Win Model 70 Short Throat

mr.orange

mr.orange

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So my particular Winchester model 70 seems to have a short throat for a 30-06, leading me to create a round with spec's from Hornady's website:

- 3.225 COAL
- max distance to lands using Hornady's OAL gauge 3.241
- 2.484 trim length
- 45.5 grains of IMR4895 (min 44.4, max 47.8)
- CCI 200 LR primer
- 165 gr Hornady Interlock BTSP

Results in a sub-moa zero'd at 200 yard round/rifle.

Question I have is, when moving up to 180 gr bullets, I can't find any reload data that fits this short throat. Virtually every recipe jumps to a trim length of 2.494 with a COAL of 3.340, which obviously won't fit in my rifle. When I say virtually every recipe, I mean what's in my Lee Reloading manual, Hornady website, or IMR's website.

I have 2 powders available to me, IMR4895 and H4831SC.

Does anyone's manual have a recipe that would fit either of these powders to the OAL I'm looking for?

Thanks in advance.
 
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Measure to lands - can use "gizmo" that you have to buy, or use one of several procedures described for decades in various manuals or articles.

Decide what you want for bullet "jump" - might eventually take testing or trial and error to determine what is best for your outfit. 0.030" about good average place to start. Woodleigh manual suggests to start between .020" and .040" with their bullets (page 41). I think Barnes suggests 0.050" for their solid bullets. After finding your best powder charge, with the bullets of interest, you will likely want to play with more or less seating depth in your reloads.

Verify that what you get will fit into and feed from your magazine, if you intend to use the rifle as a repeater.

Work up your powder load from Start level to most accurate for you.

Is several of us who have never found what loading manual COAL length is useful for, other than fitting into the rifle's magazine? I started a thread on CGN where out of five 30-06 rifles here, none had identical distance from bolt face to lands - if I remember, like 0.060" difference among them. Go here to read it: https://www.canadiangunnutz.com/forum/showthread.php/2230590-A-cautionary-tale. As I recall in some cases, a loading manual listed COAL for that specific bullet would be significantly jammed into the lands on some of these rifles.

OP - you do not say what brand / type of 180 grain bullets that you intend to use in your 30-06. I see in Hornady 9th Edition manual that they show 5 different 180 grain bullets, with three different COAL given. I suspect that means about nothing for other brands of 180 grain bullets, and may not mean much for your rifle. It appears that Hornady used a Model 70 Winchester rifle with 23 3/4" 1-10" twist barrel - but unknown era and no specifics about the lands to bolt face distance.
 
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I may be missing something. Is this a typo for your max distance to lands = 3.241"? That would be a base to ogive measure for a bullet touching the lands, and it is impossible for that to be longer than your cartridge overall length of 3.225". (The SAAMI spec for 30-06 COAL is 3.340"). Nothing in your post is showing data for a shorter than SAMI spec chamber throat. The trim length is for the case, not the base to ogive measure of the bullet. (Forgive me if I am missing something, but I am not seeing the issue in your OP. The 180gr bullets are not too long for the 30-06, unless your barrel is stamped with the wrong caliber stamp?).

The distance to lands is not directly linked to bullet weight, because heavier bullets can have long sleek noses (like VLD bullets).
COAL is only relevant for magazine feeding in your rifle. You want to work with "base to ogive" measure to the lands in order to determine your seating depth back from the lands. You will need a bullet comparator tool to attach to your calipers, with the correct insert for the bullet diameter. The Hornady bullet comparator kit is probably the most readily available, but there are other good brands.

For my bolt action rifles, I stopped using the Hornady OAL gauge after I watched Eric Cortina's method to find jam, and then start seating 20 thou back from jam, and seat shorter (deeper in the case) from that -0.020 starting point.

Jam is found by sizing the neck on a NON-primed, NON-charged fire-formed case dummy round, and just barely seating the bullet. Then apply sizing wax lube on the bullet's ogive area. Place the dummy round in the chamber and close the bolt on it. Then open the bolt fast, and the dummy round should extract with the bullet seated to the jam length. Measure the base to ogive length with your bullet comparator, times 3 dummy rounds to establish an average.

