, I have to exert much effort to cycle the bolt up from the closed position.

I'm measuring my brass to insure it's below the max case length prior to reloading. Haven't trimmed these cases yet since all were once fired and still short enough. Makes me wonder about my dial calipers, but it would seem if they were off, I'd have problems with other loads as well. ?? I am not trying to run the bullet out til it touches the lands.

Will double check my data tonight, but am sure I'm shooting Nosler partition 250 grainers over 68 grains of IMR 4350 with Fed large mag rifle primers. I'm sure it's not too little or too much powder because I cross referenced several manuals and this is well within Hornady, Sierra and Lyman (Lyman has scared me a time or two!). Would appreciate any thoughts. Thanks.
 
I am seeing a shiny ring on the brass just forward of the belt and my primers are getting flattened. After firing, I have to exert much effort to cycle the bolt up from the closed position.

Definitely overpressure signs. Others have mentioned possible causes. But, I've seen this before, even with what should be "moderate" loads.
 
Check recalls

If you are using that particular powder in only that load, check to see if there might be a recall on it. There has been several this year on various powders and maybe you just happened to get some of it.
 
Oh, bolt lift is stiff--that's way bad. I was believing that perhaps it was your pullback stroke that was off. Sorry.

Your experience is why we don't just blindly follow the load recommendations, but watch for how they perform in OUR firearms. Accumulated "tolerance stack" can make one gun with certain components exhibit far higher pressures than expected.

Just another thing to look for, as I learned many years ago with a gun that suddenly started flattening primers, expanding 1 out of 20 primer pockets, and showing these really neato annular rings on the case body that were the chamber's machining marks (military rifle, not the greatest "finish" though the fit was great). Turns out the cases had grown too long and were able, with the tiny crimp used, to extend a bit into the throat and beyond the chamber. That led to the very end of the case mouth having nowhere to go to "open up" and release the bullets, essentially pinching the brass into the channelure.

The ammo went into the chamber and back out just fine when unfired. Trimmed the cases and the problem went away, and the just-below-max load was once again safe.

Was your load data cross-referenced specifically for the Nosler bullets you used? Same-weight bullet data is not always interchangeable, either...
 
Since your cases are shorter than published max, your investigation should include seeing whether your chamber is short--not on headspace (your cases would most likely show bright marks on the shoulder or be sticky when extracted unfired if that were so), but to the chamber mouth cut.
 
No. I didn't check the nosler book. If you have one, I'd love a check if you have the time. I'm also loading 243 with that same powder with no problems. No other shiny marks on the brass.
 
Get a Wilson adjustable case gage -

Pay as much attention to head to shoulder dimensions as you do to overall length. Get a Wilson adjustable case gage and/or RCBS mic or other gage of your choice for your cartridge.

Check head to shoulder on your virgin, fired factory and fired with a bright ring cases.

I'm taking the cartridge to be the .338 Win Mag which headspaces on the belt. Section one of the cases with a bright ring and see if the bright ring is a stretch mark. Some people use a wire feeler to feel for a groove inside the case where the bright ring is outside the case. Sounds to me as though the once fired has stretched and reload has stretched again. That is the shoulder is blowing forward. This is less obvious than it might be because the case as designed headspaces on the belt.
 
violating copyright in the interests of safety.

RCBS makes a couple of tools to do the same job in a different, perhaps better way.


THE WILSON ADJUSTABLE CARTRIDGE CASE GAGE

FOR BELTED CALIBERS

(Patent No. 3,209,461)

In the making of rimless ammunition and in the chambering of rifles for the same, a close relationship is maintained between the cone-to-head length of the cartridge and the same dimension (headspace) in the chamber. This is because uniform ignition depends on this fit, as the shoulder in the chamber supports the cartridge against the blow of the firing pin. In many rimless calibers the cone-to-head length of a new cartridge will be slightly greater than the cone-to-bolt face length (headspace) of a correctly chambered rifle. Thus there may be some "feel" in. closing the bolt on a new cartridge. In belted calibers, proper ignition does not depend on the cone-to-head length of the cartridge relative to the chamber. Instead, the firing pin thrust is taken by the belt against its seat in the chamber. This means that cone-to-head length of belted cartridges is of no consequence as far as ignition is concerned and the factory can be, and in many cases is, quite tolerant regarding the fit of the cartridge beyond the belt recess. The factory is concerned only with the firing of the cartridge once and new brass will stand a lot of stretching. The reloader, however, is concerned with the fit of the cartridge beyond the belt and the less the brass is worked in reloading and firing the longer it will last.

