Bullet Seating Depth ?

[eric.s]

Hi, new to reloading so I'll try to put in as much information as possible:

-308 win -175 smk hpbt/virgin lapua brass/cci br large primers/varget powder

-RCBS press/redding competition bullet seating die/Frankford arsenal digital caliper/Hornady comparator body/30 cal insert

Basically my oal are varying +/- .1 tenth and bullet ogive on loaded round is +/- thousandths

Primer seating depth is good, not protruding out.

So I know meplate cuts are off, but is it normal for smk to be off by tenths?! Basically I'm getting handfuls of 2.7's to 2.8's(trying to keep OAL to 2.80) Even my loaded bullet ogives are off by +/- a couple of thousandths. I neck sized a few rounds .002- from loaded rounds using reddings competition neck sizing die and bushing = same results though. I seat my bullet seating die by having the ram in uppermost position, screw die until sleeve is compressed in and contact is made with shellholder, than back off till micrometer adjustments are in front for easy reading. I've tried seating the round,backing it off, rotating it 180 and seating it again....same results. Am I being to picky? Is it possible that it could be my dial calipers that are off? Any recommendations?

I'm sure I'm missing some information so I'll answer any questions you guys ask.

Thanks in advance!

 

[vinsonr]

Your seating die touches the ogive part of the bullet, not the tips, thus the low variation of that measurement vs OAL. Are they shooting well for you? If so, then charlie mike. If not, then change bullets. Amax are very uniform.

 

[eric.s]

Honesty, I haven't gone out and shoot with them yet. I'm working on loads for a ladder test. But before I continued to load more, I wanted to see if I could atleast get OAL within atleast 2.80 without +/- variations in the tenths. Unrealistic? Thanks for the reply and advice vinsonr

 

[Texas solo]

I have the exact same issue with SMK 175's. I use a Forster Ultra Seater die. I use the same style die on my .223 and they're always within .001" on the ogive measurement. I could care less about the OAL, it just doesn't matter. But my .308 CBTO measurements were having .006" variance. That's too much. I contacted Forster and got the following reply:

"Thanks for contacting us about this issue you seem to be having with the base to O-give measurement variation on your 308 loads. Your problem is very important to us.

The first thing to check would to make sure the bullet seating stem is coming in contact with the O-give of your bullets. Take that die apart at the knurled portion, separating the top of your die from the threaded sleeve. Then hold the bullets you are using up to the seating stem and make sure it is making contact all the way around the O-give of the bullet. If it is not we would have you send in the seating stem with some of the bullets you are using so we can polish it to fit better.

We try and make those stems be universal for all bullets, but with the vast amount that are out there, on the rarest of occasions we will see an instant that one wont match up as it should."

I had already checked that, and the bullet tip does not make contact with the seater stem. I have solid contact on the ogive of the bullet
Next I randomly chose 5 bullets from the box and checked them against each other. They were all identical.
Next I loaded those 5 and got 3 different CBTO measurements

Something about that bullet and some dies just isn't working. I loaded some Hornady 168's and Nosler 155's.....all within .001" of each other.

I'd stop worrying about the OAL (as long as it fits the mag) and just look for consistency in the CBTO measurement. That's where your accuracy comes from.

 

[eric.s]

Yeah I checked to see if the seating stem was making contact with the bullet's ogive without hitting the tip as well, and it is. However I'm getting .004 +/- variations from the bullets ogive from 10 random bullets(same box). I'm beginning to think it might be my calipers or comparator that is off, because when I put two hornady comparators on my caliper and bring them together, they don't even line up.(having the tightening screw in on same side and flush with the calipers). If SMK are off this much, I really screwed up by buying a box of 500 haha. Either that or I'm just using my seating die incorrectly. The way I have it set up is I pretty much dial my micrometer in at the OAL I want, then turn the adjustment screw in till I'm within .002+/-. But from what I'm gathering from you guys, I shouldn't even be worried about OAL. I know the standard OAL for 308 rem action is 2.80, so what's the recommended CBTO with SMK 175 in a rem 700 SA? Thanks Texas solo for the advice

 

[limige]

My hornandy dies have always been very uniform. .001 difference at most. Check to see where your seating stem contacts the bullet. Otherwise it may be poor design.

