• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Felt recoil between powders

Looking to learn from the experts on felt recoil from two different powders. I loaded 168 gr smk for my AR10 for load development and used imr 4895 and 8208 xbr. There was a significant difference in felt recoil between the two even when powder weight were a grain apart. Does this have to do with there burn rates and how the combust. 4895 gave the bigger recoil felt over 8208 xbr. Used same brass same primers same seating depth on both loads. Any info would be great to learn about the world of powders.
 
I havent tried 8208 in an AR-10 but did try 4895 and yeah it had a snappier recoil impulse
4895 worked best for short 16 inch barrels, shot great
W-760 worked better for 20 inch or longer barrels, and was a smoother push recoil as opposed to harsh and snappy.
The differences are yes the burn rates, but could also be due to how much % of Nitro-Glycerin
is in the powder which can range from anywhere from 8-25%
I read that Ball powders like W-748 and BLC-2 are double based while IMR and H-4895 are single.
I notice the Double based Balls feel smoother to me,
could be due to a more complete burn as I've read that Nitro provides for the powder to be oxygen neutral, instead of one molecule off of being oxygen deficient.
maybe somebody else knows more why
 
Last edited:
I havent tried 8208 in an AR-10 but did try 4895 and yeah it had a snappier recoil impulse
4895 worked best for short 16 inch barrels, shot great
W-760 worked better for 20 inch or longer barrels, and was a smoother push recoil as opposed to harsh and snappy.
The differences are yes the burn rates, but could also be due to how much % of Nitro-Glycerin
is in the powder which can range from anywhere from 8-25%
Ahhh makes sense being that I have a 20" barrel.
 
I'm guessing that your velocities were higher with your 4895 loads too. Pressure higher even though grains the same. All powders do not burn at the same rate or pressure curves.
This is a good point and will start reading on this info. Maybe some of the programs for loading would also help but when it comes to computers and programs I get lost. I need to start somewhere lol
 
This is a good point and will start reading on this info. Maybe some of the programs for loading would also help but when it comes to computers and programs I get lost. I need to start somewhere lol
Loading programs have the information you’re looking for. Along with pressure curves, they generally have a recoil calculator, I know quickload does.

The rise and fall of the pressure curve, will more or less mirror the speed and time of the rifle moving in recoil.

The amount of time of the bullet in the barrel can be completely different for the exact same velocity. Producing a different recoil impulse

If you’re interested in learning some basic computer skills, doing that with something you’re interested in sure helps.
 
All things being equal, wouldn't the same velocity produce the same recoil?
Depends on when the peak pressure builds I believe
Near the chamber or more near the muzzle
If peak pressure builds near the chamber, the bullet is still under pressure so still accelerating
You can have a drag car, hit HARD to the 1/4 track mark within 1 second then let up and run a 10.00
Then have a muscle car be constantly smoothly accelerating the whole time and run a 10.00
 
All things being equal, wouldn't the same velocity produce the same recoil?
Personally I am not quite an expert on the subject. Though, lets offer an example where nearly all of the acceleration takes place in the first 10" of barrel length with one propellant. then another propellant does a better job of stretching out the same acceleration (velocity) over 18" of barrel length, which one can we spect a greater recoil from, all else being equal?
 
Last edited:
Loading programs have the information you’re looking for. Along with pressure curves, they generally have a recoil calculator, I know quickload does.

The rise and fall of the pressure curve, will more or less mirror the speed and time of the rifle moving in recoil.

The amount of time of the bullet in the barrel can be completely different for the exact same velocity. Producing a different recoil impulse

If you’re interested in learning some basic computer skills, doing that with something you’re interested in sure helps.
I downl9aded GRT and Quickload is next. Between both I will figure one out. Graphs curves math.......brings back nightmares from high school lol.
 
I worked up some loads using Gordon’s Reloading Tool. Running a 168 gr Sierra Matchking down a 20 inch barrel of a 10 lb rifle at max pressure:

H4895 44.0 gr yields velocity of 2687 fps, recoil impulse 13 ft-lb. Burnout happens at 13 inches at 0.86 milliseconds.

8208XBR 43.8 gr yields velocity of 2656 fps, recoil impulse is 13 ft-lb. Burnout happens at 17.5 inches at 0.98 milliseconds.

On paper it seems that 8208 should feel a little softer because muzzle velocity is slightly lower and it takes longer to burn the charge.
 
I worked up some loads using Gordon’s Reloading Tool. Running a 168 gr Sierra Matchking down a 20 inch barrel of a 10 lb rifle at max pressure:

H4895 44.0 gr yields velocity of 2687 fps, recoil impulse 13 ft-lb. Burnout happens at 13 inches at 0.86 milliseconds.

8208XBR 43.8 gr yields velocity of 2656 fps, recoil impulse is 13 ft-lb. Burnout happens at 17.5 inches at 0.98 milliseconds.

On paper it seems that 8208 should feel a little softer because muzzle velocity is slightly lower and it takes longer to burn the charge.
There are more numbers to look at. That 13 lbs of recoil will be spread over time, there will a rate of acceleration, there will be an acceleration as the bullet leaves the muzzle.

The biggest problem with those two powders is that they are too similar. Felt recoil is a feeling, and open to interpretation.the bigger the spread in burn rate the easier it will be to feel.

If you look at 8208xbr and both IMR and H4895 on burn charts over the years, they trade places. That’s how similar they are. If a computer can’t figure out the energy they produce there’s a good chance your shoulder won’t either.

This might be of interest

 
Good discussion here.

 
I definitely experienced this with 300 WM. H1000 recoils more at lower Velocity than Reloader with the same bullet. (220 gr VLDMs) It was troubling because we have like 32 lbs of H1000, and just a few pounds of Reloader.
 
I definitely experienced this with 300 WM. H1000 recoils more at lower Velocity than Reloader with the same bullet. (220 gr VLDMs) It was troubling because we have like 32 lbs of H1000, and just a few pounds of Reloader.
Noticed similar with 338 Norma and 338 edge
In the norma at same bullet speeds retumbo is more pushy and H1000 snappy
In edge retumbo is similar to Norma recoil
N570 is a bit snappier.
 

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
165,739
Messages
2,201,463
Members
79,068
Latest member
Nonesuch
Back
Top