In our first Case Gage for a belted cartridge, the 300 H. & H., the shoulder angle was so gradual that cases had much less tendency to stretch (and pull apart) than would be the case with a more abrupt angle. With the advent of later belted calibers like the 7x61', the Weatherbys, the 264, 300 and 338 Winchester Magnums, etc., with their more abrupt shoulders, the problem has become a real one. To complicate matters, different rifles of the same make will be found to vary greatly in chamber dimensions forward of the belt.

After a great deal of time spent on this problem we have come up with a solution. This is the WILSON Adjustable Case Gage. Now the customer can readily adjust a case gage to fit his particular rifle and can then adjust his resizing die to correspond.

DIRECTIONS

Note correct position of insert in gage body. The cone is inside and the lettered end out. Loosen the small screws, which have fibre pads underneath, and push insert out of gage body. A soft instrument like a wood dowel will not damage the gaging surface of the insert. Remove all grease from insert and gage body. Check to see fibre pads are still in place, then push insert into gage body until outer end is about 1/8 inch inside. Tighten screws very lightly. .

Drop one of your fired cases into the gage. The head should protrude. Next, push the case into the gage, causing the insert to slip, until the head of the case is even with the high part, or high parts, of the gage. A narrow, straight instrument, like a Brown & Sharpe #306 steel scale will do for this and will be fine for subsequent gaging. If your Wilson case gage is the stepped type, hold the gage with the lower step toward you and with the scale edge resting on the right edge of the upper step, use a slow, rocking motion to force the case and the insert down until the head of the case is even with the upper step. Be sure the scale is resting on the case head and not on the primer. Tighten screws. Check to see insert did not move when screws were tightened.

If your Wilson case gage is the new, grooved type, hold the gage with one end of the groove toward you and with the scale at 90 degrees to the groove, use the same rocking motion to force the case head and insert down so head of case is even with upper surfaces. Tighten screws. With this adjustment completed you now have a case gage adjusted to your particular rifle.

Now adjust your full-length die to produce a cone-to-head length that will allow the case head to stop about halfway between upper and lower gaging surfaces. It should not be necessary to shorten the cone-to-head length to where the case head will register with the lower gage surface. A slight reduction in cone-to-head length, which will permit closing the bolt without undue effort, is all that is required.



It is suggested, after the gage is adjusted to your rifle, you drop in a new factory cartridge and note the location of the head. This will show how the brass will be unnecessarily overworked if brought back to new dimensions for each reloading, and why the case will separate after a few firings.

With the gage adjusted for your own cases you can check over-all length by standing it, with a cartridge case inside, on a flat surface, head end down. If the case mouth checks above the upper step, or upper surface, of the gage the case is over length and should be trimmed back to the lower gaging surface. The over-all length of the gage body represents maximum case length. Don't allow your cases to become longer than the gage.

WILSON CARTRIDGE CASE GAGES FOR RIMMED CALIBERS

CARTRIDGE CASE GAGES are now available for most popular rimmed rifle cases. Like the belted Magnum cartridges, these rimmed calibers do not depend on their shoulder to position the cartridge and take the firing pin thrust. They are also subject to the same overworking of the brass at the shoulder when reloaded if the resizing die is set incorrectly. The use of a Wilson Cartridge Case Gage can extend the useful life of rimmed brass and indicate the need for trimming when they lengthen.

L. E. WILSON, CASHMERE, WASHINGTON, OCTOBER, 1969

The bright ring may or may not be, depending, a clear sign of case stretching. A little experience will make it easier (MOST of the time) to distinguish the pressure ring and the stretch ring - the stretch ring, like pregnancy stretch marks, is an indication of brass stretched beyond its elastic limits and so unsafe.

It's possible the pressure is simply too high for some reason we have not considered here frex thick case necks but that is unlikely. What about any difference between reloads with virgin and once fired brass?
 
