I have a DPMS LR-6.5 semi auto rifle. Chambered in 6.5 creedmoor. I have an OAL gauge and a bullet comparator. I measured the lands with oal gauge than put the comparator on my caliper. I got an average measurement of 2.2815. Now my problem is mag restriction. The max length I can put in the mag is 2.1890. Does anybody know of an AR-10 mag I can use that allows me to put a longer round in???
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Measuring lands
- Thread starter kuca_2004
- Start date
Mags are all the same size. They're made to fit the rifle. The cartridge is loaded to SAAMI Max OAL,(2.825" from the pointy bit to the flat bit with no ogives involved). Since you're measuring a tick less than the Max, you should be fine. If your loaded ammo doesn't fit the mag, reduce the OAL until it does.
And you don't measure the lands with an OAL gauge. Isn't how you find the OAL to the lands either.
And you don't measure the lands with an OAL gauge. Isn't how you find the OAL to the lands either.
how to find lands with pictures even
http://www.accurateshooter.com/gear-reviews/hornady-oal-gauge-and-comparator/
don't be obsessed with chasing lands unless you are shooting some of the scenars. even the VLD's can be used with a jump
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
My .260 likes SMK's .025 to .050 out, my .204's best group ever was a 5 shot group measuring .280 with 39 grain SBKs seated .120 off the lands
http://www.accurateshooter.com/gear-reviews/hornady-oal-gauge-and-comparator/
don't be obsessed with chasing lands unless you are shooting some of the scenars. even the VLD's can be used with a jump
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
My .260 likes SMK's .025 to .050 out, my .204's best group ever was a 5 shot group measuring .280 with 39 grain SBKs seated .120 off the lands
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What he says.
If you want full freedom then a bolt action with blind mag and or using it as a single shot like they do with AR competitions.
I have one I built that is purely a single shot as no mag is made for 7.5 Swiss (could maybe make a Short magnum mag work but its a target gun on the bench.
If you want full freedom then a bolt action with blind mag and or using it as a single shot like they do with AR competitions.
I have one I built that is purely a single shot as no mag is made for 7.5 Swiss (could maybe make a Short magnum mag work but its a target gun on the bench.
My 308 Rem 700 started out with the first barrel having so much leade the bullet would just about be out of the case neck before it hit the lands. So I would seat to the recommend OAL & work on a powder charge for accuracy . After 4000+ rounds down the barrel , I had a match barrel installed , I could jam or jump my rounds .
I can get accuracy by jumping or jamming my rounds . With hot loads I don't jam , l feel it best to go .002 jump better the a jam . Check the OAL on loaded match grade rounds , for a 308 its 2.800 , that's the standard listing for the 168 gr. Sierra Match King . Your rifle my shoot better with a jump , work with your magazine with listed OAL & fine tune your powder .
I can get accuracy by jumping or jamming my rounds . With hot loads I don't jam , l feel it best to go .002 jump better the a jam . Check the OAL on loaded match grade rounds , for a 308 its 2.800 , that's the standard listing for the 168 gr. Sierra Match King . Your rifle my shoot better with a jump , work with your magazine with listed OAL & fine tune your powder .
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Reloader270
New member
You may also make a dummy round and cutting the neck vertically with a thin angle grinder blade. Then take away burs and size again. Then insert a bullet at maximum length and chamber it in the gun. Then measure it.
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Reloader270
New member
Go to this website. Click on Reloading and Shooting Tip. Then go to Best OAL for accuracy:
http://www.larrywillis.com/
http://www.larrywillis.com/
Doesn't seem like anyone answered your question . First I'd have to ask what mag are you using ? If pmag then you can try metal mags they tend to have thinner walls allowing you to seat a little longer . There is a company that makes metal AR-15 mags that puts the connecting fold in the back or side that allows the COAL to be much longer then 2.260 . Maybe they make them for the LR-308 platform as well . I'll see if I can find a link . I don't remember the company name off hand .
Then I think Mobuck is on to something there . What bullet are you using . It seems most guys that are shooting the 6.5 creed are using VLD bullets or similar . If you are , try some SMK's because they don't have as long a tip and may allow you to get your Ogive closer to the lands while still being able to use your mag . At least you'll still be using a match bullet .
If this is for hunting , seat just short of mag length and work up the best load you can and don't worry about where the lands are .
Then I think Mobuck is on to something there . What bullet are you using . It seems most guys that are shooting the 6.5 creed are using VLD bullets or similar . If you are , try some SMK's because they don't have as long a tip and may allow you to get your Ogive closer to the lands while still being able to use your mag . At least you'll still be using a match bullet .
