NEW TO RELOADING- HOW DO YOU DETERMINE CORRECT BULLET SEATING? HELP

[marathonrunner]

Guys, I got a lot of good advice from everybody. I am new to reloading and so far I have managed to decap, resize, and once I figure out how to use my electronic scale, I don't know how to determine the correct bullet seating. I have read you take any factory cartridge, and then you match that seating depth when you crimp the bullet. But I have seen rifle reloaders use the comparator and using the bolt carrier to see if it fully closes. Then the reloader gradually seats the bullet lower and lower. How do you do this on a pistol cartridge like a 9mm? I don't see how it is possible on a semi auto chamber. Can somebody please tell me how to find the correct depth>? Thanks

 

[photoman]

I measure the overall length and match up to the load data in the reloading manual. Also, I seat and crimp in two different steps.

 

[nawilson]

^^^ What Photoman said! ^^^

Look in the manual for the Combined Over All Length (C.O.A.L.). Slowly seat the bullet deeper and deeper until you reach the correct COAL.

 

[arjay]

If there is a cannelure,you go by that,but you need to get a few reloading manuals and read the front section until you really understand it.Rifle and pistol reloading are similar,but different.

 

[jmmitc06]

Seating depth and OAL (overall cartridge length) are not the same, but in general if you are using a bullet from the manual or something similar we can assume that OAL will be sufficient. From the procedure you described using a factory round you are measuring the OAL which may be a good guide for approximating your die settings but you should use the setting for your formula: powder, charge, bullet from the manual. Slight derivations from OAL can have a big difference in pressures and 9mm is already high pressure.

Here's what I do in 9mm. First, look at the manual OAL for the load I'm using. Second, take a factory or previous reload that I think has an OAL close (similar bullet profile) put it on the press up in the seating die, lower the seating die as low as possible. Now OAL for die should be set to factory length. If the OAL is greater than factory length, loosen and load one round, measure loaded round's OAL. If acceptable, load the rest, else loosen and load another, repeat until you are to the OAL. Same procedure if OAL is less than factory length but tighten the die and I just keep reseating the same bullet. Often times too, XTPs and other plated bullets have a crimping groove on them that's obvious, typically you will seat it to there.

To make sure that the OAL works in your firearm, you can do the following. My 1911 is very picky about crimping and OAL, I remove the barrel and stick a loaded round in it just like the gun will do when it is in battery. The head of the cartridge should be flat with the end of the barrel. Also load some dummy rounds (no primer, no powder) and see if they feed well. For these finicky guns I do crimp and seat in separate steps with a factory crimp die.

 

[BLUEDOT37]

For all my automatic ammo, I always load it as long as possible without going over the max OAL for the cartridge & still pass the plunk test. This way you maximize the powder space available. Whenever you change bullet brands/styles always redo these steps & don't reuse the last COL" for that weight bullet. And also be mindful of the empty space to seating depth if it's a max. load. You don't have to make it overly complicated.
PS: Seating depth is a product of the overall length.

 

[Twoboxer]

The book that gave you the min-max load range for your powder also gave you the CO(A)L (Cartridge Overall Length) the range was developed at. That is your starting point, measured with calipers.

Make a dummy load and test it to see if it will feed in your pistol. The odds are VERY good it will feed correctly. If it does not, try a longer length (which will lower pressure when charged) until it does feed correctly.

Any other approach puts you at risk that internet advice is not compatible with your pistol.

Then go ahead and make a few rounds (eg 5) at a few charge weights within the safe min-max range. Normally the minimum charge (or slightly higher) is all that is required to successfully cycle your pistol. You may choose to see which charge (fired from a rest) is most accurate for your pistol, and/or compare charges to the recoil/ejection of your factory ammo.

Making a lot of ammo the first time around too often results in a lot of work tearing it back apart. YMMV.

 

[marathonrunner]

thanks

Seating depth and OAL (overall cartridge length) are not the same, but in general if you are using a bullet from the manual or something similar we can assume that OAL will be sufficient. From the procedure you described using a factory round you are measuring the OAL which may be a good guide for approximating your die settings but you should use the setting for your formula: powder, charge, bullet from the manual. Slight derivations from OAL can have a big difference in pressures and 9mm is already high pressure.

