GlockTalk.com
Home Forums Classifieds Blogs Today's Posts Search Social Groups



  
SIGN-UP
Notices

Glock Talk
Welcome To The Glock Talk Forums.

 
  
Reply
 
Thread Tools Display Modes
Old 01-04-2012, 20:07   #1
gforester
Motorhead
 
gforester's Avatar
 
Join Date: Feb 2009
Location: Cocoa, FL
Posts: 652
Rifle Cartridge OAL Question

Today while at the range shooting my new to me Rem 700 in .223, one of the old timers told me I should try using a custom tailored OAL to improve my groups. I was shooting Sierra 52 grain HPBT Match Kings that I was trying different powder weight charges with. I had settled on one particular charge weight because I seemed to get better groups with it than the other weights.

Anyway, the guy said I should measure the chamber and try setting my OAL about .005-.010" off the leade and then back it up in small increments to find the optimum length. Will this really make much of a difference? Fact is I was making basically one hole at 100 yards with the load I had settled on. If I go out to say 200 or 300 yards would this make a noticeable difference?

For point of reference I did measure the length with a dummy round when I got home and with my OAL I am sittiing about .095" off the leade right now.
__________________
Florida Glocker #209
Free Body Piercings by Glock, Inquire Within!
gforester is offline   Reply With Quote
Old 01-04-2012, 20:20   #2
Zut
Senior Member
 
Join Date: Dec 2009
Posts: 162
It makes more difference with bigger bullets and longer ranges, but the short answer is yes. Try 75 or 77 grain bullets at 300 yards and 80 grain bullets at 600 yards. They should be sitting just off the lands, not jammed into them.
Zut is offline   Reply With Quote
Old 01-04-2012, 20:33   #3
fgutie35
Senior Member
 
fgutie35's Avatar
 
Join Date: Jul 2007
Location: deep southeast Texas
Posts: 2,691
If it ain't broken, don't fix it!
On the other hand, the old timer is partially right. OAL does make a difference in your groups, when I was working up loads, I used to visit the sniper forums and learned a lot about load development. In a nutshell, you want the bullet to just touch rifle lands. Not too loose, not too tight. Just enough to give the bullet a straight launch rather than a wobbly or a high pressured launch. The way I measured for my chamber, was to use a freshly fired case and neck sized but only used half the force. The I inserted a bullet and pressed just enough to stay in the cartridge. The I loaded it in to the chamber and I slowly closed the bolt allowing for the rest of the bullet to go inside the case. Then I carefully extracted it by using a concave rod I designed myself to push gently on the bullet thru the muzzle while removing the bolt. That way, the bullet would not move forward or backward. Finally took it out and could barely see the lands dents, which is a good sign. The I applied superglue where the bullet meet the case and let it dry. Voila! Now I have a dummy round I can use to measure true OAL.
__________________
A good firearm, is the one that puts food on the table.
fgutie35 is offline   Reply With Quote
Old 01-04-2012, 21:01   #4
PCJim
Senior Member
 
Join Date: Aug 2008
Location: FL
Posts: 2,948
What fgutie35 said is correct, however with caveats. Seating dies, except for those made to seat a flat nose projectile, do not press against the tip of the bullet, rather the ogive. Every different bullet will make contact with the seating die in a different location, thus every different bullet profile/weight/manufacture must be tested as was stated.

I use a slightly altered method of determining COL for my rifles. Take a case fired in the rifle, neck size it only, then cut two slits in the neck on opposite sides almost to the shoulder. The idea is to allow the bullet to easily slip into the neck when it encounters the leade. Same principle as stated, just an easier method of doing so. Insert the bullet into the case LONG, carefully chamber this modified case/round, close bolt, carefully remove extracted case/bullet. Measure for COL. Repeat three times to ensure your measurement is correct and record it in your reloading logbook. Do this for every differing bullet you use - you'll see that they will have varying COL's.

Reloading
PCJim is offline   Reply With Quote
Old 01-04-2012, 21:04   #5
wanderinwalker
6 of .44
 
Join Date: Feb 2003
Location: New Hampshire
Posts: 973
Send a message via AIM to wanderinwalker
Quote:
Originally Posted by gforester View Post
Today while at the range shooting my new to me Rem 700 in .223, one of the old timers told me I should try using a custom tailored OAL to improve my groups. I was shooting Sierra 52 grain HPBT Match Kings that I was trying different powder weight charges with. I had settled on one particular charge weight because I seemed to get better groups with it than the other weights.

