PP gas cutting

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kwilliams
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Re: PP gas cutting

Post by kwilliams » Mon Mar 15, 2021 6:45 pm

Don tried .448 the other day but this is in a Ballard and could not thumb them in, and a caming tool of sort does not work with out a frame stud. Hence maybe I am answering my own question by leaning towards the dual dia. option.
kw

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Don McDowell
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Re: PP gas cutting

Post by Don McDowell » Mon Mar 15, 2021 6:48 pm

Thinner paper. Or seat a touch deeper.
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semtav
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Re: PP gas cutting

Post by semtav » Mon Mar 15, 2021 7:52 pm

kwilliams wrote:
Mon Mar 15, 2021 6:40 pm


Brian I may have to come see you and "borrow" a few DD slugs!

kw
Unfortunately I currently only have groove diameter bullets. But testing a few of those might give you your answer.

semtav
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Re: PP gas cutting

Post by semtav » Mon Mar 15, 2021 8:07 pm

Kim what is your groove dia? That bullet kenny had made up might be the answer

bruce m
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Re: PP gas cutting

Post by bruce m » Mon Mar 15, 2021 9:29 pm

wow you do have an issue.
you have set yourself up for a problem with bore diameter bullets in a chamber for groove diameter ones plus freebore.
the part ( in the case + freebore) has to bump up too far to get a quick enough seal.
a bullet like the one kenny has just bought is what you need, where the patched to diameter slides into the freebore, the rifling, and the case with just a little friction.
i can shoot bullets like that as hard as 10:1 with no problems, and they bump into the rifling well.
if you want to continue with the bullet you have, it will work breech seated at 16:1 using a breech seater and a case full of powder.
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kwilliams
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Re: PP gas cutting

Post by kwilliams » Tue Mar 16, 2021 5:27 am

MY barrel is a Green Mountain .408" groove. Saw Kenny's DD drawing/sketch and waiting to see his posted results. I Know this is a GG chamber by Design, but wanted to see if I could wring out some positive results by experimenting, And a few loads have come close....very close and then you get a flyer(s) that kills the whole string.
thanks all
kw

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Distant Thunder
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Re: PP gas cutting

Post by Distant Thunder » Tue Mar 16, 2021 7:30 am

kw,

I would think that a 2-Diameter paper patch bullet would solve your problem, but you have to do as Bruce said and fit the 2 diameters to your specific chamber. Just any size 2-diameter bullet may or may not work. It is fitting the diameters to the chamber that is the benefit of the design. This probably calls for a custom mold and to avoid multiple mold purchases and to get there you would need accurate dimensions from your chamber and a good understanding in how a 2-diameter bullet works.

Just any 2-D ppb might be and improvement but may not be optimal. You could certainly try some one else's 2-D ppb to see what effect it might have, but to get the top level of accuracy you would be best to have one made for YOUR rifle.

Kenny put a lot of thought into his bullet and got good feedback from those who have been trough the process of developing a 2-D pp bullet(s) for their rifles(s) and that should give him a high probability of success, that and the fact that Kenny is not the average shooter and he is not new to paper patch bullets.

Looking at you chamber cast and just guessing it does not appear to me that your freebore is excessively long, maybe .150" (?). That would make it an excellent choice for a 2-D pp bullet. Since it is a .45-90 a groove diameter would work, but would either have to be seated deep enough that a bullet of any weight/length would take up a lot of your powder capacity or be short and light enough to make it a less desirable choice for longer range shooting. So that would somewhat depend on what you want to do with the rifle.

With a properly designed 2-D ppb you could decide what powder charge would be best for your intended use and design a bullet that would seat accordingly. You would still have to develop a load with the best charge weight and compression, but you could ballpark the powder charge in your design.

It seems that most often for bore diameter ppb to work out well in a grease groove chamber it is best to have a fairly tight chamber and minimum freebore. Those two characteristics are present in the designs that Shiloh uses in their rifles and I have used their chambers with with straight bore diameter ppb and had good results and I have seen many others do the same. The only rifle I have that has never played well with paper patch bullets of any design I've tried is a .45-70 that has both an oversize chamber and a longish freebore (.200"). All my other rifles have responded very well when a paper patch bullet was properly sized to fit the chamber, whether bore diameter, 2-Diameter or groove diameter designs were used.