Here's what I do in 9mm. First, look at the manual OAL for the load I'm using. Second, take a factory or previous reload that I think has an OAL close (similar bullet profile) put it on the press up in the seating die, lower the seating die as low as possible. Now OAL for die should be set to factory length. If the OAL is greater than factory length, loosen and load one round, measure loaded round's OAL. If acceptable, load the rest, else loosen and load another, repeat until you are to the OAL. Same procedure if OAL is less than factory length but tighten the die and I just keep reseating the same bullet. Often times too, XTPs and other plated bullets have a crimping groove on them that's obvious, typically you will seat it to there.

To make sure that the OAL works in your firearm, you can do the following. My 1911 is very picky about crimping and OAL, I remove the barrel and stick a loaded round in it just like the gun will do when it is in battery. The head of the cartridge should be flat with the end of the barrel. Also load some dummy rounds (no primer, no powder) and see if they feed well. For these finicky guns I do crimp and seat in separate steps with a factory crimp die.

By taking the barrel out of the gun, it seems like that is a really good method. I have seen videos of loaders taking a bolt action rifle and kind of doing the same but using the bolt to close gently to see if it can go in battery without being stuck. So am I correct in saying doing this same process will make my cartridge better than stock? Why do some reloaders choose not to do this process and elect to just take a factory bullet and use that as the bench measure rather than taylor the OAL to the actual chamber is beyond me.

 

[jmmitc06]

By taking the barrel out of the gun, it seems like that is a really good method. I have seen videos of loaders taking a bolt action rifle and kind of doing the same but using the bolt to close gently to see if it can go in battery without being stuck. So am I correct in saying doing this same process will make my cartridge better than stock? Why do some reloaders choose not to do this process and elect to just take a factory bullet and use that as the bench measure rather than taylor the OAL to the actual chamber is beyond me.

I'm speaking from experience here more so than from facts and science, but in general I think that OAL is more of a boolean than a continuous variable in producing good hangun ammo. It is either greater than the minimal and the pressures will be good and it is not too long to feed reliably or it fails one of those criteria. If it passes that's good and I don't modify OAL. Checking with the barrel not only checks that it goes into battery because of OAL but in my case with the 1911, that the crimp is sufficient. This isn't done by everyone because typically a firearm will function with the manual OAL, especially modern firearms. But being a C&R guy, some of my weird old firearms really like OALs that aren't factory (still within spec though).

Most of the improvements in reloaded ammo vs factory is consistency, measuring each powder charge can give a lower amount of variance from charge to charge. This combined with the brass being resized to spec leads to very consistent cartridges and therefore great precision (which is commonly referred to as 'accuracy', couldn't resist pointing that out, it's the chemist in me). The one factor that does seem to be a major component of accurate loading for me at least, is crimping. When I first started, I didn't set the die appropriately in 44mag and my crimp was non-existent and accuracy was poor until I fixed it.

The following isn't a direct reply to your question but since you are new to reloading I am curious what powder you have chosen for 9mm? I'm assuming you have some semi-auto 9mm and when I started reloading 9mm I had a M&P pro 9 which seemed to function best with power pistol. Powder choice is probably the single most important variable for good reloads. I tried bullseye, unique and they "worked" and grouped better than factory but recoil was either greater than I wanted (bullseye) or had some cycling issues (bullseye and unique, maybe 1/100 rounds). Using berry's 9mm 124gr RN, I found that power pistol gave a nice recoil, always functioned the slide and produced the best groups.

 

[rwsmith]

Slow way...

By taking the barrel out of the gun, it seems like that is a really good method. I have seen videos of loaders taking a bolt action rifle and kind of doing the same but using the bolt to close gently to see if it can go in battery without being stuck. So am I correct in saying doing this same process will make my cartridge better than stock? Why do some reloaders choose not to do this process and elect to just take a factory bullet and use that as the bench measure rather than taylor the OAL to the actual chamber is beyond me.

That works, but with a rifle it is slow and I've gotten some cartridges stuck in the chamber. You can buy cartridge gauges that do almost the same thing, but chambers vary some and I've had a little trouble getting it to work out just right. But I'm working on it.

 

[jmmitc06]

That works, but with a rifle it is slow and I've gotten some cartridges stuck in the chamber. You can buy cartridge gauges that do almost the same thing, but chambers vary some and I've had a little trouble getting it to work out just right. But I'm working on it.

Yeah I guess the thing to say that I didn't is that I do it with the first few rounds, then maybe 1 every 50 to make sure that my dies haven't moved. Not every time.

