Flyer vs. Poof in Flight?

[KVO]

Gun in question is a 7mm-08, 26" barrel 1-8" twist Obermeyer most often shot with heavy weight jacketed loads. Pillar bedded, etc. Very accurate gun, so this is strictly a test of my ability to load PP. Optics are 5-25x Vortex Viper PST Gen 2. For reference I have never had outstanding results with cast in this rifle. Thought I'd try paper patched both low and high velocity "just because."

Boolit used was an NOE 150gr Loverin style. Two wraps of tractor feed paper, no pre sizing. Wet wrapped, finger smear of BAC and run through .286" push thru sizer. WW-ish alloy.

Using arbitrary loads, no workup on either end, 38gr of RL15 @ 2546fps looked not too shabby... except I fired 5 shots and only 3 made it to the target at 100yd? Possible blow up in flight?
256792

Slowing things down, I tried 14gr of Alliant 2400. Two groups on the same target: Black circles are PP, red squares are gas checked and lubed. Again, same150gr Loverin and load, only difference is PP vs lubed+GC. Velocity =1575fps. As you can see the PP group was an order of magnitude larger. Patch not separating from boolit at the lower velocity?
256796

All PP were wrapped, lined, sized, etc from the same batch between both loads. Brass is FL sized Lapua, annealed necks, expanded w/NOE expander mandrel. Any thoughts phenomena at work? Did I err on the weight of my Eye of Newt?

[popper]

243K rpm says poof! 1500 says 135K rpm - maybe OK. And yes, the PP should shred at the muzzle.

[country gent]

Im thinking the grooves wet wrap and bac smear and heavier paper may be hindering the paper release from the bullet. I shoot paper patched BP rounds and I use Seth Cole 55W (a shade under .002 thick) dry wrapped tight. The bullets are smooth sided cup based, no tail but a small circle of the base shows in the center this makes a very square flat base. Just before seating they get a very light wipe of JoJoba oil, just enough to give a sheen to the paper. A drop will do 3-4 bullets and then wipe excess with a patch

If your wrapping with a tail and paper isnt releasing the same the tail and drag changes may be a problem. the wound tail at the base could be steering it.

[KVO]

I definitely believe that the wrong lube can cause uneven patch release and wreck accuracy. I previously tried tumbling patched bullets for a different rifle in a healthy amount of BLL (seemed like a good idea at the time) and accuracy went to hell, as in barely able to stay on a 8 1/2x11" piece of paper @100yd. Those had a definite confetti puff at the muzzle none the less.

Given common options for patch lube, does any one have a go-to for smokeless PP accuracy? Something like a finger dab of Bag Balm, Vaseline, or Ballistol would be convenient but I'm open to suggestions and am not opposed to buying something not on hand.

As far as tails go I've been wet twisting and clipping when dry, then push thru size nose first. I intend to try the shorter patch forming a circumferential ring around the base as country gent suggests. I appreciate the input!

Ultimate goal with this gun would be to develop a 100-200yd target load with better than cast/lubed/GC accuracy (as compared to the mediocre performance of those in this particular gun). Fallback plan is finish the 40X with a 1-14 twist barrel I've been working on specifically for cast and reserve this gun for jacketed only.

[bmortell]

have you ever gotten accuracy at that much rpm ?

[JimB..]

I don’t know if your bullet is coming apart, I kinda doubt it, but there have been challenges over the years trying to find a cast bullet that will shoot well at 200,000+ rpm and I don’t remember anyone having much success.

[dave roelle]

Fold the base when wet patched, size point first, the pushing pin will iron the base patch fold over flat and square, lite coat of JPW prior to sizing

[popper]

I have to add Cu to the alloy for high rpm loads for 308W, else 'poof'. Soft PB won't cut it.

[KVO]

To be honest I hadn't given a lot of thought about what effects fast twist/ RPM would yield for this gun. It was more of a spur of the moment "let's just try it and see what the target tells us." I definitely think there is a component of inconsistent patch release with the particular way these bullets were assembled. Statistically inferior sample size of 3 aside, my speculation is that the higher RPM and velocity helped to jettison the patches sooner than the lower velocity (shotgun pattern) PP load.

I don't need a screaming velocity cast or PP load, just one that shoots accurately. Whichever end of the speed limit sign that ends up on is not terribly important to me. As an aside, jacketed bullets are as boring as they are easy...

