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Imr 8208 xbr

This is a discussion on Imr 8208 xbr within the Ammunition forums, part of the M14 M1A Forum category; Originally Posted by 2336USMC What was the case fill with that load? How close to the neck, base of the bullet touching the powder, compressed? ...


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Old July 27th, 2010, 09:48 PM   #31
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Originally Posted by 2336USMC View Post
What was the case fill with that load? How close to the neck, base of the bullet touching the powder, compressed?

Thanks...
I finally sat down and did the math and it looks like the 42.4gr charge weight is using about 93% of the usable space in the WCC 08 case that has been trimmed to 2.005" and the 168gr A-Max was seated to give me an overall cartridge length of 2.816". The COAL is slightly longer than my previous posted info and this gave me slightly different muzzle velocity info but my groups were the best I could get with the speeds I was looking for.

5 shots from a bench using sand bags at 100 yards.
Muzzle Velocity
Avg - 2637 fps
High - 2646 fps
Low - 2624 fps
Extreme Spread - 22.4 fps
Standard Deviation - 8.88 fps

Groups sizes were averaging about 1". I also tested my groups at 200 yards and got about 3" average using the 168gr bullets. I also tested 175gr Federal Gold Medal Match at 200 yards and I got a little tighter groups averaging about 2" but the 175gr bullets gave almost 2" groups at 100 yards.

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Old August 11th, 2010, 06:43 AM   #32
 
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Maximum chamber pressure for the M14 came up in this conversation, what is the minimum? I found a thread stating 28,000, which was quoted from a Lee manual, but i am not sure if it pertains to M14 cycling.

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Old August 11th, 2010, 10:13 PM   #33
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I like to do load development, so now I'll have to pick up a pound of 8028 err, 8208. I'll post my findings as I get them. Its going to be a while before we get any big temperature swings, so that part will come later. But for now I'll see what it does in warm weather.

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Old August 25th, 2010, 08:11 PM   #34
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Sorry guys, it's been so hot here in Oklahoma lately I've just been staying home. Got a break in the weather today (84 degrees) so I finally managed to get out and chronograph my Speer 125 gr. TNT load. It's a very accurate load but I'd like to get the velocity up to 2850 - 2900 fps, and maybe get those ES and SD numbers down. Plenty of information on this thread for the heavier bullets so I'll work with a light one. More to come.

Bullet: Speer 125 gr. TNT
Powder: IMR 8208 XBR 42.1 grs
Primer: CCI-200
Case: Lake City 64
LOAL: 2.695 (2.117 with Stoney Point Gage)
Average Velocity: 2702.48 fps
Extreme Spread: 72.61
Standard Deviation: 27.42


#01 2698.39 fps
#02 2689.39 fps
#03 2731.26 fps
#04 2733.11 fps
#05 2679.27 fps
#06 2677.50 fps
#07 2743.02 fps
#08 2722.66 fps
#09 2670.41 fps
#10 2679.87 fps

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Old October 27th, 2010, 02:57 PM   #35
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Imr 8208 xbr charge weight warning

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BE ADVISED THAT (according to QuickLOAD data) 39.4 GRAINS OF IMR 8208 XBR WILL, IN MOST CASES, PUT YOUR CHAMBER PRESSURES RIGHT AT 50,000 PSI AND JUST OVER 40 GRAINS WILL PUSH THE PRESSURES TO RIGHT AT 60,000 PSI (assuming a 168gr Hornady A-Max bullet, a COAL of 2.81", a TTL of 2.005", and a case with a 54.2 gr water volume capacity).
QuickLOAD software predicts that the load I posted in this conversation would produce chamber pressures of over 70,000 psi!! Please be careful. The problem I found with the powder is that the pressures don't seem to produce any really bad pressure signs until you are well above a reasonable load. I pushed my loads up to 44 grains of powder and stopped because I was getting head separations after the second or third reload.

It looks like charge weights for the lighter bullets will max out around 45 grains and for the heavier bullets around 39 grains.


pbcaster, QuickLOAD software ( I have the updated database with 8208 in it) says that you should be able to go up to about 45 grains of powder and get pretty close to the velocities that you are wanting. Using your basic info the software predicts 2924 fps (the real world may be around plus or minus 50 fps) and a chamber pressure of around 50,044 psi. This will fill your cases right to about the 98% mark by usable volume which is the top end of where most loads seem to work well. QuickLOAD predicted that your 42.1 grain load would give 2741 fps with a chamber pressure of 41,139psi.