 

[Rule3]

This is a 1911 45 ACP but the principal is the same


Using an auto pistol barrel find a MAX O.A.L with your bullet This topic comes up a lot, or should I say this question.
Quote:
Why won't my reloads chamber?
A short throat is sometimes the culprit. Too long an O.A.L. is sometimes the problem, even with barrels with average throats.

This pic is often used to help explain correct headspacing and how O.A.L. can affect chambering and headspace.

 

[BLUEDOT37]

Plunk Test

For all my automatic ammo, I always load it as long as possible without going over the max OAL for the cartridge & still pass the "plunk test".

marathonrunner: in case you aren't familiar with the "plunk test" for a semi-automatic pistol, here's more:

This is how you do a "plunk test" but for me it's most important, and accurate, how the assembled "test" round sounds, and feels, when you drop it in the barrel's chamber, rather than where the rim is in relation to the hood.

Make sure you've added a minimal (taper) crimp that's just enough to remove any case flare from the sample round, otherwise the results are deceiving. When you drop the round in the removed barrel's chamber, it should make a nice metal to metal clink/plunk sound. That's the case mouth hitting the chamber's shoulder, where the cartridge headspaces on. If the bullet is seated out too much (long) then the bullet's ogive hits the rifling & you don't get the same sound, but rather a dull thud. Additionally, if you rotate the round in the chamber it should be nice & smooth (case mouth on chamber shoulder). If it's too long, it'll feel rough because the bullet's ogive is rubbing against the rifling. (Remember, eliminate any flare before checking.)

Initially, seat the bullet out farther than needed & slowly adjust your seating die deeper, doing a plunk test between adjustments until you get the proper results. Then set your final crimp & double check the results before continuing loading.

It doesn't take long to get the right adjustment & once you record the OAL", for that specific bullet, you can use that measurement next time & forego the plunk test, if you like. Make sure it's at or below the max. OAL" for that cartridge.

Also, different guns have different amounts for freebore/leade (space between the chamber shoulder & the start of the rifling), so one gun that can handle a max OAL" assembled cartridge may not be ideal for another, due to bullet shape, so double check if in doubt. (All my 3rd Gens. have ample freebore.)

I've never seen the need for a case gauge (for pistols) as the barrel/chamber already acts as "custom" one that you are trying to match. Also, I have no idea how they could indicate if your particular gun's leade would interfer with the bullet you were loading for. It only takes a minute to remove & use the barrel in question & eliminate any doubts.

 

[blujax01]

(1) The OAL stated in the manuals is the minimum. You may go longer but, especially as a new reloader, you do not want to go shorter. As Twoboxer says, using the stated OAL in the manual will most likely give you good results.

(2) If yo don't already have a set, you need a reliable set of calipers. There are those here who say that the $10 set at Harbor Freight is as good as the $100 Starrett or Mitutoyos. Purchase what you will but personally, if I'm attempting to reliably and repeatedly make measurements in the 0.000" range, I'm starting out by spending more than $10 to do so. YMMV

 

[Cdog]

Are you loading for only one firearm?

The great thing about customizing a load for a particular purpose in a particular weapon is superior performance.

The downside, these same loads may not function or shoot well at all in another near identical weapon.

Selfloaders can be picky, minor chamber dimension differences can wreak havoc. Wheelguns are much more forgiving.

For many magazines and chambers plinking load apps I usually fall on the conservative end of spec for best weapon to weapon reliability.

Especially true for bottleneck rounds, precision loading is done for one specific firearm. It takes range time to discover that weapon's/load's particular sweet spot.

 

[forestswin]

What bullet are you trying to seat?
Manufacturer?, weight?, type?
Have you found a similar bullet in a manual?

 

[scooter123]

Keep in mind that loading for maximum accuracy in a Rifle requires approaches that just do NOT make any sense for a Handgun round. Rifle shooters commonly approach and exceed an accuracy of groupings under 1 inch at 100 yards. One facet of achieving this level of accuracy is to load the ammunition so the bullet is basically resting at the very start of the rifling when the cartridge is chambered. Doing this reduces the "free bore" distance to near zero and, in theory, maximizes accuracy. Note, whether this actually works is dependent on the chamber, barrel, and bolt design and dimensions so what works with some rifles won't do squat with others.

There are at best perhaps 10 handgun shooters on the planet capable of shooting to that same 1 inch at 100 yards standard of accuracy shooting standing on their hind legs holding the handgun extended at arms length. Quite simply, if you are in the top 1-2% of handgun precision shooters you may shoot to 1 inch at 25 yards on a good day which works out to 4 inches at 100 yards. So, there really isn't any benefit to using precision Rifle loading techniques for a Handgun load because no person on the planet is capable of shooting to the level of accuracy that might[/b] be produced.

