Help Me Decipher my COAL

[zeeohsixinc]

I just got a fresh box of 500 175 SMKs to load for my Savage FCP-K 308 and am having trouble with a starting COAL. I used the method of taking a piece of fired brass, partially re-sized so the bullet fit snugly but could be moved, loaded it and closed the bolt, then removed carefully. I have tried several pieces of brass and several bullets. They all come out at 2.785" + or - .005". This seems incredibly short. I checked some of the SW Ammo 175s I got awhile back and they are all between 2.810" and 2.820". This is the same bullet in the same piece of brass. Does 2.785" seem too short? Have I been firing bullets jammed .025" or more in to the lands? Is my method incorrect?

Thanks,

Nate

 

[918v]

I use the slit case method. Take a FL sized case, cut a slit lengthwise though the neck and shoulder, insert your bullet and chamber. Sounds your device is defective.

 

[demolitionman]

It's a .308. Develop your loads using a COAL of 2.8 and a charge and primer combo that work best. I tried messing with jump and jam in my new to me .308 as well as my friends and we just keep going back to 2.8 oal. Just my opinion with the .308.

 

[Boogaloo]

Spend the $35.00 and get a Hornady OAL gauge. It really is the best/least expensive way to determine maximum OAL for any given bullet/brass combo. I disagree with the 2.800 is "best" method. Some bullets like to be jumped more than others. I do not jam bullets personally, but I get jump down to .005" in some of my loads. Just depends.

 

[P7id10t]

I agree with 918 in doing a slit case to measure your base to lands. Then get the Hornady bullet comparator Measure the split case bullet. Repeat 5x and take the average. If they're all the same, your technique is great. If they vary a bunch (i.e. > +/- 2 mils), check your methods.
I have found, of the ~150 of the 500 SMKs I have, the ogives vary so OAL is not a good measure of "jump to lands" for that bullet.
2.8 is a great start. My 308 is a gasser so I set up for 2.815

 

[pell1203]

Please don't take this the wrong way as I'm pretty certain this is not your problem and your method of measuring sounds just fine. However, I'd hate to overlook the obvious so I'll go ahead and ask a really silly question.

Are you initially pulling the bullet out of the cartridge far enough so that the measured COAL is at least 2.960" when preparing to check your chamber length?

Like I said, it is a really silly question! Just want to make sure you are starting out with an overly large COAL from which to shrink.

 

[zeeohsixinc]

I smoked some bullets to see what was going on. They are definitely reaching the lands. Also smoked some of the SW ammo rounds and they are indeed being jammed. I'm pretty confident my COAL to the lands with the 175 SMKs is around 2.785, obviously varying a little (.005) with the difference in each bullet. My savage must have an incredibly short throat. The book says min COAL 2.800. I really don't want to jam them in though. Would loading to 2.775 cause any pressure issues?

Nate

 

[40xs]

There is a lot of variance in length from the ogive to the tip of most bullets. both measurements need to be considered, especially if you are running tactical ( from the magazine). the mag. length is the most important unless you are only using match rounds as it matters not how much bullet tip is in the barrel and you are shooting single shot. Get a comparator gauge to establish your ogive measurement or as said before use the slit case method. Determine the extreme ogive length for your barrel's lead to the lands while considering the magazine length, so they will all load in the magazine if this is your plan. I only load my rounds for my match rifle using the ogive length as I do not feed from my magazine and it has a very close tolerance match chamber. Even factory rounds chamber tightly in it. I have another rifle that I use the mag. length meaurement, and t has a very generous throat and lead.

 

[FN in MT]

SMK's /Berger LR Match ,vary a bit so I use a Sinclair Comparator to measure loaded OCL.... by using the ogive reading, not the true OCL.

Sinclair Hex Style Bullet Comparators | Sinclair Intl

I found that my old 40X barrel has a LONG throat and with Bergers a jump of .045" is my sweet spot. That is a raw ocl of 2.920". With the Berger comparator I get 3.240".
Few days ago I opened new boxes of bullets and they were .002 to .003" off if simply seated with my old seater die setting. The comp showed me they were a bit shorter at 3.237 or so.

I adjusted the seater die out to allow slightly longer length and seated to the 3.240" I require. WHY I like the comparator method vs simple OCL.

Sounds confusing sorry for that. I'd also suggest the Hornady OCL kit to check for your "to the lands" dimension. Simply the easiest method to get that dimension.

FN in MT

 

[zeeohsixinc]

I think the direction of this thread is moving way from my original intent. My COAL to the lands with 175 SMKs is 2.780 - 2.785, that is fact. When I chamber the SW ammo which is at 2.81, there are 6 land marks right at .025 long, confirming my COAL. I am loading some cartridges at 2.770 to start with for a ladder / OCW test. I'll watch for pressure signs and post the results.

 

[Fuzzball]

"The book says min COAL 2.800."

Book OAL is the length the book makers used to develop the listed powder charges in their rifle and there's no more to it than that. Your rifle, case/bullet/powder/primer lots are different from theirs. No loading mamual is a scientific cook book that can be relied on as more than a general guide to start with. Find your own OAL and use it, same as the powder charge.

 

[targaflorio]

Surprisingly short throat on a factory rifle. How does it shoot?
I suggest you work up your load at 2.81" coal to find your max charge and then set bullets progressively deeper to find the sweet spot. You may want to choose a powder that doesn't run over 100% fill. Good luck!

