Gas checks or not? advice please

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  • Last Post 13 January 2012
2frogs posted this 09 January 2012

Figured I would ask this here to some of you seasoned guru's.... Rifle in use--Pedersoli Sharps 45-70 Useing smokeless powder.. Ok so I am using smokeless powders not and not the old Goex any more... I am trying to stay within the BP MV'S muzzle velocity's.. Do you think I should be using a gas check bullet or maybe I should be using a card wad over the powder..But we are talking not a full case as with BP.. Or maybe I really have no worry about the bullet base..These are 500 and 535 grain bullets...Thanks,John

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RicinYakima posted this 09 January 2012

twofrogies,

If you are really staying below 1250 f/s the only thing the gas check will do is scrap out the lead in the bore left by too hard / too small of bullet. I have shot pounds of 2400 in the Trapdoor in the 22 to 25 grains range. Never had a leading or powder position problem. If the bullet is big enough and soft enough it will work fine without wads, etc.

Ric

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mike morrison posted this 09 January 2012

saeco 525gr postell bullet cast soft sized .459 loaded over 25.0 gr IMR-4198 1/10 sheet of TP to hold the powder at the primer. WLR primer .060 card wad push in by the bullet when seated. as best i remember about 1200fps. Browning BPCR. works to 1000yds. or more. will hit the white buff at raton. this is a plain base bullet. no need for a gas check. imho m

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Ed Harris posted this 09 January 2012

As a general rule GCs not required in subsonic handgun loads or in rifles below about 1400 fps and 20,000 psi. Approximation only. Your mileage may vary.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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andym79 posted this 09 January 2012

Hi guys i want to propel, 165gr cast bullets at between 1050 and 1400 fps. I have been advised by some that to avoid leading I will have to load below 1200 fps, without a gas check. Yet I read above 1400fps which is what I thought!

But at 1200 fps according to Lyman the pressure for a 170grn projectile propelled by 6.5grn of Red Dot will produce 24600 psi so at that rate pretty much all cast bullets need a gas check to avoid leading?

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Mike H posted this 09 January 2012

andym79 wrote: Hi guys i want to propel, 165gr cast bullets at between 1050 and 1400 fps. I have been advised by some that to avoid leading I will have to load below 1200 fps, without a gas check. Yet I read above 1400fps which is what I thought!

But at 1200 fps according to Lyman the pressure for a 170grn projectile propelled by 6.5grn of Red Dot will produce 24600 psi so at that rate pretty much all cast bullets need a gas check to avoid leading?

What calibre are you intending to use? Should be alright in a 308 Winchester. I use AS-30,6.5 grains with 196 grain,no Gc. Have shot the same bullet with 10 grains of AP-70,1399 feet per second,no problems. Mike.

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2frogs posted this 09 January 2012

thanks for your replys....My bullets are the big 500 grain round nose and the postell bullet's

I have not put them over the chrony yet..need a new battery....I am not sure of the alloy mix as these are bullets that I have bought since I no longer cast my own...But the Postell is on the soft size,I know that..Haven't shot the round nose yet....I am using either 5744 or the Trail Boss and As far as the data from the book I am under 1200 fps..I am lubing them nyself and if I remember right the lube in the sizer is SPG...

I have finally found a place here in NEW YORK to shoot 200 yards which makes me happy as a pig in poop...ha ha...And close to home as well...

Anyway,I appreciate you help and if you have anything else to share please feel free to do so....John

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mike morrison posted this 09 January 2012

to add to what i said. i get no leading. also you jogged my memory. a fella i usta shoot with was shooting the same as i described except he used 5744. identical guns, bullets only difference was the powder. our sight setings were identical to the 500 meter line. your bullets should be good unless too small. SPG=good stuff. m

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2frogs posted this 09 January 2012

I wanted to add here that I am running these through a .459 luber sizer-LYMAN- which is the same as I used when shooting the Goex powder...Thanks again John

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R. Dupraz posted this 09 January 2012

Personally, I wouldn't use a card wad in any straight walled case that was not plumb chuck full of powder. I know of two incidents where this occured. One was Shiloh Sharps 45-70 where the chamber end was sectioned and clearly showed the rings.

