20 gauge centerfire bras cases

[rickt300]

I finally got a 20 gauge USH barrel. What should I build a mold for weight wise and what might be the diameter? Size die wise what should I use? Lastly where should I begin with what powder?

[IOWA DON]

Rocky Mountain Cartridge can make cases. Bullets should measure about .622-inch for a barrel with a .620-inch diameter. Mine cast at 720 grains and can be drilled our for hollow-pointing witha 3/8-inch drill to reduce weight to 550 grains. I get 1000 fps with the 720-grain bullets and 1300 fps with the 550-grain bullets with Accurate 5744 powder. Accuracy is good and pressure seems low.

[rickt300]

That sounds just like what I am looking for. A 550 gr. HP at 1300 fps. Where did your mold and dies come from?

[IOWA DON]

The mold is from NEI Handtools Inc (Scappoose Oregan 503/543-6776). It is a shortened version of their mold for a 900-grain bullet for the .600 Nitro Express. The dies are from CH Tool & Die Company (Mt. Vernon Ohio 740/397-7214). They are custom made and one needs a press large enough for the .50 BMG to use them. Also, I got the mold and dies 6 years ago so don't know if the telephone numbers and addresses are still current.

RocKy Mountain Cartridge (Cody Wyoming 307/587-9693) made the cases to precisely fit the chamber of my gun based on a chamber cast I sent. CH Tool & Die got both the chamber cast and a couple cases for custom making the dies. Note that the cases have very thick brass where the bullet is. They are not like the brass cases for loading bird shot.

The cases fit the bullet and chamber so well that after the first loading I have never had to resize a case. That is, the neck area of the case springs out to release the bullet when fired, but springs back to its original diameter afterwards so that the next bullet is held into place. I understand the cases bench rest shooters use do the same thing.

My TCR barrel is custome made and has the outside contour of a 10-ga barrel, and the ction is strong enough for a .416 Remington Magnum. I did some rough calculations and figure it would stand 20,000 psi loads for the larger 20-ga cartridge. I think the 1,000 fps load with the 720-grain slugs is very low pressure by looks of the primers. The cases use shotgun primers.

For the loads with the 550-grain hollow points I looked at .45-90 loads with Accurate 5744 powder. The .45-90 cartridge is of similar length and the 300-grain .45 caliber bullets have the same secional density as the 550-grain 20-ga bullets. Anyway, either the 20-ga with 550-grain bullets or the .45-90 with 300-grain bullets would require about 12,000 psi for a velocity of 1,300 fps using Accurate 5744 powder. At least that is my thinking. However, I have a gun good for around 20,000 psi so if I am wrong by a little thats not a big problem.

I mostly use the cast slugs and brass cases for plinking at the rifle range. My gun with the 23-inch barrel weighs about 8.5 pounds with scope and recoil is mild with the 720-grain load. However, I have plinked two deer with the cast slugs (1) a doe shot with the 720-grain solid which ran about 50 yards before going down, and (2) bedded down spike buck shot with the 550-grain hollow point which never got up. The 550-grain loads seem to recoil more than the 720-grain loads. I got the 550-grain slugs up to 1,520 fps and the recoil was starting to get real noticed, but still not that bad compared to some 12-ga slugs in very light guns.

For serious deer hunting I used to use the best Winchester sabots but now use the Hornaday SST's. I've got a lot of deer with the 20-ga and good sabot ammo. A lot of them were over 150 yards and a couple deer were at just over 200 yards (measured with a laser rangefinder). Saturday, during our Thanksgiving Holiday doe-only season I got one at about 150 yards with the Hornaday SST's. (That is "about" because I did not use the rangefinder.) It ran about 50 yards before going down which is fairly typical.

[rickt300]

How long is this bullet. I may build myself a mold with a more pronounced flat in the 600 grain weight range. Does 5744 come anywhere near filling the case? I think you could get 1900 fps but recoil would be just more than too much.  I am planning to use my gun on feral hogs hunting at night and want plenty of slap and good blood trails.

[IOWA DON]

The 720-grain bullets are 1.03-inch long. I cast them out of pure lead and at 1,000 fps I think there was no expansion at all on the deer I shot. At least the entrance and exit hole appeared the same size.

The deer shot with the 550-grain holow point was facing me at a very close range. The slug hit it in the chest and went through some of the spine and ended up just back of the diaphram. The second photo shows two shot slugs.

The first is a 720-grain recovered from dirt behind a paper target. The second is the 550-grain slug recovered from the deer. Note that all the lead around the hollow point is missing. These slugs were made from a harder alloy. I think pure lead would have mushroomed instead of fragmented.

