Using IMR4895 in place of H4895 for 168gr SMKs

[Snakum]

I've been using 41.5 grains of H4895 under my 168gr SMKs, trimmed to 2.007 with an OAL of 2.800, to match the HSM 168gr BTHP Match ammo I like. With my Savage 10FCP-K's 24" heavy fluted and braked barrel I'm getting close to 2700fps and I have been able to shoot my dope tables pretty closely with either round.

But Gander Price was out of H4895 tonight so I came home with IMR4895. Based on everything I've found via SEARCH it seems 42.0 grains of the slower burning IMR would get me pretty close to 41.5 grains of H4895. Does this sound like a good start point?

I found some posts stating that IMR4895 was FASTER burning than H4895, but the majority of Google hits said the reverse, and that I could add about 1.75% to the IMR data for an eqivalent Hodgen load. Any other suggestions for using IMR4895 instead of H4895? Comments?

 

[former naval person]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

They all differ. Start at 41 and run up by 0.3 till you get your best load. I have another lot of 4895 that is hotter than usual...but gives less speed with the same pressures. Again...try each lot and adjust as necessary. JMHO

 

[Victor N TN]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Like FNP said above, start a little low and work it up.

Personally, I prefer IMR 4895. My favorite 400 to 600 yard load with 168 Bergers is 42.5 grains in Lapua brass and poped with a standard Winchester Large Rifle Primer. In the past that load has been a solid sub 3/4 MOA load. If the wind doesn't bite me.

 

[macv]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

During my high power days all I used was IMR4895. 40.5 grs with a Fed. 210M primer, 168 SMK bul. in LC match cases. Rifle used was a Rem. 40X. Good luck with your loads. Still useing that rifle today, but it now sports a scope and shot off the bags. But the load is still the same.

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Thanks for the info. Big question ...

So you're saying <span style="font-style: italic">individual lots</span> of powders can vary enough to throw off avg velocity?

 

[Victor N TN]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

All powders can vary from lot to lot.

 

[Top Cat]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Seriously. You're just grabbing your Johnson with both hands trying to figure out a .5 gr difference without a chrono.

It's hard to find a better place to invest $75 into your shooting future that will return bigger dividends.

Safety not a minor one.

TC

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I like grabbing my johnson. In fact, I consider it it my avocation.

(Chrono is second on the list.)

 

[Greg Langelius *]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Despite some nominal similarities, we are discussing two different propellants.

I would simply repeat the same basic advice.

When changing handloading components, redevelop the load; working up from a reasonably safe starting charge.

Data from loading manuals can provide good comparisons regarding propellant suitibility, etc. and give some insight into reasonable charge weight limits; but in the end, you still have to do trial and error development testing while observing performance and pressure signs.

Greg

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I just finished shooting and have pretty much nailed an "HSM equivalent" for both powders in my weapon. IMR4895 needs 41.8gr while the H4895 needs 41.5.

Still blown away by Georgia Arms 168gr BTHP (not the Super match ... plain Match). Here's the first target I shot, 100 yards, was getting warmed up and had a couple flyers. The GA Match ammo is noticeably hotter than others and hotter than the 2600fps listed on the label. And it consistently shoots holes-touching groups at 100 yards in my gun. Simply outstanding accuracy and equals Federal GMM every single time in my weapon. But when I measure the COL and OAL on the GA ammo it is all over the map.

So it begs a question: how critical is COL and OAL length to consistent ammo?

 

[Queequeg]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

How are you measuring your OAL? Overall length will avry but the more accurate distance is from the head to the ogive. I think you'll find that distance held to a tighter tolerance. You need a caliper adapter to guage that distance.

H and IMR 4895 are 70 and 72 on the Hodgdon 2009 burn rate chart. For all intents, nearly interchangeable.

You can also go to Hodgdon's website to get the load information for Hodgdon, IMR and Winchester powders.

http://data.hodgdon.com/cartridge_load.asp

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs


I am measuring from base to meplat and GA is running from 2.785 to 2.806. Can you explain the "head to ogive" measurement? Seems like I'd have to have some sort of special gauge to measure to the ogive?