 

[witchhunter]

Are you saying a tenth of an inch! As in .100? That seems excessive, I would look at the die, maybe it is dirty or has some debris? Take it apart and clean it, then retry. Keep us posted.

 

[Texas solo]

The way I have it set up is I pretty much dial my micrometer in at the OAL I want, then turn the adjustment screw in till I'm within .002+/-. But from what I'm gathering from you guys, I shouldn't even be worried about OAL. I know the standard OAL for 308 rem action is 2.80, so what's the recommended CBTO with SMK 175 in a rem 700 SA? Thanks Texas solo for the advice

Now you're thinking Eric. There is no "recommended" CBTO for any rifle....because every chamber is different. My buddy and I have the exact same rifles, only 10 serial #'s apart. My chamber measures .010" longer than his. Thus, when we're both .005" off the lands, my loads are .010" longer than his. You'll need to get a chamber gauge, the Hornady OAL gauge is the most popular and not really expensive. You'll also need the modified case of your choice. Using this tool, you will measure YOUR chamber, then load to that length +/-. My .308 shoots best when loads are .015" off the lands. My .223 with Shilen Select Match barrel, likes to be .005" off the lands with 80gr Bergers. Those figures can/will also change with every different bullet you try. Every different bullet you try will require a new chamber measurement, because no bullets are shaped the same. SMK's will give you one measurement, and Berger, Hornady, Nosler, etc will give you something different. I have data on every bullet I've tried, to include seating depth, powder charge, primer, group size, MV,etc etc etc. Keep good records of your work.
Once you have a load worked out, and all your ammo is jumping the same amount, your golden. OAL's WILL vary, but who cares? As long as their all jumping the same amount, you have consistency.

I gave up the SMK 175's because my rifle just doesn't shoot them well. 1.250" was the best group I could get. Hornady 168's will shoot .440", and I'm just starting to play with some 155's.
I think the seating issues are just the way that bullet hits the seater stem. We "could" have the stems polished to fit better, but why? Unless your rifle shoots bugholes with that bullet, it's pointless. Try another bullet brand, then play with different bullet weights and powder brand/charges.

Welcome to reloading......it never ends.

 

[eric.s]

Are you saying a tenth of an inch! As in .100? That seems excessive, I would look at the die, maybe it is dirty or has some debris? Take it apart and clean it, then retry. Keep us posted.

Yes tenth of an inch for OAL! Some of my OAL are 2.7, 2.8, 2.9, etc. That's why I was concerned with the OAL, it seemed excessive even with uneven meplates.

 

[eric.s]

Now you're thinking Eric. There is no "recommended" CBTO for any rifle....because every chamber is different. My buddy and I have the exact same rifles, only 10 serial #'s apart. My chamber measures .010" longer than his. Thus, when we're both .005" off the lands, my loads are .010" longer than his. You'll need to get a chamber gauge, the Hornady OAL gauge is the most popular and not really expensive. You'll also need the modified case of your choice. Using this tool, you will measure YOUR chamber, then load to that length +/-. My .308 shoots best when loads are .015" off the lands. My .223 with Shilen Select Match barrel, likes to be .005" off the lands with 80gr Bergers. Those figures can/will also change with every different bullet you try. Every different bullet you try will require a new chamber measurement, because no bullets are shaped the same. SMK's will give you one measurement, and Berger, Hornady, Nosler, etc will give you something different. I have data on every bullet I've tried, to include seating depth, powder charge, primer, group size, MV,etc etc etc. Keep good records of your work.
Once you have a load worked out, and all your ammo is jumping the same amount, your golden. OAL's WILL vary, but who cares? As long as their all jumping the same amount, you have consistency.