Anyway, the guy said I should measure the chamber and try setting my OAL about .005-.010" off the leade and then back it up in small increments to find the optimum length. Will this really make much of a difference? Fact is I was making basically one hole at 100 yards with the load I had settled on. If I go out to say 200 or 300 yards would this make a noticeable difference?

For point of reference I did measure the length with a dummy round when I got home and with my OAL I am sittiing about .095" off the leade right now.
I'd LOVE to see a 52gr Matchking loaded out to the lands of a Remington (or an AR-15) in .223! How would you keep it all together without the base of the bullet in the case mouth?

Okay, now for serious. Yes, it can make a difference, but it might not either. I shoot NRA Highpower (see my sig line) and use an AR-15 in .223. Don't ask me how far 69-77gr bullets jump to the rifling, I don't know. They have to fit and feed from the magazine, so you load them to 2.25-2.26" and go to work. Sierras (and Noslers, my preference) are very tolerant of bullet jump in the under-80gr designs. Ammo loaded like this is capable of MOA-accuracy to 300 yards, so it's nothing to stress over.

Bullet jump can become critical when loading the long-range bullets, either the various 75+gr Hornadys, 80gr Sierras/Noslers or any of the VLD-type bullets. Again, I know from experience the Noslers will tolerate being over .025" from the lands and still shoot excellent groups at 600 yards. I prefer to keep them at about .010" off, but err on the side of being able to extract a loaded round versus jamming a bullet into the rifling.

(As a side note, I think a properly loaded 80gr .223 load shoots wonderfully at 300 yards. I just rarely shoot 300 slow-fire so normally use my magazine bullets for that and reserve the long slugs for 600-yd matches).

Edited: Forgot to mention, I actually seat 52gr bullets around 2.23-2.24" because they're pretty short and I like having more bullet in the case neck when cycling through the AR. I also use the Hornady L-N-L OAL Tool, although mine is old enough to be a Stoney Point.
__________________
NRA Master - Highpower Rifle, Across the Course
NRA Expert - Highpower Rifle, Mid-Range Prone

Last edited by wanderinwalker; 01-04-2012 at 21:08..
wanderinwalker is offline   Reply With Quote
Old 01-04-2012, 21:06   #6
dsa1115
Senior Member
 
Join Date: Sep 2010
Location: Suburban Chicago
Posts: 639
Yes....OAL's matter. Consider an OAL gauge. They're not expensive.
dsa1115 is offline   Reply With Quote
Old 01-04-2012, 23:09   #7
F106 Fan
Senior Member
 
F106 Fan's Avatar
 
Join Date: Oct 2011
Posts: 6,426
For my Savage F Class 6.5x284 Norma, I couldn't possibly get the bullet to touch the lands. The boat tail would prevent the bullet from even touching the case mouth.

So, my bullet jumps about 0.060" before hitting the rifling. Does it matter? I don't think so. All the bullets go in the same hole at 100 yards. Before I can get serious about longer distances, I need to get a better scope. There is just too much mirage in my 40x bench rest scope.

I figure Savage must know something about chamber design and I assume they intended the rifle to use HPBT bullets because they tend to be among the most accurate. So, I just load 'em and shoot 'em.

Richard
__________________
"No matter how cynical you become, it's never enough to keep up." - Lily Tomlin
F106 Fan is offline   Reply With Quote
Old 01-05-2012, 00:44   #8
fredj338
Senior Member
 
fredj338's Avatar
 
Join Date: Dec 2004
Location: so.cal.
Posts: 22,233
Blog Entries: 3
Quote:
Originally Posted by gforester View Post
Anyway, the guy said I should measure the chamber and try setting my OAL about .005-.010" off the leade and then back it up in small increments to find the optimum length. Will this really make much of a difference? Fact is I was making basically one hole at 100 yards with the load I had settled on. If I go out to say 200 or 300 yards would this make a noticeable difference?

For point of reference I did measure the length with a dummy round when I got home and with my OAL I am sittiing about .095" off the leade right now.
IME, it varies too much from rifle to rifle & bullet to bullet to say there is any magic distance off the lands. SOme bullets like to be close some well off, it just depends. It's a good starting point though, as long as it fits the mag.
__________________
"Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified".

Last edited by fredj338; 01-05-2012 at 00:47..
fredj338 is offline   Reply With Quote
Old 01-05-2012, 08:13   #9
steve4102
Senior Member
 
steve4102's Avatar
 
Join Date: Jan 2009
Posts: 1,272
Quote:
Originally Posted by fredj338 View Post
IME, it varies too much from rifle to rifle & bullet to bullet to say there is any magic distance off the lands. SOme bullets like to be close some well off, it just depends. It's a good starting point though, as long as it fits the mag.
^^^ this^^^.

