Squared heads

[RichCoyle]

Some interesting information with multiple five shot groups at 100 yards.

The .223 cases have been squared and fire formed and neck sized. The Remington primed unmodified factory cases did O.K. at .843" and .606". The Remington primed square cases made groups of .513" and .685".

The CCI primed unmodified factory cases are backing the theory with a .800" and .909". The squared CCI primed cases are looking good at .396" and .469".

The Remington primed unmodified factory cases average .7245" with the square cases doing .5990". The CCI primed unmodified factory cases do .8545" compared with the square case .4325".

Another eight groups were fired to verify the findings. This gives us four groups with each type of case for comparing. The first Remington primed unmodified factory cases produce groups of .800" and .668". The square head Remington primed groups are smaller at .757" and .599".

The CCI primed unmodified factory groups come in at .556" and .539". The first squared case CCI primed case group triumphs with a .500"; it is followed by a sorry .683".

The averages for the four groups are as follows: Remington primed unmodified factory case is .7293" and the Remington primed square head is .6385". This favors the square heads by more than an 1/8".

The CCI primed unmodified factory average is .7010" and the CCI primed square head average is .512" which is more than 3/16" smaller.

This Savage .223 rifle definitely prefers a square head, fire formed, neck sized case primed with CCI 200s. In this test, the discount store CCI 400 primers grouped better than the Remington benchrest primers!

The importance of trying different primers in one's quest for maximum accuracy is readily apparent. Absolutely I am not saying the CCI 200 is better than the Remington 7½ Bench Rest primer. My .17 Remington prefers the Remington 7½ B.R. and my .454 does best with the CCI 450 Magnum primer. I worked up loads for a 7STW and discovered it likes Federal's 215 Magnum.

 

[Seabeeken]

Very interesting! I'd love to hear your procedure for squaring them.
Also interesting the floating bolt head of the Savage didn't make up the difference between turned and unturned.
I ran a primer test in my match rifle and saw quite a difference between the CCI BR and a foreign primer.
How out of square was the brass?

 

[RichCoyle]

Seabeeken,

I have a Wilson case trimming setup and normally people use it to trim to length. One day I had the idea to check to see how square the factory ends were. To my surprise they were only two thousands of an inch out of square from the high side to the low side.
And yet that little bit made the difference in accuracy, measurable accuracy.

I, too, was surprised at the inability of that floating Savage bolt head to take care of the .002".

I did 2000 rounds of testing with that .223. It produced .021" of erosion in the throat. I proved beyond a shadow of a doubt that neck turning in that particular rifle is more accurate than full length sizing. I proved that it liked .015" of an inch from rifling more than .010" or .005" or .020" or .025".

One of the funnest things was to test two different heights of scope rings. One was with the scope at 2.2" above the bore and the other was at 1.68" above the bore. The test took about 4 hours and fortunately that day was overcast so the temperature didn't vary all day and there was no wind. I fired 10 shot groups at 100 yards and 300 yards after sighting it in for 200 yards with both scopes.

The higher mounted scope gave what appeared to be a better trajectory. At 100 yards and 300 yards the impacts were closer to the line of sight. After that I decided to find out how much velocity increase would I need with a 1.68" rings to match the trajectory of 2. 2" height rings. It was 100 feet per second. I posted my results on 24 hour campfire and was attacked by many people. Their attacks didn't change the facts. I repeatedly suggested that they run a ballistic test on JBM and they still wanted to argue. Some ran the ballistic program and posted their results; which agreed with my real world experience.

About a month later Barnes did the same test and discovered the same thing! Even after that, one of the posters still wanted to argue about it.

The load I used produced 10 shot group at 100 yards of 7/16" and 7/8" 10 shot group at 200 yards.

 

[AkleyFan]

Great information - appreciate all your efforts. Any info on your rifle build? Barrel/twist/length and all the other sundries.

I recently purchased a Savage Model 16 Youth for my Grandson in 7mm-08 and have purchased the proper bolt for a .223 and will be buying a barrel so he has a low recoiling rifle for training and fun. Not going to shoot matches but it's always fun to be able to shoot tiny groups, and it's not difficult to do so with these Savage rifles.

 

[Seabeeken]

Seabeeken,

I have a Wilson case trimming setup and normally people use it to trim to length. One day I had the idea to check to see how square the factory ends were. To my surprise they were only two thousands of an inch out of square from the high side to the low side.
And yet that little bit made the difference in accuracy, measurable accuracy.

I, too, was surprised at the inability of that floating Savage bolt head to take care of the .002".

I did 2000 rounds of testing with that .223. It produced .021" of erosion in the throat. I proved beyond a shadow of a doubt that neck turning in that particular rifle is more accurate than full length sizing. I proved that it liked .015" of an inch from rifling more than .010" or .005" or .020" or .025".

One of the funnest things was to test two different heights of scope rings. One was with the scope at 2.2" above the bore and the other was at 1.68" above the bore. The test took about 4 hours and fortunately that day was overcast so the temperature didn't vary all day and there was no wind. I fired 10 shot groups at 100 yards and 300 yards after sighting it in for 200 yards with both scopes.

The higher mounted scope gave what appeared to be a better trajectory. At 100 yards and 300 yards the impacts were closer to the line of sight. After that I decided to find out how much velocity increase would I need with a 1.68" rings to match the trajectory of 2. 2" height rings. It was 100 feet per second. I posted my results on 24 hour campfire and was attacked by many people. Their attacks didn't change the facts. I repeatedly suggested that they run a ballistic test on JBM and they still wanted to argue. Some ran the ballistic program and posted their results; which agreed with my real world experience.

About a month later Barnes did the same test and discovered the same thing! Even after that, one of the posters still wanted to argue about it.