I gave up the SMK 175's because my rifle just doesn't shoot them well. 1.250" was the best group I could get. Hornady 168's will shoot .440", and I'm just starting to play with some 155's.
I think the seating issues are just the way that bullet hits the seater stem. We "could" have the stems polished to fit better, but why? Unless your rifle shoots bugholes with that bullet, it's pointless. Try another bullet brand, then play with different bullet weights and powder brand/charges.

Welcome to reloading......it never ends.

Thank you very much for the great advice Texas Solo. I assumed the headspace was pretty much the same for most rem 700 SA. I will definitely be picking up Hornady's OAL gauge/modified case to determine the CBTO, best for my rifle.

 

[Texas solo]

Yes tenth of an inch for OAL! Some of my OAL are 2.7, 2.8, 2.9, etc. That's why I was concerned with the OAL, it seemed excessive even with uneven meplates.

You're correct, that's just nuts! Is the die, and all it's components tight? Is your routine consistent? Your bullets are jumping all over the place, and your pressures will vary a lot too.
We gotta get you consistent.

 

[Texas solo]

Thank you very much for the great advice Texas Solo. I assumed the headspace was pretty much the same for most rem 700 SA. I will definitely be picking up Hornady's OAL gauge/modified case to determine the CBTO, best for my rifle.

You're very welcome, glad to help a newbie.
I don't know when we started talking about headspace, but your length of loads has nothing to do with it.
Headspace is all about how the brass fits the chamber. To little, the bolt won't close. Too much....KABOOM! It's a factory/SAAMMI spec. Unless you change barrels or bolts, don't worry about it.

.308 data specs attached.

 

[eric.s]

Yeah, sorry I didn't mean to say headspace. The Die,locking ring and everything else is tight. I keep my routine consistent . Tomorrow I'm going to try a different digital caliper and compare. The way I've been setting up my die is adjusting my test round to the OAL +/0 .002. Using the zero screw and corresponding it to micrometer setting. There's been greater than .003 +/- variations in CBTO and some of the OAL's are off by a tenth(for example I will have some 2.801, 2.796, 2.795, 2.803, etc.) Tomorrow I'll check corresponding CBTO with them and post it up. Thanks again Texas solo for the help, I really appreciate it.

 

[KelsonAK]

is this a compressed load by chance?

 

[Ultraman550]

It's not the dies. Sierra is notorious for this shit with their SMK bullets. I have about 8 different lengths that I divided 500 bullets into. My measurements using the Hornady bullet comparator gave me .650 (bullet ogive to base) up to .690+ . Huuuge variation but if you sort your bullets first it makes everything work.

 

[vinsonr]

Yeah, sorry I didn't mean to say headspace. The Die,locking ring and everything else is tight. I keep my routine consistent . Tomorrow I'm going to try a different digital caliper and compare. The way I've been setting up my die is adjusting my test round to the OAL +/0 .002. Using the zero screw and corresponding it to micrometer setting. There's been greater than .003 +/- variations in CBTO and some of the OAL's are off by a tenth(for example I will have some 2.801, 2.796, 2.795, 2.803, etc.) Tomorrow I'll check corresponding CBTO with them and post it up. Thanks again Texas solo for the help, I really appreciate it.

Off by a tenth would be 2.702 or 2.899. Yours are off by several hundredths.

 

[eric.s]

KelsonAK- I don't believe they are compressed loads, I'm going from 40 to 42.5 in increments of .5 of varget. Correct me if I'm wrong but I don't believe I'm hitting compressed (maybe the 42.5 and 42.0) but I'm not getting any extra resistance when I seat the bullet.

Ultraman550- Thanks for the advice after checking the ogive from base of random bullets I did notice they were all over; I sorted and loaded another group and got +/- .001 thousandths for CBTO, which is a much better improvement! I think that was my problem.

Vinsonr- Oh wow, yeah I'm an idiot. So being off by several hundredths for OAL is normal I assume?