OAL does make a difference and most barrels have more than one "Sweet Spot" for optimum accuracy. If you are already getting one hole groups I would guess you have found one of those "sweet spots".

Here is a study by Barnes testing OAL for accuracy and pressure. Note that most rifles tested had more than one sweet spot, one up close and another quite short. Scroll down to "From the Lab". Going long is not always the best.
http://www.barnesbullets.com/resourc...rnes-bullet-n/
__________________
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe and some Air Jordan's and he votes Democrat for a lifetime.
steve4102 is offline   Reply With Quote
Old 01-05-2012, 09:24   #10
gforester
Motorhead
 
gforester's Avatar
 
Join Date: Feb 2009
Location: Cocoa, FL
Posts: 652
Quote:
Originally Posted by PCJim View Post
What fgutie35 said is correct, however with caveats. Seating dies, except for those made to seat a flat nose projectile, do not press against the tip of the bullet, rather the ogive. Every different bullet will make contact with the seating die in a different location, thus every different bullet profile/weight/manufacture must be tested as was stated.

I use a slightly altered method of determining COL for my rifles. Take a case fired in the rifle, neck size it only, then cut two slits in the neck on opposite sides almost to the shoulder. The idea is to allow the bullet to easily slip into the neck when it encounters the leade. Same principle as stated, just an easier method of doing so. Insert the bullet into the case LONG, carefully chamber this modified case/round, close bolt, carefully remove extracted case/bullet. Measure for COL. Repeat three times to ensure your measurement is correct and record it in your reloading logbook. Do this for every differing bullet you use - you'll see that they will have varying COL's.

Reloading
That is exactly how I did my measurements. I recorded the OAL for my Sierra 52gr. Match Kings, Nosler 77gr. FMJBT's and some Xtreme 55gr. FMJBT's and recorded the info in my loading notebook.

I loaded the Sierra's to 2.200" as that is what was in my Speer loading manual. I can't load those much longer, as was pointed out by wanderinwalker, the bullet is simply too short. Now I do have some Nosler 77gr Match bullets that are quite long and I can play with the OAL with them. They didn't shoot nearly as accurately as my Sierra's at 100 yards so I suppose there is room for improvement with them.

I appreciate the input here as I am really quite new to rifle reloading. I am finding it quite a lot of fun to learn about the ins and outs of precision loading rifle bullets though.
__________________
Florida Glocker #209
Free Body Piercings by Glock, Inquire Within!

Last edited by gforester; 01-05-2012 at 09:32..
gforester is offline   Reply With Quote
Old 01-05-2012, 11:32   #11
wanderinwalker
6 of .44
 
Join Date: Feb 2003
Location: New Hampshire
Posts: 973
Send a message via AIM to wanderinwalker
Quote:
Originally Posted by gforester View Post
That is exactly how I did my measurements. I recorded the OAL for my Sierra 52gr. Match Kings, Nosler 77gr. FMJBT's and some Xtreme 55gr. FMJBT's and recorded the info in my loading notebook.

I loaded the Sierra's to 2.200" as that is what was in my Speer loading manual. I can't load those much longer, as was pointed out by wanderinwalker, the bullet is simply too short. Now I do have some Nosler 77gr Match bullets that are quite long and I can play with the OAL with them. They didn't shoot nearly as accurately as my Sierra's at 100 yards so I suppose there is room for improvement with them.

I appreciate the input here as I am really quite new to rifle reloading. I am finding it quite a lot of fun to learn about the ins and outs of precision loading rifle bullets though.
On the 77s, what is the twist rate of your barrel? A 1-9" *might* stabilize a 77, but to be certain a 1-8 or 1-7 are superior. This is more likely to contribute to so-so accuracy with those bullets than the distance the bullet jumps to the lands. Also, what powder did you use? I'd suggest something in the burn range of 4895-Varget for that weight, as would probably 99% of the other Highpower shooters I know.

At any rate if it shoots little knots with 52s seated at 2.20", I'd probably just keep making and shooting those!
__________________
NRA Master - Highpower Rifle, Across the Course
NRA Expert - Highpower Rifle, Mid-Range Prone
wanderinwalker is offline   Reply With Quote
Old 01-05-2012, 12:37   #12
gforester
Motorhead
 
gforester's Avatar
 
Join Date: Feb 2009
Location: Cocoa, FL
Posts: 652
Quote:
Originally Posted by wanderinwalker View Post
On the 77s, what is the twist rate of your barrel? A 1-9" *might* stabilize a 77, but to be certain a 1-8 or 1-7 are superior. This is more likely to contribute to so-so accuracy with those bullets than the distance the bullet jumps to the lands. Also, what powder did you use? I'd suggest something in the burn range of 4895-Varget for that weight, as would probably 99% of the other Highpower shooters I know.