If this is for hunting , seat just short of mag length and work up the best load you can and don't worry about where the lands are .
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Company name is ASC ( amunition staorage components )
The only ones they have for 308 semi auto are SR-25 that allow a COAL of 2.865 Which is not much really
http://www.ammosc.com/308-sr-25/
Here are the AR-15 mags that allow a COAL of 2.316 which is impressive
http://www.ammosc.com/223-stainless-steel/
The only ones they have for 308 semi auto are SR-25 that allow a COAL of 2.865 Which is not much really
http://www.ammosc.com/308-sr-25/
Here are the AR-15 mags that allow a COAL of 2.316 which is impressive
http://www.ammosc.com/223-stainless-steel/
Kuca 2004,
Am I right in thinking the measurements you posted were measured with a comparator insert and not the overall length from base to tip of the cartridge? The comparators vary with the maker. There is no standard comparator insert hole diameter. The Sinclair inserts measure lower down on the ogive than the Hornady ones do. The Hornady ones have a hole edge radius that varies some from one batch to the next, so that you can get a few thousandths difference in reading depending what lot your insert is part of.
The reason for the above is that these devices, as their name says, are comparators, meaning you can use one to compare two cartridges loaded with the same components to see how different their bullet seating is or compare bullet seating of a finished round with the gauge type cartridge used to find the lands with the same bullet. But the absolute value of the measurements taken with them has no other meaning and there is no SAAMI standard for them so nobody else will be able to use them.
The case comparators are a little different in that the holes do match a SAAMI standard diameter, but, again, they are comparators and the hole radius makes the absolute readings short, usually by two to ten thousandths, depending what lot your insert came from. So use them to compare shoulder setback from as-fired to as-resized, but forget about getting an absolute number without having a headspace GO gauge to compare your case readings to.
Am I right in thinking the measurements you posted were measured with a comparator insert and not the overall length from base to tip of the cartridge? The comparators vary with the maker. There is no standard comparator insert hole diameter. The Sinclair inserts measure lower down on the ogive than the Hornady ones do. The Hornady ones have a hole edge radius that varies some from one batch to the next, so that you can get a few thousandths difference in reading depending what lot your insert is part of.
The reason for the above is that these devices, as their name says, are comparators, meaning you can use one to compare two cartridges loaded with the same components to see how different their bullet seating is or compare bullet seating of a finished round with the gauge type cartridge used to find the lands with the same bullet. But the absolute value of the measurements taken with them has no other meaning and there is no SAAMI standard for them so nobody else will be able to use them.
The case comparators are a little different in that the holes do match a SAAMI standard diameter, but, again, they are comparators and the hole radius makes the absolute readings short, usually by two to ten thousandths, depending what lot your insert came from. So use them to compare shoulder setback from as-fired to as-resized, but forget about getting an absolute number without having a headspace GO gauge to compare your case readings to.
And keep in mind, the AR was designed for a mission and its been adaptored all beyond anyone's thoughts.
There is a reason that a lot of AR shooters in some matches single load.
What works for long range is too long for the magazine.
The magazine of an AR is fixed to the 5.56 as it was never thought to do anything else.
Just goes with the territory.
Steel mag will be thinner, but we are not talking a whole lot.
Its not the clip that's the limit, its the magwell.
ie. back to a bolt action.
There is a reason that a lot of AR shooters in some matches single load.
What works for long range is too long for the magazine.
The magazine of an AR is fixed to the 5.56 as it was never thought to do anything else.
Just goes with the territory.
Steel mag will be thinner, but we are not talking a whole lot.
Its not the clip that's the limit, its the magwell.
ie. back to a bolt action.
JeepHammer
Moderator
Back to what I've often said and been shouted down...
People go about things backwards all the time & it's hard to hammer the 'Common Belief' out of their heads...
How a gun Smith goes about this issue is to move the barrel backwards & rechamber, setting the THROAT backwards to match the MAXIMUM allowable ammo length.
The magazine setting the maximum length of ammo.
Simply make the chamber fit the round when you run into this restriction.
I ran into this with my .300 WSM AR a few years back, the chamber was cut too long, throat too far forward,
There were two choices,
1. Order a new barrel with a semi finished chamber and make the chamber fit the ammo,
2. Cut some off the back of the barrel, moving the chamber backwards, then rethreading the barrel for the chamber nut to stop in the correct position.
0.250" barrel face off moved the throat rearwards 0.250", trim & thread barrel for chamber nut, then simply used a chamber reamer with throat ground off to adjust headspace for the bolt position.
YUP! You read correctly, chamber 'Free Travel'/'Free Bore'/'Bullet Jump', what ever you want to call it, was 1/4" too long!