Subtract 0.020" from this length and that is your starting point for testing (but see caveat below). The -0.020" is a good safe distance to avoid any pressure spikes, and of course start at your reloading manual's minimum powder charge and work up. Cortina recommends seating tests in increments of -0.003" back from the -0.020" starting point.

Caveat: Depending on the bullet and the rifle barrel's throat, the jam minus 0.020" might not be enough to grip the bullet enough to your liking, so you can seat it deeper in the case if necessary. In my experience the lack of neck grip is usually for the lightest shortest bullets, not the longer heavier bullets.

The 30-06 accommodates bullets up to 220 gr. I would bet that your Winchester Model 70 30-06 will accommodate your 180gr bullets just fine.

EDIT: Nothing wrong with the Hornady OAL Gauge, don't get me wrong. I used it for many years. I start seating at -0.010" back from what this gauge measures for cartridge base to ogive length touching the lands. I just found that the jam method was easier for me.

EDIT 2: If your 30-06 cases truly cannot be loaded with a .308 180gr bullet and chamber properly in your rifle, then I suggest you take that rifle to a gunsmith immediately because that chamber is way, way out of spec, and not a 30-06 chamber.
 
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Biologist said:
I may be missing something. Is this a typo for your max distance to lands = 3.241"? That would be a base to ogive measure for a bullet touching the lands, and it is impossible for that to be longer than your cartridge overall length of 3.225". (The SAAMI spec for 30-06 COAL is 3.340"). Nothing in your post is showing data for a shorter than SAMI spec chamber throat. The trim length is for the case, not the base to ogive measure of the bullet. (Forgive me if I am missing something, but I am not seeing the issue in your OP. The 180gr bullets are not too long for the 30-06, unless your barrel is stamped with the wrong caliber stamp?).

The distance to lands is not directly linked to bullet weight, because heavier bullets can have long sleek noses (like VLD bullets).
COAL is only relevant for magazine feeding in your rifle. You want to work with "base to ogive" measure to the lands in order to determine your seating depth back from the lands. You will need a bullet comparator tool to attach to your calipers, with the correct insert for the bullet diameter. The Hornady bullet comparator kit is probably the most readily available, but there are other good brands.

For my bolt action rifles, I stopped using the Hornady OAL gauge after I watched Eric Cortina's method to find jam, and then start seating 20 thou back from jam, and seat shorter (deeper in the case) from that -0.020 starting point.

Jam is found by sizing the neck on a NON-primed, NON-charged fire-formed case dummy round, and just barely seating the bullet. Then apply sizing wax lube on the bullet's ogive area. Place the dummy round in the chamber and close the bolt on it. Then open the bolt fast, and the dummy round should extract with the bullet seated to the jam length. Measure the base to ogive length with your bullet comparator, times 3 dummy rounds to establish an average.

Subtract 0.020" from this length and that is your starting point for testing (but see caveat below). The -0.020" is a good safe distance to avoid any pressure spikes, and of course start at your reloading manual's minimum powder charge and work up. Cortina recommends seating tests in increments of -0.003" back from the -0.020" starting point.

Caveat: Depending on the bullet and the rifle barrel's throat, the jam minus 0.020" might not be enough to grip the bullet enough to your liking, so you can seat it deeper in the case if necessary. In my experience the lack of neck grip is usually for the lightest shortest bullets, not the longer heavier bullets.

The 30-06 accommodates bullets up to 220 gr. I would bet that your Winchester Model 70 30-06 will accommodate your 180gr bullets just fine.

EDIT: Nothing wrong with the Hornady OAL Gauge, don't get me wrong. I used it for many years. I start seating at -0.010" back from what this gauge measures for cartridge base to ogive length touching the lands. I just found that the jam method was easier for me.

EDIT 2: If your 30-06 cases truly cannot be loaded with a .308 180gr bullet and chamber properly in your rifle, then I suggest you take that rifle to a gunsmith immediately because that chamber is way, way out of spec, and not a 30-06 chamber.
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No, you're not missing anything, but you picked up on my 'mixing' of terminology and procedure for expedience sake of the posting. What I was trying to say is exactly what you described in procedure. Measuring from base to ogive results in a max coal of 3.241, so I made rounds to 3.225, so that the ogive would sit 0.016 off the lands. And like I said, results are sub-moa at 200 yards.