Thanks everyone for the help and advice!

 

[Ultraman550]

KelsonAK- I don't believe they are compressed loads, I'm going from 40 to 42.5 in increments of .5 of varget. Correct me if I'm wrong but I don't believe I'm hitting compressed (maybe the 42.5 and 42.0) but I'm not getting any extra resistance when I seat the bullet.

Ultraman550- Thanks for the advice after checking the ogive from base of random bullets I did notice they were all over; I sorted and loaded another group and got +/- .001 thousandths for CBTO, which is a much better improvement! I think that was my problem.

Vinsonr- Oh wow, yeah I'm an idiot. So being off by several hundredths for OAL is normal I assume?

Thanks everyone for the help and advice!

Nice!! Yeah man, it's a pain the ass but if you sort them into lots it'll make reloading more rewarding and you wont have to constantly adjust your seating die. Here's what I did although some here would also break them down into smaller numbers.

.650-.655
.655-.660
.660-.665
.665-.670
.670-.675
.675-.680
.680-.685
.685-.690+

If the bullets were something like .6855 I would put them into the .685-.690 bag. Start out withe the bag that has the lowest number and then just adjust your die per bag/group

 

[eric.s]

Nice!! Yeah man, it's a pain the ass but if you sort them into lots it'll make reloading more rewarding and you wont have to constantly adjust your seating die. Here's what I did although some here would also break them down into smaller numbers.

.650-.655
.655-.660
.660-.665
.665-.670
.670-.675
.675-.680
.680-.685
.685-.690+

If the bullets were something like .6855 I would put them into the .685-.690 bag. Start out withe the bag that has the lowest number and then just adjust your die per bag/group

Oh yeah, great advice! I honesty didn't even think about presorting them into bags and then adjusting die depending on size. I'll probably be sorting the same groups as well. Thanks man!

 

[Texas solo]

Ultraman550- Thanks for the advice after checking the ogive from base of random bullets I did notice they were all over; I sorted and loaded another group and got +/- .001 thousandths for CBTO, which is a much better improvement! I think that was my problem.

Vinsonr- Oh wow, yeah I'm an idiot. So being off by several hundredths for OAL is normal I assume?

Thanks everyone for the help and advice!

Glad we got something figured out Eric. I apologize for not having you double check that earlier. When I randomly checked 5 bullets, they were all the same. ??????
Still, there can always be a seating stem issue to some degree, but you seem to be on the right track now. At least you know what to look for.

Your OAL's will vary quite a bit, but HUNDREDTHS still sounds excessive. On the other hand...who cares? Get the OAL gauge as discussed and see what your chamber measures.
More tools = more fun

Best of luck.

 

[eric.s]

Glad we got something figured out Eric. I apologize for not having you double check that earlier. When I randomly checked 5 bullets, they were all the same. ??????
Still, there can always be a seating stem issue to some degree, but you seem to be on the right track now. At least you know what to look for.

Your OAL's will vary quite a bit, but HUNDREDTHS still sounds excessive. On the other hand...who cares? Get the OAL gauge as discussed and see what your chamber measures.
More tools = more fun

Best of luck.

Don't apologize! I kinda of feel like an idiot for not doing that sooner, oh well, live and learn. Haha, so you randomly check 5 smk 175 bullets that were the same??? I wish I could say the same. Majority of mine were in the .645 -.649 range but still had plenty that were all over. I just ordered the hornady OAL gauge and the modified case (I hope the SMK's fit in it). Problem now is I have to wait another 3 weeks because my rifle is getting glass/piller bedded and cerokoted. Thanks again for the help and advice Texas solo!

 

[KYpatriot]

A few hundredths in base to ogive measurement is unlikely to cause you any problems. The SMK is a great bullet, and very tolerant of seating depth inconsistencies because of the tangent ogive profile. In a stock Rem700 you will very likely run out of magazine room before you can seat them to the lands, which is ok because SMKs are very tolerant of jump as well. I won't shoot any load in the lands...maybe for a benchrest rifle but a tactical rifle shouldn't have that kind of ammo, you need to be able to unload the rifle in the field without pulling a bullet and dumping powder. Anyway, that isnt likely to be a worry in a stock 700 anyway but as suggested above it always a good idea to know how far you are from the lands.