The load I used produced 10 shot group at 100 yards of 7/16" and 7/8" 10 shot group at 200 yards.

Awesome info. Thanks for sharing. This should be useful in my ubr matches.
Is it possible the bolt lugs are causing the face to be out of square to the chamber? Possible with the floating head.

 

[RichCoyle]

Great information - appreciate all your efforts. Any info on your rifle build? Barrel/twist/length and all the other sundries.

I recently purchased a Savage Model 16 Youth for my Grandson in 7mm-08 and have purchased the proper bolt for a .223 and will be buying a barrel so he has a low recoiling rifle for training and fun. Not going to shoot matches but it's always fun to be able to shoot tiny groups, and it's not difficult to do so with these Savage rifles.

That rifle was a heavy 26" 9" twist factory barrel. The stock was a factory Tupperware. The factory trigger was adjusted to about twenty ounces. In those days I used Burris Signature rings. I was using a Burris 8-32X scope. AT about 2,100 rounds the groups opened up so I figured the barrel was wore out since I normally have magnums. When I mentioned it to Bob of Bob's Accuracy Shop he asked,
"What cartridge is it?"
"It's a .223 Remington."
"That should be good for 10,000 rounds! Your scope is messed up."
So, I purchased a Tasco World Class. The next five shots at 100 yards measured .312"!

 

[AZShooter]

Rich:

Interesting results.

I remember seeing my (late) friend Ed Brooks at least 25 years ago using the Wilson case trimmer to square the ends of his wildcat case. The case was a 6mm/22-250 which is very similar to today's 6mm Creedmoor! I had never seen that before or since until you posted this information.

You said: "The .223 cases have been squared and fire formed and neck sized". Did you fireform first or square the case heads first?

It is interesting stuff. Two of my friends who shoot 1000 BR never squared the case heads. One of them, Charles Greer, currently holds the highest score / smallest 10 shot world record:
2.862″ 10X group
https://www.thefirearmblog.com/blog/2021/04/08/world-record-nbrsa-1000-yard/

==============================

I wondered if other BR guys squared their caseheads.

Found this discussion where the posters reported mixed results:

Squaring case heads.

I was just reading a 1989 Handloader magazine #141, specifically an article by Layne Simpson on case prep. He didn't endorse it, but mentioned that some handloaders square the case head with a Wislon's case trimmer (or a lathe) when preparing cases for reloading. Seems to me that when you fire...

www.shootersforum.com

====================

Going even deeper I found one guy on another benchrest forum that stated:

"If you bisect a Lapua 220 Russian case, you find that the solid head is .160 deep. The bolt face on most actions is .150 deep and you need a minimum of .005 clearance from the bolt nose to the coned breech. If you sketch it out and add it up you find there is only .005 of the solid head that's up into and supported by the chamber. This puts you right at the border line of having unsupported case hanging out of the chamber. Turn off .004 to .005 squaring the case heads in a lathe and you reduce this to zero."

Noted BR shooter Randy Robinette said: "I'm with Al - 55-60K PSI squares 'em pretty well".

It was also stated that the primer pockets would need to be uniformed as they would be too shallow.

link for this thread:

squaring heads

does any one do any thing to the heads of the 6 mm br or the 6mm ppc? gary

benchrest.com

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As to the scope height the guys that argued were wrong. Jim Carmichael mentioned it in his Book of the Rifle (1985). He said higher scopes yield what appears to be a flatter trajectory due to where the bullet crosses the line of sight. He said it was a known fact helping in certain types of rifle competitions. Due to this information I have been careful to input scope height above bore in my JBM inputs.

 

[RichCoyle]

AZShooter,

Today was a very business day for the first half. At least three failures in the garden building some kind of tent frame to keep the birds out of the grapes. I told my son-in-law I am a wannabe. He reminded me I used to be pretty good at this sort of thing and suggested "I used to be". No matter I wanted a little time to relax so I watched a movie called "Mom's Night Out". I laughed a lot. My wife laughed at me for enjoying it.

Back to your question. The brass was fired several times after being squared. After every shot I would run a primer cutting tool into the primer pocket to make sure they were all the same depth. In fact, after every seven firings, I had to full length size them to get them to fit into the chamber with neck sizing. Full length was only about .001"-.002" setting the shoulder back. It was enough for the necked sized cases to go into the chamber and the bolt close like an empty chamber.

Since this barrel was so accurate I pulled it and had a wildcat reamer run into it to fire the Hornady 75 grain A-Max. I made my longest rock chuck kill with that 75 grainer (527 yards). They worked fine as a .223, but failed miserably in my .220 Extremist. They still made 3/8" groups for three shots every time with Nosler 55 grains Ballistic Tip.

Here's a fun discovery: From the same box of 55 grain Ballistic Tips ammo with the Savage .220 Extremist with the 26" barrel and a 26" Black Star barrel the velocities were surprising. The Savage averaged 4,005 feet per second and the Black Star barrel averaged 4,300 feet per second.

 

[AZShooter]

Never heard of the Savage .220 Extremist. Just tried looking cannot find anything on it. What is it?

 

[RichCoyle]

Never heard of the Savage .220 Extremist. Just tried looking cannot find anything on it. What is it?

It was my wildcat. I took a .220 Swift and blew the shoulders out and forward enough so there was a 1/8" long neck.

Some where I have the carbide reamer. If someone wants to use it, I will gladly loan it, if I can find it. I doubt I will get any requests.

 

[AZShooter]

Thanks for the info. Rock chuck shooting is a blast!

I miss the days when I used to go to the West Yellowstone area for much of the summer. We would cast and blast depending on the day. Rock chucks and ground squirrels or fishing for trout.