RD

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onondaga posted this 10 January 2012

2Frogs:

John,

You may have read my posts mentioning BPI Original filler. I consider that product a useful and reliable substitute for gas checks when used on plain based bullet, straight walled cartridge loads.

Plain base bullets are so easily damaged handling or even tumble lubing. The slightest nick can be a pathway for gas jetting to start. This problem is avoided with BPI, as it acts as a quasi gas check by protecting the seated bullet base from direct fire of the charge and I believe most of it also stays right against the bullet base the length of the barrel to do the job all the way.

I shoot plain base bullets in 500 S&W (250 gr.) at 1885 fps and .458 WM at 1610 fps (329 gr.) with #2 Lyman clone alloy. Those are my sweet spot accuracy loads for both calibers and both are sub MOA for me. My bullets fit well and are .002 - .003” over G to G and tumble lubed with 45:45:10 Recluse or even straight LLA . I think that is pretty impressive and have been very happy with the product. Your Sharps 45-70 would likely love this stuff with plain base bullets and H4895.

 When designing loads with BPI, add the weight of BPI to the bullet weight for a total projectile weight when figuring pressure. The BPI is high heat resistant particulate plastic, it is fluffy and easily compresses to 50 % of its own volume. I generally add enough filler to obtain 105% or more load capacity. Ignition has been 100% for me with thousands of rounds fired. My bores stay remarkably clean and no unburned powder kernels are left in the bore.

My source: http://www.midwayusa.com/product/695248/bpi-shot-buffer-original-500cc-approximately-1-2-lb>http://www.midwayusa.com/product/695248/bpi-shot-buffer-original-500cc-approximately-1-2-lb

Gary

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Big Iron posted this 12 January 2012

I have been using 34 gr. of IMR-3031 with both 340 gr. and 405 gr. cast bullets. I'm using corn meal as a filler to keep the powder back by the primer. I fill the case with corn meal to within about one quarter inch from the top and seat the bullet. These are shot in a Trap Door and a Repro. Winchester 1886. No leading, no problems!

Lock and Load!  :D

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mike morrison posted this 13 January 2012

has anyone used ground corncob media instead of cornmeal? i tried it and it seemed to work fine. when fired it would seem to me that it is compressed to make a natural wad and clean the bbl at the same time.

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onondaga posted this 13 January 2012

I have used corn cob, creme of wheat, grits, bulgar wheat, peat moss, pharmaceutical dietary fiber, etc. They will all work but all of those have a commonality that steered me away from them. They are all plant based, organic stuff and easily absorb moisture from the air. They can be stored with dessication packs to make then safer and more reliable, but the moisture is a problem with contaminating ammo propellants and effecting load reliability and consistency of  propellant burn.

Ammo with organic filler should be used quickly to avoid any problem with filler that has absorbed moisture. One month is a safety guideline I follow with organic filler in the ammo unless I have taken extreme dessication precaution with the storage of the organic filler before loading it into ammo.

Dacron Filler, particulate plastic filler like BPI Original and Precision Reloaders PRPSB filler all do not have the moisture attraction and retention characteristic that the organic fillers do.

A really big plus for Dacron and BPI is that they weigh many times less per volume than grits and the like. This is important because in ballistic applications,  the weight of the filler used in a particular load is added to the weight of the bullet or even to shot in shotgun loads for a total projectile weight for the calculation of appropriate powder charges, pressure and recoil calculations too. The filler is fired down the barrel and counts as part of the projectile and it has weight. This is why fillers increase ballistic pressures.

 Pufflon is a somewhat popular and very pricey filler I have also experimented with. It has many claims for it's surprisingly simple ingredients. It is made from dietary fiber and a variety of dry lubricants like powdered mica, graphite or non caking food additives to keep the dietary fiber from sticking to itself from exposure to air moisture and forming glue!!!!!! Buyer beware, a Pufflon like filler isn't that special and you could make it yourself easily.

My favorite is the BPI Original with light weight and it acts as a quasi gas check on plain base bullets to extend the pressure range of your alloy and it enhances a broad sweet-spot of accuracy for me with plain base bullets in my big caliber straight walled case reduced loads. 

There is also a common error that many hand-loaders are unaware of. A small, light weight powder charge combined with a large volume of heavy weight filler does little to reduce felt recoil with large capacity straight walled cases and a danger zone in ballistic pressure can be achieved by ignoring that.

Gary

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