The problems started when trying to make rounds to 3.340. Bullets were being jammed into the lands and became stuck when extracting, dumping powder all over the shooting bench. Only a dowel would remove them. Groups became 10" at 200 yards.

And you kind of answered my next question too. If I can't find an appropriate recipe to fit the shorter throat, do I take the rifle to a gunsmith if it's shooting great as-is. Feeling conflicted as I dropped my biggest deer ever this year - 270 lbs mulie buck, at 313 yards, with my own ammo (the 165's at 3.225 length). It's incredibly satisfying to have those three things come together. Do I risk f***ing up this rifle getting the chamber brought back into spec???

Edit: For context, I've been hunting for close to 40 years whether it be archery, rifle, or shotgunning, but only started reloading maybe 5 years ago. Reloading has been a fascinating experience, but I don't really have much experience doing it.
 
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mr.orange said:
No, you're not missing anything, but you picked up on my 'mixing' of terminology and procedure for expedience sake of the posting. What I was trying to say is exactly what you described in procedure. Measuring from base to ogive results in a max coal of 3.241, so I made rounds to 3.225, so that the ogive would sit 0.016 off the lands. And like I said, results are sub-moa at 200 yards.

The problems started when trying to make rounds to 3.340. Bullets were being jammed into the lands and became stuck when extracting, dumping powder all over the shooting bench. Only a dowel would remove them. Groups became 10" at 200 yards.

And you kind of answered my next question too. If I can't find an appropriate recipe to fit the shorter throat, do I take the rifle to a gunsmith if it's shooting great as-is. Feeling conflicted as I dropped my biggest deer ever this year - 270 lbs mulie buck, at 313 yards, with my own ammo (the 165's at 3.225 length). It's incredibly satisfying to have those three things come together. Do I risk f***ing up this rifle getting the chamber brought back into spec???

Edit: For context, I've been hunting for close to 40 years whether it be archery, rifle, or shotgunning, but only started reloading maybe 5 years ago. Reloading has been a fascinating experience, but I don't really have much experience doing it.
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Load your ammo to the length and powder levels that YOUR rifle likes. I assume it digests factory ammo ok? Then I wouldnt worry about it. Load manual data is a guideline, nothing more. - dan
 
mr.orange said:
Measuring from base to ogive results in a max coal of 3.241, so I made rounds to 3.225, so that the ogive would sit 0.016 off the lands.
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No. I think we found our problem here. COAL does not determine where the ogive is relative to the lands. You are confusing two different measurements. The tip of the bullet is COAL - it does not touch the lands. It is the ogive of the bullet which touches the lands. You do not use COAL to determine how deep to seat a bullet relative to the lands - these things are not related.

Base to ogive for the specific 180gr bullet you are using determines where it touches the lands. Your reloading manuals do not specify base to ogive because it is different for every bullet brand, model and weight, and every individual rifle. You have to determine base to ogive for each different bullet brand, model and weight, using a bullet comparator tool, and a method for measuring to the land for where the bullet touches (either the jam method, or use the Hornady OAL gauge. By the way the Hornady tool is mis-named because its not true OAL, it is base to ogive length that it is measuring).

Ignore COAL for now. COAL has nothing to do with how long you can seat the bullet without getting it stuck into the lands. It is only for max magazine length for feeding from a magazine (and your rifle's magazine may be different than the standard SAMMI spec too).

I suggest you go to Youtube and enter a search for "how to determine bullet seating depth", or "how to use the Hornady OAL gauge", or "how to find where the bullet touches the lands". And also "how to use a bullet comparator" since that is the tool you use to measure the seating depth touching the lands, which is the baseline for subtracting back for the bullet jump distance. There are dozens of good videos on YT showing how all this is done, and this should get things sorted for you in no time.

As Dan mentioned above "Load your ammo to the length and powder levels that YOUR rifle likes".
 