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Oh I was going to mention ... every few rounds with the GA Match I get a sticky bolt and really have to whack it over to get it to release. They are definitely a hot round. Should I be concerned if they are exhibiting this kind of pressure sign?

Damn they are accurate, though.

 

[Queequeg]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

The tools for measuring from the base of the case to the Ogive are varied and range from inexpensive to fairly pricey.

For example, see here.

http://www.midwayusa.com/viewProduct/?productNumber=348740

The length of the bullet varies and you can see it without tools if you look at the variation from meplat to meplat of any sample of bullets. Even polymer tipped bullets will vary in length. But the point where they become full caliber, the ogive, is more uniform, especially with match bullets. So measuring there gives you a more accurate basis upon which to make decisions regarding how much jump there is to the lands.

Your GA match ammo sounds prety hot or your chamber is just a little on the tight side. Either way, if the rifle is well maintained and of good quality you are very likely feeling symptoms of excessive pressure. That is what is often derisively referred to as "a sign". You should be concerned.

A chronograph will tell you something there too.

 

[DedicatedShooter]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I use 43.5 grains IMR 4895, 168gr SMK, many different types of brass, neck sized or FL sized, CCI BR2 primers, 2.800"-2.815" COAL.

This load shoots 1/2 MOA, consistently.

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Today I was able to shoot from the prone with a rear bag and I got my first almost-one-hole group at 100 yards. Wouldn't ya know it ... Georgia Arms BTHP. Out of ten rounds of GA HPBT three of them caused the bolt to stick. The stuff is amazingly accurate for such inexpensive ammo, but it's damn hot ammo. POI is consistently about .2 mils higher than anything else from 100 to 600 yards.

I'm shooting a new Savage 10FCP-K and it does have a pretty tight chamber, as I get the occasional HSM or handloaded round causing a sticky bolt. But every fourth or fifth Georgia Arms round locks it up pretty tight, including once I thought I was going to have to take it home to clear it. I'm not getting any of the other classic over-pressure signs, but the bolt really locks up on some of them. Should I quit using the GA BTHP Match, or am I just being too over-protective about my weapon?

 

[Queequeg]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I think you should stop using the hot ammo.

But then I'm amazingly good looking and don't want to disappoint the ladies or frighten small children.

 

[Greg Langelius *]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Snakum;

I note that the FCP-K has the Savage Muzzle Brake. At one time, they were designed so the outer shell could be rotated to turn the brake on and off. Does the current brake still employ this feature?

Also, check the lengths of the fired cases which show pressure signs, in case they may be getting near trim length.

Greg

 

[Queequeg]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Greg,

Is Georgia State Ammo reloaded? That might answer some questions mightn't it?

 

[Greg Langelius *]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

Don't know, I seldom buy commercial ammo. Usually, what I buy 'store-rolled' is hunting stuff; I don't bother with hunting load development.

Greg

 

[Snakum]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

The brake on the FCP-K is the same threaded LE model used on the 10BAS and 10BAT series, rather than the on/off model on their model 16 Weather Warrior series.

Georgia Arms is, as far as I know, a large bulk reloading company. I often find cases from various manufacturers, wild swings in OAL, and variances in COL. Doesn't make sense that it would be as accurate as FGMM - the GA "Match" ammo I buy is not even their top of the line 308 match load which is called "Super Match". But my 10FCP shoots lights out with that stuff, across many different lots. It is by far the most consistently accurate ammo in both my scout gun and my LE tactical rifle. Clover leafs every single time from a good, solid position. Weird, considering the variances and obvious pressure signs in some rounds.

 

[shooter308]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I'd say they were not trimming at all on what they think is 1x fired brass when maybe its 2x, 3x, fired then they are loading it with a varget or 4895 type powder at max load and you are getting the groups you are. Why dont you open one up and tell us the weight charge and what kinda powder it is.........Ball, Stick, flake, etc.) and let us guess

 

[KeithR41]

Re: Using IMR4895 in place of H4895 for 168gr SMKs

I shoot the 168MK with 41.5 grains of IMR 4895. I'm getting 2650 FPS. Federal brass with CCI 200 primers.

KeithR41