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Author Topic: Bullet Seating Depth  (Read 18824 times)

Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #15 on: March 14, 2011, 05:10:11 PM »
The link that Killbilly posted above has some great info, especially if you read all the way to the bottom. I'm copying and pasting one such post:
Thanks for your question.

To answer you, seating depth in relation to the distance from the lands should not affect the efficiency of the powder burning completely, if it is a powder/bullet combination that has performed well for you in previous occasions. However, the closer you are to the lands, you will see an increase in pressure, and this should be approached with caution, especially with hot/compressed loads. If you want to try closer to the lands, we suggest reducing your load for safety reasons.

Many bullets perform very well with some jump. In most of my rifles I have found that jump of .020″ to .030″ has been the “sweet spot”. This will differ from rifle to rifle, and bullet to bullet.

As for your nickel plated brass, we suggest it not be reloaded for a few reasons: First of all it is hard on dies, the nickel is harder than brass, and can scratch and ruin a good set of dies. Second, it is hard to size, it must be undersized to achieve the proper sizing. Third, nickel plating is used for corrosive conditions such as hunting, and is designed to be shot and “left”.

I hope this helps you out. If you have further questions, please feel free to contact our reloading technicians at 1-800-717-8211.

Good Shooting

Pete Petros
Lead Reloading Technician
Sinclair International

What I get out of this one post is that a cartridge with a COAL .025 off the lands might be a great place to start.

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Offline high country

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Re: Bullet Seating Depth
« Reply #16 on: March 14, 2011, 09:06:13 PM »
It depends on the rifle, bullet and intention of the gun for me. I have found tsx bullets shoot well with .125 in my ultra's, yet bergers seem to want to make out with the lands.

Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #17 on: March 15, 2011, 12:06:07 AM »
High Country, You're right. I was mainly posting the reply above because of the bullet seating depth info in it posted by Sinclair International's Lead Reloading Technician.

Another copied/pasted:  I use the rod down the barrel method. When using a brass rod the way I mark it is with a sharp knife held flat across the muzzle and pressed into the brass rod until a mark is left on the rod. The mark is razor thin and consistent and the only challenge to accurate measurement is getting the dial calipher blades exactly aligned to the marks when you measure between the lines left by knife. With a cleaning rod I usually place some masking or other tape on the rod where the knife contacts to make mark easier to see.

The above post was in relation to holding a bullet against the lands with a dowel and sliding a rod down the barrel from the muzzle end. First against the cocked bolt face, next, with bolt removed, against the bullet tip that would be just lightly held against the lands with a dowel.
I just went thru every caliber, weight and style of bullet on my bench for 3 rifles today. Measured exact CAOL. Wrote them down for future reference. Now I can set up a dummy round for each bullet and know for sure exactly how far off the lands I am.
Thanx for the info guys. I'm going shootin tomorrow - weather providing.
Rhinelander, WI
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Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #18 on: March 15, 2011, 11:30:30 PM »
I just loaded a batch for the range in 30-06 with 165gr Swift Scirroco IIs and 168gr Barnes TTSXs and used the rod down the barrel for seating depth. Simple and I'm sold on it without buying anything further than I already had in my shop. Accurate to within .001 or .002 I'd say. Basically as accurate as a person can see.
Does anyone else use this method?
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Offline carpsniperg2

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Re: Bullet Seating Depth
« Reply #19 on: March 16, 2011, 12:33:31 AM »
Never heard of that method. How does it work? I would be interested 2 hear more about it.
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Offline high country

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Re: Bullet Seating Depth
« Reply #20 on: March 16, 2011, 04:57:06 AM »
try loading some tsx's at .08 to .125 off.....see what it does for you. scirroccos can't do that they are too long and seem to like to be close to the lands.

Offline JLS

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Re: Bullet Seating Depth
« Reply #21 on: March 16, 2011, 09:14:26 AM »
I load my TSXs just short enough to fit in the magazine and have had very good luck with that.  Am I missing something here, because with my M70s I cannot seat right off the lands and still have the cartridge fit in the magazine?
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Offline high country

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Re: Bullet Seating Depth
« Reply #22 on: March 16, 2011, 06:18:14 PM »
I load my TSXs just short enough to fit in the magazine and have had very good luck with that.  Am I missing something here, because with my M70s I cannot seat right off the lands and still have the cartridge fit in the magazine?

