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View Full Version : Throat design and PP



Nobade
03-23-2009, 08:00 AM
Recently I have been playing with PP in my 308, with terrible results. Typically 6 foot groups at 200M. I have tried about everything I could think of, but still no luck. Yesterday I wrapped a bullet a lot further out than I had been, and tried to chamber it. The patch got pushed back and wrinkled up. Ah Ha! This rifle has a very short, accuracy type throat that shoots really well with naked bullets. Perhaps a longer or more generous throat would work better? Perhaps something like military Mausers have, a big taper instead of a cylinder section? I have a take off 30-06 barrel I think I'll fit to this rifle as a switch barrel, and throat it bigger and longer to see what happens with that. Any ideas or comments?

pdawg_shooter
03-23-2009, 08:06 AM
I patch all my bullets to engage the rifling when clambering. Get my best accuracy that way.

45 2.1
03-23-2009, 09:33 AM
All efforts with PP boolits should have the patch engauging the rifling origin (for all you smokeless shooters). If it doesn't and the patch has to jump to engauge the rifling, you accuracy will be NON EXISTANT. The blackpowder guys usually have their patched boolits a little small and into the rifling more than we do.

oso
03-23-2009, 10:09 PM
Agree with the above replies. Seat to touch rifling, longer or larger throat won't help. If trouble chambering the longer patched boolit size it down til it fits. Does your un-patched projectile fill the bore enough to show the lands?

Nobade
03-24-2009, 07:25 AM
Yes, I am sizing the unpatched bullets to .300, and they are a hard thumb press in the muzzle, with light engraving. Then patching and sizing to .309, and I'm thinking I might have to make up a .308 die to reduce them a bit more so they will engrave the rifling without bunching up the patch.
The idea with the other barrel is, I have almost zero paralell bullet shank outside the case in this .308, and it seems to me that the projo would get a better, straighter start if it had some throat to align it with the bore first. Besides, the barrel I want to use already has a long throat from the factory so instead of setting it back 1/4 inch I would rather use it as is, just straighten out the crooked factory throat a bit with my own throater.

This PP stuff has been fun so far, and it will be a lot more fun once I get it to shoot well!

oso
03-24-2009, 10:20 PM
Gosh, if you have almost zero parallel boolit body outta the case I gotta ask what is the weight of the boolit and are you seating it below the neck?

docone31
03-24-2009, 10:34 PM
A suggestion.
I size my .30s to .308, then wrap two wraps with 8 X 11 notebook paper. This I size down to .309, smearing either JPW, or Turtle auto wax lightly for lube.
I use starting load data for the weight of the comparable jacketed load.
Once I found my diameter, I outshoot my identical jacketed loads. On a bowling pin at 100yds, my patched load hits the neck, same point of aim with jacketed, hits the body.
My prime casting drops at .301 on the nose portion. If you are sizing to .300, this might also be an issue.
You are close enough that it might be something small.
At 200 meters, small means a lot.

Nobade
03-24-2009, 11:42 PM
Bullet is 180gr, and does seat below the neck. This throat is set up for VLDs, with only .030" parallel. I'm going to do some more playing with it when time allows to see if I can patch it a bit shorter and let the nose ride the lands further out to keep the base in the neck. I do think it is a small thing I haven't been doing right, so hopefully I can isolate it soon. I just got my 366" sizer done to start playing with PP in the 375 Taylor, and that should tell me if I'm on the right track since it has a long amount of parallel throat to get the bullet well out there.

docone31
03-25-2009, 09:38 AM
That is the fun of paper patching.
Once I got it dialed in, I did backflips! From there I could adapt the principles to my other calibers.
Just a thought,
If you smeared lightly some Clover Lapping compound on the patches, you might take the "edge" off the rifleing entry. If that is an issue.
I suspect it is nose diameter however.
I use the Lee 180gn for patching in my .30s. It is for gas checking. I do not use the gas check, and size that one down. All my bases are in the case below the neck. It is cheap enough to give it a try. I size it to .308, then wrap and size to .309.
They hit fast, hard, with no keyholes. I have yet to recover one from the berm! They go in deeply.

oso
03-25-2009, 08:31 PM
Yep, I keep the PP base in the neck of the case.