Seating depth

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  • Last Post 13 December 2021
Revolverman posted this 08 June 2015

Real beginner question here. I always assumed that keeping gas checks at or above bottom of the neck was one concerning accuracy.  Is that the only consideration?

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LWesthoff posted this 08 June 2015

Gas checks that don't crimp on can fall off inside the case if they are not confined by the case neck. Lyman gas checks used to be the “non crimp” style, but they are now identical to Hornaday crimp-on checks - in fact I understand they are made by the same company.

The other problem is that hot combustion gasses may get ahead of the check and cause leading and inaccuracy. Note I said “may", that doesn't always happen.

It's still a good idea to keep at least the front edge of the check in the neck of the case.

Wes

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Wineman posted this 08 June 2015

I shot some RD 165's that were at 0.314 in my M1903a3. The blunt nose had me seating them below the neck. They were GC shot as plain base over 7 gr of Promo (same as 7 gr Red Dot), three coats of 45:45:10 and a WLR. The 3'x4' election sign I “removed", after the election of course, (as a backer they are weather proof) was not large enough to have all the shots land on it at 50 yards. Many were sideways.

Dave

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358156hp posted this 09 June 2015

I have heard of, but never seen myself, instances of bullet shanks seated below the case neck mushrooming, and raising pressures. It would seem to me that they'd need to be really long bullets, or the chamber throat would have to be really short for this to be possible. But I thought I'd mention it for the sake of discussion.

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Brodie posted this 09 June 2015

Somewhat the same thing (the base of bullets seated below the case neck mushroooming) has been suspected if not prooven with paper wrapped bullets seated below the case neck. At least recovered bullet bases are seen to be cupped and in some cases peaned looking as if they had been beaten with tiny hammers.Brodie

B.E.Brickey

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John Alexander posted this 09 June 2015

I have read several reports on good performance with the gas check seated below the bottom of the neck.  That of course doesn't prove that it never causes trouble.

I suspect that problems usually come when a bullet with a bore riding nose has a nose too big to go in the bore as it was designed to do resulting in loss of gas seal and the resulting gas cutting and leading ruins accuracy but that is just my guess.

The speculation that the pressure on the base might cause mushrooming of the base flies in the face of the fact that the pressure is equal in all directions (as with all fluids) and the sides of the base are being supported by the same pressure as on the base. When equal pressure is put on the ends and sides of a cylinder of soil in the lab nothing happens and soil is a lot weaker than lead. If it mushroomed under these conditions it would be magic.

Mann and others have reported that high pressure loads in very short barrels, can mushroom the bases of very soft bullets AFTER they leave the barrel and the sides are no longer supported by the bore, but that is a different story.

The peening of a plain base with tiny hammers noted by Brodie was seen and photographed and published in Precision Shooting by Merrill Martin.  He attributed it to yet unburned powder grains flying around at high speed and denting the bases of soft plain base bullets. John

 

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Reese posted this 09 June 2015

What is the significance of the gas check falling off the bullet? Excess pressure?

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Tom Acheson posted this 09 June 2015

Some have theorized this....the check ending up in the barrel and then the next shot.......at minimum a bulged or rung barrel.

Tom

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Reese posted this 09 June 2015

Thanks, I need to pull some bullets to find the one.

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billglaze posted this 09 June 2015

In shooting the .308 I find myself routinely seating the bullets with the gas checks projecting into the powder space. With the 311299 and the 311284, it can't be easily avoided, particularly with the Mod. 12 Savage, which has quite a tight throat. No problems so far, but, (as they say in ladies reducing salons, “there's always that big butt") I have used nothing except crimp-on GC's for years.

Just today, I shot some lead/zinc bullets where, when removing them from the Lubrisizer, the GC had actually bit into the bullet base so hard, that it broke the very base end off the bullet, leaving me with a GC filled with bullet metal; it was in the shape of a tiny, .30 cal. wafer. It happened on 2 out of 10. Seemed to shoot passably, even though the bullet was about 1/16” or so shorter.

Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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LWesthoff posted this 09 June 2015

Got a hunch it was the zinc (which is VERY hard) that caused your bullet to break. Do you really cast - and shoot - lead bullets with zinc in them? On purpose?

Wes

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billglaze posted this 10 June 2015

Actually,  I did cast with some Zn contaminated stuff that I didn't know about until later.  The alloy made  beautiful looking bullets, well filled out, and I only figured it out when I weighed the results--my usual 200 gr bullets were weighing ca. 187 or so.  Figured I'd shoot some just because I had them.  So far, no world's records, but pretty surprising accuracy.  About 1955 or so,  I cast some all-Zn Swift bullets; a re waste of time, at that time.  Now,--I'm not so sure I wasn't a mite hasty. Bill Clinton

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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billglaze posted this 10 June 2015

I have absolutely no idea how that particular last name got attached to my first name.  It is a mysterious cyber-accident; that particular name is just about the last one I would choose. Bill GLAZE

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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rockquarry posted this 14 June 2015

I always use crimp-on Hornady gas checks and routinely must seat with the bullet base extending below the case neck as with the .308 and a long, heavy bullet.

Not that it couldn't happen, but I've never had a problem of any kind and accuracy has sometimes been exceptional. Some of the negative aspects often mentioned when this topic comes up are pure conjecture and speculation, i.e., not based on fact.

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gpidaho posted this 15 June 2015

Mr. GLAZE:  As Larry T.C.G.  would say, “Now that's a funny one right there"  More Voo-Doo on the net. than in casting bullets.   GP

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Revolverman posted this 16 June 2015

I've been loading 31141's below neck level for my wife's Ruger 77 Ultralight in 308 since about 1980. Since its a short, light barrel I only shoot 3 shot groups at 100 yards to test it. Groups run about 1- 1 1/4 inches and are consistent. Since recoil bothers her a lot I only load it to about 1,800 fps---plenty good for 40-50 yard shots on deer. I had seen a lot about keeping bullets seated out and just wanted to learn if I should be changing my ways....guess not, I'll stick with what I've been doing.

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Dirtybore posted this 15 April 2016

I'm not loading cast bullets in cartridges with short necks so seating the gas check below the case neck hasn't been an issue. In any event, I try to avoid the situation.

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karlrudin posted this 19 April 2016

In the past 3 years of learning cast bullet casting and shooting, I've talked to everyone I have seen in life and in cyber for tips and tricks. I've also heard the theory of not seating bullets with GC below the neck. In my case I have to and would think about changing bullets but this bullets flies well. But I had a fellow cast shooter at the range give me a tip. Before putting on your gas checks, aluminum slip-ons, in my case, a dab of Super Glue in the cup. I find then in the dirt back stop all the time. Just saying.

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Buttersdad posted this 13 December 2021

I have been using gas checks since I started casting, Hornady, then Gator and Sage. They all crimp on and I haven't ever lost one or had any barrel leading. I bought my 6.5 Creedmoor most recently and anyone who shoots any 6.5 rifle knows how long these bullets are. I use the Lyman 266469 bullet with a gas check and powder coating. I read an article in Handloader magazine, don't remember which volume, but it said the concern is not necessary especially with powder coating.

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