Another factor to consider is that handguns generally have rather small cases and use fast burning powders designed to work with a certain amount of "air space" in the case. As a result, in many semi auto calibers the powders used may be sensitive to that "air space" and it's effect on pressure during ignition. Load too short and you may see pressure spikes that could result in a case head seperation. Load too long and you may see a lot of unburned particles in your handgun and wide swings in the produced velocity of the load.

The bottomline is this, that COAL that is published for your powder and bullet are guidance for developing your load and should be considered a minimum length if you are pushing the upper limits on your powder charge. In some cases it can make sense to load a bit short to solve feed or ignition issues but in general it's best to load to the recommended length given. Note, at any time when intentionally loading short you should only do this if your powder charge is at mid range or lower and you'll need to carefully check for any indicators of an over pressure charge.

 

[marathonrunner]

thanks

marathonrunner: in case you aren't familiar with the "plunk test" for a semi-automatic pistol, here's more:

This is how you do a "plunk test" but for me it's most important, and accurate, how the assembled "test" round sounds, and feels, when you drop it in the barrel's chamber, rather than where the rim is in relation to the hood.

Make sure you've added a minimal (taper) crimp that's just enough to remove any case flare from the sample round, otherwise the results are deceiving. When you drop the round in the removed barrel's chamber, it should make a nice metal to metal clink/plunk sound. That's the case mouth hitting the chamber's shoulder, where the cartridge headspaces on. If the bullet is seated out too much (long) then the bullet's ogive hits the rifling & you don't get the same sound, but rather a dull thud. Additionally, if you rotate the round in the chamber it should be nice & smooth (case mouth on chamber shoulder). If it's too long, it'll feel rough because the bullet's ogive is rubbing against the rifling. (Remember, eliminate any flare before checking.)

Initially, seat the bullet out farther than needed & slowly adjust your seating die deeper, doing a plunk test between adjustments until you get the proper results. Then set your final crimp & double check the results before continuing loading.

It doesn't take long to get the right adjustment & once you record the OAL", for that specific bullet, you can use that measurement next time & forego the plunk test, if you like. Make sure it's at or below the max. OAL" for that cartridge.

Also, different guns have different amounts for freebore/leade (space between the chamber shoulder & the start of the rifling), so one gun that can handle a max OAL" assembled cartridge may not be ideal for another, due to bullet shape, so double check if in doubt. (All my 3rd Gens. have ample freebore.)

I've never seen the need for a case gauge (for pistols) as the barrel/chamber already acts as "custom" one that you are trying to match. Also, I have no idea how they could indicate if your particular gun's leade would interfer with the bullet you were loading for. It only takes a minute to remove & use the barrel in question & eliminate any doubts.

I only plan on reloading for one 9mm which is my MP Compact 9mm. I definitely think using the ker plunk method sounds best because that is proof in pudding. And to answer others, I hope I did not screw up buy I bought Bayou Bullets. These are polymere coated rounds. Hopefully I won't be raked over the coals for buying them. Thanks everybody for the great advice!!! I think it will be about another month before I figure all this out

 

[Nevada Ed]

With 9mm ammo, there is a Minimum and a Maximum OAL for any bullet weight/design.

1.169" is stated as a maximum oal for the 9mm but............
try this length with just a 90gr Jhp and you will see that you have to make adjustments for a ......"correct"...... oal.

The "Plunk test" is a great way to test out your loads the other is if they fit in your magazine and feed well.
Some pistols will actually shot the shorter oal better and have less feeding failures. One reason you should always test loads to see if they will work in "Your pistol".

I have had 9mm's that will give me accuracy or good feeding but a accurate load that does not jam or stove pipe is what it is all about.

The oal of factory ammo is the best of the best for that style of bullet, for the majority of pistols tested. There will be a few pistols that this ammo does not work in but that is why there are other brands of ammo. You do it until you get it right.

There are no magic numbers...............
You may have the perfect bullet and velocity ..........
but a bad magazine can put a damper on the days outing.

Best of luck, putting the puzzle together.

 

[H Richard]

Just make sure you are using the correct bullet that match's up with the book you are using. A Hornady 200 gr XTP may not be the same O.A.L. as a Nosler 200 gr. HP, etc. The differences in seating depth can cause you to seat a bullet too deep and create excessively high pressure. Follow the guidelines.