Win made a run of model 70's in the early to mid 80's that had short throats for some reason or other? Hornady mentioned this as the reason their cannalure was moved on their 130gr SP .270 bullet.
 
I'm so confused. I've been reloading for thirty years, and I can't figure out what's going on. Are you using Hornady 180 grain Interlocks. If so, will the rounds chamber if you seat to the cannelure. Do the rounds chamber easily, without any signs that the lands are contacting the bullet. Again, if so they should fit in the magazine easily. That's your starting point. Try them at the range. You may be surprised. You may be able to achieve great accuracy with that combination. Of course at the same time you are trying different powder charges til you find one that works with your rifle. Now, if you want to possibly get even better groups, you can find out where the ogive of that particular bullet contacts the lands, and back it off from there in increments starting with what is recommended(.020, .050) whatever. You have various means to do this, as others have pointed out. Hornady comparator/OAL gauge, smudging the bullet with soot, the jam method, and Sinclair gauge, are just a few examples. Good luck.
 
Quigly - you will find many brands of bullets (other than many Hornady ones) do NOT have a cannelure, so where to seat them? Also, as per that link that I posted in Post #2 of this thread - go to Post #5 in that linked thread - is at least one 30-06 rife here, that a 180 grain Accubond, seated as the Nosler manual lists, will "jam" into the rifling in that rifle.

Is almost a year later - not finding any 180 Accubond here to know if they have cannelure groove or not - either sold them or used them. For sure, the 9.3 mm 250 grain Accubond has a cannelure groove, but the 225 grain .338" do not - at least the boxes that are open here.

In my reloading I pretty much have been ignoring those crimp grooves, since I almost never crimp centre fire rounds - sometimes those grooves end up inside the case neck or out in front of case mouth - depends what that rifle wants - what I think delivers "best".

But, I suspect is your point, that there are many ways available to the hand loader to know where the bullet is, in relationship to the lands in that hand loader's rifle.
 
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Loading manuals, as someone has already stated are just a guide. Don't consider it gospel. If a bullet does not have a cannelure, and you don't have the tools to seat it to a set distance from the rifling, it just requires a little more trial and error. So, if a round loaded with an Accubond bullet doesn't fit when employing book data, you incremently seat the bullet deeper until it fits. Again, if you don't have specific tools to find out at what OAL the bullet first contacts the rifling, use a less sophisticated method. It may not be as precise, but will get you close. All you need for that is a caliper, and eyeballing the bullet for marks made by the lands . Once you are there, measure the round overall length, preferably from the ogive, but if not from the base to the point. Then seat the bullet, incrementally until you have achieved the gap that you want to start with.
Of course specific tools give you more precision, but are not a requirement. I went for years without a Hornady comparator/OAL gauge, yet achieving accuracy was not that difficult.
 
More often than not, at least with my rifles, a precise gap has been useless, because most of my rifles have long throats. This means the finished round will be longer than the magazine length while attempting to achieve a gap that is even close to what is recommended. Accuracy has been very good nonetheless.
 
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Quigly said:
More often than not, at least with my rifles, a precise gap has been useless, because most of my rifles have long throats. This means the finished round will be longer than the magazine length while attempting to achieve a gap that is even close to what is recommended.
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Yes, I agree - for most rifles here, either as made originally, or as the lands have become eroded with use - my loads end up way shorter to fit into the magazine, then to have ideal "jump". But as per that linked post - was my intent back then to try to load up the same loading to use in several rifles - so got me to think to verify for them all if they were the same or if they were different to each other. These ones had differences. So, I presume that anyone with "a" particular rifle will not know, unless they measure it or make some effort to establish where those lands are - and then, as a bench rest shooter acquaintance advises - the damn things will wear with use, and one ends up "chasing the lands" with his "best" hand loads.
 
Yes, every rifle is different. What works for one will not necessarily work for another. It's all trial and error, and will use up a lot of components.
I'm more a hunter than a target shooter, so a specific load will do me for as long as I have a certain rifle, or a lifetime. Whichever comes first. Definately, barrel wear, will have one making changes throughout the life of the barrel.
 
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