In the case of that particular rifle, that left 0.0015" gap between maximum seated bullet & throat contact, groups tightened from 1.75" to 0.5" changing nothing with the load.
You have to remember, that chamber MUST be cut to accommodate ANY crap ammo the owner might lay hands on to keep it from being dangerous to operate.
I won't buy a 'Finished' barrel, semi-finished chambers and a reamer that matches your particular profile bullet will give you the best results...
On AR barrels, I buy from barrel makers that can supply a full profile barrel at the chamber,
That allows me to thread the barrel a little extra, and use (precisely ground) shims between barrel & barrel nut.
As the throat wears, I can reduce the thickness of the shim and tighten up the bullet to throat distance again without all the machine work done over.
Just one of those gun smith kinks for the AR rifles 'Common Belief' says you can't do, but works fine if you are smarter than rumor control...
People go about things backwards all the time & it's hard to hammer the 'Common Belief' out of their heads...
How a gun Smith goes about this issue is to move the barrel backwards & rechamber, setting the THROAT backwards to match the MAXIMUM allowable ammo length.
The magazine setting the maximum length of ammo.
Simply make the chamber fit the round when you run into this restriction.
I ran into this with my .300 WSM AR a few years back, the chamber was cut too long, throat too far forward,
There were two choices,
1. Order a new barrel with a semi finished chamber and make the chamber fit the ammo,
2. Cut some off the back of the barrel, moving the chamber backwards, then rethreading the barrel for the chamber nut to stop in the correct position.
0.250" barrel face off moved the throat rearwards 0.250", trim & thread barrel for chamber nut, then simply used a chamber reamer with throat ground off to adjust headspace for the bolt position.
YUP! You read correctly, chamber 'Free Travel'/'Free Bore'/'Bullet Jump', what ever you want to call it, was 1/4" too long!
In the case of that particular rifle, that left 0.0015" gap between maximum seated bullet & throat contact, groups tightened from 1.75" to 0.5" changing nothing with the load.
You have to remember, that chamber MUST be cut to accommodate ANY crap ammo the owner might lay hands on to keep it from being dangerous to operate.
I won't buy a 'Finished' barrel, semi-finished chambers and a reamer that matches your particular profile bullet will give you the best results...
On AR barrels, I buy from barrel makers that can supply a full profile barrel at the chamber,
That allows me to thread the barrel a little extra, and use (precisely ground) shims between barrel & barrel nut.
As the throat wears, I can reduce the thickness of the shim and tighten up the bullet to throat distance again without all the machine work done over.
Just one of those gun smith kinks for the AR rifles 'Common Belief' says you can't do, but works fine if you are smarter than rumor control...
JeepHammer
Moderator
RC20,
I always loose IQ points reading the 'AR Guru' of the day articles.
I'm older & dumber for having wasted my time on the 'Internet Experts' ...
.223 wildcat shooters had the little round worked out, fast & hyper accurate long before the internet was invented!
When you cast those chambers & barrels you pretty quickly see for yourself where the real issues are!
They were shooting 25 to 45 grain bullets in excess of 3,000 fps, and doing it hyper accurately with 1:16" & 1:14" twist barrels with 1940s & 1950s bullets, powder & primers!
Along comes the military, and wants 52 grain bullets, then 55 grain bullets... On and on up to stupid weights...
The military, being schizophrenic, chops off the barrel, but wants more muzzle velocity, increases the bullet weight, but wants to increase muzzle velocity...
Being limited to a .224" diameter but wanting more weight, the length of the bullet had to increase,
Not wanting to loose velocity, powder volume couldn't change, so the longer bullet had to stick out further...
This increased throat lengths...
Then came along the bullets up to 99 grain and any hope for a chamber to fit a reasonable bullet went right out the window.
I was actually present when an idiot bought 77 grain 'Match' bullets and stuffed them into an older AR marked .223 Rem, and prompt blew the gun up!
Since the internet generation 'Experts' can't figure out the difference between a .223 Rem chamber bullet and a 5.56mm military bullet, pretty much all .223 chambers had to be cut to accommodate the longer (heavier) 5.56mm rounds and still be safe...
Those stupid long/heavy bullets at high pressures required faster twist rates to stabilize the bullet, so now you have these stupid chamber/twist rates combinations that screw you for easily building a rifle...
1:6", 1:7", 1:8" twists are common, 0.250" freebores are common, and completely screw you for those little, light bullets that made the .223 reputation in the first place!
I don't need 3,400 FPS or 90 grain bullets to kill a ground hog or punch holes in paper at 300 yds,
What I need is a pin point, inherently accurate rifle since the ground hog can't tell if it was a 77 grain bullet or a 25 grain bullet that just took it's head off!