The pure lead slugs do not lead up the barrel. The harder alloy 550-grain hollow point slugs seem to lead the barrel a little. I think the lead was too hard for the pressure and that they did not obturate to seal the barrel. I use a very soft lubricant.

I think either a hollow point or a slug with a very large flat on front would be a lot better than the round nose slugs. At least that is my experience with air rifle pellets. The pointed ones do not have nearly the killing power of the flat nosed ones. Also, I suspect that even with a flat nose or hollow point penetration will be good. That 550-grain hollow point slug failed to penetrate the deer lengthwise, but it lost a lot of weight. I just weighed it and its remaining weight is about 310 grains. If it had retained more weight I bet it would have penetrated a lot farther.

One time I shot a doe with a 10-ga slug at about 40 yards. It was a doe facing me and the 750-grain slug hit it right in the middle of the chest. (That was luck because the gun/ammo combination was not good enough to do that every time.) The slug completly penetrated the animal lengthwise exiting an inch or so flom her rear vent. The 10-ga slugs were supposed to have a muzzle velocity of about 1,200 fps. That's a lot of weight, but the diameter of a fired 10-ga slug is .775 and thats a lot of frontal.

[IOWA DON]

Accurate 5744 is a black powder substitute which does not generally fill up much of the case. I think the cases are only half full of powder or so. A gunsmith told me its not a real good cold weather powder, but it works real well for what I need.

[rickt300]

My in order of doing this starts with a thumbhole stock hopefully to make recoil easier to handle. Right now I have a couple of years worth of Remington Buckhammer slugs to test and hunt with. Then I'll order some of the cases your talking about and build my self a hand style die similar to a lee rifle die so I won't need a big press. Last I may turn some slugs on my lathe. I might even be satisfied with the Buckhammers as they shoot nicely in my rifle and if they do well killing hogs.

[peternap]

Rocky Mountain Cartridge can make cases. Bullets should measure about .622-inch for a barrel with a .620-inch diameter. Mine cast at 720 grains and can be drilled our for hollow-pointing witha 3/8-inch drill to reduce weight to 550 grains. I get 1000 fps with the 720-grain bullets and 1300 fps with the 550-grain bullets with Accurate 5744 powder. Accuracy is good and pressure seems low.

Slight thread drift.

Don, where did your stocks come from?

[IOWA DON]

The stocks in the top photo above are both made by Thompson Center. The one on the 20-ga with the longer barrel is the one that came with the gun, a TCR-87. The one on the 20-ga with the short (18-1/4") barrel is a replacement from Thompson Center after the original stock broke. I think it is from a TCR-83 since it has more drop, is shorter (for the double triggers) and has the small cheek peice. The wood stock below was made by Virgin Valley which is no longer around and the fiberglass stock was made by me, about 80 hours work. That's a .50-140 barrel on the TCR with the fiberglass stock. It's way more thump than the 20-ga guns with heavy slugs.

[rickt300]

I just ordered my thumbhole stock from Boyds. What's your take on barrel length with the 20 gauge barrel?

[IOWA DON]

The longer barreled 20-ga gun in the above photo is 23 inches has an OD of 1.05 inch so the gun with scope weighs about 8.5 pounds. For me it has a perfect balance for offhand shooting. The shorter barreled one has an 18-1/4 inch barrel. The short barreled one was made up for my son to use. He wanted a very compact gun with a higher powered scope than the one I use. The short one is accurate from a bench rest. However, for me it is difficult to hold steady offhand. It also bucks up during recoil and make more noise. I doubt that there is much of a velocity loss for slug loads in short barrels so I would mostly consider balance.

[rickt300]

I am considering shortening the 24 inch barrel on mine but I like the balance and the weight has to have some good effect on recoil. I did take the sling swivel stud off the forearm and will reposition it when the thumbhole stock gets here along with bedding the forearm. This gun is shooting so well I hate to start tweaking it but forearm fit is miserable on it and I like to cover all bases.

[mogwai]

I am considering shortening the 24 inch barrel on mine but I like the balance and the weight has to have some good effect on recoil. I did take the sling swivel stud off the forearm and will reposition it when the thumbhole stock gets here along with bedding the forearm. This gun is shooting so well I hate to start tweaking it but forearm fit is miserable on it and I like to cover all bases.

My USH has youth barrel.  I think that is 22" and weight/balance are very good.  I don't know what would happen with a shorter barrel.  As for recoil, this setup is fine with commercial sabots.  You will exceed the recoil from those with this venture.