At any rate if it shoots little knots with 52s seated at 2.20", I'd probably just keep making and shooting those!
My rifle has a 1 in 9" twist. I was using some SMP844 military surplus powder I got from Widener's. I also have some SMP846 but I don't think it is much different from the 844. I don't have any slower powders at the moment but I guess I will have to get some for those heavier bullets. I only picked up the Nosler's because I was able to get a 100 pack for $13 at the gun show last Saturday.

Here is what the Sierra's shot like. Left plate is 3 shots, right is 2 shots.

Reloading
__________________
Florida Glocker #209
Free Body Piercings by Glock, Inquire Within!
gforester is offline   Reply With Quote
Old 01-07-2012, 09:41   #13
wanderinwalker
6 of .44
 
Join Date: Feb 2003
Location: New Hampshire
Posts: 973
Send a message via AIM to wanderinwalker
Quote:
Originally Posted by gforester View Post
My rifle has a 1 in 9" twist. I was using some SMP844 military surplus powder I got from Widener's. I also have some SMP846 but I don't think it is much different from the 844. I don't have any slower powders at the moment but I guess I will have to get some for those heavier bullets. I only picked up the Nosler's because I was able to get a 100 pack for $13 at the gun show last Saturday.

Here is what the Sierra's shot like. Left plate is 3 shots, right is 2 shots.

Reloading
Unfortunately, even switching to a slower powder, you may not find accuracy with the 77gr bullets in a 1-9" twist barrel. Some of the shorter 75gr bullets *might* work, but for certain accuracy, I'd say you're probably looking at the 68-69gr match bullets at the top end.

Maybe pick up a box of 68gr Hornadys or 69gr Sierras (or Noslers) and give them a try? It's what I use in Highpower at 200 and 300 yards in a 1-7" AR barrel. Use Varget or RL-15 and see what you get. At the risk of being told not to give out unsafe loads, I will suggest using between 24.0 and 25.0 grains of either powder with a 69gr bullet, but CONFIRM WITH OTHER SOURCES FIRST.

FWIW, I've shot 100-scores at 300 yards using both powders with 69gr Nosler HPBT match bullets. No double-cleans yet, just a few 198s and 199s. That's a 2-MOA 10-ring at 300 yards (6") using iron sights shooting prone.
__________________
NRA Master - Highpower Rifle, Across the Course
NRA Expert - Highpower Rifle, Mid-Range Prone
wanderinwalker is offline   Reply With Quote
Old 01-07-2012, 11:04   #14
gforester
Motorhead
 
gforester's Avatar
 
Join Date: Feb 2009
Location: Cocoa, FL
Posts: 652
Yes, I was thinking the 77gr. might be a bit too heavy. Friday I ordered another box of 52gr. HPBT in Hornady (my source was out of Sierra) along with a box of 69gr. Barnes Match Burners. Maybe the 69gr. Barnes will work out well without being too heavy for my barrel.

I was also recommended Varget from some of the "old hands" at the club this week. I might just pick up a pound of it to try out. Your advice is much appreciated, thanks again.
__________________
Florida Glocker #209
Free Body Piercings by Glock, Inquire Within!
gforester is offline   Reply With Quote
Old 01-07-2012, 20:26   #15
PCJim
Senior Member
 
Join Date: Aug 2008
Location: FL
Posts: 2,948
I've gotten some of my best groups (5 shots, .769 or less at 100 yds, rested and scoped) out of my 16" HBAR 1:9 using those Hornady 52gr HPBT Match bullets. Load them over 23.5gr AA2230 @ 2.25 COL.

I'll second the above comments regarding your twist and appropriate bullet weights. The 1:9 will reach its upper limit at the 69gr bullets. You'll need a 1:8 or 1:7 to stabilize heavier projectiles.
PCJim is offline   Reply With Quote

 
  
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump




All times are GMT -6. The time now is 12:55.




Homepage
FAQ
Forums
Calendar
Advertise
Gallery
GT Wiki
GT Blogs
Social Groups
Classifieds


Users Currently Online: 1,046
275 Members
771 Guests

Most users ever online: 2,672
Aug 11, 2014 at 2:31