The result is chambers that are just STUPID long for common/reasonable bullets, and twist rates that require you to do weeks of testing to find just the right powder/primer to make a reasonable bullet stablize correctly... Totally screwing g up that 'Inherently Accurate' thing the original .223 had going for it.
I catch a lot of crap for ordering semi-finished chambers with NO throat cut,
Then using TWO or three chamber reamer to finish the chamber, but it's the ONLY way to insure a chamber that fits common .223 rounds anymore.
The manufacturers MUST make barrels with stupid chambers to accommodate what ever crap the end user might stuff into it,
I make my own rounds, not shoot what ever is 'Cheap', and the rounds fit the chamber... Inherent accuracy is back!
These internet twits are never going to realize that this 'Super Duper' coating, that 'Wonder Metal' or some other marketing scam isn't going to do squat for you until the round fits the chamber, the bullet fits the bore/twist rates, and the bolt locks up solidly & squarely EVERY TIME...
It always has been, and always will be about the basics, fit & finish matter, the rest is just eye candy.
I always loose IQ points reading the 'AR Guru' of the day articles.
I'm older & dumber for having wasted my time on the 'Internet Experts' ...
.223 wildcat shooters had the little round worked out, fast & hyper accurate long before the internet was invented!
When you cast those chambers & barrels you pretty quickly see for yourself where the real issues are!
They were shooting 25 to 45 grain bullets in excess of 3,000 fps, and doing it hyper accurately with 1:16" & 1:14" twist barrels with 1940s & 1950s bullets, powder & primers!
Along comes the military, and wants 52 grain bullets, then 55 grain bullets... On and on up to stupid weights...
The military, being schizophrenic, chops off the barrel, but wants more muzzle velocity, increases the bullet weight, but wants to increase muzzle velocity...
Being limited to a .224" diameter but wanting more weight, the length of the bullet had to increase,
Not wanting to loose velocity, powder volume couldn't change, so the longer bullet had to stick out further...
This increased throat lengths...
Then came along the bullets up to 99 grain and any hope for a chamber to fit a reasonable bullet went right out the window.
I was actually present when an idiot bought 77 grain 'Match' bullets and stuffed them into an older AR marked .223 Rem, and prompt blew the gun up!
Since the internet generation 'Experts' can't figure out the difference between a .223 Rem chamber bullet and a 5.56mm military bullet, pretty much all .223 chambers had to be cut to accommodate the longer (heavier) 5.56mm rounds and still be safe...
Those stupid long/heavy bullets at high pressures required faster twist rates to stabilize the bullet, so now you have these stupid chamber/twist rates combinations that screw you for easily building a rifle...
1:6", 1:7", 1:8" twists are common, 0.250" freebores are common, and completely screw you for those little, light bullets that made the .223 reputation in the first place!
I don't need 3,400 FPS or 90 grain bullets to kill a ground hog or punch holes in paper at 300 yds,
What I need is a pin point, inherently accurate rifle since the ground hog can't tell if it was a 77 grain bullet or a 25 grain bullet that just took it's head off!
The result is chambers that are just STUPID long for common/reasonable bullets, and twist rates that require you to do weeks of testing to find just the right powder/primer to make a reasonable bullet stablize correctly... Totally screwing g up that 'Inherently Accurate' thing the original .223 had going for it.
I catch a lot of crap for ordering semi-finished chambers with NO throat cut,
Then using TWO or three chamber reamer to finish the chamber, but it's the ONLY way to insure a chamber that fits common .223 rounds anymore.
The manufacturers MUST make barrels with stupid chambers to accommodate what ever crap the end user might stuff into it,
I make my own rounds, not shoot what ever is 'Cheap', and the rounds fit the chamber... Inherent accuracy is back!
These internet twits are never going to realize that this 'Super Duper' coating, that 'Wonder Metal' or some other marketing scam isn't going to do squat for you until the round fits the chamber, the bullet fits the bore/twist rates, and the bolt locks up solidly & squarely EVERY TIME...
It always has been, and always will be about the basics, fit & finish matter, the rest is just eye candy.
Jim Watson
New member
The "original .223" was the 1964 commercial version of the round designed for a military weapon. Perhaps you are thinking of the .222 or .222 Magnum as "inherently accurate" sporting rifle cartridges dating back to the 1950s. Wiki thinks the .222 Magnum was a mil-spec project, but it never made it into a finished rifle. The .222 held the benchrest record of a group scored on the range as 0.0 MOA; the sanctioning organization read it as 0.009 MOA.