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lreed
07-11-2009, 10:40 PM
Hello; Is there any scenario in which a p-patched or g-checked cast bullet can equal or exceed the chamber pressure generated by a j-bullet of like loading,same weight bullet ,powder ect? Which will have the higher pressure the g-checked or the p-patched everything else being the same? Thanks for any answers! lreed

windrider919
07-12-2009, 01:19 AM
I have been shooting PP for years in cal from 30 to 45 and just recently I am starting on 22. Based on your question where all conditions are the same except type of bullet I have found that j-bullets have higher pressure, cast/gas checked next and then Paper Patch, I attribute this to two factors. 1) The PP bullet is under size compared to all the other bullets and the paper is more compressible so although the PP seals the bore it does not 'plug' the bore so tightly, reducing the amount of pressure required to push the bullet. 2) this may actually be a sub-part to the first but it appears that there is actually less friction between the paper and the barrel then there is for lead or copper. I have found that in loads with the same bullet weight and same powder charge i frequently get unburned powder grains left in the barrel. This is an indication that the bullet is being pushed down the barrel so easily that full combustion pressure does not build up. And the primer is not as flattened as if it had had less pressure. The only way two bullets having equal weight could do this is if one traveled down the bore easier. Also, shooting PP bullets for a while seems to polish but not wear out a barrel.

By the way, smokeless and BP use different barrel fit rules for good accuracy. My best bullet for 458 Win Mag is .454 with it PPed to .463. I shot this bullet through a match .458 barrel with the same powder load as a jacketed .459 cast grease grooved or .458 jacketed bullet but with less pressure. If I were to shoot a lead or jacketed bullet of .463 it would blow up the gun. With PP the paper just swages down. Note that this is true for my rifle and chamber and you should determine your rifles sizes and what bullet fits. Each rifle is slightly different and my load might blow up your rifle and injure you. Only because I have a .464 chamber throat can I shoot a .463 bullet.

303Guy
07-12-2009, 03:46 AM
I have found pressure indications to be pretty proportional to powder charge but probably a lower with patched. This is with a 303 Brit. There is a thing about bullet size, that the No4 Lee Enfield came out with a two groove barrel (not all of them). What's different there is that the bore is .303/.304 with two narrow grooves of .312/.313 diameter. That means the standard .312 bullet gets swaged down to .303/.304. No problem! Another point is that my cast g/c and pp'd, are somewhat over size. So much so that they fit the neck of a fired case and actually swage a little on entering the throat. I cannot say there is too much untoward happening pressure wise. However, an over sized cast or pp'd boolit can get pushed back into the case, reducing case volume. I know this because .... well! Again, not too much happening. But then I am not overloading and I use slow enough powder to fill the case but not at the loss of pressure. But, as windrider919 points out, what works or happens in my gun is not necessarily going to work in another. My 'data base' is only three rifles.

1874Sharps
07-16-2009, 12:57 PM
Dittos to the above posters. I have no stress gauge or other fancy ballistic lab tools, so I cannot quote numbers to you from pressure tests done with jacketed, cast gas checked and paper patch bullets. But I can quote noted author Paul Matthews (he wrote "The Paper Jacket" as well as numerous other works). He states what the above posters have stated: For bullets of equal weight with a given load, the paper patch bullet will have the lowest pressure, followed by the cast bullet, followed by the jacketed bullet. I think the aforementioned posters have also done a great job proposing the reasons for this. Good luck in your pursuits of wrapped galena, Ireed. I have found in patching for my 45-70 and various 30 calibers that the paper jacket is probably the best and most versatile type of homemade bullet. With this old technology (first patented in 1870) the home caster and reloader can make effective high velocity hunting loads and accurate target loads of a wide velocity range. In my humble opinion it gives folks like us a cheaper alternative to jacket bullets without sacrificing much if anything in 30 and larger caliber cartridges.

303Guy
07-16-2009, 02:20 PM
I may be able to offer part of the explanation. Ever tried to push a rag ball down your bore? There comes a point where it won't move. What's happening is the pressure from the rear is compressing the rag, squeezing it outward against the bore. Bullets do the same. But paper has a property that prevents it from 'binding' on the bore. J-words don't do this quite so much but then they are harder to engrave in the first place and they maintain a load against the bore. But j-words do something else also, they expand from bore to jacket friction, which obviously increases the friction further.

357maximum
07-16-2009, 02:59 PM
When I did my 35remington paperpatching work I found evidence (to me) that supports all the above posts.

Using H335 , BLC2 and W748 with the rem 200 grain RNCL bulk J-words I had not one sign of unburned powder and all was consistant and accurate.

When I went to the RCBS 35-200 as a greased groove boolit I had to bump the powder charge a few grains to get consistant velocities/tighten groups/burn all the powder. I did get increased velocities also before the powder charge was increased, but it was a bit "SWINGY" as to the constancy of velocity. The increase in powder brought it all back to where I wanted it accuracy wise.