spend 3 bullets and try what what I said^^^^^^

Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #23 on: March 16, 2011, 06:25:30 PM »
After reading that link Killbilly posted all the waaaaaaaaaaaaaaay to the bottom I put a few ideas together that I'd read on it and came up with this:
I'll word this the way I did it and you guys can adlib from there. Or PM me and I'll give ya my phone number.
To establish C.A.O.L.(case over all length) and/or seating depth with each bullet I'll ever use, here's what I did.
1) Put my gun in my cleaning rest on my reloading bench. Bolt cocked(gun empty of course)and closed. No protruding firing pin if it's cocked.
2) Using a wood dowel(long), small enough to fit down the barrel, insert it untill it touches the bolt face. Using a razor blade, make a slight cut/mark on the dowel exactly flush with the end of the muzzle.
3) Remove the bolt.
Both dowels could be the same diameter. Match the caliber.
4) Insert another dowel(short) (just small enough to fit into the bullet recess area of the chamber) into the chamber from the breech end with each bullet  you're going to use. One at a time of course. It takes a little finageling sometimes as some bullets want to slip into a bolt lug recess. Using the dowel from the muzzle end at the same time helps align the bullet so it enters the chamber correctly.
Anyhow, slowly slide the bullet into the chamber using the short dowel with your left hand while sliding the other dowel down the barrel from the muzzle end with your right hand untill the long dowel contacts the tip of the bullet.
Note: It's easy to push the bullet into the lands so be very gentle and use the same force on each bullet for a consistent measurement.
Remember that your bolt face measurement is already established and will be the same for all measurements with that particular gun.
I pushed the bullet off the lands a few times with my right hand dowel while pushing it back against the lands with my left hand dowel at the same time untill I was satisfied with it just barely making contact.
5) Now, slightly lift up on the long dowel to put pressure against the muzzle so the dowel won't move while you're reaching for the razor blade you forgot to set close enough to reach, LOL.
Providing that the dowel is still exactly in place against the bullet tip  and the bullet is barely touching the lands, make another cut or mark with the razor blade flush with the muzzle.
6) Remove the long dowel and using a reloading micrometer(knife edge), measure the distance between the two cuts. I used a fine point pen to make the cuts easier to see.
The resulting measurement(write it down)is the C.O.A.L. for THAT bullet TOUCHING the lands. Rember that this measurement is Touching The Lands. This might not be a safe seating depth for some established loads as greater chamber pressure will result with a bullet seated against the lands. Most of you already knew that but thought I'd better say it.
Based on a posting from Sinclair International stating that they'd found the 'sweet spot' to be between .020 and .030 off the lands with most guns/bullets, I adjusted my seating depth to be .025 off the lands based on all the new measurements I just took. My rifle magazies will allow this. Yours might not. Check it out as your magazine might be the determining factor for COAL.
Each bullet will extend into the lands differently, so rotate the dowel and make a new mark for each bullet you have on your bench.
I did this and wrote down the COAL for each cal(3 rifles)and 13 bullets. I then subtracted .025 from each measurement and am going to use this as my new starting point for working up loads. I recorded all of it so I won't have to do it again unless I try a different bullet.

Over the years I've always used a felt tip marker to color a band around a seated bullet right at the ogive, chamber it, re-seat it again and again untill no marks appeared from touching the lands. I established 'dummy' rds for most bullets over the years but really never knew exactly how far off the lands I was with any given bullet untill now.
Upon checking out some of my dummy rds that I thought were barely off the lands, surprise!! They all varied considerably. I adjusted them yesterday with an enertia bullet puller and re-seated them to my new COAL based on my new findings.
It's actually really easy to do this and now I know exactly where each bullet is seated and can use a micrometer to double check each time.
Rhinelander, WI
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Offline quadrafire

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Re: Bullet Seating Depth
« Reply #24 on: March 16, 2011, 07:04:45 PM »
Good post. I am new to reloading, but I have 3 calibers at this time that I am working up loads. This sounds pretty strait forward. You described it well enough that even a dummy like me could do it.

Offline high country

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Re: Bullet Seating Depth
« Reply #25 on: March 16, 2011, 07:27:12 PM »
You can smoke a bullet with a candle, just hold it low in the flame. Remember you can only use col on like meplats and ogives. Change either and your measurement flies out the window.

Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #26 on: March 16, 2011, 08:37:26 PM »
High Country,
You're right but as stated in my post, EVERY BULLET needs to be measured separately. Smoking is no different than a felt marker. It works but it is not very accurate and leaves you still guessing as to exactly how far or close you actually are to the lands.
Using the dowel method, the guessing is eliminated and is actually faster than smoking or marking.
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Offline sakoshooter

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Re: Bullet Seating Depth
« Reply #27 on: March 20, 2011, 02:23:38 PM »
Has anyone gone to the trouble of checking their bullets with this method since we talked about it on here?
I did 3 cailibers and 13 different bullets in about 30 minutes on my bench.
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Offline JackOfAllTrades

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Re: Bullet Seating Depth
« Reply #28 on: March 20, 2011, 07:33:02 PM »
I haven't done it since this thread started. But I've done it that way before.  I certainly don't have that many bullets/loads to validate for each gun.

My question to you is.. Now that you know exactly the distance of ogive to lands is, what have been your experiences with even a few of those loads regarding accuracy?

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Offline high country

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Re: Bullet Seating Depth
« Reply #29 on: March 20, 2011, 07:45:02 PM »
I would think that if you must use something down your bore, a rod might be more accurate. When you measure off the meplat there is a lot of room for error, measure off the ogive and it should be consistent.....or you could use one of the oal case gauges.

 


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