According to the latest Nosler and Hornady books you are right at max, Speers #13 shows you one (1) gr under. I didn`t bother with Lyman, Hodgdon, or Sierra. You did work up to this load, right?I`d be inclined to believe your rifle won`t take book max loads and drop back a gr or two. I doubt the sticking is related to the case lenght, headspace, or your sizeing methods.
Remember the book loads are only valid with that combination of bullet, powder, case and rifle at the temp tested. Change any component brand, style, lot number, the chamber used, or temp fired at, and the result WILL be different. Higher or lower? Only testing will tell.
 
Are you measuring the case length after firing or after being resized? It makes a difference (should be measured after resizing).

Your brass with the "ring" in front of the belt should not be loaded again; it's not safe IMO. IIRC the case has streched too much and is thinner at the ring; it's the weak point. You may be able to feel the ring on the inside of the case with a metal probe or a bent wire. That's a case head seperation waiting to happen.

As is, those loads are too hot for that rifle even if safe per a book. My hunch is the cases are too long after sizing and the long case neck is not allowing the bullet to move freely into the rifling.
 
I did work the load up. I started about 4 grains down and worked up a half grain at a time. I think if memory serves, I'm still about 2 grains below hornady's max load, but my reloading manuals are all about 10-12 years old. Might need to update.

Oh, I'm measuring after resizing. Thanks.
 
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How about seating depth? Is your seating depth consistent with the guides? Or conversely,are the bullets getting jammed into the lands? Both conditions can cause overpressure with otherwise reasonable published loads.
 
My seating depth and COL is by the book. I pulled out my data for the loads last night and checked it against the hornady book again. I'm loading 68.5 of IMR 4831 under a 250 grain bullet. (I apologize, I had incorrectly said earlier I thought it was 68 of 4350). ANyway Max is 69.0 I worked up to it from several grains down and had great results with Hornady bullets. Thought the noslers would do well there also. Guess I'll have to buy a nosler book. I know everyone says if you change one componenet all bets are off, but really don't see why nosler's 250 grain spire point flat base bullet would demonstrate higher pressures than Hornady's of similar construction and weight. Any body got a Nosler book out there and the time/inclination to give me the min/max for IMR 4831 and 250 gr partitions?
 
According to Nosler's Manual #4, the min/max for IMR 4831 with their 250 gr. Partition is 67.0 - 71.0. So you are well within their safe range. They indicated that their most accurate loads were achieved at the minimum load, not the max or near max. That would, of course, be very dependent on the rifle/barrel used.

There are several reasons why you still want to back off when changing the bullet even though it is the same weight and "similar" construction. When you are in the pressure ranges of calibers like the .338 WM, small, seemingly insignificant differences can make a big difference in the max pressure achieved.

1) The jacket thickness might be (probably is) different. That could cause a slightly different amount of neck tension.

2) The new bullet might be slightly longer. If you set the OAL to the same length as the old bullet, there could be more of the bullet inside the neck = less volume and therefore more pressure.

3) The amount of bearing surface on the new bullet could be greater than on the old bullet = slightly more barrel friction and therefore more pressure. Jacket thickness/alloy could affect barrel friction as well.

4) Ogive shape can be a factor. A spire point might ease into the leade and lands with less friction than a rounded nose like the Hornady.

I 'spose those are enough reasons to back off a little when changing bullets. :)
 
Thanks Mal. Makes sense. I'm better educated thanks to you. If you don't mind, what did Nosler list as cartridge OAL using their 250 grainer and what primer did they use?
 
Also, that makes sense that the lower loads gave better accuracy. I was getting 1 inchers with that load with hornady bullets. Switching to nosler jumped it out to 2.5 inches.
 
The OAL listed by Nosler is 3.340". However, they stated that better accuracy is achieved with a slightly longer OAL. Due to differences in various rifle barrels, how much longer has to be determined by you by the usual methods (Stoney Point gauge or the old magic marker on the ogive method).

They used Federal 215 primers.
 
Just a thought

What bullets are they using in the factory ammo? Why don't you get a handful of them and make your own. If you still get pressure then it can be narrowed down to either the brass, the primer, the powder of the way you put it together. Process of elimination.

Unless you've sorted it - i've been away mowing the grass! :cool:

D
 
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