When I went to the paperpatched 358315 and the RCBS 35-200 I had to switch to a mag primer to get consistant velocities/tighten groups/burn all the powder/get rid of neck smoke. There was also a slight softening of the alloys used at this point..FYI..not sure how that would have changed things, but it should have improved ignition so I think it was mostly to do with the paper/sizing of the boolit.


You could use this same evidence to show some general thoughts about ball powders are not all wet also.

303Guy
07-16-2009, 04:41 PM
So, that means we can get more power with paper patched boolits! Cool! Heavier boolits at the same speed as j-words. That means good BC to boot!

lreed
07-17-2009, 12:56 PM
Thanks gentlemen for your replies, exactly the answers that were needed. I have been working with two different 8mm cast, sized down and patched for 30-06, and have no published data for loading cast of their weight. I'm trying for the highest velocity- with accuracy, am having fun but it's almost over,my supply of slower powder is exhausted and no more to be had! lreed

303Guy
07-17-2009, 02:26 PM
... am having fun ...Reloading has never been so much fun for me until I started with patching. A great thing for me is being able to chat with the masters and see their results!

Like windrider919's 100yd five shot group!
http://i388.photobucket.com/albums/oo327/303Guy/100ydPP22.jpg

I have been drooling over this pic ever since he posted it.:drinks:

runfiverun
07-18-2009, 12:12 AM
if you have an oversized nose jammed into the rifling with a cast boolit it will definately raise the pressure a ton.
like a 304 nose in a 302 bore.
especially combined with a 313 body in a 308 bbl.

303Guy
07-18-2009, 03:59 AM
If you have an oversized nose jammed into the rifling with a cast boolit it will definately raise the pressure a ton.But will it actually? Some folks crimp their loads to raise initial pressure for better and more consistant pressure. Just a thought, but an oversize boolit (one that just enters the throat) might actually enhance accuracy by providing more inital resistance which seems to be lacking with cast boolits. When I was still into hornet loading, I found a need to stuff in more powder (Lil'Gun) to bring pressure up enough to get consistant pressure and accuracy. I wasn't neck sizing. I also went for the heaviest bullet that would still give me a reasonable tractory - that being a 55 grainer. The 60 grainer was better but had more drop at longer ranges. (Those were .224 in a .223 bore). Trajectory indicated a muzzle velocity of 2700fps plus with the 55 grainers.

runfiverun
07-19-2009, 12:20 AM
i know it will
here's why, i was using a boolit and load in my wifes 0-6 rifle and was upping the vel's along into the 2300 fps range using 7828 powder.
now it was not burning all the powder, and powders have a definate burn pressure where they are at their most efficient for full burn.
for some powders as low as 10k is sufficient, others are fine at 40k ,and some do their best at 50k.
7828 is a slow powder meant for magnum sized rifle cases.
when i went to the oversized boolit [for 311's] as i was considering using a harder alloy and know it will make a larger boolit so why not just try the same design in a larger size?
when i went to the 304 nose it was very tight in the bore [to the point of not being able to remove them without pulling it from the case ] depending on the neck tension. [brass brand]
they should have been in the mid to high 40k pressure range.
lo and behold these loads began to show some pressure signs to the cases and very flat primers,with a wipe mark from the ejector.
the powder was also burning very clean and i was seeing a very dry bore with no lube ring at the muzzle.
the only conclusion to this was i had just jumped into the very high 5's maybe the low 60k range, and think another 2 grains would have caused a sticky bolt handle.
i could shoot two shots and let the bbl cool down and hold accuracy.
i just wish i had taken the chrono along that trip but i was just doing a quick 15 rd test for any type of accuracy.
[i live 2.5 miles from the range so i can make 10 trips a day if i need to]
this has started to lead me down a path that might prove out for high velocity in a couple of rifles i have, but i am going to have to work on the details. [lube,and possibly the nose size again. and maybe lube on the nose] and back to the short nose riding boolit.

303Guy
07-19-2009, 01:00 AM
Thanks for the info, runfiverun.

I have been shooting quite a soft alloy boolit but mine are seriously over groove! I have one mold which drops them at .319 at the heel. These are 200gr and they work - seemingly - just fine in my two groove 303 Brit. Today I tested one with a near full case of AR2209/H4350 and had a heap of partially burned powder and a very rounded primer. Because the rifling cut halfway through the lands, I would not like to increase the charge. (I was expecting the boolit to strip the rifling so I did not determine the exact charge but it was about 80% available volume).

runfiverun
07-19-2009, 06:29 PM
generally i don't worry about a boolit being oversized as every .001 over should only raise pressures about 300 psi.
but this was a case of way over sized with good neck tension and it had to be changing the characteristics of the powder,by holding it under tension all the time it did.
it may have also been trying to bump up the base of the boolit as it left the case and into the throat area [called riveting]
i think it was taking the slow powder and changing the time pressure curve to a shorter faster one by consuming more and more of it in the case and not letting it burn it's way at a gradual rate that it was designed to do.

303Guy
07-20-2009, 02:49 AM
I wondered about 'riviting' (I didn't know what it was called) but that would require a very rapid pressure rise to the point of exceeding the yield strength of the boolit while still in the neck! There's a thought.:!: