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Clarification on OAL/COL

3K views 47 replies 19 participants last post by  Mark204 
#1 ·
Loading my first batch of 6.5CM for my Ruger American. Using load data from Hornady’s 11th manual for 140bthp’s over 35.6gr of H4350 to use a COL of 2.8”. When I did this I had trouble closing my bolt. So I reset my dies according to the instructions. Same result. Used my Lee load data book and the closest comparable data I could find was 142 jacketed over 38.8gr of H4350 and they listed a minimum OAL of 2.780”. I lowered my seating stem and to 2.78 and it chambered correctly. This seemed to make sense because i thought I could see marks on my longer cartridges like they were hitting the rifling. But that confused me because saami lists max COL at 2.825”. Lol. Can someone explain COL/OAL? How much wiggle room is there? Why does it seem that the chamber is shorter than saami spec?
 
#2 · (Edited)
Over-All Length (OAL) and Cartridge Over-all Length basically are the same thing - the measurement from the cartridge base to the bullet's tip. What can cause problems with chambering when reloading is the ogive (shape of the bullet). For example, a spire-point or spitzer-shaped bullet may go further into the chamber throat without touching the lands than a round-nose bullet.

Maximum OAL is usually to SAAMI specs. It also pertains to the fit of the cartridge into the magazine. Obviously, a cartridge must fit in the magazine.

Minimum OAL has to do with how deeply the bullet is seated into the case. The deeper the bullet is seated, the pressure increases (lowers the case volume).

Generally, the bullet manufacturer's specs in their manuals, such as Hornady, are the ones to use.
 
#3 ·
Over-All Length (OAL) and Cartridge Over-all Length basically are the same thing - the measurement from the cartridge base to the bullet's tip. What can cause problems with chambering when reloading is the ogive (shape of the bullet). For example, a spire-point or spitzer-shaped bullet may go further into the chamber throat without touching the lands than a round-nose bullet.

Maximum OAL is usually to SAAMI specs. It also pertains to the fit of the cartridge into the magazine. Obviously, a cartridge must fit in the magazine.

Minimum OAL has to do with how deeply the bullet is seated into the case. The deeper the bullet is seated, the pressure increases (lowers the case volume).

Generally, the bullet manufacturer's specs in their manuals, such as Hornady, are the ones to use.
I’m using once fired Hornady brass, sized, trimmed, and stuffed with a Hornady bullet. You’re saying that using their spec it should fit, so I have a different problem ?
 
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#7 ·
Guys, cut the political stuff in the reloading forum. I deleted the inappropriate comments. Keep it in the minefield.

@bowsandguns question for you, are you using the exact bullet the load in the Hornady manual lists? Bullets have different ogives as mentioned above, and the best load data is from a manual using the exact bullet you are loading. Yes, seating a bullet too deep can raise pressures, but not as much as jamming the bullet into the lands. If you are seating the bullet within spec, you should be fine as long as you are closing without final seating of the bullet. The other issue it can cause is that if you are hunting for instance and you have the bullet pushed into the lands to the point it is leaving marks on the bullet, when you go to unload the rifle, you can pull the bullet, leaving it stuck in the throat as well as having an action full of powder.
As far as the rifle, you may have a throat that is on the short side.
 
#9 ·
The answer is why Hornady lists an exact OAL. Hornady is listing the exact OAL that was used for the load data listed. As mentioned above, changing OAL (among many, countless other factors) changes pressure. So Hornady is listing the exact recipe for their load, brass, primer, case, OAL, everything. Any changes will affect things, so Hornady is listing as many of the parameters and variables as possible to recreate the performance they have in their manual.
 
#11 · (Edited)
@Bowsnguns, this isn’t a major issue, but if you want some answers do this….fully resize a case, take a dremel and make 3 relief cuts on the case mouth, (start shallow) start the bullet and chamber the round. Open the bolt, remove the cartridge and measure the OAL. This will give you a measurement from the bolt face to the point where the bullet contacts the lands, it’s actually making contact with the Ogive, but it will still give you a fairly accurate reading of the max length you can load a particular bullet. I say particular because that number will change when you change bullet style/profile. Take that number, reduce it by .005”, load 3 up and shoot ‘em. I’d also bump your H4350 charge up to 40.4 and start there. You’re gonna go through a lot of powder starting that low initially.

Yes loading into the lands can spike your initial pressure, as much as 7k PSI, but with no crimp and .002” neck tension, (which is average) the bullet’s not coming out should you need to eject an unfired round. Loading into the lands is a bench rest shooters trick because they run minimal neck tension, as in less than a .001”. The “Jam” in the lands is their crimp so to speak so the chances of the bullet getting stuck in the lands is a real thing upon removal. There’s absolutely nothing wrong with jamming the lands, provided the load was developed that way, and yes, I’ve done it.
 
#24 ·
@Bowsnguns, this isn’t a major issue, but if you want some answers do this….fully resize a case, take a dremel and make 3 relief cuts on the case mouth, (start shallow) start the bullet and chamber the round. Open the bolt, remove the cartridge and measure the OAL. This will give you a measurement from the bolt face to the point where the bullet contacts the lands, it’s actually making contact with the Ogive, but it will still give you a fairly accurate reading of the max length you can load a particular bullet. I say particular because that number will change when you change bullet style/profile. Take that number, reduce it by .005”, load 3 up and shoot ‘em. I’d also bump your H4350 charge up to 40.4 and start there. You’re gonna go through a lot of powder starting that low initially.

Yes loading into the lands can spike your initial pressure, as much as 7k PSI, but with no crimp and .002” neck tension, (which is average) the bullet’s not coming out should you need to eject an unfired round. Loading into the lands is a bench rest shooters trick because they run minimal neck tension, as in less than a .001”. The “Jam” in the lands is their crimp so to speak so the chances of the bullet getting stuck in the lands is a real thing upon removal. There’s absolutely nothing wrong with jamming the lands, provided the load was developed that way, and yes, I’ve done it.
Did this and seated to the lands. Got 2.830” for OAL. I’m so confused. Back to the drawing board for me, I guess. Maybe I got something wonky with my seating die? There’s no cannelure on these bullets so I’m setting up not to crimp.
 
#12 ·
The COAL is actually not that important, different companies' chambers are not consistent and some bullets are varying lengths depending on the tip.
The first barrel I bought (in 6.5 Grendel) had a chamber so short it might have been dangerous to fire regular cartridges. I checked and caught it and sent it back to be fixed.
As chamber reamers wear the lead-in to the lands can shorten.

What really matters is where the ogive of the bullet matches up with the start of the rifling. Hornady makes a whole series of tools that allow you to precisely measure and set this up.
Lock-N-Load® O.A.L. Gauges & Modified Cases - Hornady Manufacturing, Inc

I understand that you are new to reloading but for the most accurate ammo the bullet-to-lands relationship is important.
 
#13 · (Edited)
#17 · (Edited)
Just a heads up......You have to buy a specific modified 6.5 CM case for use with the tool also. The case has the primer pocket drilled out and is threaded for mounting on the tool. The length rod goes through the case and pushes the bullet to the lands. You can then measure.

Hornady offers the modified cases for most popular calibers. They did not offer one for my 7-30 Waters. I had to send them a virgin case and they drilled and tapped it for me. Cheap money and fast turn around.

Bepe
 
#15 ·
Bowsnguns, if were me I'd telephone Ruger, them what you told us and see what they say. I would try some random factory rounds to see if they fit and maybe send the rifle back. I don't want to be locked in to a specific length until I've determined the best length for my self. The Hornady gauge is great but get a 1/4" dowel to push the trial bullets out of the chamber 'cause it won't stay in the gauge.
Good Luck have fun and Be SAFE.
 
#20 ·
Far be it for me to say anything about this subject, But, it can be as simple as a digital caliper to measure OAL. But an entirely different and more complicated AND more accurate to use the method BR shooters use. Not needed if you only want a hunting round out to a couple hundred yards to take a game animal.

Real reloading for an accurate round no matter the CF Rifle caliber. You must use what people use to get to that level. Hornady makes several tools to get you there. OAL case guage (threaded primer pockets) for the rifle caliber your using, Comparator gauges, for measuring. Hornady Lock-N-Load Overall Length Gauge kit. At least that way you know when/where the bullet you want to use IS at the rifle land/grove. If you choose, you can back it off 1 or 2 thousandths'. But for just a hunting round close to Factory for your firearm is fine. You want to really reach out and touch the target? Then do what the pros do.
 
#31 ·
I spent a summer seeing how small I could get 5 shot groups out of a 22-250. The oal tool was key. I got a couple of very accurate very consistent loads. Another thing that tightened up the groups was neck size only the brass. It also extends the life of the brass. Quick note, I got some brass from a friends mixed with mine. It had a larger chamber and after neck sizing the brass, when fired from my rifle pressure spikes, flattened primers and very hard to extract. Keep track of your brass.
 
#35 ·
Another thing that tightened up the groups was neck size only the brass. It also extends the life of the brass. Quick note, I got some brass from a friends mixed with mine. It had a larger chamber and after neck sizing the brass, when fired from my rifle pressure spikes, flattened primers and very hard to extract. Keep track of your brass.
Neck sizing is a plus but there will come a point in time where your shoulder will move forward far enough that you will need to run them through a body die or F/L die, there’s no getting around it.

Your friends larger chamber and the pressure spike makes no sense to me. I’d say your friend had a smaller chamber if you were able to chamber his fired brass in your rifle without F/L sizing. Your pressure spike is related to something else, it’s not the brass. My buddy is a Tikka guy, we both shoot the same 3 calibers, 7Mag, 6.5 Creed and the .22-250. I can neck size and fire his .22-250’s because his chamber is smaller, the 6.5’s and 7’s won’t chamber because his chamber is larger. Again your pressure spikes are not related to the brass.
 
#32 ·
The oil/coal was meant as an attempt on humor more than politics but point taken. Most of the advice was good the specific bullets manufacturer data should provide the COAL that you want to use. One point of contention though bullet seating was mentioned in reference to headspace. Rimless shouldered cartridges headspace off the shoulder not on any point on the bullet.

My reload goals are safety and reliability. If it loads and shoots reliably I'm happy. Accuracy is a consideration but I have never tried to seat bulets close to the leade to minimize freebore.
 
#33 ·
I dug my set out of my loading tool chest. It was actually from Stoney Point. I don't believe Hornady had marketed their version when I bought this set. Hornady may have had to wait until the patent expiration. I had a couple of modified cases from Stoney Point. Their selection was limited. Shortly after when Hornady introduced their version they had a wider array of modified cases. The nickel case is my 7-30 Waters that I sent to Hornady. The collets allow precise measuring off of the bullet ogive.

Only rifle round I load now is 7.62x39mm. Bullets have a cannelure so I set OAL to that. haven't used the Stoney Point in awhile.

Bepe

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#37 · (Edited)
Good stuff ^^^^^^^^^

Pretty much what has been mentioned here. I saw where Hornady now charges $15 to modify a case. IIRC I paid $10 way way back. Still pretty darn reasonable with the prices of everything else.

Absent of a machine shop it would be tough to accurately make your own for use with the tool. The slotted neck method appears to be easy to fabricate and should work perfectly.

Bepe
 
#38 ·
I saw where Hornady now charges $15 to modify a case. IIRC I paid $10 way way back. Still pretty darn reasonable with the prices of everything else.
I remember when it was $7 to thread your case……. It’s still a good price at $15, especially if you’ve blown your shoulder forward. The case sits better in the chamber.
 
#40 ·
I agree, It's a very good website that takes the 'mystery' out of what we've been talking about. Even though most of us here aren't taking 1000yard shots, the principal is exactly the same. It really boils down to 'attention to details' even the so-called small stuff can be and is important.

You don't have to be a scientist to reload accurate and safe ammunition
 
#42 ·
What I have been using for quite a few years is the Sincliar Seating Depth Gauge. It does not require any specially adapted cases but will give best results with a case fired in the rifle being measured (unsized, fired primer still in place).


Unfortunately Sinclair is now a part of Brownell's. I like Brownell's and their products a lot but their website sucks in my less than humble opinion. Finding things there can be quite a challenge but they DO still make a printed catalog that actually 'works'!

I find it best to measure several times as the pressure used to set the bullet against the rifling can make a big difference with some bullet/rifling combinations.

Bruce
 
#43 ·
Don’t neck size only. This was a fad among benchrest shooters in the 1990’s after one guy won a bunch doing it, but which has since been disproven and abandoned in all forms of precision competition. Full length size, bumping the shoulder for minimum clearance, around 2 thousandths. Neck sizing only is an invitation to inconsistency, and simply has been disproven - thoroughly so - as “the most accurate way.”

This thread does make COAL seem far more complicated than it is.

New reloaders get too caught up on book values for COAL. The book is not your rifle, so their COAL is just a generic waypoint, like saying Minnesota is north of Kansas… it’s not concrete directions. Reloaders will almost never be loading to book COAL, because real rifles don’t always have SAAMI minimum chambers, and bullets don’t always shoot their smallest when jumping whatever throat the books specs would promote. Seat your rounds based on your chamber, your mag, and your bullet ogives, nothing else.

A caution for those using the Stoney Point - now Hornady - OAL gauge and modified cases: if the modified cases don’t exactly match your chamber’s headspace length (and in principle, they do not, and will typically be shorter than the real length), then you are not actually measuring the correct COAL for your rifle. Bullet comparator bushings also do not give a consistent representation for all bullets approaching your leade, so even using Base-to-ogive measurements with these bushings isn’t anything more than a reference length, and will always be specific to each individual brand and model of bullet (or lot of bullets).

Bolt lift method is far and away the only reliable and repeatable method for finding your lands. Fool proof. Smoking bullets, magic markers, cut case necks, dipping cleaning rods, soft seating, etc can all be useful, but bolt lift method is the best way to get reliable and repeatable, precise results. But there are a dozen ways this task can be done, all of which work at least to some degree, so there really shouldn’t be so much confusion. Find the lands, ignore the book, and live happy.

Sounds like the OP just has a short throated chamber. Not a big deal unless he can’t chamber factory ammo or can’t seat the bullets he wants without falling into the case - at which point the choice is really to send it back to Ruger to have the throat fixed (or pay a local smith to do so).
 
#44 ·
Easy & cheap way to Accurately measure your rifle for OAL (COAL).

How "I" determine max OAL for a cartridge (courtesy of my Uncle Ivan).

1. Find the average length of 10 of your chosen bullet. Use one that is average.
2. Close the bolt of your rifle and push a rod (preferably one that is plastic coated... never use bare steel rods!) and if possible, attach something in the way of a flat tipped jag to the end (I have melted an old broken jag with a soldering iron until it was about .22 cal. in diameter and it works for everything. Of course, you cannot use the open, threaded end of the rod for pointed bullets!).
3. When the rod stops against the bolt face, put a couple inches of masking tape on the rod, 1" in the barrel, 1" outside the muzzle.
4. Holding the rod against the bolt face, put a fine line around the masking tape. Use a sharp felt pen or ballpoint pen but make sure you are consistent in how you hold the marking device against the barrel. I usually put the point as even with the muzzle as possible. Remove the rod.
5. Remove the bolt and carefully drop your average bullet point first into the chamber. Look and make sure the bullet did not reverse itself! With a short rod, tap gently 2 or 3 times on the base of the bullet to make sure it is fully seated against the lands.
6. Get another 2" piece of masking tape ready and slowly & gently reinsert the rod until the flat tip of the rod touches the tip of the bullet. Withdraw the rod an inch or so and put the second piece of tape on the rod.
7. Push the rod back in until it's touching the tip of the bullet and make another fine mark around the tape, holding the marking device exactly the same way you did when you marked the bolt face.
8. Give the bullet a tap to knock it loose and remove the rod from the bore. Using calipers, measure the distance between the marks on the tape and bingo! you have the maximum OAL of your cartridge. Don't forget to write it down! I keep a single page for each rifle with all of the OAL's for each different bullet I have for that caliber, which I keep in a manila folder with all my load data for that rifle. If you have several bullets you want to get the OAL for, the first piece of tape used on the bolt face will work for the rest of your bullets, even if you have to change the tape at the other end.

So, obviously, do not skip the part about tapping the bullet back out of the bore. And you are always limited by the maximum length of any magazine fed ammo unless you want a single shot rifle. Using this method does not require any disassembly of the rifle or bolt and as long as it's done carefully will give the OAL while keeping your bullets hard out of the lands. I have never pulled a bullet using this method.

As to neck sizing, while it does nothing as far as accuracy (and never has as far as I know), it certainly is easier on your brass. I neck size whenever possible and have reloaded cartridges such as 300 RUM, known as as a destroyer of brass, over 15 times during load development! Knowing how to do it helps. So don't dismiss it out of hand!
Cheers,
crkckr
 
#47 ·
For some calibers, COAL is critical. One manufacturer has a lot of free space for seating bullets one example is my 7mm Weatherby magnum. On the extreme, the 5.7 cartridge COAL is critical, cannot be any longer than what is specs say. My 6.5 has never had a problem chambering reloads.
 
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