Something strange happened

[Wayne S]

I was at the range testing and this will sound strange .
three loads ;
1. A 115 gn cast bullet sized .310 on top of 7.5 gn of 231 in a 30-20 {32-20} 10" scoped Contender
2. A 150 J- bullet .308 oner 7.0 231
3. .310 J. bullets for the 7.72X39 over 7.5 231
[B]The strange part[B] the .308 150 J bullet load had noted less or a different recoil ???????

[mpmarty]

What you percieve as "different" recoil is not objective enough to form an opinion.

What were the firearms involved in each case? What did they weigh?

[Wayne S]

What you percieve as "different" recoil is not objective enough to form an opinion.

What were the firearms involved in each case? What did they weigh?
ONLY ONE FIREARM shot testing the different loads, a pistol type rest was used.
When fireing the cast and the .310 J bullet the recoil would cause the back of the trigger guard to fit with force my "finger" knuckle, the .308 J bullet loads recoil hardly touched the above mentioned knuckle

[44man]

ONLY ONE FIREARM shot testing the different loads, a pistol type rest was used.
When fireing the cast and the .310 J bullet the recoil would cause the back of the trigger guard to fit with force my "finger" knuckle, the .308 J bullet loads recoil hardly touched the above mentioned knuckle
Losing gas pressure around the smaller bullet?

[Wayne S]

Losing gas pressure around the smaller bullet?

T/C uses a .308 bore in all their .30 Cal. so I don't think thats it ??

[303Guy]

Perhaps it is hard to comprehend what is being explained unless one has actually experienced the phenomena. Actually, there is nothing mysterious about it. The J-word has a lot more resistance when entering the bore which burns the powder much earlier in the bore and therefor reduces barrel duration time. The recoil impulse is therefore shorter and the gun has less reaction time to actually recoil significantly. The sensation is of a 'short, sharp' recoil effect. The recoil is still there (moreso actually) but the energy dissipates quicker with less 'push' or 'shove'. The gun was Contender, which is hand held so the 'kick' to the shoulder normally associated with the 'short, sharp' recoil is not there but it would 'hurt' the shoulder more than the 'shove' type recoil.

Not sure if that muddies it or clears it!:veryconfu

[lwknight]

303guy brings me to another idea in that issue.
Different bullet resistances and case shapes cause different burn efficiencies in the powder.
This could have an impact on the amount of jet propulsion from your gun.
The jet effect is a real issue and is more profound in larger capacity cases.

[KYCaster]

Perhaps it is hard to comprehend what is being explained unless one has actually experienced the phenomena. Actually, there is nothing mysterious about it. The J-word has a lot more resistance when entering the bore which burns the powder much earlier in the bore and therefor reduces barrel duration time. The recoil impulse is therefore shorter and the gun has less reaction time to actually recoil significantly. The sensation is of a 'short, sharp' recoil effect. The recoil is still there (moreso actually) but the energy dissipates quicker with less 'push' or 'shove'. The gun was Contender, which is hand held so the 'kick' to the shoulder normally associated with the 'short, sharp' recoil is not there but it would 'hurt' the shoulder more than the 'shove' type recoil.

Not sure if that muddies it or clears it!:veryconfu


I'm thinking just the opposite. Heavier bullet = slower acceleration = longer recoil impulse = softer feel.

Jerry

[lwknight]

Agreed.
Actual recoil energy and percieved recoil are different animals.

[Wayne S]

I'm thinking just the opposite. Heavier bullet = slower acceleration = longer recoil impulse = softer feel.

Jerry
Interesting, I'll have to take some 31141's and snip the nose back till I get about 150 gn's and see how that effects things

[303Guy]

I'm thinking just the opposite. Heavier bullet = slower acceleration = longer recoil impulse = softer feel.Yes, I agree completely. But that's if J's are being compared with J's. In comparing cast and J's it can happen that the J, by resisting entry into the bore, raises pressure and combustion speed as opposed to a cast boolit.

Then there is the jet effect. Mmmm..... Good point! And if the jet effect combines with other factors to iether increase or decrease a particular effect? Now it's just gone from simple to quite complex!:mrgreen:

I have in the past suggested to folks to switch to a heavier bullet to reduce felt recoil. Even when the energy of the two are nearly the same and the heavier bullet has a lot more momentum, the felt recoil of the heavier bullet could be less (but muzzle lift would be more). Again there is the jet effect question! There would be more powder behind the lighter bullet and hense a higher muzzle pressure and gas mass. That must be significant. If it weren't, my muzzle blast/ recoil reduction devices would not work! And they work so well that I have taken the recoil pad off my 303 Brit and I hold the rifle real lightly when shooting from prone with no fear of the scope smacking my countenance. I don't even bother to hold the butt against my shoulder! (And trust me, I've had half moon syndrome! And that was holding the gun firmly - also a 303 Brit).

[Bret4207]

Different burn rate/pressure curve.