[Good Cheer]

FPS...
Was always a great fan of coasting a boolit into where it was supposed to go. It's like making a puck nudge the other one out on the far end of the shuffle board.
:drinks:

[ShooterAZ]

Have you tried working with any slower powders? I've had really good results PP in 308W and 30-06 with WW760. Start at the listed minimum charge for the bullet weight and work up.

[303Guy]

You didn't mention whether or not you weighed the boolits. I've had nice looking boolits having cavities that showed up after firing. That kind of thing could explain the extreme flyers.

When I did have success with paper patching, I was using a softish copper alloy. It cast well and was pretty tough. Velocity was not high though. That was in a 303 carbine. Near MOA with original Enfield sights.

Have a close look at those circled boolit holes - notice the yaw? Unless you can capture a fired boolit, it's hard to say what's causing it. Since they are the same boolit with the same powder charge, I would say the patch not coming off cleanly as you suggest.

[KVO]

There sure is some yaw in those lower velocity PP, especially the low left shot which I hadn't noticed before- Good eye 303Guy!
These were not weighed prior to loading. All my PP experimentation to date has been with conventional GG designs either sized to bore +.001" or sized after patching, all GC designs. Is there a significant improvement to be had with PB designs or potential issues caused by using a GC style bullet w/ PP?

I tried slower powders in 308 with some success, the above are the only PP shots fired with this gun though. I have lots of powder choices on hand. When the unseasonably wet Texas weather clears up I'll shoot some more with the above recommendations built into ammo. Thanks!

[popper]

2 observations. 1) lubed loads show a circular pattern (pretty accurate though) on the target. I've gotten this before with bases NOT flat/good.
2) PP are horizontal stringing. Doubt that is PP problem. Note that there is a dark ring around the holes indicating dirty lube/(PP?) carried to the target. I've heard several theories about vert vs horiz stringing being related to fps and barrel harmonics - but no real physics discussion. Mine tend to be me and recoil.
RL15 is a slow powder. Have you tried something like 335 or 4895?
I gave up trying to PP on the 30/30 - just too much trouble so I now PC that I can push to 2700 accurately in 308W.

[mattw]

Not the same cartridge as you... but, I shoot a 6mmx284 and love to hit pdogs with a 55 grain bullet that launches at nearly 4000fps. About one in 7 of these will go poof, cool to see happen. But when the 6 in 7 make contact it is amazing to see. The accuracy with them is not as good as with proper bullets at high velocity, but minute of dog out to 300 or so yards. Past that, not so good.

[303Guy]

I don't know which is better, PB or GC based. I was getting cupping which is not necessarily bad. What I think is bad is an uneven trailing edge. The GC design would eliminate that problem. Then again, the GC rebate might be smaller than the bore diameter which would reduce support in the bore. Does that matter? The patch would still be in contacted with the bore. My failing is that I have not had (or made) the opportunity to go to the range and test these things. Life just got in the way!

I have a Lee 180 gr .311 mold which casts a little under bore diameter. Yet, with patching, the patch actually transfers a small rifling impression onto the bore ride nose section. My question is whether the patch will come off cleanly at the muzzle? With that boolit, I don't see any problem with the GC rebate.

[BPCR Bill]

Have you looked at the patches after firing the rifle? Bullet upset upon firing will seal the bore, and your rifling should neatly cut the patch down the sides. When the bullet exits the muzzle, you should get nicely cut confetti laying on the ground in front of the bench. Traditionally, paper patched bullets are smooth sided, no grease grooves. Wrapping a grease groove bullet will likely up the chance that paper remnant will stick in the side of the bullet causing inaccuracy. Just a theory, as I've never attempted wrapping a grease groove bullet.

Bill

[Dan Cash]

303,
If I may weigh in regarding the slight rifling impression on the bullet nose patching. I am using a paper patched grease groove bore riding bullet in my .30-40 which does exhibit slight rifling marks on the nose after chambering. It gives very nice full length confetti upon firing and accuracy is as good as the gun will give with any projectile. This bullet is a gas check design and my jury is still out on best accuracy; with or with out gas check.

[303Guy]

Thanks for the thumbs up, Dan.

Bill, I've done most of my testing into a 'test tube' so depending on velocity, I catch the patch fragments. With heavier loading and I find very little patch remnants. The catch medium is rubber tyre grounds which gives a reasonable indication of real life performance but with lighter loads will catch a boolit almost intact.

The bore condition tends toward pretty worn or rust damaged which changes how a patch performs in the bore. I haven't done a lot of testing in my good bore rifles.

It's a bit ironical that now when I have a bit of time to actually go to the range, I can't for the very reason I have the time. :( Besides, I'm busy doing stuff on my home. 8-)