The two places most shooters seem to invite failure with paper patch bullets is in understanding the need for a proper fit and having the OAL of the bullet match the twist rate of their barrel. They seem to miss on one or both of these points and then conclude that paper patching simply doesn't work. If however you can get both of those right in a bullet of the correct alloy and do a good job of load development the results are amazingly accurate. After that loading paper patch bullets with very good results is an easy thing to do.
Jim Kluskens
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semtav
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Re: PP gas cutting

Post by semtav » Tue Mar 16, 2021 8:08 am

kwilliams wrote:
Tue Mar 16, 2021 5:27 am
MY barrel is a Green Mountain .408" groove.
kw
Guessing you meant .458.
My bullets are .454, so unless you can find some really thin paper they might be a touch big. Got a bunch cast if you want to try some.

What is your twist?

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Kurt
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Re: PP gas cutting

Post by Kurt » Tue Mar 16, 2021 8:25 am

The .454" diameter will work with that free bore. Load it like you would a GG with the ogive snug intoto the throat leads. You will loose a little powder room having to seat it deeper in the case but with the .45-2.4 it will do it's job.
With your bullet your having a problem with, use a 3/16" lube wad between two .03" cards and this also will hold the gas cuts down. The lube wad helps sealing the gas blow by.

Using a groove diameter PP bullet breach seated that rifle would put a smile on your face.
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kwilliams
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Re: PP gas cutting

Post by kwilliams » Tue Mar 16, 2021 8:45 am

Brian, yes .458 groove. my fumble......and yes weather is miserable today, so no testing. Free bore is 1.30", not good at trigging that out for the angle.
Thanks Jim and Kurt, lots of food for thought. So its back to the bench to try a couple different wad stacks and OAL before I bench it.
Putting down some dim's to have a dd mold cut.
thanks all
kw

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Re: PP gas cutting

Post by TGC » Tue Mar 16, 2021 9:01 am

Kw, would you please post the measurements of the case mouth inside and outside after firing . Also what is the rate of twist of your barrel? Kenny's bullet may be a little long for a 18" twist rate. Tim.

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Re: PP gas cutting

Post by Kurt » Tue Mar 16, 2021 9:31 am

Kim,
Another component to use is a dense 1/16 cork wad. I have found nothing that will seal gas pass by better than a good dance cork wad.
If Obturation is a none issue I have found nothing that works better. Cork will dampen the blow on the bullet base so it's best not to use it with hard alloys and slightly undersized PP bullets.
Good quality small grain dense cork gasket material is hard to find. I get mine from Tractor Supply. Napa has cork gasket material but the grain is a lot courser. I use a OJ carton wad over the powder and a cork under the bullet.
I have used the cork wads when I was heavy in the front stuffer rifles that I carried it over to the suppository rifles because they work so well. :D
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kwilliams
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Re: PP gas cutting

Post by kwilliams » Tue Mar 16, 2021 10:00 am

TGC
Case id after firing is .459+ , hence the neck size step to get to .451, with 1-18" twist.
Kurt, I do have good fine dense cork and I guess I forgot to give that a try, but will soon. Today loaded some back up with a lube cookie between 2 .030 veggies, for another try when weather improves here, this combo showed some promise last week, and since then I have change case length ....stay turned.
thanks
Kim

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bpcr shooter
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Re: PP gas cutting

Post by bpcr shooter » Tue Mar 16, 2021 11:16 am

My bullets are pretty close to what you need, when I get home I can verify and let you know. If you want then I can send you a few to play with?? Jim designed the nose profile and it works VERY well!! My large Dia measures out at .290 long, leaving .160 in the case for your cases.
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Kurt
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Re: PP gas cutting

Post by Kurt » Tue Mar 16, 2021 11:27 am

Once you get the gas seal problem fixed with that free bore throat you will see that rifle shoot. Those gas cuts or even the small mouse nibbles on the bullet bases will kick up dust around the target more than putting holes through it.
I fought my .400" free bore chamber for better than a year till I found a patched groove diameter or a tapered bullet with it's base at groove diameter and the cork wad under those bullets the sun started to shine with that early Pedersoli Quigley rifle.
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