As far as inconsistent seating depth, the most likely culprit is that the bullet is "sticking" to various degrees in the seating stem of the micrometer seating die. When you lower the loaded round from the die the bullet will stick and get pulled out a little, resulting in more variance than you are wanting in the base to ogive measurement. Look at the bullet and see if there is a shiny looking ring around it where the seating stem contacts the ogive. If there is, that is what is causing it. You fix it by polishing the inside of the seating stem. I took some 000fine or 0000fine steel wool, chucked an old bore brush in a hand drill, and let the brush pull of some steel wool to create a bullet shaped wad of steel wool for polishing. Spin that in the seater stem and that will take care of the microscopic tool marks causing this. Once that stem is smooth inside your seating consistency will go way up.

 

[Ultraman550]

I'm trying this immediately.

 

[eric.s]

A few hundredths in base to ogive measurement is unlikely to cause you any problems. The SMK is a great bullet, and very tolerant of seating depth inconsistencies because of the tangent ogive profile. In a stock Rem700 you will very likely run out of magazine room before you can seat them to the lands, which is ok because SMKs are very tolerant of jump as well. I won't shoot any load in the lands...maybe for a benchrest rifle but a tactical rifle shouldn't have that kind of ammo, you need to be able to unload the rifle in the field without pulling a bullet and dumping powder. Anyway, that isnt likely to be a worry in a stock 700 anyway but as suggested above it always a good idea to know how far you are from the lands.

As far as inconsistent seating depth, the most likely culprit is that the bullet is "sticking" to various degrees in the seating stem of the micrometer seating die. When you lower the loaded round from the die the bullet will stick and get pulled out a little, resulting in more variance than you are wanting in the base to ogive measurement. Look at the bullet and see if there is a shiny looking ring around it where the seating stem contacts the ogive. If there is, that is what is causing it. You fix it by polishing the inside of the seating stem. I took some 000fine or 0000fine steel wool, chucked an old bore brush in a hand drill, and let the brush pull of some steel wool to create a bullet shaped wad of steel wool for polishing. Spin that in the seater stem and that will take care of the microscopic tool marks causing this. Once that stem is smooth inside your seating consistency will go way up.

Right, I'm going to be using it for hunting and target shooting not benchrest, so I was going to have the CBTO anywhere from .025'' - .015'' off the threads.(That's what I gathered is the best for tactical/hunting rounds). It looks like I have about 2.860 for max COL using AI mags. As far as the seating stem actually sticking, I didn't even think about that! I do have a shiny ring on all my seated bullet's ogive. Texas Solo said you can send them in along with the bullets to get them polished but if 000fine steel wool works, I might give that a shot (I feel like I would probably make the seating stem worse and uneven doing that though). Just out of curiosity would putting on a little bit of imperial dry neck sizing powder on a q-tip and putting some in the seating stem work, or is that suppose to stay dry/clean? Thanks KYpatiot, for the advice!

 

[KYpatriot]

You won't mess up the stem if you just polish it, it would take quite a while to hurt it you aren't using a grinder here. If you send it end they are just going to polish it, which you can try at home.

There is a pretty fair amount of force involved with bullet seating so I don't feel that lube is going to fix the problem, and in any case would have to be replaced often. If you fix the root cause you won't have to worry about that.

 

[eric.s]

Ok, yeah good valid points. I think I will be giving that a shot this week. Thanks again!

 

[bruddah]

For reference:
.001" = one thousandth of an inch
.010" = ten thousandths of an inch
.100" = one hundred thousandths of an inch (or one tenth of an inch)

For reference a human hair is around .003" thick.

I think people are getting confused with terminology on measurements here.