Im new to reloading and have been researching formulas for the 308. Ordered 200 gr smks and followed the manual for charges. Using imr 4064 any charge larger than 39 grains the bullet seems to smash the powder as it is too long when seated to maximum OAL at 2.81. I know that smashing powder will result in some unknowns and will have to be pulled. Any Info is much appreciated.
reloading 308 with 200 gr smk
- Thread starter chuckfc
- Start date
Highpower-FClass
Gold $$ Contributor
Welcome to the site and to reloading. When the projectile is seated into the powder in the case it is called a compressed load. Compressed loads are not uncommon, if you look in reloading manuals or at Hodgdons website they are (typically) identified by a C after the charge. For example 41.2C.
For any type of hand loading, make sure to follow published data and work up from starting loads to avoid over-pressures.
For any type of hand loading, make sure to follow published data and work up from starting loads to avoid over-pressures.
Turbulent Turtle
F-TR competitor
Some tricks to help settle the powder before seating a long bullet; use a long drop tube or funnel, or to hold the charged cartridge against a vibrating tumbler. I cover the mouth and tap the case a few times on a wood block to settle the powder (Varget.)
Since you are new to reloading, there may be a few things you might not be familiar with. Since you are shooting MatchKings, I am assuming you are using these for some level of competition. Most, but certainly not all competitions, are single load, single fire ordeals. Being that, most competitors use considerably LONGER freebores (throats) to seat the bullets well out past the neck should junction, thus actually INCREASING case capacity. However, judging from the "compressed" 39.0gr load, it is doubtful you have a long freebore. This is probably why you are getting the compression, although IMR 4064 has logs for kernels! LOL!!!
I would get with someone who is shooting F-T/R and knows about extended freebore(s) and how to help you load heavy bullets with precision. There are some very well versed F-T/R shooters on this forum who you might get in touch with. They can help greatly.
Ned Ludd
Silver $$ Contributor
You're loading a [relatively] long bullet to a short length (2.810" COAL) so it will feed from a magazine. There are reasons ammunition manufacturers rarely use bullets heavier (longer) than about 190 gr in commercial .308 Win ammunition. As mentioned above, long heavy bullets need a longer freebore so they can be seated out farther so as not to use up so much case capacity. The downside to that is that they are then too long to feed from a mag. In a compressed load, there are tricks for getting all the powder to fit such as long drop tubes, tapping the cases to settle the powder, etc. But you also run the risk of pressure issues by running highly compressed loads, and seating bullets to a uniform depth can be a b*tch.
If you are using virgin brass, you will get more useable case volume once it has been fire-formed. In my hands, fully prepped 1x-fired brass has a capacity about halfway in between that of virgin brass and fired (but not yet resized) brass. So you may gain some space there if using virgin brass. Another possibility would be to try a powder with smaller kernels, such as H4895. As compared to Varget, typical .308 loads with H4895 and 185-200 gr bullets requires almost a grain less powder, because it is a faster burning powder and higher energy powder. Less total charge weight and smaller grains will be your friend in your current application. Trying a different powder can sometimes be accomplished for a relatively small expense as compared to changing other things. Another possibility would be to consider a different bullet. For it's weight, the 200 SMK has a pretty mediocre BC. The Berger 185 Juggernaut is about .050" shorter in OAL and has very close to the same performance. I don't have the base-to-ogive measurement for the 200 SMK, which is the critical measurement to compare to determine whether you're helping the compression issue, or making it even worse. A bullet with shorter base-to-ogive length than the 200 SMK, but with as close a BC as possible would likely help your situation. There are a number of choices in the 175-85 gr range that would likely put you fairly close to the performance of the 200 SMK with the added velocity possible for the lighter bullet. Whatever approach you use, just be extra careful because effects can be magnified in compressed loads. Start low and work up carefully.
If you are using virgin brass, you will get more useable case volume once it has been fire-formed. In my hands, fully prepped 1x-fired brass has a capacity about halfway in between that of virgin brass and fired (but not yet resized) brass. So you may gain some space there if using virgin brass. Another possibility would be to try a powder with smaller kernels, such as H4895. As compared to Varget, typical .308 loads with H4895 and 185-200 gr bullets requires almost a grain less powder, because it is a faster burning powder and higher energy powder. Less total charge weight and smaller grains will be your friend in your current application. Trying a different powder can sometimes be accomplished for a relatively small expense as compared to changing other things. Another possibility would be to consider a different bullet. For it's weight, the 200 SMK has a pretty mediocre BC. The Berger 185 Juggernaut is about .050" shorter in OAL and has very close to the same performance. I don't have the base-to-ogive measurement for the 200 SMK, which is the critical measurement to compare to determine whether you're helping the compression issue, or making it even worse. A bullet with shorter base-to-ogive length than the 200 SMK, but with as close a BC as possible would likely help your situation. There are a number of choices in the 175-85 gr range that would likely put you fairly close to the performance of the 200 SMK with the added velocity possible for the lighter bullet. Whatever approach you use, just be extra careful because effects can be magnified in compressed loads. Start low and work up carefully.
I had a similar problem trying to use IMR4064. I ended up using N140 because I could get it all in the case with no problem. You might also look at N150.
If you want to try a funnel with a long drop tube, http://www.xxicsi.com/ makes a nice one.
If you want to try a funnel with a long drop tube, http://www.xxicsi.com/ makes a nice one.
I have found that placing a loose fitting bullet in the neck (7mm bullet for 308 case) while touching the case to a vibrator type tumbler will settle the powder better and faster than any thing I have tried. The bullet adds to the vibration with enough weight to help the powder settle to its lowest volume.
We don't know why he chose a 200 rain bullet and we don't know what it will be used for so how can we recommend a different bullet that is used in another gun for, perhaps, a completely different use? He is asking for information on a specific bullet and load.
If he said he wanted us to help with a bullet for 1000 yard targets or 300 yard white tail we could recommend bullets and loads for those situations but all we know is that he is asking for help with a specific problem of getting the space he needs to seat a 200 grain bullet over a powder charge.
The powder charge is stated to come from reliable information and the solution is to use a long feed tube and pre-settle the powder with a weight and vibration to allow the room for the bullet to seat.
If he said he wanted us to help with a bullet for 1000 yard targets or 300 yard white tail we could recommend bullets and loads for those situations but all we know is that he is asking for help with a specific problem of getting the space he needs to seat a 200 grain bullet over a powder charge.
The powder charge is stated to come from reliable information and the solution is to use a long feed tube and pre-settle the powder with a weight and vibration to allow the room for the bullet to seat.
dsinfour
Silver $$ Contributor
He didn't say what type of shooting he is doing and at what distance.. The 200 grain bullet is a little heavy and can't be pushed to fast.. Also he didn't state what powder he will be using..It's just that I found 4895 work the best in about 4 different 308 with lighter bullets out to 1000yds but every rifle is different...did find 4064 a little slow burning...If he is new to reloading read a couple of reloading manuals and what the rifle likes....Happy shooting
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