 

[zeeohsixinc]

Yeah it certainly surprised me at how short it is. Shoots right at 1 MOA at 100 with the SW Ammo 175 SMKs. I did a little research and other savage shooters have noted short throats as well. I'm trying a .010 jump first. 175 SMKs seem to like a little jump. I got up to 44.5 of IMR 4064 with just a little compression at 2.770 COAL.

 

[targaflorio]

I chrono'd SWAMMO 308 and my load with 43.5 Grs of varget smk 175 and win brass was almost identical.
Be careful if you allow the bullet to touch the rifling (by increasing coal) after you have set the charge weight as the pressure will likely spike higher.

 

[elfster1234]

Easy, don't use COAL when seating your bullets,,,, and go by OGIVE seating depth. This way you know 100% if you're touching the lands, jammed into the lands, or jumping the bullet FOR the bullet being used FOR the rifle being reloaded for.... If you don't know what I'm talking about between seating bullets by OGIVE and not by COAL, then you have some homework to do.... Dont take this the wrong way but you don't know what you're doing.


I personally wouldn't do anything until you can get a hornady OAL case gauge with bullet comparator so you know for damn sure the max OGIVE seating depth touching the land of the bullet you're trying to use FOR the rifle you're reloading for... I would personally seat bullets by OGIVE and not COAL.... not only will you know the jump to lands or touching lands by seating by OGIVE, but will give much more consistent readings than going off the tip of the bullet / COAL... Each bullet is different for different rifles. Then the amount of bullet jump or touching the lands is up to you... I would only touch the lands in a bolt gun... and I would do a .020 to .025 jump for semi autos. I still check bullets with my semi auto LMT as I have had once instance using sierra gamekings 165gr that was WELL below not only max magazine length, but well under sierra's recommended COAL by .025!!! If I didn't check with that bullet & my LMT the bullet would've been massively pushed into the rifle lands and pushed back into the brass.

I just got a fresh box of 500 175 SMKs to load for my Savage FCP-K 308 and am having trouble with a starting COAL. I used the method of taking a piece of fired brass, partially re-sized so the bullet fit snugly but could be moved, loaded it and closed the bolt, then removed carefully. I have tried several pieces of brass and several bullets. They all come out at 2.785" + or - .005". This seems incredibly short. I checked some of the SW Ammo 175s I got awhile back and they are all between 2.810" and 2.820". This is the same bullet in the same piece of brass. Does 2.785" seem too short? Have I been firing bullets jammed .025" or more in to the lands? Is my method incorrect?

Thanks,

Nate

 

[elfster1234]

these are not the best videos in the world, but should give you an idea of what im talking about


Hornady OAL Gauge - YouTube

Hornaday Lock-N-Load overall length gauge - YouTube

Using The Hornady Overall Length Gauge And Bullet Comparator - YouTube

Dont take this the wrong way but you don't know what you're doing.


I personally wouldn't do anything until you can get a hornady OAL case gauge with bullet comparator so you know for damn sure the max OGIVE seating depth touching the land of the bullet you're trying to use FOR the rifle you're reloading for... I would personally seat bullets by OGIVE and not COAL.... not only will you know the jump to lands or touching lands by seating by OGIVE, but will give much more consistent readings than going off the tip of the bullet / COAL... Each bullet is different for different rifles. Then the amount of bullet jump or touching the lands is up to you... I would only touch the lands in a bolt gun... and I would do a .020 to .025 jump for semi autos. I still check bullets with my semi auto LMT as I have had once instance using sierra gamekings 165gr that was WELL below not only max magazine length, but well under sierra's recommended COAL by .025!!! If I didn't check with that bullet & my LMT the bullet would've been massively pushed into the rifle lands and pushed back into the brass.

 

[zeeohsixinc]

Elfster- I get it dude. I'm sure you are itching to spread your vast reloading wisdom, but maybe next time take a second to read what I'm writing and respond to it. There are people out there that measure by COAL. According to you, none of them know what they are doing. SMKs vary by about .005. I'm willing to accept that variance, as once I set my bullet seating die, it seats by ogive.

I don't need to spend $30 on a comparator right now. I just want to know if others have experienced similar short throats in savage barrels, and if anyone had loaded 175 SMKs to under the book minimum recommended COAL of 2.800.

 

[elfster1234]

Ok, im sorry.... nm then.

Elfster- I get it dude. I'm sure you are itching to spread your vast reloading wisdom, but maybe next time take a second to read what I'm writing and respond to it. There are people out there that measure by COAL. According to you, none of them know what they are doing. SMKs vary by about .005. I'm willing to accept that variance, as once I set my bullet seating die, it seats by ogive.

I don't need to spend $30 on a comparator right now. I just want to know if others have experienced similar short throats in savage barrels, and if anyone had loaded 175 SMKs to under the book minimum recommended COAL of 2.800.

 

[918v]

Your rifle is a unicorn. Why would Savage cut a chamber that won't accept factory loads? Cuz if a SMK @ 2.8" won't chamber, then neither will anything else.

 

[zeeohsixinc]

Your rifle is a unicorn. Why would Savage cut a chamber that won't accept factory loads? Cuz if a SMK @ 2.8" won't chamber, then neither will anything else.

I thought so too, but then I googled ' savage 308 short chamber ' and got more results than I thought I should. I called my brother, who also has a savage FCP-K, but loads 178 AMAXs, and he loads them to 2.775" because of his short throat.

It will accept factory loads. I've shot about 200 FGMM and SW Ammo 175s jammed in the lands and they still shoot at 1 MOA. Not optimal but it works. No pressure signs either.

 

[cappy227]

I too have a Savage 10FCP with a short throat - my measurement readings ask for 2.780" seating an SMK 175gr just touching the lands.