Last edited by RAMMAC; October 27th, 2010 at 03:09 PM.
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Old October 27th, 2010, 07:10 PM   #36
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uhmm... read post #8

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Old October 27th, 2010, 07:42 PM   #37
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ummmm, I don't agree. I have seen some very impressive groups using this powder with 168 gr bullets. Admittedly I have noticed that the lighter bullets enable you to use a wider range of powder charges but that doesn't mean that it doesn't work with heavier bullets it just might not work the way some people would like it to.

My goal is to come up with a good hunting load for larger animals so I'm not necessarily looking for a sub-MOA group, as long as I can keep the groups at less than 8" out to 300 yards I will be happy. It won't take long for me to test things and I'll post the results. My reason for working with 8208 is the temp stability. I want a load that will work from the summer to the winter and where I hunt that can be as much as a 100 degree change in temps.

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Old October 28th, 2010, 06:32 AM   #38
 
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It burns on the faster end of the spectrum (but still within) for proper burn rates for a 14, so might not be "great" for heavier bullets, like beyond 150 grs. I bought a 1 lbs canister to try for 223, but haven't tried it yet. I'm curious to hear of your results, but I would still be hesitant to use it in a 14...

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Old October 28th, 2010, 06:40 AM   #39
 
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Originally Posted by m1a_scoutguy View Post
Well said 9th !!! And when my "Varmint" just happens to be a 10X in the middle of a circle,,,I am all for making the X go away !!!! I am at the bench right now,,,just came up to check a few things on here !!!! I'll Be Back !!
So, you are going to go by the "marketing material"?

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Old October 29th, 2010, 01:55 PM   #40
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This group wasn't done...

...with an M1A/M14 platform. However, since this topic is about IMR 8208 XBR, I thought I'd add a little plug for 8208.

Yesterday's conditions were damp, rainy at times, with temps not getting to 50 degrees. However, I was able to shoot from a sheltered position on our 200 yard range. The wind was out of the west; the range points west-to-east.

Let me state that this group was obtained from a R.W. Hart benchrest, sitting on a 500 lb bench. This was not position shooting. I was testing ammunition loads for my Remington 700 BDL Varmint, in .308, and my Remington XR100, also in .308. The 700 BDL still doesn't group very well, and the experiment goes on. The XR100 is a single-shot based on the XP100, with an XR trigger, 26" barrel, thumb-hole stock. The scope is a Bushnell 4200 8-32x40.

The load was 41.5 gr IMR 8208, 165gr SMK, once-fired Winchester .308 brass, CCI 200 primers, and seated to a C.O.A.L. of 2.945".

The first five shots with the XR100 grouped just over 1", and then this group was fired. After this group I more or less lost my concentration, and packed things up.

I loaded the image through my scanner, and plugged it into ON TARGET software, which measures group size, etc. The data is .507" and .242 moa maximum spread; average-to-center .212", .101 moa; Width .507", "Height .445".


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Old October 29th, 2010, 02:18 PM   #41
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Originally Posted by pendennis View Post
...with an M1A/M14 platform. However, since this topic is about IMR 8208 XBR, I thought I'd add a little plug for 8208.

Yesterday's conditions were damp, rainy at times, with temps not getting to 50 degrees. However, I was able to shoot from a sheltered position on our 200 yard range. The wind was out of the west; the range points west-to-east.

Let me state that this group was obtained from a R.W. Hart benchrest, sitting on a 500 lb bench. This was not position shooting. I was testing ammunition loads for my Remington 700 BDL Varmint, in .308, and my Remington XR100, also in .308. The 700 BDL still doesn't group very well, and the experiment goes on. The XR100 is a single-shot based on the XP100, with an XR trigger, 26" barrel, thumb-hole stock. The scope is a Bushnell 4200 8-32x40.

The load was 41.5 gr IMR 8208, 165gr SMK, once-fired Winchester .308 brass, CCI 200 primers, and seated to a C.O.A.L. of 2.945".

The first five shots with the XR100 grouped just over 1", and then this group was fired. After this group I more or less lost my concentration, and packed things up.

I loaded the image through my scanner, and plugged it into ON TARGET software, which measures group size, etc. The data is .507" and .242 moa maximum spread; average-to-center .212", .101 moa; Width .507", "Height .445".

