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-   -   Throat depth on H&R Ultra .223 (http://www.shootersforum.com/single-shot-rifles/19477-throat-depth-h-r-ultra-223-a.html)

cgpro856 03-18-2005 04:15 PM

Throat depth on H&R Ultra .223
 
I'm reloading for a rifle for the first time and looking for some info. I have a SB2-833 .223 REM Ultra Varmint that shoots pretty well with Winchester 45gr hp white box ammo. I'm looking for the best accuracy I can get. I have read that you should seat the bullets out close to the rifling for max accuracy, so I measured the difference from the back of the chamber to the tip of a 55 gr psp bullet lightly touching the rifling. it is about 2.55" or .29" over the standard max length for a .223 cartridge. with the 55 gr flat base bullet that puts the bullet .05" out of the case before it hits the rifling.

Is this normal for the H&R?
Where should I start with COL?
Also, should I get a crimp die?

Thanks,
Chris P.

ribbonstone 03-18-2005 05:28 PM

With a single shot, what do you care about the standard OAL? No magazine to limit the seating depth; so long as it chambers freely and is loaded to a reaoanble pressure, it's a "go".

cgpro856 03-18-2005 05:52 PM

"with the 55 gr flat base bullet that puts the bullet .05" out of the case before it hits the rifling."


It seems to me that I'd need about a 110 grain bullet to be long enough to even get close to the rifling and still be in the case

???

ribbonstone 03-18-2005 07:05 PM

Was a bit confused by those numbers...a flat base 55gr. bullet will be shorter over all, but usually has a longer bearing area than the same weight boat tail....with a longer bearing area, the flat base usually contacts rifling sooner than the boat tail will.

Not real sure we're are talking about bearing area or over-all-length.

Reguardless, the closer you can get a bullet to rifling, generally the better that bullet will shoot. Free-bore (un rifled barrel section between bullet and rifling) doesn't have to be the kiss of death toaccuracy, but that section needs to be very close to bullet diameter to not be a cause of inaccuracy.

Try the old type rule of thumb...place a bullet upside down in a case, and put it in the chamber. IF the rifling forces the bullet back into the case, then the bearing area of that bullet is greater than the free bore. Is a limit to how long a bullet a given twist barrel will spin, but a blunter nosed bullet (like the Sierra 55gr. SMP) has more bearing area and will often allow you to seat it to nearly touch the rifling when a 55gr. sharp pointed boat tail will not.

Have a .225Win. that has such a long throat that it needs 63gr. bullets to get really close (and shoot its best) or the Speer 70gr. Semi-Point. Anything longer and the 1:14 twist won't stabilize it...anything shorter and the jump to rifling (in an over sized throat) degrades accuarcy.

BUT

.226" cast lead bullet shoot well even with a bit of a jump to rifling...why?..becasue the extra .002" diameter keeps them centered in the over sized throat and they enter the rifling on center...short bearing area jacketed bullets tend to wander a bit in that large throat and enter rifling off center.

Rosco 02-18-2007 08:17 AM

Quote:

Originally Posted by cgpro856
I'm reloading for a rifle for the first time and looking for some info. I have a SB2-833 .223 REM Ultra Varmint that shoots pretty well with Winchester 45gr hp white box ammo. I'm looking for the best accuracy I can get. I have read that you should seat the bullets out close to the rifling for max accuracy, so I measured the difference from the back of the chamber to the tip of a 55 gr psp bullet lightly touching the rifling. it is about 2.55" or .29" over the standard max length for a .223 cartridge. with the 55 gr flat base bullet that puts the bullet .05" out of the case before it hits the rifling.

Is this normal for the H&R?
Where should I start with COL?
Also, should I get a crimp die?

Thanks,
Chris P.

I found the same thing with my SB2-2S3 .223.

I found that my COL using 50 Grain Sierra Spitzer needed to be way over the recommended 2.210 inches leaving only .050 of the bullet seated in the case. I asked around and was told that wasn't enough so I decided to start with the recommended COL.

I worked up a load trying 2 powders that i had on hand. I tried Benchmark and IMR 4895 and the latter gave me the most accuracy. I am planning on trying some different loads using longer COL as soon as it warms up.

I ended up with 25 grains of IMR 4895, 2.210 COL, Winchester Primers, Remmington Brass, and 4 out of 5 under an inch. I thought that to be pretty good for a $140 gun. I had a hard time getting 3" groups out of factory loads (American Eagle, Remmington, and Wolf) with the same gun shooting off a bipod and sandbag.

I think crimping is mostly for shells that are going to be handled a little rougher. I don't crimp mine. I think you would need to buy bullets with the ring for the crimp.

I'd be interested in seeing your data after you find a good load and how you came up with it.

I see i am waking up an old thread, but it might do someone good.

Rosco


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