That's what I don't get with this powder; my 42.4 gr load with 168 gr Barnes TTSX bullets gives me 1" (plus or minus about a quarter inch, depending on my concentration and the weather) groups out of my SOCOM 16 and I get velocities that I really like (2600 fps) but QuickLOAD says that I'm way over on chamber pressure. I can believe that I'm over on chamber pressure because my cases don't last as long as they usually do so I will be dropping my load but I sure hope I can continue with those impressive groups.

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Old October 29th, 2010, 02:38 PM   #42
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Quote:
Originally Posted by RAMMAC View Post
That's what I don't get with this powder; my 42.4 gr load with 168 gr Barnes TTSX bullets gives me 1" (plus or minus about a quarter inch, depending on my concentration and the weather) groups out of my SOCOM 16 and I get velocities that I really like (2600 fps) but QuickLOAD says that I'm way over on chamber pressure. I can believe that I'm over on chamber pressure because my cases don't last as long as they usually do so I will be dropping my load but I sure hope I can continue with those impressive groups.
The XR100 was just my "take along" rifle yesterday. I was going to devote the entire session to the 700 BDL. I had relieved the stock where it was bumping the barrel over the sling swivel stud. I had also measured the chamber for C.O.A.L. and the length ended up .015" off the BDL's lands. I never got groups any better than 2" for the BDL. I think I'll go back to IMR 4895 or Varget and see how they work. I may also go back to the recommended Sierra C.O.A.L. and go from there.

I still haven't heard from IMR with my query on port pressures.

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Old October 29th, 2010, 03:38 PM   #43
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Quote:
Originally Posted by pendennis View Post
The XR100 was just my "take along" rifle yesterday. I was going to devote the entire session to the 700 BDL. I had relieved the stock where it was bumping the barrel over the sling swivel stud. I had also measured the chamber for C.O.A.L. and the length ended up .015" off the BDL's lands. I never got groups any better than 2" for the BDL. I think I'll go back to IMR 4895 or Varget and see how they work. I may also go back to the recommended Sierra C.O.A.L. and go from there.

I still haven't heard from IMR with my query on port pressures.
I can tell you what QuickLOAD predicts; port pressure should hit about 13,500 psi when the powder charge reaches about 40.3gr. The pressure doesn't seem to go below 12,000 psi until you drop the charge weight to below 35.3gr.

Now taking in consideration that the original design spec for port pressure was about 12,000 psi and that the recommended charge weights would be conservative as compared to the total range of powder loads, I think that they will recommend charge weights from about 37.6gr - 40gr. All of these numbers are assuming that you used a case with a volume of 54.2gr of water (Lapua with a TTL of 2.005"), a COAL of 2.864", and a Barnes 168gr TTSX bullet.

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Old September 9th, 2014, 06:25 PM   #44
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I been using it in my 700P 308 here in Texas where it gets very hot, and it has no change with temp changes and burns very clean too, i was using Varget before in the 700p and it was very dirty, in a 308 bolt gun the 8208 yeilds very tight groups using 168 SMKs, i hope we can get a safe load worked up for the M1a


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Old September 13th, 2014, 05:57 AM   #45
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Quote:
Originally Posted by Phil McGrath View Post
Well, we all know that our rifles run at about 50000psi chamber preasure or a smidge over and like both the 168 and 175 at about 2600fps this seems to be the node that most rifle shoot there best at.

with XBR-8208 43.3grs pushes a 168 at 2700fps@ 61500psi. I dont think droping the speed down to 2600fps is going too drop preasures down to a tolerable level.

XBR-8208 42.5grs pushes a 175 at 2664fps@ 61800psi, downloading to 2600fps isn't hard too do but the preasure level is still way up.

I picked this info out of the Hodgdon Basic Reloading Manual. I'm all for trying new powders but I think I will hold off from this one in a M1a.
According to Quickload, in a 22" bbl.:
-Dropping the charge of 8208 to 42.0grns with a 168SMK, will produce 2,603fps, and still generate 53,558PSI max pressure and 7,819psi muzzle pressure.
-Dropping the 8208 with a 175SMK to 42.0 also, will produce 2,597fps, with 57,325psi max pressure and 7,770psi muzzle pressure.
For me, they are all a little too warm for my M1A, and close to the 62,000 SAAMI max.

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